INSECTS AND DISEASE OF MAN
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BY C
CARROLL) FOX, M.D. fi
SURGEON, U. S. PUBLIC HEALTH SERVICE; L! CTURER ON MEDICAL ENTOMOLOGY TO THE ? 7 A A

CLASS OF STUDENT OFFICERS, HYGIENIC LABORATORY, WASHINGTON, D. C.; FELLOW
OF THE AMERICAN PUBLIC HEALTH ASSOCIATION, MEMBER OF THE AMERICAN
STATISTICAL ASSOCIATION, THE PACIFIC COAST ENTOMOLOGICAL SOCIETY,

THE AMERICAN MEDICAL ASSOCIATION; ONE TIME ASSISTANT
DIRECTOR OF HEALTH, BUREAU OF HEALTH, PHILIPPINE
ISLANDS, AND ASSOCIATE PROFESSOR OF HYGIENE,

MEDICAL SCHOOL, UNIVERSITY OF THE PHILIPPINES

WITH 92 ILLUSTRATIONS

PHILADELPHIA

P. BLAKISTON’S SON & CO.
1012 WALNUT STREET
COPYRIGHT, 1925, BY P. BrakisToN’s Sox & Co.

CAT. FOR
PUBLIC HEALTH

PRINTED IN U. S. A.
BY THE MAPLE PRESS COMPANY, YORK, PA.
 

PREFACE

In this book I have attempted to gather together in a concise and
practical way, the information necessary for a student taking up the
study of medical entomology, or for the health officer working in
the field of preventable diseases transmitted by anthropods.

The subject is large and any one of its branches is a specialty in
itself. Much of the literature appears in the form of separate articles
in serial publications, or as, monographs, bulletins, etc. Therefore it
is hoped that this book which aims to give only the essentials for
public health practice may be found to be helpful and worth while.
As the time of the student is limited, and this is particularly true
of the student officers forming my classes, I have not burdened the
text (for which no claim to originality is made) with references;
therefore, mention must be made here of my indebtedness to the
writings of those who have devoted their time to the subject, and
particularly G. H. F. Nuttall, Cecil Warburton, Nathan Banks,
H. E. Ewing, C. W. Stiles, N. Charles Rothschild, Karl Jordan,
Carl F. Baker, Ll. Lloyd, V. L. Kellogg, G. F. Farris, Edward R.
Stitt, Victor B. Vaughan, W. B. Herms, Herbert Osborn, G. Ender-
lein, L. O. Howard, H. G. Dyar, F. Knab, J. M. Aldrich, R. C.
Shannon, W. H. W. Komp, C. S. Ludlow, Bruce Mayne, J. A.
LePrince, J. W. Folsom, J. H. Comstock, E. T. Cresson, Jr.and W. R.
Walton; to W. S. Patton and F. W. Cragg and their valuable ‘Text
Book of Medical Entomology; to Aldo Castellani and Albert J. Chal-
mers and to the various authors who have contributed to Byam and
Archibald’s “Practice of Medicine in the Tropics,” as well as to the
authors of the various official publications of the Bureau of Ento-
mology, U. S. Department of Agriculture, the U. S. Public Health
Service and State Departments of Health.

I am greatly indebted to Doctor Philip P. Calvert, Professor of
Zoology in the University of Pennsylvania, to Doctor Henry E.
Ewing of the Bureau of Entomology, U. S. Department of Agri-
culture, and to Professor C. W. Stiles, U. S. Public Health
Service for their kindness in reading the manuscript and offering

many valuable suggestions; to Surgeon-General Hugh S. Cumming,
Ve

370
vi PREFACE

U. S. Public Health Service, for permission to use illustrations belong-
ing to the Hygienic Laboratory, many of which were made by the
artist Mr. L. H. Wilder, under the personal supervision of the author
for his class at the Laboratory; and to Commander J. R. Phelps
(M. C.) U. S. Navy, Assistant Surgeon-General Henry R. Carter
and Surgeon George W. McCoy, U. S. Public Health Service for
advice and assistance in preparing the chapters on diseases trans-
mitted by arthropods.
Carrorr Fox.
CONTENTS
PART 1

Medical Entomology

CHAPTER 1

Page

DEFINITION—THE ARTHROPODA—CLASS INSECTA—GENERAL DESCRIPTION L
CHAPTER II

THE D1pTERA (FLIES AND MOSQUITOES) . . . . . . . . . . 4

Description—The Head—The Thorax—The Abdomen—Classification==
Key to the Suborders, Sections and Families.

CHAPTER III

SUBORDER ORTHORRHAPHA, SECTION NEMATOCERA. THE CuricipAE (Mos-

OUITOES Yohei obi ie Saar hen tai” he! et usin atari gb Sb UEC ie Che Bo A Te SR

Description—The Hexd—The This Wings legs Abdcner=alner
tary Tract—The Larva—The Pupa—Life History.

CHAPTER IV

CuLicipAE (CONTINUED) .
Classification and entification—Geneial Conddesations—Key to Sib
families—XKey to the Genera of American Culicidae—Key to the Larva—
Key to the Species of Anophelines—Key to the Larva—X ey for the Determina-
tion of Species of Adult Female Mosquitoes—Key to Full Grown Larva.

CHAPTER V

CuLiCIDAE (CONTINUED) TRIBE ANOPHELINI . . . . . . . . : ;

Genus Anopheles—A. quadrimaculus—A. crucians—A. purctipenis—
A. pseudopunctipennis—A. argyritarsus—A. albimanus—A. tarsimaculatus—
A. maculipennis—Tribe Culicini—Genus Culex—C. quinquefasciatus—
C. pipiens—C. salinarius—C. territans—C. testaceus—C. erraticus—Genus
Aedes—A. aegypti—A. vexans—A. sollicitans—A. taeniorhynchus—Genus
Psorophora—P. ciliata—P. columbia—P. sayi—Tribe Uranotaenini—U.
sapphirinus. :

CHAPTER VI

SUBORDER ORTHORRHAPHA, SECTION NEMATOCERA (CONTINUED). . . . . . . .
Family Chironomidae—Family Simuliidae—Family Psychodidae—Phleboto-
mus papatasii.

vii

10

22

34

49
viii CONTENTS

CHAPTER VII

PAGE

SUBORDER ORTHORRHAPHA, SECTION BRACHVCERA . . . . . . . . . .
Tribe Brachycera Homodactyla—Key to Some of the Genera in the Family
Tabanidae—Family Tabanidae—Anatomy—Adult—Alimentary Canal—Egg
—Larva—Pupa—Subfamily Pangoninae—Genus Chrysops—C. discalis—
C. fulvaster—Family Leptidae—Symphoromyia grisea—S. hirta—Brachy-
cera Heterodactyla—Scenopinus fenestralis—Family Asilidae, Phoridae.

CHAPTER VIII

SUBORDER CYCLORRHAPHA. . . . . . x
Section Achice-Descdption-Famnlly Syrphidee~Eristolls tones Section
Schizophora—Description—Muscoidea Acalyptratae—Piophila casei—Sepsis
violacea—Microneurum funicola—Drosophila melanogaster—Borborus equi-
nus.

CHAPTER IX

CYCLORRHAPHA, (CONTINUED) MUSCOIDEA CALYPTRATAE. . . . . . . ~
Description—Anatomy—Head—Proboscis—Thorax—Wings—A bd ome n—
Alimentary tract—Larva—Pupa—Family Oestridae—Key to Some of the
Genera—Genus Hypoderma—H. bovis—H. lineata—Genus Dermatobia—
D. hominis—Genus Oestris—O. ovis—Genus Gastrophilus—G. equi—G.
hemorrhoidalis. F

CHAPTER X

CYCLORRHAPHA MUuscoiDEA CALYPTRATAE (CONTINUED) . . . . . . . . :
Family Muscidae—Key to Some of the Genera—The Non-biting Muscidae
Genus Musca—M. domesticus—Life History—Eradication—Genus Mus-
cina—M. stabulans—M. assimilis—Genus Cryptolucilia—C. caessarion.

CHAPTER XI

CvCLORRHAPHA, CALYPTRATAE (CONTINUED) THE BITING MUSCIDAE. . . . . .
Genus Philaematomyia—Genus Stomoxys—S. calcitrans—Genus Glossina—
G. palpalis—G. morsutans—Genus Haematobia—Genus Lyperosiops.

CHAPTER XII

OTHER NON-BITING MUSCOIDEAN FLIES. . . . . . . .

Family Sarcophagidae—Key to the Gonna Deseription=-(36ius Sarco
phaga—S. communis and Other Sarcophaga—Genus Wohlfahrtia—Key to
the Species of Sarcophaga—Family Calliphoridae—Key to the Genera—
Description—Key to Tribe Luciliini—Key to Tribe Calliphorini—Genus
Calliphora—C. vomitoria—C. erythrocephala—Genus Cynomyia—C. cada-
verina—Genus Lucilia—L. caesar—L. sericata—Genus Phormia—P.-regina—
Genus Protophormia—P. terrae-novae—Genus Cochliomyia—C. macellaria—
Genus Bengalia—B. anthropophaga—Genus Auchmeromyia—A. luteola—
Genus Protocalliphora—Genus Pollenia—P. rudis.

CHAPTER XIII

FAMILY ANTHOMYIIDAE.. . . . « + + .
Description—Genus Fannia Glomaloiirid Gon Tvienviaa Gens Hy
drotea.

53

60

62

79

Qo

. 107
CONTENTS ix

CHAPTER XIV

3 Pace
Key 10 THE LARVAE CAUSING MyIasis . . . . . . at bin Balt) Jl en
CHAPTER XV
SUBORDER PupiparA . . . . . . . meee ER ely

Description—Malophagus ovine ppabonts equina.
CHAPTER XVI
ORDER SIPHONAPTERA. . . + + « » +» 112

Description, Adult. Anstoray—Byp-LareimPupe-Cliicrtion=Key to
the Genera—Family Sarcopsyllidae—Genus Tunga—T. penetrans—Genus
Echidnophaga—E. gallinacea—Genus Pulex—P. irritans—P. dugesi—Genus
Xenopsylla—X. cheopis—X. astia—X. brasiliensis—Genus Ctenocephalus—
C. canis—C. felis—Genus Hoplopsyllus—H. anomalus—Genus Ceratophyl-
Ius—C. fasciatus—C. acutus—Genus Leptopsylla—L. musculi—Eradication.

CHAPTER XVII

ORDER ANOPLURA ty ES 143
Description—Adult, Anstony-Taes and Nymphs—Family Pediculidae—
Description—Species—Habits—Pediculus corporis—P. humanus—Phthirus
" pubis—Lice of Domestic and Laboratory Animals—Key to the Families,
Subfamilies and Genera—Eradication. =

CHAPTER XVIII

OrpEe HIuMIPTERA hi. in a a wy baie a let Cd al Sele, She 158
Description—Family Cimicidae—Genus Cimex—Adult, Anatomy—Eggs and
Immature Forms—Classification—Genus Cimex—C. lectularius—C. hem-
ipterus—Family Reduviidae—Genus Conorrhinus.

CHAPTER XIX

ORDER ORTHOPTEBA:. is 0. ela LUNE Ee i i att Ft Se Se ae 168
Description and Habits—Anatomy of Mouth Parts—Internal Anatomy—
Eradication.

CHAPTER XX

CLASS ARACHNIDAT. rt ih re af eet tnt, «174
Order Acarina—External Anatomy—Internal Anctony--Lite Histor
Ticks—Anatomy—Classification—Key to the Superfamilies and Families—
Superfamily Ixodoidea (Ticks)—Key to the Genera of Argasidae—Genus
Argas—Genus Ornithodoros—Family Ixodidae—Genus Ixodes—Genus Bo-
ophilus—Genus Haemaphysalis—Genus Dermacentor—Genus Rhipicentor—
Genus Rhipicephalus—Genus Hyalomma—Genus Amblyomma—XKey to a
Few of the Species of Amblyomma.

CHAPTER XXI

Crass Amacai (CONTINUED). Fo = % urn pial ee ER Ral hh ee . 109
Family Eupodidae—Family Bdellidae—Family Chivletidas—Tamily Tetrany-
chidae—Family Trombidiidae—Key to the Family—Family Parasitidae—
BODENTS Vo tts wy Pn TA aa SS at pe

INTRODUCTION ooh

Nerrow BRVER. boi onan 0 as alien i A aa EE a SA ne

DENGUE REY RR i Ce a LF Thi ey Tr Mie rape Fi ne tp oi i of

CONTENTS

Key to the Family—Key to the Dermanyssidae—Family Tarsonomidae—
Key to the Tarsonomoidea—F amily Tyroglyphidae—Family Sarcoptidae—
Key to the Sarcoptidae.

CHAPTER XXII

Detsiftion—~Fomily Maridne—Rattus torvegions—Tattus Futins = Retis
alexandrinus—Mus musculus—Diseases of Rats—Natural Enemies—Eco-
nomic Considerations—Ectoparasites of Rats—Family Sciuridae—Citellus
beecheyi—Arctomys bobac.

CHAPTER XXIII

A FEw NOTES ON PECHNIQUE 2. 5 ie inl al, oh el ates SVS JE NE CRS,

PART II
Diseases Carried by Arthropods among Human Beings

CHAPTER XXIV

General Considerations.

CHAPTER XXV

VA ABTA A ER a WL i a i ea Te

Causative Agenit-<Sotrce x Tndection-=Mods of Teansndssion —Petiod
of Incubation—Period of Communicability—Epidemiology—Life History
of Malarial. Parasite—Economic Considerations—Seasonal Prevalence—
Epidemiological Study—Method of Making Thick Smears and Staining—
Mosquito Survey—Recognition of the Disease—Prevention and Control—
Drainage—Sub-soil drainage—Vertical Drainage—Filling—Clearing—Im-
pounded Water—Oiling—Larvacides—Fish Control—Area to be Controlled—
Eradication of Adult Mosquitoes in and Around Houses—Preventive Measures
Applied to Malaria Patients—Treatment of Carriers—Protection of Healthy
Persons—Quinine Prophylaxis—Screening— Biologic Barriers.

CHAPTER XXVI

Causative Agent—Source of Infection—Mode of Tramsiston-Period of
Communicability—Period of Incubation—Epidemiology—Habits of the
Yellow Fever Mosquito—Recognition of the Disease—Methods of Prevention
and Control—Early Recognition—Reporting—Placarding—Isolation—Quar-
antine—Fumigation—Screening—General Measures—Immunization—A
Guide for Formulating a Mosquito Ordinance.

CHAPTER XXVII
Causative Agent—Source of Infection—Period of Coummuniesbility=Pestod

of Incubation—Epidemiology—Recognition of the Disease—Methods of
Control.

Pa

y 213

1237

. 204

- 274
CONTENTS

CHAPTER XXVIII

x1

PAGE

FILARIASIS. :
Causative Agent=Fllnris, Vancrobt=Source ot Tnfection—Mode of Trans
mission—Period of Communicability—Period of Incubation—Epidemiology—
Life History of Filaria bancrofti—Complications and Sequellae of the Dis-
ease—Other Filariae—Loa loa—Dracunculus midinensis.

CHAPTER XXIX

PAPPATACLI FRYER. oid ie Sd Sh
Causative Abente-Sonive: of Tntection=—Mods of TrtsntssonBerind of
Incubation—Phlebotomus papatasii—Recognition of the Disease—Methods of
Control.

CHAPTER XXX

TRYPANOSOMIASIS. . . . . . . .
Causative Agents—African Seoping $idehese=-Canntive "Agent-Method
of Transmission—Source of Infection—Period of Communicability—Period
of Incubation—Epidemiology—Recognition of the . Disease—Methods of
Control—South American Trypanosomiasis.

CHAPTER XXXI

PULARNEMIA Lo oe Bn i 0 Es
Causative AuehitaiBonrce of Tnfection=Method ot Transmision-~Period
of Communicability—Period of Incubation—Epidemiology—Recognition
of the Disease.

CHAPTER XXXII

Paw Prague: ooo YE
Forms of Planio—-Cousttive Ager~Tubonic Pl gat—Period of Commnnie.
ability—Method of Transmission—Period of Incubation—Epidemiology—
Biting of Man by Rat Fleas—Recognition of the Disease—Prognosis—
Treatment—Plague in Rats—Plague in Ground Squirrels—Plague in Guinea
Pigs—Susceptibility to Plague of Certain Small Mammals of the United
States—Morphology and Cultural Characteristics of Bacillus pestis—Exam-
ination of Rats for Plague—Plague Rat Card—Methods of Control—Organi-
zation—Foremen, Trappers and Laborers—Depopulation—Traps—Guinea-
pig Controls—Poisoning—Bacterial Virus—Rat Proofing—Double Walls—
Wooden Floors—Chicken Coops—Stables—City Sewers—Wharves—Freight
Cars—Ships—Garbage—Infected Buildings—Pneumonic Plague—A Guide
for Formulating a Rat Proofing Ordinance.

CHAPTER XXXIII

Tyraus FevER. . 0. 0c. in fe cr ec SA ER UT Re
Causative Agent Source of Infection—Period of Communicability—Mode
of Transmission—Period of Incubation—Epidemiology—Recognition of the
Disease—The Weil-Felix Reaction—Methods of Control.

. 276

« 270

Li-28y

28%

288

315
xii CONTENTS

PAGE

CHAPTER XXXIV

TRENCEPRVER. nl le ran a eae . 319
Causative Agent—Method of Transmission—Period of Comuiniiosbilliy=
Period of Incubation—Epidemiology—Recognition of the Disease—Methods
of Control.

CHAPTER XXXV

RPEEAPSING PRVER - 5. 0 a a hl i a I se EE 321
Causative Agent—Method of Transmission—Period of Incubation—Epi-
demiology—Recognition of the Disease—Methods of Control.

CHAPTER XXXVI

RockY MOUNTAIN SPOTTED FEVER. . . . . . . . . . . . ..... 324
Causative Agent—Source of Infection—Incubation Petiod—Vpiderdiologys—
Recognition of the Disease—Methods of Control.

CHAPTER XXXVII

MSOTSUGAMUSHY OVER. fo Gs, abi 158 naa emai as 327
Causative Agent—Method of Trnunlstin=Souce of Infection—Period
of Incubation—Epidemiology—Recognition of the Disease—Methods of
Control.
PART I
MEDICAL ENTOMOLOGY
 
INSECTS AND DISEASE OF
MAN

CHAPTER 1

Entomology is that part of Zoology which treats of insects.
Medical entomology may be defined as that part of entomology
which ‘treats of those insects which are directly or indirectly con-
cerned with the occurrence or spread of diseased conditions in human
beings or animals or which serve as pests. Itis generally agreed
that the term may include acarines or other arthropods which have
been implicated in the occurrence or spread of disease.

The Arthropoda.—The Phylum Arthropoda is that great sub-
division of the animal kingdom, the members of which are inverte-
brates having paired, jointed appendages to the segments of the
head, thorax and sometimes the abdomen; a ventral nervous system;
a dorsal digestive system and an ecto-skeleton. The Phylum is
subdivided into the following classes:

Class Insecta (Insects, sometimes spoken of as  Fesapoda)

Class Arachnida (Mites, spiders, scorpions)

Class Crustacea (Crabs, lobsters, shrimps, cyclops, sow bug)

Class Myriapoda (Centipedes and millipedes)

Class Protracheata (Peripatus)

, CLASS INSECTA .
(The Insects)

General Considerations.—The body of an insect is composed
of a head, a thorax and an abdomen.

The head is provided with eyes, simple or compound or both,
two antennae or feelers, and the mouth parts including the maxillary
palpi. The structure of the mouth parts varies depending upon the
feeding habits of the insect. They may be masticatory or suctorial
and may be adapted to piercing or cutting the skin and sucking blood.

I
2 INSECTS AND DISEASE OF MAN

The thorax is divided into three segments, the pro- meso- and
meta-thorax. Each segment is divided into two main portions the
tergites or nota forming the dorsal part and the sternites the ventral
part. The lateral surfaces are known as the pleura. From both
sides of each sternite there arises a leg, making three pairs of legs in
all. Each leg is composed of a coxa, trochanter, femur, tibia and
“tarsus. From each side of the meso- and metathorax there arises
a wing, making two pairs of wings in all. This however is not true
of all members of the Class for in the Order Diptera there is but one
pair of well developed wings the second or hind pair being rudi-
mentary; in some of the Hemiptera there are merely vestiges of
one pair of wings only, while in the Orders Siphonaptera and
Anoplura wings are entirely wanting.

There is no osseous system. The hard chitinous integument,
the ecto-skeleton, which invests the body of the insect serves not
only as a protecting covering to the soft parts but as an attachment
for muscles, as well as to maintain rigidity.

. There is no vascular system. The blood, which is colorless,
circulates in the body cavity and is kept in circulation by passing
through a thin-walled pulsating aorta located in the extreme dorsal
part of the abdomen and thorax.

There is no lung or gill. Air is taken in through stigmatic open-
ings located on the sides of the thorax and abdomen. It is carried
to the most. remote parts of the body by a system of branching
tracheae which have their origin at the stigmatic openings.

The central nervous system is represented by a chain of ganglia
running close to the ventral wall, from the head through the thorax
and into the abdomen. The first or largest ganglion, the brain, is
located in the head and is pierced by the oesophagus.

The special senses are well developed.

The kidneys are represented by the Malpighian tubules which
empty into the intestines.

The digestive system, the salivary glands and the reproductive
organs are well developed. The salivary glands and their ducts
have no connection with the alimentary tract, other than the buccal
cavity.

The number of | segments of the abdomen varies. There are
normally ten, the terminal segments being modified to form the
accessory organs of generation. Each segment is composed of a
tergite dorsally and a sternite ventrally. They are connected to
CLASS INSECTA 3

each other by a soft membrane. The membrane connecting the
tergite with the sternite contains the opening of the trachea and is
called the pleural membrane.

The body of an insect is furnished with setae (hairs and bristles),
and at times with spines and perhaps with spurs.

Depending on the species an insect in its life cycle may undergo
a complete or an incomplete metamorphosis. The former requires
four stages namely, egg, larva, pupa and imago or adult. Growth
occurs in the larval stage, the larva shedding its old skin as it
increases in size, a new one having formed to take the place of the
old. The larva is active and voracious. When fully grown it turns
into a pupa in which stage the insect ceases to eat and is usually
quiescent but may be active as in the case of mosquitoes. It is
in the pupal stage that the wonderful changes take place which
transform the lowly wormlike larva into the fully developed, highly
organized adult insect.

The incomplete metamorphosis is somewhat different. The
young emerge from the egg looking not unlike the adult except in
size, color and hardness. They eat the same food as the adult.
These immature forms grow by successive moultings similar to the
larval stage of the complete metamorphosis. The sexes are not
differentiated until the final moult which results in a fully formed
and fully grown insect. These immature moulting forms correspond
to the larval and pupal stages of the complete metamorphosis.

There are a number of Orders in the Class Insecta which are of
no interest in preventive medicine even though economically they
may be of great importance because of their destructive influence
on growing vegetation. If these are excepted together with those
insects which can sting but can not bite and those which have habits
not endangering the health of man, it is found that the insects which
are concerned in the present study fall within five Orders, namely
the Diptera (flies and mosquitoes), the Siphonaptera (fleas), the
Anoplura (lice), the Hemiptera (bugs) and, not so important, the
Orthoptera (roaches).
CHAPTER II

THE DIPTERA
(The Flies and Mosquitoes)

Description.— Insects of this Order are characterized by having
two well developed transparent wings, with a second pair of rudi-
mentary wings or halteres, the so called balancers. The mouth
parts are well developed and adapted to piercing and sucking, or to
suction only. The mesonotum forms a large part of the thorax.
Its dorsal aspect forms a plane surface but it may be interrupted by
a transverse suture, or by a marked V-shaped suture as in the Tipuli-
dae (crane flies). There are two compound eyes and in some species
ocelli or simple eyes are also present. The metamorphosis is com-
plete, that is, the insect passes through the four stages of develop-
ment—egg, larva, pupa and adult insect. In some Diptera the egg
is not laid but develops in the body of the female which then gives
birth to a larva.

Like all insects the body is divided into a head, thorax and
abdomen.

The Head.—In certain large groups of the Diptera there is to
be seen an anterior depressed area on the head known as the lunula
which is bounded by an arched suture, the ptilinal suture, passing
over the base of the antennae. This suture represents the invagi-
nated ptilinum or the vesicle with which the fully developed insect.
breaks its way out of the pupal covering. The antennae may be
many or few jointed, and may have on the third joint a bristled
appendage called the arista, or a style. The mouth parts consist
of a labrum (with which may be combined an epipharynx) mandibles,
maxillae, hypopharynx and labium. These however differ greatly
in the different families. :

The Thorax.— The thorax is divided into the prothorax, the meso-
thorax and the metathorax. From each side of the mesothorax
between the sternite and tergite dorsally of the epimerum there
arises a wing and farther posteriorly may be seen the smaller, club
shaped halteres arising one on each side of the metathorax. The

4
THE DIPTERA 5

disposition of the veins in the wings is of importance in classifying
the members of the Diptera as aré also the presence or absence of
setae (scales, hairs and bristles). The discal cell, when present, is
a good land-mark from which to locate other wing characters. It
is bounded by the 4th. and sth. longitudinal veins. A membranous
prolongation backwards from beneath the base of the wing and
known as the squama may be present and may be so large as to
conceal the halteres.

Legs.—The tarsus consists of five segments, the last segment
ending in two claws and often two pulvilli which when developed
are membranous pads. Between the pulvilli may be present what
is called the empodium, which may be absent, bristle-like or tapering,
or may be pulvilliform (membranous like the pulvilli).

Abdomen.—The abdomen is normally divided into ten segments,
the terminal segments being modified in the different sexes.

CLASSIFICATION OF THE DIPTERA

Diptera may be classified into certain large groups according to
the characters of the larva, the pupa, and the antennae, as follows:

First, they are divided into two great Suborders depending upon
the means of escape of the adult from the pupal covering. If by a
dorsal T-shaped slit, they are placed in the Suborder Orthorrhapha.
The larvae of this Suborder have a distinct head. If the adult
escapes by a circular opening in the head end of the pupal case it is
placed in the Suborder Cyclorrhapha. Larvae of this Suborder
are without a distinct head.

The Suborder Orthorrhapha is then subdivided into two Sections,
one, Brachycera or Orthorrhaphous Diptera with short antennae,
and one, Nematocera or Orthorrhaphous Diptera with long antennae.
The former are then further divided into those having two well
defined pulvilli and a pulvilliform empodium, the Brachycera homo-
dactyla, and those which if they have two pulvilli and an empodium,
the latter is bristle-like and does not resemble a pulvillus, the Brachy-
cera heterodactyla.

The Suborder Cyclorrhapha is divided into three sections namely,
Aschiza, Schizophora and Pupipara. The Aschiza contains no
species known to bite man. The Schizophora contains the true
flies. This Section is subdivided into two tribes depending upon
whether the squamae are small or rudimentary, Muscoidea acalyp-
6 INSECTS AND DISEASE OF MAN

tratae, or whether they are large, Muscoidea calyptratae. The
third Section is known as Pupipara because the fully developed
larvae are passed directly from the body of the adult female. It
must be kept in mind that certain flies of the other groups are also
larviparous.

Key to Some of the Families in the Order Diptera

1. Abdomen indistinctly segmented, sac-like; integument leathery; body flat-

tened dorso-ventrally; wings present, absent or vestigial (Page 111).

Pupipara

Abdomen distinctly segmented; wings rarely absent................... 2

2. Antenna long and composed of more than six segments, all but the first two

similar; arista absent; discal cell usually absent (present in Tipulidae and
Rhyphidae); anal cell widely open at margin

Suborder Orthorrhapha, Section Nematocera................vccu.... 3

Antenna short and composed of three (or four) segments, differing from

one another, the third joint simple, annulated or pseudo-segmented, with

or without style or arista; discal cell rarely absent; anal cell closed or

narrowed ai margin, rarely absent... Ln DO ee ees. 8
3. Wing venation much reduced, fewer than nine veins reach margin of wing 4
Nine or more veins reach margin of wing (Fig. 4)...................... 5

4. Antenna shorter than thorax, rather stout, never plumose and composed
of ten or eleven closely united segments; abdomen in both sexes with a
conspicuous flap-like scale at base of dorsal surface which is detached
posteriorly and fringed with long hairs; rather stout short insect (Page 50)

Simuliidae

Antenna longer and slender, usually feathery in the males; abdomen with-
out flap-like scales at anterior corners (Page 50).......... Chironomidae

5. All cross veins placed towards base of wing (before the middle) and body
very hairy or scaley; minute moth-like flies (Page 51)....... Psychodidae

One or more cross veins at or beyond middle of wing; unlike minute moths

I APPearance. . on a a Ce a a Set 6
GOCE IDI SENT oe as an a a a eae mba sl Rhyphidae
CO LL eT ca Lins i eh a aa retention AEE Eu allah FA SB A 7

7. Mesonotum with a V-shaped suture; usually a discal cell and two anal
veINSIPresant. 0 Ll hn eed ER Tipulidae

Mesonotum without suture; wings never with two anal veins or a discal
cell; veins clothed with scales; posterior margin of wings with a close
Fringe oliscalen (PRES TO). vu. i hv sions wi a le ata lstet ma Sha ia Culicidae

8. Third longitudinal vein usually forked; empodium often pulvilliform;
-arista or style present or absent, when present usually terminal; antenna
usually prominent, projecting; lunula and ptilinal suture absent........ 9

Third longitudinal vein never forked; empodium never pulvilliform; arista
usually dorsal, rarely absent; antenna pendulous; lunula or lunula and
plilinalisuture present... ..- sc Eh we ae Sl elie DD

9. Third longitudinal vein forked. ............ cin s ibis k dial vn, 10
IO.

II.

12.

13.

14.

15-

16.

17.

18.

19.

20.

21.

22.

THE DIPTERA y

Third longitudinal vein not: forked. i. ov tin a 20

Discal cell small, little if any longer than broad; subcostal and 1st., 2nd., and
3rd. longitudinal veins crowded together near costal border.

Stratiomyiidae

Discal cell distinctly longer than broad; veins not crowded together as

Third segment of antenna annulated, without style or arista............ 12
Third segment of antenna simple, with or without style or arista....... 14
Squamae large; third segment of antenna marked with from four to eight

annuli or rings; five posterior cells; forks of third vein inclose apex of wing

(Fig. 20) (Page sa)... 0 ale am Sh as sl es) Tabanidae
Squamaesmallac cl ES Le 13
Fourthiposterior cell closed. nlm a li vl uriie Fa di Xylomyiidae
Fourth posterior cell open... cc Shi dv iin La Xylophagidae

Coenomyiidae
Vertex hollowed ont between the eves... ..... 0 uo 0 Do csv So, 15
Nertex plane Or CONVEX. lr we eae eh os 16

Antenna four segmented more or less clubbed at end; proboscis fleshy at
tip; 1st., 2nd., and 3rd. longitudinal veins coalescing before the apex of
wing; 4th. longitudinal vein terminating before apex of wing Mydaidae

Antenna three segmented with or without terminal style; proboscis pointed

at tip; longitudinal veins'not as above... L000 hii ae Asilidae
Squamae very large, head very small, thorax and abdomen large; forks of
3 rd. longitudinal vein ending before apex of wing.......... Acroceridae
Squamae smallior vestigial... nb a GS 17
Forking of 3rd. longitudinal vein tending to inclose apex of wing, at least
the posterior branch of the fork ending behind the apex of wing. ..... 18
Both branches of third longitudinal vein ending before the apex of wing;
antenna without style or arista; three posterior cells. ...... Scenopinidae
Empodium pulvilliform; five posterior cells usually open; antenna with
style or arista; ‘abdomen tapering... .. LL Sa Lani Leptidae
Empodium rudimentary or absent... 0 nL de JU Sr ee 19
With five posterior cells, the fourth narrowly open or closed; anal cell
usually closed; style usually present; abdomen tapering... . .. Therevidae

With four posterior cells (rarely 3 or 3); 1st posterior cell narrowly open
or closed; anal cell narrowly open or closed; antennae with or without
style; abdomenmot tapering........... sain Lu Nh Bombyliidae

Veins near costal horder strong, those extending across wing weak; antenna
apparently composed of one globular segment with a three segmented

artista; small, black, hunch-backed flies. ..... vw... Loin) Phoridae
NVeinsinot as above... Jv. un a a a Sa ss a 27
Discal and basal cells not separated by a vein; anal cell vestigial; usually
bright metallic blue or green flies....................... Dolicopodidae
Discal and basal cell distinct; anal cell present but small......... Empidae

Lunula present, ptilinal suture absent; third segment of antenna simple;
arista either terminal or dorsal.
Suborder Cyclorrhapha Section Aschiza. . ..24
23.

24.

25.

26.

27.

28.

29.

30.

ar.

32.

33-

INSECTS AND DISEASE OF MAN

Ptilinal suture well defined; lunula present; antenna lie in separate grooves
and are composed of three simple segments; arista well developed, dorsal;
anal cell usually present, small; three posterior cells.

Suborder Cyclorrhapha, Section Schizophora. . . .23

Squamae large; thorax with complete transverse suture; subcostal vein
present well developed.................. Muscoidea Calyptratae. ..:25

Squamae small or rudimentary; thorax without complete transverse suture;
subcostal vein often small or rudimentary.

Muscoidea Acalyptratae....31

Wings with a spurious longitudinal vein (a thickening of the membrane)
between the 3rd. and 4th. longitudinal veins; arista usually dorsal occa-
sionally with terminal style; no antennal grooves (Page 60). ..Syrphidae

Without spurious vein; head very large and composed almost entirely of
eyes iavistaivdorsal LG ol BL ULL BIE RRS Re Pipunculidae

Mouth parts greatly reduced, almost absent, mouth opening small; antenna
small more or less hidden in round pits; body very hairy (Page 75).

Oestridae

Mouth parts well developed; adapted to piercing and sucking or to suction
only; antennae well developed, nothidden.......................... 26
Hypopleural bristles absent or only some fine hairs present.............27
Eypopleural bristles well developed... cL. 0 i ai vita sei tsi 28

First posterior cell more or less narrowed; outer portion of 4th. longi-
tudinal vein more or less strongly angled or curved towards third vein,
at least slightly but noticeably curved at apical end (Page 79) .. Muscidae

First posterior cell widely open; 4th. longitudinal vein not angled or curved
towards third vein, apical end straight (Page 107)........ Anthomyiidae

Post scutellum very pronounced i.e. metanotum with a double convexity. . 29
. Post scutellum rudimentary or absent i.e. metanotum with a single con-
WeRIlY. a 30
Avistathare rasan Dr Gan an I Ge Tachinidae
Anista.plamoselud. of noah aE el SR a Dexiidae
Arista hairy or pubescent above and below for half or a little more than
half its length, outer half bare (Page go)................. Sarcophagidae
Arista hairy for its entire length or nearly so; body often metallic blueish or
greenish (Pageso7)i i o, L000 cab hai ae Bue ee J) Calliphoridae
Subcostal vein present; 1st. longitudinal vein ends near or beyond the
middle ol Re WINE. i a a be me pr 32
Subcostal vein absent, vestigial or incomplete; 1st. longitudinal vein ends
before the middle of the wing; eye not stalked...................... 34
Oral vibrissae present, distinet. oo. 0a dale nig, en 33
Vibrissae absent; lower fronto-orbital bristles absent; wings marked with
darlespotsor banda. a. Ll. en Fi re Sate Ortalidae
With a break or scar in the costa near the termination of the subcostal vein;
frontals convergent fairly large yellow or brown flies. .... . Scatophagidae

Without a break or scar in .the costa; front not bristly near the antenna;
palpi vestigial; small, slender black flies with elongated, cylindrical
BROT EG Sepsidae
34.

35.

30.

37.

THE DIPTERA 9

First segment of hind tarsus thickened and swoolen shorter than second

segment CL es he ee Borboridae
First segment of hind tarsus not thickened, longer than second segment. .35
Discal and posterior basal cells confluent........... Lenn se dae 36
Discal and:posterior basal cells separate... 0. aL rst ali 37
Anal cell absent; vibrissae rarely present; small bare, light colored flies
(Page GT) nest via ee ats ela a 4 A Spe ba Oscinidae
Anal cell present small; oral vibrissae present; arista long plumose (Page
BTN ah a te a LL I i SD Drosophilidae

Wings marked with dark spots or bands; vibrissae absent; fronto-orbitals
numerous extending to antenna; anal cell often with a narrow lobe.

Trypetidae

Wings not marked; vibrissae present; arista long, plumose; anal cell not

Joba, a Drosophilidae
CHAPTER III
SUBORDER ORTHORRHAPHA

SECTION NEMATOCERA

Family Culicidae
(The Mosquitoes)

Mosquitoes can be distinguished from all other Diptera by the
wing venation and the presence of scales on the wings and head and
generally on the thorax and abdomen. These scales are flat scales
which may be broad or very narrow. They may be forked, lanceo-
late, curved etc. and they may stand upright or lie flat (appressed).

Adult. Anatomy (Fig. 1). The Head.—There are two com-
pound eyes, the area between them being known as the frons ante-
riorly, the vertex above and the occiput posteriorly. Projecting over
the attachment of the proboscis is a bulbous prolongation of the
frons known as the clypeus.

The proboscis, (Fig. 2) which is straight in all forms of mosqui-
toes of interest to medical entomologists, consists of,—

1. A fleshy, scaled, grooved organ known as the labium. It
terminates in two short hinged processes known as the labellae. At
the end of the labium, between the labellae, is a thin membrane
called Dutton’s membrane. In the groove of the labium and protected
by it, rests the actual piercing organs,—the stilette bundle, which
is made up of,

2. The labrum-epipharynx, grooved on its under surface,

3. The hypopharynx, which coming in contact with the labrum-
epipharynx closes its groove and forms a tube through which the
- blood is sucked. In the hypopharynx is a channel, the salivary
canal down which the salivary juice passes and, when present, the
sporozoites of Malaria. There are also

4. A pair of mandibles and

5. A pair of maxillae.

The mandibles lie on either side of the hypopharynx above and the
maxillae lie on either side of the hypopharynx below. The maxillae

and mandibles are serrated. In the act of biting they move up and
IO
SUBORDER ORTHORRHAPHA II

mmm e—13

LABELLAE ......

 

oh
js

   
 
 
 
 
 
  
  

ANTENNAE...

 

Occipur........................."

PROTHORACIC LOBES.

MESOTHORAX oceania fons

 
   

SCUTELLUM.
*++.POSTERIOR OR BASAL,
55 VEIN

 

S™ LONGITUDINAL VEIN

™ Lonarrupinia Vein
(ANAL VEIN)

 

 

 

 

S\FEMUR

 

ABDOMEN

BASAL PORTION OF ABDOMINAL SEGMENT. |. I=rmer
APICAL PORTION OF ABDOMINAL SEGMENT... ....
(TiBia
BASAL LOBES OF FEMALE...........
; .
15% TaRsAL JOINT

en

®

 

 

 

2° TARSAL JOINT

I TARSAL ToiNT

4™ TARSAL JOINT

S™ TARSAL JOINT

LH WILDER
&~UNGUES

 

Fi1G. 1.—An adult mosquito to show anatomical parts (Semi-diagrammatic).
12 INSECTS AND DISEASE OF MAN

down, thus sawing a way through the skin until they meet a capillary
blood vessel. As the stilette bundle, steadied by the labellae,
enters the skin, the labium bends beneath as the piercing organs go
deeper and deeper. :

Lying a little above and on either side of the proboscis are two
sensory organs known as the palpi. These are important in differ-
entiating the species.

   
  

LABRUM

EPIPHARYNX * ue ANTENNAE

....LABIUM

MANDIBLES

MAXILLAE J
Im.........LABELLAE

F16. 2.—Mouth parts of a female mosquito (Anopheles quadrimacularus).

Above the palpi on either side of the clypeus are the antennae,
two in number. They are composed of 14 or 15 joints, all, except
the basal joint, similar to each other. The antennae are important
in differentiating the sexes, as stated below.

The Thorax.—The thorax is largely made up of the mesothorax.
The prothorax in front and the metathorax behind are much reduced
in size. The mesothorax has no transverse suture; it terminates
behind in the scutellum which may be simple or trilobed; behind and
beneath the scutellum is the metathorax sometimes called the post-
SUBORDER ORTHORRHAPHA I3

scutellum; attached to the mesothorax are two wings one on each
side. Figure 3 gives a lateral view of the thorax.

MESOPLEURA

  
   
      

PRONOTUM.... ....
SPIRACULAR ="
SCLERITE
A+ .. MESEPIMERON
STENOPLEURA --=*""
LATERAL SCLERI(TE
* > OF
METASTERNUM
FORE COXA .-=*""

Mio coxa" vi
HIND COXA

Fic. 3.—Lateral view of the thorax of one of the Culicidae (Uranotaenia). (From
Dyar and Shannon in the Journal of Washington Academy of Sciences.) (Note: Steno-
pleura should read Sternopleura.)

  

7st BAsALCELL

 

2° BAsAL CELL

 
 
 

AXILLARY CELL re
En rr pra Sa IR Cy ING POSTERIOR, 0R BASAL.
CROSS VEIN

Ne 1 5™ LONGITUDINAL VEIN
Pp LONGITUDINAL VEIN
(ANAL VEIN,

Fi1G. 4.—The wing of a mosquito to show wing veins and cells.

Wings. (Fig. 4).—FEach wing has six longitudinal scaled veins
and three distinct fork cells. The costal vein extends all round the
I4 INSECTS AND DISEASE OF MAN

margin of the wing its scales forming a fringe. The three fork cells
are formed by the bifurcation of the second, fourth and fifth longi-
tudinal veins. The wing veins from before backward are the costal,
the subcostal or auxiliary vein and the first, second, third, fourth, fifth,
and sixth longitudinal veins; or using another nomenclature, these
veins would be known as, the Costal, Subcostal, Radius 1 (=1st
Longitudinal). Radius2 + 3 (= 2nd longitudinal). Radius4+j5(=
3rd longitudinal). Median 1 + 2 (= 4th longitudinal). Cubitus 1
+ 2 (= sth longitidunal) and anal 1 42 (= 6th longitudinal). These
veins mark off hyaline areas on the wing known as cells which are
from before backward the costal cell, the subcostal cell, the 1st.
marginal cell, the 2nd. marginal or first fork cell, the sub-marginal
cell, the 1st. posterior cell, the 2nd. posterior or second fork cell, the
3rd. posterior, the 4th. posterior or third fork cell, the anal cell and
the axillary cell (not to be confused with auxiliary which is not a
cell but a vein). Attention should be paid to the petiole of the 2nd.
marginal cell which is that part of the second logitudinal vein between
its bifurcation and the angular root of the third longitudinal. The
cross veins should be noted. The anterior cross vein lies between
the third and fourth longitudinal veins. The basal cross vein
lies between the fourth and fifth longitudinal veins. The position
of these cross veins with relation to each other should be noted.
Near the base of the wing between the costal and auxiliary veins is
the humeral cross vein. The angular bend at the beginning of the
third longitudinal vein is sometimes spoken of as the ‘ supernumerary
cross vein.” It is not a true cross vein.

Attached to the metathorax, behind and below the root of the
wings, are the halteres or balancers, one on each side.

Comstock and Needham have adopted another system of
terminology to designate the veins and cells of the wings of insects.
Their system is based on the principle that all of the longitudinal
veins are branches of certain main stems which are from before
backwards, the Costa (C), Subcosta (Sc), Radius (R), Media (M),
Cubitus (Cu), First Anal (1st. A), Second Anal (2nd. A) and Third
Anal (3rd. A). Of these the Subcosta, Radius, Media and Cubitus
may be branched, the number of branches varying in the different
groups of insects. If, for example, one examines the basal half of
the wing of a mosquito there will be seen anteriorly, first the costal
vein which borders the wing, then the subcosta which terminates
at the costal border approximately half way between the base and
SUBORDER ORTHORRHAPHA 15

the tip or apex of the wing, and then a vein which if followed up
towards the apex of the wing is seen to branch or fork several times.
This is the radius. Its first furcation forms two branches. The
first branch is the vein which we have designated above as the 1st.
longitudinal vein but which in Comstock’s nomenclature would be
known as Radius-one or vein Ri. The second branch known as the
Radial sector (Rs) typically separates into four branches R,, Rs,
Rs, Rj, but in the mosquito only divides into three branches Rs, Rs,
Ry, the latter designation indicating that, in the wing of a mos-
quito, Radial-four and Radial-five have coalesced. A wing cell
takes its name from the vein which forms its anterior boundary.
Thus the cell back of the Radius is known as cell R, that back of the
first branch of the Radius, i.e. vein R;, is known as cell Ry, and so
forth. Cell Cu; is bounded in front by vein Cu,. This cell is shown
in the illustration (Fig. 4) as the ath. posterior cell.

Legs.— There are six legs, one attached to either side of each
thoracic sternite. Each leg is divided into nine segments. Begin-
ning with the segment attached to the thorax these are, coxa, trochanter
(both short), femur, tibia, and five tarsal segments (collectively tarsus).
The last tarsal segment terminates in a pair of claws. The first tarsal
segment, i.e. that next to the tibia, is sometimes called the
metatarsus.

Abdomen.—The abdomen has len segments, the last two being
modified according to the sex. In the male these are termed the /ypo-
pygium. Arising from the roth. segment of the female is a pair of
appendages known as the cerci.

The genital armature of the male (Fig. 5) is carried on the
hypopygium, the oth. and roth. segments which are crowded
together. It consists of two thick conical appendages, the side
pieces, each bearing a small terminal appendage, the clasp filament
or clasper. There may also be lobes near the base or near the tip
of the side pieces known as subbasal or subapical lobes. Three sets
of paired basal appendages may be seen, the karpes or 10th. sternite,
the harpagones or claspettes and the wunci or aedoeagus. The oth.
segment usually has a pair of haired basal appendages.

Alimentary Tract. (Fig. 6).—When blood is sucked up through
the canal formed by the apposition of the labrum-epipharynx and
the hypopharynx, it first passes into the buccal cavity in the head;
it then enters the aspiratory pharynx which dilates and collapses
alternately, thus acting as a pump to draw the blood up from the
16 INSECTS AND DISEASE OF MAN

Clasp filament

 
      
   

Subapical lobe
+" Harpagones \

 

J i
/ Japagenes, - Ny XR
A i Aedoeagus
NY

F16. 5.—Male genitalia of the mosquito. (A) Culex quinquefasciatus. (B) Same»
basal parts enlarged. (C) Culex pipiens. (D) Aedes aegypti.  (E) Anopheles quadrima-
culatus. (From Howard, Dyar and Knab, Mosquitoes of North and Central America
and the West Indies, by courtesy of the Carnegie Institution.)
dorsal reservoirs _-seutellum

\, mesonotum. : _-postnotums-

CL

malpighian tubule

  
   
     
 
 
 

   
     
  

ventral reservoir
“oesoph. valve “stornach”
~sufivary glands

 

it umes ike
oesophagus ey = mr
“pharynx rectal papillae"

Fic. 6.—Showing internal anatomy of a female Anopheles mosquito. (From Herms’ Medical and Veterinary Entomology, 2nd.

Edition. Courtesy of the Macmillan Company.)

VHAVHIIOHLIO IHAIOINS

Ly
18 INSECTS AND DISEASE OF MAN

wound and then to force it backwards into a short oesophagus;
connected with the latter are three thin walled pouches or food
resevoirs called the oesophageal diverticula. The blood passes into
the mid-gut or stomach through the proventriculus a musculo-valvular
arrangement which prevents regurgitation. The mid-gut lies in
the thorax and abdomen. Its first part is tubular. This part has
been termed the cardia. The second part of the mid-gut, that part
lying within the abdomen, is dilated and is the stomach proper.

The midgut is lined with a single layer of epithelial cells. These
lie on a basement membrane outside of which is a layer of circular
muscle fibers with a few scattered longitudinal fibres. It is in the
stomach walls that the oocysts of malaria are commonly found. In
the stomach, digestion and absorption take place and the residue
passes into the /hindgut or intestine and then into the rectum which
contains the rectal glands. At the junction of the mid- and hindgut
empty the Malpighian tubules, five in number.

The salivary glands lie ventrally in the anterior part of the thorax.
There are two groups of glands of three each, a group on each side.
They are tubular ascinous glands. The secreting portion consists
of a single layer of cubical or short columnar cells resting on a base-
ment membrane. The cells of the lateral glands in the group are
compressed and the material in the lumen of the gland does not
stain with eosin. The middle gland of the group is the smallest;
its cells are not so compressed and contain more protoplasm and the
secretion contained in the lumen of the gland stains with eosin.
The ducts of each of the two groups unite to form two main ducts
which pass into the head and then join to form a common salivary
duct which empties into a salivary pump and finally becomes con-
tinuous with the salivary canal in the hypopharynx.

The Larva. (Fig. 7).—A mosquito larva or wriggler is composed
of a head, thorax and abdomen. The head is large and more or less
globular with a prominent dark colored eye on each side. In front
of the eyes, one on each side, are the antennae which are provided
at or near the middle (Equator) with a tuft of hairs called the anfen-
nal tuft. On the dorsal surface of the head are located three pairs
of hair tufts named, from before backward, the anteantennal tufts
and the lower dorsal and upper dorsal head hairs.

Projecting from the anterior and under part of the head are ‘the
mouth brushes. There are also a pair of mandibles and a pair of
maxillae. In the mid (Sagittal) line at the posterior end of the
SUBORDER ORTHORRHAPHA 19

/

ANAL GILLS

oo
'
.
:
«

SUBDORSAL TUFTS OF ANAL
SEGMENT 3

  
 
 
 
 
 
   
 
 
  
  
 
  
 
 

APICAL SPINE

HAIR TUFTS OF AIR TUBE ~v

PECTEN OF AIR TUBE

Scate patch oF 8% }
ABDOMINAL SEGMENT - ----vnnnsz-

VENTRAL
BRUSH

.

ABDOMINAL 4 *
NAL 5.
LATERAL ** EGMENT

TUFTS

= ABDOMINAL
SUBDORSAL
TurFrs

THORACIC HAIR
TUFTS

 

   

==~-FYES
UPPER DORSAL HERD HAIRS
-« LOMER DORSAL HEAD HAIRS
~~ ANTE-ANTENNAL TUFT

 

eed deme eee ANTENNAE
er, TUFT OF ANTENNA

Mout ... ’
BRUSHES 7 LHWILDER _

F1G. 7.—Larva of a Culex mosquito (Culex quinquefasciatus).
4 hairs,

20 INSECTS AND DISEASE OF MAN

mouth may be seen the mental plate or mentum which is in con-
nection with the hypopharynx. Itisa triangular, heavily pigmented

plate of chitin with its edges serrated. :
Arising from the sides of the thorax are numerous groups of

The abdomen is composed of nine segments each provided with
hair tufts. On the 8th. segment is a patch of spines known as the
scale patch. On this segment is also located the breathing spiracle
which in the non-anophelines is to be found at the tip of a siphon
or breathing tube. This tube may have a double row of spines—tke
pecten—which runs longitudinally from near the base. There is
also one or more pairs of hair tufts along its length. The oth. last
or anal, segment has a conspicuous tuft composed of many hairs
and known as the anal hair tuft. This segment terminates in four
membraneous projections, the anal gills. The 8th. segment may
be ringed at the base. This ring may or may not extend around
the entire circumference of the segment.

 

 

 

 

 

Fic. 8.—Mosquito pupae. (1) Culex pipiens; (2) Aedes aegypti; (3) Anopheles
punctipennis. (From Stitt, after Howard,} Dyar and Knab, by courtesy of Carnegie
Institution.)

The Pupa. (Fig. 8).—The pupa of mosquitoes is active. In
its formation the last larval skin is cast and the appendages and
body are bound together by a closely applied layer of chitin. The
adult emerges through a T-shaped slit in the dorsum of the thorax.
ha

*

SUBORDER ORTHORRHAPHA 21

This is known as an obfect pupa. The pupa consists of an anterior
swollen portion made up of the head and thorax, and a posterior
Shrimp-like tail, the abdomen. From the dorsum of the cephalo-
thorax project a pair of siphon tubes—the breathing tubes.

Life History.—The egg, larval and pupal stages of mosquitoes
are spent in water. Ordinarily the eggs are laid on the surface of
water but some species deposit their eggs above or at the margins
of collections of water and some will even deposit their eggs on the
dry mud of what were temporary puddles. Such eggs hatch soon
after rain water has collected. The larva and pupa can not survive
except in water. It has been shown however that the larvae of
certain mosquitoes may live for periods as long as fourteen days in
damp surroundings such as moist earth and moistened filth paper.
Usually they breathe by bringing the breathing tube to the surface
thus securing oxygen from the air, but the species of one genus
(Mansonia) attach themselves to the roots of certain water plants
and thus derive oxygen from the plant. Mosquito larvae are vora-
cious, some predaceous. The pupa does not feed. The egg stage
lasts from 24 to 48 hours. The larval stage lasts from five to ten
days depending upon temperature. The pupal stage lasts from
48 to 42 hours also depending upon the temperature. Warm
weather hastens, cool weather delays development.
CHAPTER IV
CULICIDAE (CONTINUED)
CLASSIFICATION AND IDENTIFICATION OF MOSQUITOES

To be able to identify all mosquitoes an elaborate key’ to the
classification is necessary. It is however, an easy matter to deter-
mine whether a mosquito may be one of interest as a known carrier
of disease.

=

   
 
     
  
 
  

~
Vv;

/
7

Z—
NS
HRs i

Li

2

/

7
fl

F16. 9.—Antennae of mosquito, Culex pipiens. A, male; B, female. The antenna
has a short basal segment, not shown in the figure. (From Folsom’s ‘‘ Entomology,”
3rd. Edition.)

In the first place the mosquitoes are the only members of, the
Order which have wings bearing scales. In all other Diptera the
wings are naked or contain hairs or perhaps a few bristles but
never scales.

Then, usually only the females bite. The males live on the juices
of fruits and flowers, therefore, it is necessary to distinguish between
males and females. In the forms of interest in preventive medicine
this can be done by the form of the antennae. In the female the
antennae are only sparsely decorated with short hairs and are there-
fore inconspicuous. In the male the antennae are generously

decorated with longer hairs in whorls giving them a feathery or
22
CULICIDAE (CONTINUED) 23

plumose appearance and rendering them very conspicuous. (Fig.
9.) If the antennae have been broken off it may be necessary to
examine the terminal abdominal segments where, if a male, the
clasping organs may be noted.

Having determined the sex it is then necessary to distinguish
between the Anophelines to which group belong the malaria carrying
mosquitoes, and the Culicines to which belong the carriers of certain
other diseases.

In the Anophelines the palpi in both sexes are more than half
as long as the proboscis. The proboscis in the female is straight.
* In the Culicines the proboscis is
straight or only slightly curved
and the palpi in the female are less
than half as long as the proboscis.

The anophelines have a char-
acteristic position when at rest.
(Fig. 10.) They rest with the

 

tf
1 2 3
F16. 10.—Resting position of mosqui- Fi16. 11.—Egg mass of Anopheles quad-
toes; 1 and 2, Anopheles; 3, Culex pipiens. rimaculatus. (After Howard.)
(From Stitt, after Sambon, from P. H.

Reports.)

abdomen forming a straight line with the proboscis and at an angle to
the resting surface. The Culicines rest with the abdomen forming
an angle with the proboscis and more or less parallel to the resting
surface. :

The wings of the Anophelines are usually spotted (Fig. 14), those
of the Culicines unspotted. :

The Anophelines lay their eggs singly, but deposited in groups
so as to form patterns as for instance, a ribbon or triangle. The
eggs rest horizontally on the surface of the water supported by the
air cells, “floats,” which may be seen as little projections on each
side. (Fig. 11.) The shape of these air cells differs somewhat
according to the species. The egg is flat above, convex below, with
24 INSECTS AND DISEASE OF MAN

an outline somewhat oval or boat shaped. Among the Culicines,
the eggs of Aedes aegypti (Stegomyia fasciata) are laid singly on the
sides of the receptacle above the level of the surface of the water.
Each is surrounded by a pearl-necklace-like fringe. Culex lays its
eggs in rafts, each egg standing vertically. The dark brown raft

\\

WW
Nl

  
  
 

 

FEATHERED
HAIRS

 

BREATHING.
SPIRACLE.

 

Fic. 12.—An Anopheline larva Fic. 13.—Larva of Aedes aegypti.
(Anopheles quadrimaculatus).

is convex below and concave above. These egg rafts of Culex are
readily seen. Eggs laid singly are more difficult to detect.

With regard to the larvae it may be said that those of the
Anophelines, (Fig. 12),instead of hanging head down from the surface
of the water as in the case of Culex and Aedes, lie with the body
close to and parallel with the surface of the water. There are other
aquatic Nematocerous insects (Chironomidae, and Uranotaenia.
CULICIDAE (CONTINUED) 25

a non-anopheline mosquito) which also lie parallel to the surface of
the water and which on superficial examination might be mistaken
for Anopheline larvae. Anopheline larvae have no siphon tube,
but breathe through a stigmatic opening on the eighth segment.
Culicine larvae have a drawn out siphon tube, at the end of which
is a breathing spiracle. The siphon in Culex is long and slender (Fig.
7), while in Aedes it is relatively short and barrel shaped. (Fig. 13.)

Projecting from the sides of the thorax and abdominal segments
of Culicine larvae are groups of straight hairs. (Fig. 7.) In the
Anopheline larvae many of these hairs branch laterally, that is, they
are feathered; (Fig. 12) and in addition there is dorsally on each
side of some of the abdominal segments, a group of palmate hairs.

The larvae of Culex wriggle rapidly to the bottom when dis-
turbed. Larvae of Aedes aegypti wriggle to the bottom more slowly
than Culex larvae, their bodies describing curves with much greater
arcs. Anopheline larvae while they may wriggle to the bottom
‘when disturbed, usually move rapidly along the surface of the water.
The head of an Anopheline larva is much narrower than the thorax
and the antennae project straight forwards. Larvae of Anophelines
are variously colored,—green, gray, reddish, brown or black.

With regard to the pupae, (Fig. 8), the breathing tubes of
Culex are long and slender and arise from the posterior (caudal)
portion of the cephalo-thorax. Those of the Anophelines are broad
and funnel shaped and arise from the middle (equator) of the dorsum
of the cephalo-thorax. The siphons of Aedes are short and broad
and the opening is triangular in shape.

Key to the Subfamilies of Culicidae (H. G. Dyar and R. C. Shannon,* 1924)

Az. Eyes reniform; flagellum 13-jointed; proboscis extending far beyond clypeus;
mesosternum ridged; sternopleura not divided by transverse suture
(except Uranotaenini); lateral sclerite of metasternum triangular, in
line with (Megarhinini, Sabethini) or below (Uranotaenini, Anophelini,
Culicini), the base of hind coxa; wings scaled, hind margin with fringe
of scales; Rs forking far before tip of Sc; upper squama bare or ciliated
fame mal, ahets mee BA rg Culicinae

Az. Eyes more or less emarginate on mesal line; flagellum 13-jointed; proboscis
extending very short distance beyond clypeus; mesosternum without
ridge; sternopleura divided by transverse suture; lateral sclerite of
metasternum much reduced, not triangular; wings with hair-like scales,
hind margin with fringe of scales; Rs forking far before tip of Sc; upper
squama ciliated... oc. odin ee He Chaoborinae (Corethrinae)

* Journal of the Washington Academy of Sciences, Vol. 14, No. 20, pp. 475-478.
26 INSECTS AND DISEASE OF MAN

Az. Eyes not emarginate, nearly circular in outline; flagellum 14-jointed;
proboscis not extending beyond clypeus; mesosternum without ridge;
sternopleura nearly divided by a median transverse suture; lateral sclerite
of metasternum much reduced, not triangular; wings with only incon-
spicuous hairs on veins, hind margin with fringe of sparse hairs; Rs
forking approximately opposite tip of Sc; upper squama not ciliated.

Dixinae

Key to the Genera of American Culicidae (Dyar and Shannon)*

Az. Proboscis extending far beyond clypeus............. Subfamily Culicinae.
Bi. Base of hind coxa in line with upper margin of lateral metasternal sclerite;
upper squama incompletely ciliated to bare; spiracular setae not absent
when pronotal setae are present; (exclude Haemagogus, Culicini, by:
spiracular setae absent; proepimeral setae present).......... Series A.
C1. Clypeus much broader than long; scutellar post margin evenly rounded;
a spurious vein in Cu; cell; squama not ciliated; post notal setae

ANSEL rh Ta AL das eet MEGARHININI, Megarhinus.
C2. Clypeus at least as long as broad; scutellum trilobed; no spurious

vein in Cu, cell; post notal setae present; abdomen usually com-
pressed and with few setae... .....o. i 0 2 dl Gr SABETHINI.

Di. No pronotal setae (lobes widely separated, see Isostomyia espini).
Ez. No prealar setae.

Fx..No propleural selae. ... onion i ad shane os Sabethes. -

Fa. Propleural setae present... 0c . wisi LonuG ns, Sabethoides.
Ez. Prealar setae present.

Bs. No'spiraculap setae. Loy brain ii wh Je Limatus.

F4. Spiracular setae present.
G1. Lower sternopleurals distinctly below upper margin of
lateral metasternal sclerite.
Hi. Wing scales especially the outstanding scales on bases of
Reand Rabroad.... J... i dois Li Miamyia.
Hz. Wing seales'narrow, [55 aera lad an gel, Wyeomyia.
G2. Lower sternopleurals, extending as far as, usually above,
upper margin of lateral metasternal sclerite.
Hj. Wing scales narrow (rare). ...... ns oi veil Menolepis.
Ha. Wing scales broad........................Prosopolepis.
D2. Pronotal setae present (except Isostomyia espini).
E3. Clypeus without setae.
Fs. Lower sternopleurals distinctly below upper margin of lateral
metasternal sclerite; palpi very small in both sexes.

Isostomyia.

F6. Lower sternopleurals extending above upper margin of lateral
metasternal sclerite; palpi not small................ Goeldia.

Ba. -Clypens@etone. on bh a, rel Joblotia.

Bz. Base of hind coxa distinctly below upper margin of lateral metasternal
sclerite; postnotum rarely setose; abdomen rarely compressed and
with reduced setae. (The Sabethid-like genus Haemagogus is retained
CULICIDAE (CONTINUED) 27

here on basis of absence of spiracular setae and presence of prono-
paliigatae) lian DE A Series B.

C3. Scutellum trilobed with marginal setae only on the lobes.
D3. Anal vein extending well beyond fork of cubitus; wings villose;
upper squama ciliated (partially so in Haemagogus and Carrol-

Gad as die na RE Se RE Re Curicini (Page 39).
Es. Prescutellar setae absent; wings narrower than width of thorax;
postspiracular setae absent... ... 0... 00 Las Haemagogus.

E6. Prescutellar setae present; wings broader than width of thorax.
Fy. Post spiracular setae present.
G3. Spiracular setae absent.
Hs. Wing scales mostly narrow, or when broad (rare), setae
are present on upper side of base of first vein... ..Aédes.
H6. Wing scales broad; setae absent on upper side of base
of first vein. (See Mansonia.)
G4. Spiracular setae present, sometimes small... . .. Psorophora.
F8. Post spiracular setae absent.
Gs. Lower side of base of first vein distinctly pilose; spiracu-
lar setae present... cus, oe. a ae Culiseta.
G6. Lower side of base of first vein scaly or bare; spriacular
setae absent.
Hy. No setae on upper side of base of first vein; wing scales
broad, black and pale mixed (all black in some species
of Mansonia which have post spiracular setae).
Ir. No mid-mesepimeral setae; fourth tarsal joint of fore
tarsus somewhat thickened, as broad as long, or broader.
Orthopodomyia.
I2. Mid-mesepimeral setae present; fourth fore tarsal joint
longer than broad.
J1. Post marginal wing scales longer than width of anal cell;
antennal joints but little longer than broad.
Adéomyia.
J2. Post marginal wing scales shorter than width of anal
cell; antennal joints much longer than broad.
Mansonia.
HS. Setae present on upper side of base of first vein; wing
scales mostly narrow, dark colored.
I3. Mid-mesepimeral setae numerous. .............. Lutzia.
I4. Mid-mesepimeral setae o-3.
J3. Antenna much longer than lengh of proboscis.
Deinocerites.
J4. Antenna approximating length of proboscis (Page 39)
Culex.
D4. Anal vein ending opposite or basad of cubital fork; squamae not
ciliate; wings without villi.
URANOTAENINI, Uranotaenia (Page 47).
C4. Scutellum crescent-shaped, with marginal setae evenly distributed.
ANOPHELINI, Anopheles (Page 34).
28 INSECTS AND DISEASE OF MAN

Az. Proboscis not elongate, extending but little beyond clypeus.
B3. Radial sector forking far before tip of subcosta; wings with hair-like

scales; hind margin with fringe of scales... ....Subfamily Chaoborinae.
Cs. Anal vein ending basad of cubital fork...................Eucorethra.
C6. Anal vein ending beyond fork of cubitus.
Ds. Basitarsal joint shorter than following joint.............. Corethra.
D6. Basitarsal joint longer than following joint.
Ev. Tip of Ry much nearer tip of R, than to Sc...........Chaoborus.
ES. Tip of R; much nearer tip of Sc than to Ry.......... Corethrella.

Bas. Radial sector forking approximately opposite tip of subcosta; wings with
only inconspicuous hairs on veins, hind margin with fringe of sparse
hairs ee en, St i a Subfamily Dixinae, Dixa.

. Key to the Larvae (Howard, Dyar, and Knab, 1g17)*

Anal segment without ventral brush, the hair tufts all paired. . . Tribe Sabethini
Genus Wyeomyia

Anal segment with unpaired ventral median brush.............. Tribe Culicini
1. Air tube short, sessile, the larvae surface feeders. ............. Anopheles
Alritube distinctly elongate. . ..c.. J. if 20h vials dn san da Suis ete alata lee 2

2." Afr tube without pecten............. A sheila la BCS 1 ONE OT 3
Air tube with well developed pecten...............c.ccoviiininiinnnns 5

3. Mouth brushes of lamellate prehensile plates................ Megarhinus
Mouth brushes normal... vive iS ihie blo bpd dn Sa eal, 4

4. Air tube with the outer half attenuated...................... Mansonia
Air tube cylindrical or fusiform; antennae small, slender. . .Orthopodomyia

5. Air tube with but a single pair of ventral (posterior) tufts.............. 6
Air tube with several pairs of ventral tufts, mouth brushes normal with no
prehensile hooked lamellae... ois koe Dun vs 0 re a Culex

6. Head elongateelliptical... ... 0.00 bus son vsiids Javan Uranotaenia
Head nearly circular or transverse. Civ. i ian lumii dd ihe. 7

7. Air tube pecten produced into long hairs; hair tuft close to base. .Culiseta
Air tube pecten of short scales or if produced the hair tuft remote from

BS i Selo von vhs ls a a Ch Ra a RTE LR SR ra 8
8. Mandibles angularly projecting laterally. ................... Deinoceriles
Mandiblesiconicealed.. i. bi ii Tanti a ares ti in Ne 9

0. Anal segment ringed by plate, with ventral hair tufts piercing the ring.
Psorophora
Anal segment not ringed, or if so with the hair tufts posterior to the ring.
Aedes

Key to the Species of Anopheles of North and Central America and the West
Indies (Howard, Dyar and Knab, (1917)*

1. Tavsi ornamented with white or yellow... i oi ii ails de sanbin is 2
Parsi wholly dark colored... ... i Ls does LO al 13

* The Mosquitoes of North and Central America and the West Indies. Published
by the Carnegie Institution of Washington.
IO.

11.

12,

3

14.

is.

16.

7.

18.

CULICIDAE (CONTINUED) 29

; Hind tarsiowith a series of rings. {itl Un nina ele Sn 5

Hind tarsi all white beyond second joint. ....0. ov. shin doneians :3
Hind tarsi white beyond second joint, a black spot on the last joint......4

. Abdomen dorsally covered with scales.

ddl argyritarsis Robineau-Desvoidy (Page 38)
Abdomen clothed dorsally with hairs only..................4. lutzii Cruz

. Palpi with the last two joints white except narrowly at bases.

A. tarsimaculata Goeldi (Page 38)
Palpi with the last joint only white... ..4. albimanus Wiedemann (Page 38)

. Hind tarsi with small basal rings only; palpi wholly black scaled.

A. grabhamii Theobald
Tarsi more conspicuously ornamented; palpi not wholly black scaled. . . .. 6

. Tarsi and tibiae narrowly ringed and speckeled black and white or yellow 8

Hind tarsi with broad apical segmental white rings; not speckeled. . ...... 7

. Wings with four white spots on the costa. ....... A. bellator Dyar and Knab

Wings with two white spots on the costa; five on the first vein.
A. neivai Howard, Dyar and Knab

. Wing scales mostly blackish, many little patches of yellow ones.

A. vestitipennis Dyar and Knab
Wing scales Wack and white: or yellow, several large concrete patches of
blzelescales. 0 i. Sa ST ed ER Se 0

. Hindtarsal joints with apical rings; last joint wholly black.

A. maculipes Theobald
Hind tarsi with rings involving both ends of the joints; last joint mostly or
whelly palessealed....... 0. lin anni il Lal a ae 10
Wing scales broad and rounded... cl. Ju es admin li in fe isis 11
Wing scales narrowly ovate to lanceolate. .................. iiss 12
Tarsi yellow with small black dots. . ........... A. mediopunctatus Theobald
Tarsi black with whiterings................ A. malefactor Dyar and Knab
Hind tarsi with numerous yellow rings. .. A. strigimaculata Dyar and Knab
Hind tarsi with sparse white ring.......... 4A. apimaculata Dyar and Knab
Hind tibine without a white aplealiving. i... Jiu ais isi vo hin bibl 14
Hind tibiae broadly white at apex... ................ A. eiseni Coquillett
Wings with a white spot at outer third of costa. ...................... 15
Wingsiwithout such spot on the costa... 0. oo 0000 Sa eh 16
Palpi marked with white, third vein extensively white in the middle, wing
fringe spotted...............A. pseudopunctipennis Theobald (Page 37)
Palpi wholly black scaled, third vein wholly black scaled, wing fringe
anspotiedin in A. punctipennis Say (Page 37)
Wings with patches of yellowish scales, sixth vein with three black spots.
A. crucians Wiedemann (Page 36)
Wings without patches of pale scales... .....c... 0. ov cian, 17
Wings at apex with a coppery spot on the fringe.
A. occidentalis Dyar and Knab (Page 38)
Wing fringe uniformly dark throughout................ 0 ld 18
Body blackish throughout; hair scales of mesonotum dark brown.
A. atropos Dyar and Knab
30 INSECTS AND DISEASE OF MAN

Body not wholly blackish; hair scales of mesonotum yellow or white. .... 19
19. Palpi of the female with dull silvery white rings at the bases of the joints;
scales of wing not distinctly massed at bases of fork cells.
: A. walker: Theobald
Palpi of female blackish scaled throughout; scales of wings massed to form
distinct spots at cross veins and at bases of fork cells. :
A. quadrimaculatus Say (Page 34)

Key to the Larvae

Larvae without respiratory siphon.

1. Scales of scale patch with teeth all long, equal.................... neivas
Scales of scale patch alternately long and short................ malefactor
strigimaculata
Teeth of the comb both long and short, irregular...............cc...... 2
2. Abdomen with seven pairs of dorsal fan shaped tufts, the pair on first
segmeptsmuallisio oni Cn nS hel a sae a albimanus
tarsimaculatus
Abdomen with six pairs of fan shaped tufts................cueieiives 3
Abdomen with five pairs of well developed tufts. ..................... 5
3. Elements of fan shaped tufts slender, smoothly pointed... .... argyritarsis
Elements of fan shaped tufts notched towards tip..................... 4
4- Fan shaped tufts all equal insize. . i... 0 aids lian vo ov oiinle dn eiseni
First pairiof twig small: 20 adn a punctipennis
quadrimaculatus
5. First and last pair of tufts smaller than theothers.............. crucians
Ean shaped tuitsallequal. 05 Sit Sobivn Sli sn iin pale ne deg 6

6. Elements of fan shaped tufts with long slender apical portion.
pseudopunctipennis
4. Fan shaped tufts with normal elements. .................... occidentalis
(maculipennis)
grabhamii

In a campaign against the mosquito borne diseases many different
species of mosquitoes will be collected which are not carriers of disease
although they may be a great nuisance in the locality. Komp has
worked out a key to be used by field workers for the determination
of the species of adult females and larvae commonly encountered,
especially in the Southern United States.

Key for Determining Species of Adult Female Mosquitoes (Komp) (1923)*

Wings spotted, palpi almost as long as the proboscis....................... I
Wings unspotted, palpi much shorter than the proboscis. ...................4
¥.Palpl ringed and tipped with white... Loi dani us ander an 2
Palpluntformily dark brown... ccs oe bb Asha braid sain Ces 3

* Public Health Reports, Vol. 38, No. 20, May, 1923, pp.1079—1080.
IO.

TI.

13.

14.

15.

CULICIDAE (CONTINUED) 33

. Sixth longitudinal vein with three black spots (Page 36).

A. crucians Wiedemann
Front margin of wing with three light spots. 6th. longitudinal vein basally
pale, apically black (Page 37).....-...- A. pseudopunctipennis Theobald

. Prominent white spot on front wing. margin, 6th. longitudinal vein white

with black ends, median gray thoracic stripe (Page 37).
A. punctipennis Say

Four dark spots on wing, 6th. longitudinal vein wholly dark scaled, no

thoracicstripe (Page 34)... fain tli A. quadrimaculatus Say

+ Legs banded or marked with white... .. o.oo. Juan Gonville 5
Legs unbanded; uniform in color... onal vont vain UE aL II

+ Proboscis centrally ringed with:-white....... coy ra Lh Sas clin, 6
Probescissunbandedi vy. ha dole La i nh el I ERE 8

. Abdomen with dorsal longitudinal stripe, sides of thorax white below black
stripe (Page qd). iii oo ii te Lr Aedes sollicitans Walker
Abdomen without dorsal stripe... i tL nn Lr as sl y

. Large blackish species, tibia white spotted, femur white banded near tip,

abdomen unbanded (Page 46)... .. Psorophora columbiae Dyer and Knab
Small blackish species, tibia and femur unmarked, abdomen banded with

white at bases of segments (Page 45).
Aedes taeniorhynchus Wiedemann

+ Thorax marked'with linesor'stripes........ LL Lenn da brasil 9
IBhorax unmarked... oon an eb abt, So a A OR 10
. Large yellowish species, with broad yellow median thoracic, stripe, legs

heavily fringed with upright scales (Page 46).
Psorophora ciliata Fabricius
Small black species, thorax marked with white lyre shaped design, palpi
white tipped, abdominal segments with lateral white spots (Page 43).
Aedes aegypti (Stegomyia fasciata)
White markings of legs narrow, abdominal bands nearly divided in the

middle (Page 4.4)... 0.0 chai ay SoA Aedes vexans Meigen
Large purplish species, with two terminal joints and apex of middle joint
of hind tarsi white (Page 47)........... Psorophora sayi Dyar and Knab

Abdominal segments banded with white at the apex only (Page 42).
Culex testaceus van der Wulp

Abdominal segments banded with white at base only.................. 12
12.

Under side of abdomen with unbroken black bands (Page 42).
Culex erraticus Dyar and Knab
Under side of abdomen not completely banded. ....................0.. 13
Upper side with narrow white or yellowish basal bands................ 14
Abdomen unbanded dorsally, lateral spots of the abdomen not visible
dorsally, (Page 41). Culex salinarius Coquillett
Band on second abdominal segment somewhat triangular................ 15
This band transverse (Page 41)... ..........0. 000 Culex territans Walker
Abdominal bands joined to the lateral spots (Page 40).
Culex pipiens Linnaeus
Abdominal bands separated from the lateral spots (Page 40).
Culex quinquefasciatus Say
32

INSECTS AND DISEASE OF MAN

Key to Full-grown Mosquito Larve

Without breathing tube, lying parallel with water surface in surface

With breathing tube; when breathing, hanging from surface film at
ananEle en ES ea 2
Palmate hairs on abdominal segments 3 to 7 equal | A. quadrimaculatus.
in size. { A. punctipennis.
Palmate hairs on abdominal segments 3 and 7 smaller than those. on
segments Asn antli6, re a A. crucians.
More than one pair of hair tufts or hairs on breathing tube. ......... 10
{ A single pair of hair tufts on breathing tube................... ELE 3
Abdominal hair tufts star-shaped; head pear-shaped, with four coarse
head hairs Page 47)... nin Uranotenia sapphirinus.
| Abdominal hair tufts not star-shaped; head not pear-shaped, head
beacthatlvsiglender. cn 0 Li TR 4
Breathing tube very short, dorsal head hairs single (found in salt
er pa 5
Breathing tube at least three times longer than wide (found in fresh
LS SABRE aC ME Com a el 6
Breathing tube not more than twice as long as wide; scale of eighth
abdominal segment with long central spine (Page 44) Aédes sollicilans.
Breathing tube not more than one and one-half times as long as wide,
scale of eighth abdominal segment rounded at tip, fringed with slender
equal spines (Page 4g)... co ra la Aédes teniorhynchus.
Head square, almost straight across front; antenna arising from near
middle of sides of head; mouth brushes prominent, at outer angles
of head; a very large larva when full grown (Page 46).
Psorophora ciliata.
Head normal, rounded; antenne arising from sides of front of head... .7
Scales of eighth abdominal segment 6 or 7, joined at bases to a band;
breathing tube large, swollen, with four or five strong spines ........... 8
Scales of eighth abdominal segment 10 to 50, not joined to a band, but
arranged in a triangular patch; breathing tube short, not swollen,
witha double row of small spines...  aeibis ian. es Bo ra 9
Antenna shorter than head (Page 46)............ Psorophora columbiae.
{ Antenna much longer than head, slender, slightly curved.
Psorophora sayi.
Dorsal head hairs multiple, antennal tuft multiple; last two spines

 

 

eachother (Page 4d)... 0 cu. oul hi vis die mie ati aid id a Aédes vexans.
Dorsal head hairs single; antenna with single hair replacing usual
tuft; breathing tube dark, barrel-shaped; a long, slender larva found
in artificial containers (Pageins).. i. ive iiaii vanes Aédes egypt.

{
| in row on breathing tube larger, separated from the rest, and from
{
IO.

II.

12.

I3-

CULICIDAE (CONTINUED) 33

Antenna with tuft arising from middle of uniformly shaped joint; tufts
of breathing tube replaced by six long, coarse hairs.
Culex restuans.
Antenna with tuft arising from a notch two-thirds the distance from
base to tip of joint, part beyond tuft slender; breathing tube with
fromi6ito Iohalp tufts... Joust nn are a i A CRE IY
Breathing tube long, slender, about seven times as long as wide....... 12
| Breathing tube about three times as long as wide... ................ 13
Dorsal head hairs single, scale patch of eighth abdominal segment of many
scales in a triangular patch (Page 42)...............: Culex testaceus.
Dorsal head hairs multiple; scale patch as in C. festaceus (Page 41).
Culex salinarius.
Lower dorsal head hairs long, single; upper pair short, multiple; scale
patch of eighth abdominal segment of few, sharp, pointed scales in an
irregular double row (Page 42)... ou ive duionivils hiss Culex erraticus.
Dorsal head hairs multiple; scale patch of many scales in a triangular
patch; breathing tube slightly swollen at base, bottle-shaped; breeding
by preference in polluted water; a very common species (Page 40).
Culex quinquefasciatus.

 
CHAPTER V

SUBFAMILY CULICINAE
TRIBE ANOPHELINI

Palpi as long as or longer than the proboscis in both male and
female and in the male more or less clubbed at the end; proboscis
straight; scutellum simple, never trilobed; metanotum nude.

In the Western Hemisphere all of the malarial carriers are found
in the Genus Anopheles. (Malaria, Chap. XXV.)

Genus Anopheles (Meigen)

Description.— With scales on the head and wings, often hair
like scales only on the thorax and abdomen; mostly upright forked
scales on the head; the scales on the wings are large and lanceolate;
the palpi are usually only slightly scaled; second marginal cell at
least as long as its petiole; mesothorax elongate, over twice as long
as wide; scutellum rounded not lobed, with scales or hairs; meta-
notum nude; antennal segments in the female are without dense
lateral scale tufts; these are present in the male; wings with six
scaled longitudinal veins.

ANOPHELES QUADRIMACULATUS (Say)

A. quadrimaculatus has four black spots on the second and fourth
wing veins. The palpi are uniformly dark brown and the sixth
vein is wholly darked scaled. :

Habits.—This mosquito is rather fastidious in its choice of a
breeding place and much prefers clean, clear, quiet water, such as
large ponds and grassy puddles. It will not breed in sewage pol-
luted water. It breeds especially in ponds of considerable width
and depth but when more favorable breeding places are scarce it
may be found in small pools and occasionally in post holes, hoof
prints, and rarely at the edges of slow moving streams where there
is practically no surface flow. In ponds it is ordinarily found near
the edge in shallow water, sheltered and protected by water plants,

34
SUBFAMILY CULICINAE : 35

 

 

F16. 14.—Wings of Anopheles mosquitoes shown to the same scale. (1) A. crucians;
(2) A. punctipennis; (3) A. barberi; (4) A. albimanus; (5) maculipennis; (6) A. pseudo-
punctipennis; (7) A. atropos; (8) A. walkeri; (9) A. quadrimaculatus. (From Stitt, after
Howard, Dyar and Knab, by courtesy of Carnegie Institution.) .
36 INSECTS AND DISEASE OF MAN

but it has been reported from the middle of a large pond in six feet
of water where floatage (broken pieces of wild celery and pollen)
furnished protection by preventing any break in the waves, thus
permitting only long, smooth swells, and also furnishing protection
against fish.

A. quadrimaculatus enters occupied dwelling houses in large
numbers and therefore comes into intimate contact with people
at the time it is ready to feed. It may be guided into the house by
lights, even by light reflected up the chimney, and it may enter a
house by way of the chimney as well as through unscreened windows
and doors and through crevices and cracks in the walls and floors of
poorly constructed houses. It is also found in out buildings such as
privies. It perhaps prefers the blood of man to that of animals.
It may fly as far as 114 miles from its breeding place. This is not
usual, but from 14 to 1 mile is a common flight for 4. quadrimaculatus.
The greater the amount of breeding the greater the number that will
be found at a distance from the breeding place, and the greater the
tendency towards long flight up to the maximum. A. quadrimacu-
latus is an efficient carrier of Plasmodium vivax, P. falciparum and
P. malariae. Probably most malaria is contracted at night in the
house from the bite of this Anopheline. It may be found from
Mexico to New England, east of the Rocky Mountains.

ANOPHELES CRUCIANS (Wiedemann)

A. crucians has the wings heavily spotted, the front margin
darkest. The sixth vein has three dark spots one at each end, one
at the middle. In the female the terminal joints of the palpi are
white throughout, the penultimate joint is white at the base and
apex, and the longest joint has a white ring near its middle.

Habits.—A. crucians also may be found in inhabited dwelling
houses. It is not so widely distributed as are the other species.
It bites on porches and is commonly found under the house or around
the house in out-houses, privies, stables etc., and seems to prefer
the blood of animals to that of man. Its maximum flight distance
is probably the same as that of A. quadrimaculatus. It may be
found breeding side by side with other Anopheles but may adapt
itself to brackish water as in salt marshes, or water containing small
amounts of chemicals, conditions under which neither 4. quadri-
maculatus nor A. punctipennis will breed. A. crucians is a proven
SUBFAMILY CULICINAE 37

transmitter of Plasmodium falciparum and P. vivax. It may be
found in the eastern United States from New York to Mexico;
and in Cuba and Jamaica.

ANOPHELES PUNCTIPENNIS (Say)

Anopheles punctipennis has the front margin of the wing dark
except for a conspicuous yellow-white patch about one quarter the
way from tip to base, with a smaller white patch near the tip. The
sixth vein is dark scaled at both ends and light in the middle.
The palpi are uniformly brown and the thorax has a wide pale gray
longitudinal stripe.

Habits.— This mosquito is more widely distributed and more
numerous than either of the other species. It is most in evidence in
the early evening. It is rarely found in occupied dwelling houses
and then usually after cool weather has set in. It is a biter on
porches and is found under houses and in out houses, pig pens and
the like. It seems to prefer the blood of animals to that of man.
It does not fly far from its breeding places which may be streams,
ditches and springs as well as small ponds, marshy areas or other places
where A. quadrimaculatus will breed. It is occasionally found
breeding in artificial containers, and may also develop in brackish
water. Slight pollution of the water does not deter it from breed-
ing. Anopheles punctipennis is a proven carrier of Plasmodium
vivax and P. falciparum.

The latter two species of mosquitoes are less important dissemina-
tors of malaria than A. quadrimaculatus because they do not enter
houses so readily and as the Anophelines are shy they are not so
apt to bite while persons are moving about outside of the house.

Except in the arid regions A. punctipennis is found in the United
States from Mexico to Canada.

ANOPHELES PSEUDOPUNCTIPENNIS (Theobald)

The front margin of the wing has three light spots, one about
one-third the distance from base to tip, one about two-thirds and
one at the extreme tip. The sixth vein is white at the base and black
in the outer half. The fringe on edge of the wings has pale spots
at tips of all veins. The palpi have the tips white, the base and
apex of penultimate joint are banded with white and there is a white
ring near the middle of last joint. The markings of the palpi differ-
38 INSECTS AND DISEASE OF MAN

entiate this species from A. punctipennis in which the palpi are
unbanded.

Habits.— This mosquito is found in the southwestern part of the
United States, southern California and Texas, and extends down
through Mexico and Panama into South America. It may enter
houses. It breeds in pools, ditches, and at the edges of streams,
preferring clear pure water. A. pseudopunctipennis is a proven
carrier of P. falciparum.

ANOPHELES ARGYRITARSUS (Robineau-Desvoidy)

This mosquito has been found to breed in small collections of
water such as seepage pools, hoof prints, swampy pastures, ditches
containing but a small amount of water and in artificial containers.
The presence of algae is necessary. The adults bite at dusk and
during the night. Panama, Brazil.

ANOPHELES ALBIMANUS (Wiedemann)

This mosquito breeds in fresh, brackish or even definately salt
water but not in foul water. Larvae have been taken in swamps,
hoof prints, wheel ruts and seepage water. The adult enters occu-
pied houses in large numbers. It is found in Tropical America, the
Antilles and southern Florida.

ANOPHELES TARSIMACULATA (Goeldi)

This mosquito breeds in fresh or brackish water but not in foul
water. Larvae have been found in rivers, swamps, ditches, small
water holes and in artificial containers. The adults enter dwellings
at dusk and leave in the early morning. Panama, Porto Rico.

ANOPHELES MACULIPENNIS (Meigen)

This is a medium sized blackish mosquito with four dark spots
on wing as follows—base of second vein in the cell, on the cross
veins and forks of second and fourth vein. The tip of the wing shows
a coppery reflection in the fringe. In America this mosquito is
known as occidentalis. In Europe it is a common vector of malaria
and, it also plays a part in the spread of malaria in the Western
United States. It breeds in water puddles preferring permanent
water. It is found in Europe, As’a, Western United States (except
SUBFAMILY CULICINAE 30

the most northern Pacific strip) eastward through Canada to
Northern Maine.

 

 

 

 

 

Fi1G. 15.—Head and thorax of mosquitoes; 1 and 2, male and female Culex quinque-
fasciatus; 3 and 4, male and female Anopheles; 5 and 6, male and female Aedes
aegypti. (From Stitt’s “‘ Practical Bacteriology, Blood Work and Animal Parasitology’
7th. Edtion.)

TRIBE CULICINI

In this tribe the palpi in the male are as long or longer than the
proboscis, in the female shorter than the proboscis; the proboscis is
straight; the metanotum nude and the scutellum trilobed.

Genus Culex (Linnaeus)

Adult.—The scales on the occiput and vertex are narrow and
curved with numerous forked scales on the occiput and laterally
a patch of flat scales. The scutellum is trilobed and clothed with
narrow, curved scales. The wing scales are usually long and narrow.
The palpi in the female are three-segmented, in the male not clubbed
but hairy. The basal cross vein is remote from the anterior cross
vein.
40 INSECTS AND DISEASE OF MAN

Larva.—All species of Culex considered herein (included in
Komp’s key) have more than one pair of tufts on the breathing tube.
This immediately separates them from the larvae of other genera.
In all species except Culex territans the antennal tufts project from
an offset about two-thirds the distance from the base to the tip;
the antenna are thick at the base and the part beyond the tuft slender.

CULEX QUINQUEFASCIATUS (Say) (=FATIGANS)

Adult,—This important member of the Genus Culex transmits
filariasis (Chap. XXVIII). The mosquito has a wide distribution
over the Tropics and warmer parts of the Temperate Zone. In the
North it is represented by Culex pipiens Linnaeus. Both are found
in the vicinity of Washington D. C. The proboscis and legs are
uniformly dark brown in color, not ringed or spotted.

C. pipiens has the thorax clothed with narrow, curved, golden-
brown scales; the abdomen has continuous pale bands at the bases
of the segments joining the lateral spots, the band at base of second
segment somewhat triangular; the petiole of the first submarginal
cell is from one-fifth to one-sixth as long asits cell. It hasa northern
distribution and is common in Europe, Asia and North America
from Virginia to Canada. It is also found in Chili and Argentine.

In C. quinquefasciatus the thorax has a more grayish appearance
and the bands on the abdomen are separated from the lateral spots.
The petiole of the first submarginal cell is about one-fourth as long
as its cell. There are also differences in the male genitalia.

Larva.—The larvae of C. pipiens and C. quinquefasciatus (Fig.
7) are very much the same except that in C. pipiens the breathing
tube is about five times as long as wide, there are about fifteen teeth
in the pecten and the subdorsal hairs on the abdominal segments are
three or four double. In C. quinquefasciatus the breathing tube is
about four times as long as wide, there are about nine teeth in the
pecten and the subdorsal hairs on the abdominal segments are three
or four single.

The air tubes of both taper rather rapidly after the siidle. On
the air tube are four paired tufts of hairs the third pair being out of
line. The antennal tufts are outwardly placed with the part beyond
slender. The scale patch on the eighth segment consists of many
scales (about 40) in a triangular patch. These scales are finely
fringed at the tip.
SUBFAMILY CULICINAE 41

Habits.—C. quinquefasciatus is the common house mosquito
of the Tropics and Subtropics. It is domestic in its habits and not
at all fastidious as to its breeding place but seems to prefer filthy
water and may commonly be found breeding in cess pools, sewers,
catch basins, collections of filthy water in low areas being filled by
city wastes, dirty water in artificial containers and the like.

It may bite at any time outside but it is especially troublesome
in the house at night and during the afternoon if the room is darkened.
Aedes aegypti and Culex quinquefasciatus have a similar distribution.
The latter is essentially a night biter while the former bites in the
day time.

CULEX SALINARIUS (Coquillett)

Adult.—This mosquito closely resembles C. quinguefasciatus.
The abdomen is blackish above with or without narrow, basal,
whitish bands joining the lateral Spots, It is found in the eastern
part of the United States.

Larva.—The larva has a very long slender breathing tube, about
seven times as long as broad. Eight small tufts occur between the
spines and the tip of the tube. The paired head hairs are multiple.

CULEX TERRITANS (Walker)

Adult.—This mosquito also closely resembles C. quinquefasciatus.
The abdomen is blackish brown above with basal segmental whitish
bands transverse and even. It is found in Eastern North America
from the Gulf of Mexico to Canada. :

Larva.—It is much like C. quinquefasciatus but instead of the
antennal tufts arising from an offset about two-thirds the distance
from the base to the tip of the antenna as it does in C. quinque-
fasciatus and other members of the Genus Culex mentioned herein,
the tuft arises from the middle of an evenly tapering antenna. The
tufts on the breathing tube are replaced by six long, coarse hairs with
a small tuft near the tip.

Habits.—Culex salinarius and C. territans posdinile C. quinque-
fasciatus closely in appearance and habits and they are often found
associated with each other. C. ferritans prefers cleaner water than
C. quinguefasciatus and is more frequently found in rural sections
in dirty ground puddles. It is often found in rain barrels. Like
C. quinquefasciatus it is a house mosquito and bites at night. C.
42 INSECTS AND DISEASE OF MAN

salinarius is often found in fresh water pools near the sea, but it
also occurs inland and may breed in rain barrels. Its habits are
similar to the others.

CULEX TESTACEUS. (van der Wulp)

Adult.—A small blackish mosquito. The legs are unbanded and
uniform in color. The abdominal segments are banded with white
at the apex only. It has a wide distribution in the United States and
Europe.

Larva.—The breathing tube is very long and slender, seven
~ times as long as wide. There are eight small hair tufts between
the pecten and the tip. The head is broader than the thorax.
The antennae are light colored at the base and darker beyond the
tuft. Both pairs of dorsal head hairs are single. This differen-
tiates from the larva of C. salinarius which also has a very Jong
breathing tube but which has multiple head hairs.

Habits.— Culex lestaceus breeds in permanent pools filled with
aquatic vegetation. It is often found associated with Anopheles
larvae or with the three Culicids mentioned above in rain barrels
and other artificial containers. It does not bite man.

CULEX ERRATICUS (Dyar and Knab)

Adult.—This is a small black species with unbanded proboscis
and legs, characterized by the unbroken black band on the under
-side of the abdomen, a mark found in no other common mosquito.

Larva.— The larva is small, often bright green. The bases of
the antennae are conspicuously white. The first pair of head
hairs is long and single, the second, short multiple tufts. The
scale patch of the eighth segment consists of an irregular double
row of sharp pointed scales not fringed at tip. The breathing tube
. has five pairs of very long tufts beyond the pecten. The body is
very hairy (pilose) which character separates it from all other
common Culex larvae.

Habits.— This is a species inhabiting the southern Mississippi
Valley into Georgia and Florida. The larvae are common in
permanent bodies of water covered with duck weed, associated with
the larvae of Anopheles and Uranotaenia sapphirinus. The adult
will enter houses but is not very troublesome.
SUBFAMILY CULICINAE 43

Genus Aedes (Meigen)

Adult.—The scales on head and scutellum are broad and ap-
pressed. The palpi of the female are short, acuminate and sparsly
tufted, palpi of the male long and tufted. Palpi with three segments
in the female, the three segments equal in length. Metanotum nude.
Legs uniformly scaled with flat scales. First submarginal cell long.

Larva.—The larvae have scale patches consisting of a few to
many pointed scales not finely fringed as in Culex. There is only
one pair of tufts beyond the spines on the breathing tube and the
antennae are usually uniformly tapering with the tuft at or near the
middle.

AEDES AEGYPTI (Linnaeus) (STEGOMYIA FASCIATA)

Adult.—Thisimportant member of the genusis the mosquito which
carries yellow: fever and dengue (Chaps. XXVI and XXVII). Itis
blackish, marked with silvery white. The thorax has two median
broken silvery white lines and lateral curved silvery lines, these
markings taking the form of a lyre. The proboscis is not banded.
The abdominal segments are ornamented with lateral, triangular,
silvery white spots. The tarsal segments are banded at their bases
with silvery white, and the last joint of the hind tarsi is wholly white.
The claws of the female are toothed at least on front and middle
legs. The clypeus is white scaled. This is a tropical mosquito but,
in summer is also found in temperate regions.

Larva. (Fig. 13).—The air tube is short and stout a little more
than twice as long as broad. It has a single pair of tufts beyond the
pecten. The teeth of the pecten are long and evenly spaced in a
regular row. Each spine has two large and a few small teeth near
the base. The scales of the patch on the eighth abdominal segment
are few in number (about ten) in a single row. Each spine has a
pointed base and a long terminal spine with several curved spines at
each side. The plate of the anal segment does not form a complete
ring around it. The antennae are usually uniformly tapering with
a single hair instead of a tuft, at or near the middle.

Habits.—This mosquito is distinctly: domestic in its habits
breeding in and around houses in bottles, cans, pots, cisterns, water
barrels, buckets, roof gutters, bases of flower-pots, etc. which contain
clean, fresh water. In the absence of natural breeding places the
mosquito may deposit her eggs in small pools around a house which
44 INSECTS AND DISEASE OF MAN

contain clean fresh water or perhaps in street gutters or collections
of water in the axils of leaves or knot holes in logs or trees. When
hard pressed they have even been found breeding in slop jars and
' chambers containing dirty water. Under such circumstances it is
probable that complete development rarely takes place. They do
not like muddy water and will not breed in cess pools.

The yellow fever mosquito does not fly far from its place of birth
probably not more than 75 or 100 yards or not farther than the houses
of adjoining neighbors, but they may be carried by ships and perhaps
by trains as well. The eggs are laid at or just above the water level
and will withstand drying for a long period—six or seven months.

AEDES VEXANS (Meigen) (=SYLVESTRIS)

Adult.—This is a medium sized, brownish black mosquito with
the proboscis unbanded and the thorax uniformly brown in color.
There is a narrow, dirty white ring at the base of each tarsal joint.
The abdominal bands are constricted at the centre so that a B-shaped
band is formed at the base of each abdominal segment more notice-
able on the terminal segments. This mosquito is found in North
America from Mexico to Canada, except on the Pacific Coast and
the far north.

Larva.—The head is widest behind the eyes, tapering towards
the front. Both pairs of dorsal head hairs are multiple. The scale
patch on the eighth segment is composed of from 10 to 15 scales in
an irregular double row, each scale sharply pointed at the tip and
finely fringed on the side. The breathing tube is about three times
as long as wide. The last two teeth of the pecten are separated from
the pecten and from each other.

Habits.—This is an early spring species breeding in woodland
pools or in open swamp pools. The common wood mosquito. It
seldom enters houses but may be troublesome near its place of
breeding.

AEDES SOLLICITANS (Walker)

Adult.—This is the salt marsh mosquito. It is golden brown
in color, the proboscis is centrally banded with white, the sides of
the thorax are silvery gray beneath a black edge. The bases of
abdominal segments have a wide yellowish white band which is
crossed longitudinally by a broad line of same color extending down
SUBFAMILY CULICINAE 45

the centre. The base of each tarsal joint is broadly ringed with
white and the last joint of hind tarsus is wholly white. It is found
along the coast from Mexico to New England.

‘Larva.—The larva is stout and chunky with a very short breath-
ing tube. Both pairs of dorsal head hairs are single and rather long.
The antennal tuft is small and arises from the middle of the antenna.
The scale patch on the eighth segment consists of from 20 to 40
scales, each scale being elliptical in shape and having a sharp terminal
spine and its sides fringed with smaller spines.

Habits.—The salt marsh mosquito breeds in salt or brackish
pools on tidal marshes. Aided by the wind it may fly long distances
from its breeding places (40 miles or more) and bites during the day
especially in the late afternoon.

AEDES TAENIORHYNCHUS (Wiedemann)

Adult.—This mosquito resembles Aedes sollicitans. It is smaller
and blackish with no dorsal, central abdominal stripe. The probos-
cis is ringed centrally with a narrow white band. The tarsi have a
narrow white band at the base but the last joint of the hind tarsus
is wholly white. In a form occurring in Florida the last joint of the
hind tarsus is largely black. (Aedes portoricensis Ludlow.)

Larva.—The larva resembles that of A. sollicitans but it has a
shorter breathing tube which is not more than one and one half times
as long as wide. Each scale of the scale patch is rounded at the tip
and is fringed with from 10 to 14 spines all alike but smaller towards
the base of scale. The spines of the pecten may be toothed on the
sides with three or four small teeth.

Habits.— Similar in habits to Aedes sollicitans.

Genus Psorophora (Robineau-Desvoidy)

In this genus there are two subgenera, Psorophora proper in which
the larvae are predaceous and Janthinosoma in which the larvae are
not predaceous.

Subgenus Psorophora. Larva.—The head is quadrate and
widest between the eyes. The antennae are set well back on the
sides of the head. The scales of the scale patch are large and
placed in a single row with a large patch of very small scales above
them. The breathing tube is large and swollen and tapers rapidly
from middle to tip.
46 INSECTS AND DISEASE OF MAN

Subgenus Janthinosoma. Larva.—The scales of the scale patch
are few and arranged on a band. The breathing tube is large and
swollen, tapering from middle to tip and provided with a double row
of a few coarse, strong spines. :

PSOROPHORA CILIATA (Fabricius)

Adult.—This is a very large mosquito. The proboscis is not
banded. The thorax has a broad central band of yellowish brown
scales. On each side of this band is a bare shining yellow area
wider at the posterior end. There are no spots or bands on the abdo-
men. The tips of all femora are fringed with dense scales. The
tibiae of middle and hind legs and hind tarsi are similarly scaled,
except for yellowish white bands at base of each tarsal joint. It is
found in the Eastern and Southern United States.

Larva.—A very large larva. The head is almost square but
broadest between the eyes, almost straight across the anterior margin.
The antennae are set well down along the sides. The mouth brushes
are large and set at the anterior corners of head. The breathing
tube is large and swollen and tapers from the middle to the tip.
There are from 20 to 30 very long slender teeth in the pecten with one
or two teeth at the base. Each of the large scales of the scale patch
has a long terminal spine with one or two smaller spines on each side.

Habits.—This giant mosquito breeds in temporary puddles.
Its larvae prey upon other larvae. The adult is a hard biter but
seldom troublesome except near its breeding place.

PSOROPHORA COLUMBIAE (Dyar and Knab)

Adult.—A large brownish black mosquito, spotted and mottled
with dull white. The proboscis has a broad dirty white band and
the wings are rather heavily scaled. The abdomen is not particu-
larly marked with bands or spots. The femora of the first pair of
legs are marked near the apex with a narrow white band; the middle
femora have almost no marking while those of the hind legs have a
broad white band near the apex. The tibiae are black with a white
spot near the base and many spots of white along one side. The
first tarsal joint of the hind legs has a broad white band in centre
which is less noticeable on the corresponding joints of the fore and
mid legs. All the tarsal joints are ringed with white at their bases
SUBFAMILY CULICINAE 47

except the fifth joints of fore and middle legs which are wholly black.
It is found in Cuba, the Bahamas, Florida, and Texas northward.

Larva.—The larva is large and chunky with short curved anten-
nae. The tuft is about at the middle of the antenna and the dorsal
head hairs are multiple. The scales of the scale patch are six in
number and attached to a band at their bases. Each scale has a
long terminal spine with a curved subapical spine and two or three
smaller spines along each side. The breathing tube is stout and
swollen, tapering from middle to tip, with three to five strong spines
in the pecten, each spine with one short tooth at the base. Thereis a
small paired tuft beyond the pecten.

Habits.— Larvae of this species develope rapidly in rain water
pools in warm weather. Eggs are laid in the dry mud at the bottom
and hatch almost immediately after contact with water. After
hatching the cycle is completed in five days. The adults are not
aggressive and troublesome only about their breeding places.

PSOROPHORA SAYI (Dyar and Knab)

Adult.—This is a wood species, a large metallic purplish mos-
quito with the tips of the hind legs only pure white. It is found in
the Atlantic and Gulf States as far North as Southern Ontario,
also in Cuba and the Bahamas.

Larva.—Similar to the larva of P. columbiae but the antennae are
very long, slender and curved, with the tuft at the middle. The
spines of the pecten are three or four in number. Each tooth has
a broad base and there are a number of smaller teeth at the base
of the long terminal spine. The scale patch is similar to that of
P. columbiae.

Habits.—Psorophora sayi breeds in woodland pools. Adults
are troublesome in the woods, never leaving the shade, but they bite
fiercely during the day.

TRIBE URANOTAENINI

Uranotaenia sapphirinus (Osten Sacken).—Larvae are com-
‘monly associated with Anopheles larvae in pools with much
vegetation. The larva holds itself parallel to the surface of the
water and, like Anopheles, often darts sideways when disturbed.
It can be differentiated immediately from Anopheles larvae by
the presence of a breathing tube. This tube is short, very slender
48 INSECTS AND DISEASE OF MAN

and not tapered. The head of the larva is pear shaped, and smaller
than the thorax as in Anopheles. The dorsal head hairs are single.
The antenna has a single hair replacing the usual tuft. The abdo-
men is provided with long star shaped tufts of hair at the sides and
on the back. The adults are seldom seen and do not bite. It is
found in the Eastern United States from the Gulf of Mexico to
northern New England.
CHAPTER VI
SUBORDER ORTHORRHAPHA
SECTION NEMATOCERA (CONTINUED)

Families Chironomidae, Simuliidae, Psychodidea

Certain other Families belong to the Section Nematocera and
are therefore related to the mosquitoes and not infrequently con-
fused with them. Many are a source of great annoyance. One at

 

 
  

    

JEM DIPE DIA
0% gC HIROMI DLE |

   

 

 

— AVERY —

 

Fic. 16.—Mosquito-like insects belonging to the families Chironomidae, Simuliidae
and Psychodidae. (1) Phlebotomus papatasii; (2) P. papatasii (natural size); (3) P.
papatasii (larva); (4) P. papatasii larva (natural size); (5) Culicoides pulicaris (Chiron-
omidae); (6) C. pulicaris (natural size); (7) Chironomus larva; (8) Attitude of a Simu-
lium; (9) Simulium reptans; (10) Larvae of Simulium. (From Stitt’s “Practical Bacteri-
ology, Blood Work and Animal Parasitology’ 7th. Edition.)

least is known to be a carrier of disease. The most important of
these Families are the Chironomidae or midges; the Simuliidae, sand
flies or buffalo gnats; and the Psychodidae or moth midges.

These insects are mostly small in size, many of them being able

‘to pass through the meshes of an ordinary mosquito bar. Many

49
4
50 INSECTS AND DISEASE OF MAN

of them are vicious biters and extremely troublesome. Some breed
in water, others require only moisture. :

The sand fly (Simulium repians) a member of the Family Simul-
idae was at one time thought to be implicated in the occurrence of
pellagra. Phlebotomus papatasii, a member of the family Psycho-
didae, is a carrier of Pappatici fever.

Family Chironomidae
(Midges)

Adult.—The Chironomidae are small to medium sized flies with
a small head often retracted under and covered by the thorax.
Ocelli are absent. The palpi are short with two to five segments.
The eyes are reniform (kidney shaped). The antennae have from
six to fifteen joints; they are pectinate in the male, simple and com-
posed of fewer joints in the female. There is no transverse suture on
the thorax. The wings are somewhat narrow and without a vein
along the posterior margin, the costal vein ending near the tip of the
wing. The fourth vein is often and the fifth vein is usually forked.
The legs are long and slender.

Egg.—The eggs are small, ovoid or long and pointed. They are
laid in water, sometimes on land, separately or in a gelatinous
string of mucous.

Larva.—The larval stage is usually spent in water—such as the
blood worms found in streams and stagnant pools. The larva has
13 segments. The head is directed downward and the mandibles
are well developed. Delicate processes (gills) may be seen on the
under surface of the 11th. and 12th. segments.

Pupae.—The pupae are free, floating in water or en the bottom.
Breathing tubes are on the dorsum of the thorax. =

Family Simuliidae
(Sand flies—Buffalo gnats)

Adult.—The Simuliidae are small, robust hump backed flies
without ocelli. The antennae are short, straight,
cylindrical, eleven jointed and without long hairs.
The palpi are small and incurved. The eyes of
the male are large and meet in the middle line,
FiG. 17.—Wing of while those of the female are smaller and separate.

Simulium  (Simuli- : , .
idae). The wings are broad (Fig. 17). There is no trans-

 
SUBORDER ORTHORRHAPHA 51

verse suture on the thorax. The legs are short and the posterior
tibiae and the first joint of the hind tarsi are
dilated.

Eggs.—The eggs are small, ovoid and yellow-
ish in color. They are laid on or under the
surface of water, in masses attached to blades
of grass, leaves, stones, etc.

Larvae.—The larvae always live in water
attached to objects by a posterior sucker. An-
teriorly there are two large fan-like processes.
This is characteristic. The larva may wander
in the stream still attached to an object by a
long spun silken thread. (Fig. 18.) ire

Pupae.—The larva spins a pupal case. The i ERE
pupa within it has long, chitinous, branched, respiratory filaments.

. . (From Folsom’s *“ Entom-
breathing tubes on each side of the thorax. ology,” 3rd. Edition.)

 

Family Psychodidae
(Moth midges)

Adult.—The Psychodidae are small flies without ocelli and
with the body densely covered with coarse hairs. The antennae are
long, twelve to sixteen jointed and little different in the sexes.
The thorax has no transverse suture and is not greatly arched. The

wings are broad and hairy. There are

EE six or seven longitudinal veins, the 2nd.
and 4th. forked, the 2nd. sometimes
forked twice. (Fig. 19.) There is no

Ta sie Wine of Pitchotomus  15c81 cell. The legs are long with hairs
(Psychodidae). or scales. Claws long. Male genitalia
large and conspicuous.

Egg.—The eggs are elongate, dark brown in color with longitudinal
dark, wavy lines, laid singly orin clusters in dark, damp places,
attached to a surface by a sticky substance.

Larva.—The larva lives in dark, damp places. The head is
large with large well developed mouth parts. The segments of the
body are spiny. Posteriorly there are two pairs of black caudal
bristles, one pair as long as the body.

Pupa.—The thorax is ridged. The larval skin is found adherent
to the last abdominal segment.
52 INSECTS AND DISEASE OF MAN

PHLEBOTOMUS PAPATASII SCOPOLI

This moth midge is about two mm. long. Its body is densely
covered with long grayish hairs. The second longitudinal vein has
two distinct branches (Fig. 19). The antennae have 16 constricted
joints, the third joint the longest. The proboscis is as long as the
head. The palpi have five segments of which the last segment is
the longest. It is a carrier of Pappataci fever.

Other members of the genus will carry Pappataci fever i.e.
Phlebotomus minutus and P. perniciosus. A general description of
one will apply to all but there are certain specific differences in the
wing venation, lengths of palpi, etc. According to Franc the forms
found in America differ rather markedly from the Old World forms.
CHAPTER VII

SUBORDER ORTHORRHAPHA

SECTION BRACHYCERA HOMODACTYLA

These flies because of their blood-sucking habits are either actual
or potential carriers of disease among man and the lower animals.

Of the families mentioned in the key, Tabanidae is by far the most
important as to it belong many blood-sucking flies variously called
horse flies, gad flies, deer flies, breeze flies, mangrove flies, green head
flies etc., which have a wide distribution. Many of them are vicious
biters and a source of great annoyance to man and animals, but,
up to the present, only a few of them are known to be actual vectors
of disease. The males do not bite; they subsist on the juices of fruits
and flowers.

Family Tabanidae

Adult. Anatomy. (Figs. 20 and 21).—In general the adult
Tabanidae may be described as having a head as wide or wider
than the thorax, convex in front, with very large brilliantly
colored eyes which almost meet in the male (holoptic) but are
much wider apart in the female (dichoptic). The eyes may be
bare (glabrous) or hairy (pilose). The antennae are three seg-
mented, the third or last joint having from four to eight annuli
or rings. To definitely observe this point in a given species it may
be necessary to clear and mount the antenna. There is no
arista. The proboscis varies in length in the different genera. It
may be very long or short. It is comprised of a labrum-epipharynx
and a hypopharynx, which when apposed form the blood channel.
There are also two maxillae with their fwo-segmented palpi, and
two mandibles. The maxillae which are serrate and the mandibles
which are blade-like, serve as the weapons to make and enlarge
the gash in the skin from which the blood is sucked. These
organs lie in the groove of a thick labium which terminates in
labellae containing a pseudotracheal membrane similar to that found
in the nonbiting, sucking Muscoidean flies. The mouth parts are

53
54 INSECTS AND DISEASE OF MAN

not inserted as deeply into the integument as are those of the mos-
quito but the blood is drawn by means of the gashes or incisions made

   
   
  

COMPOUND EYE

CaLtus=""

BASAL PROCESS OF
3% ANTENNAL JOINT...

 

ANTENNAE Heats

  
 
 

LABRUM-EPIPHARYNX-- =" ..-Pseupo TRACKER

MEMBRANE

oF
w

MANDIBLES :
Maxie NW

HyPOPHARYNX ~~

Fic. 21.—Head of Chrysops (C. discalis), side view showing mouth parts.

in the skin. In some species of Tabanidae there are shiny reddish
or brown areas between the eyes known as calli. The wings (Figs.
: SUBORDER ORTHORRHAPHA 53

22 and 23) diverge at the tips; they may be mottled and they have
five posterior cells, an elongate basal cell and a large discal cell. The
third longitudinal vein is bifurcate. The legs are large and strong.

Subeostal Cell as Vern

   

 

  

Fic. 22.—Wing of Tabanus (T. molestus).

The body is not highly colored but brown, whitish or yellowish with .
perhaps markings on the abdomen. The thorax and abdomen con-
tain hairs but no bristles. The empodium is pulvilliform (Fig. 24).

 

Fic. 23.—Wing Chrysops (C. discalis).

The Alimentary Canal.—The oesophagus is short. It begins at
the pharynx in the head and runs through the brain and the neck to
enter the thorax where it branches. One branch enters the midgut
through the proventriculus. The other branch traverses the thorax
to enter the crop. The crop is a thin walled bilobed sac analagous
to the oesophageal diverticula of other Diptera, but apparently not
the same in function as it is not clear that it acts as a food reservoir.
The proventriculus is a long flattened tube traversing the thorax. At
its anterior end it is broadened but posteriorly becomes narrow and
merges into the beginning of the mid gut. The midgut or stomach is
Hino TBA

Puovieer
:

 

INSECTS AND DISEASE OF MAN

  

Fi1G. 24.—Hind leg of Chrysops.

dilated with its narrowest end anteriorly.
It is located within the abdomen. The
hindgut is divisible into two parts an upper
part, the ileum, narrow and convoluted, and
a lower part, the colon, wider and straight.
It terminates in a pear shaped rectum in the
walls of which are six rectal glands or papillae.
The Malpighian tubules, four in number,
empty into the intestines at the junction
of the mid and hind gut. They lie coiled
and twisted within the abdomen.

The salivary glands are long and tubular,
lying in the lower part of the thorax on
each side of the proventriculus and extend-
ing into the abdomen where their ends are
somewhat dilated. The Tabanidae, like the
Muscidae with a pseudotracheal membrane,
have labial salivary glands located in the
proboscis.

Egg.— The eggs of this family are spindle
shaped and are laid in large masses, raft or
flask shaped, on the leaves and stems of
water plants or plants growing in marshy
ground or in stagnant or moving water. In
some species the eggs are deposited on
rocks above the water level of streams.
The, newly hatched larvae drop into the
water and immediately bury into the
mud.

Larva.—The larvae are aquatic or semi-
aquatic breathing by means of a caudal
siphon. They are spindle shaped and have
protuberances on the segments ventrally or
encircling them. They live in the wet mud,
feed on small animal organisms and also
destroy each other. When ready to pupate
they tunnel into the earth above the water
level and are found some distance away from
the water just below the surface of the
ground.
SUBORDER ORTHORRHAPHA : 57

Pupa.— The pupae are free and provided with rings of spines
projecting backward. :

Method of Control.—Kerosene spread on the surface of bodies
of water frequented by this fly, is said to be efficacious in reducing
‘their numbers.

CLASSIFICATION

The Family Tabanidae is divided into two subfamilies Tabaninae
and Pangoninae, the latter having spurs on the hind tibiae (Fig. 24)
and usually ocelli. The Subfamily Pangoninae is important because
it contains the Genus Chrysops Meigen, members of which are known
to transmit Loa loa and tuleraemia or deer fly fever. The former is
carried by Chrysops dimidiata and Chrysops silacea, West African
species, the latter may be transmitted by Chrysops discalis in the
United States.

Key to Some of the Genera in the Family Tabanidae

1. Hind tibiae without spurs at the tip; ocelli absent.

Subfamily Tabapipmge. oS RL 2
Hind tibiae armed with spurs at the tip; ocelli usually present.

Sublamily Pangonipme. |... 0. 0b Sh i a A 6

2. Thorax and abdomen with irredescent tomentum............. Lepidoselaga
Thorax and abdomen without irredescent tomentum.. i aa hl ES

3. Third segment of antenna with well developed basal process; wings Wate

oradlonded. Clan Tabanus

Third segment of antenna without basal process or the process rudimentary. 4

4. Antenna extremely slender first joint elongate.............. Hippocentrum

Antenna not especially slender nor first joint especially elongate. ........ 5

5. Front of female as broad as long; callus transverse........... Haematopota

Front of female marrow... 0. Lo di Ra a a Diachlorus

6. Third segment of antenna with five annuli the first of which is much i
than any of the following; proboscis short... ......0.....u a. us ry

Third segment of antenna with seven or eight annuli, the first of whith is te

little longer than the following ones; proboscis long or short...........8

7. Autenna longer than the head; second segment as long as or but little

shorter than the first; wings banded (Page 58).............. Chrysops

Antenna shorter than the head; second segment about half as long as

the first fot tan 0 ml es OR dh Bo Silvius

8.  Proboscis long often projected horizontally........................ 0.5, 9

Proboscis short, directed downwards; front of female broad, callus large. 10

9. Proboscis little longer than the head; palpi large and thick........ Cadicera

Proboscis usually much longer than head, often longer than the body;
front of female narrow... 0h vs sili An Ge, Pangonia
58 INSECTS AND DISEASE OF MAN

10. Upper corner of eye in female terminating in an acute angle; wings dark-
enedihasally. (0c a Goniops
Eye of female not acutely angulated above; wings hyaline. . . .. Z patolestes

Genus Chrysops

This genus may be distinguished from other members of the sub-
family Pangoninae by the relatively short proboscis and the long
antennae, longer than the head. There are three ocelli (simple eyes)
i addition to the two compound eyes which are golden green and

arked with purplish spots. The beautiful coloration can only be
observed in fresh specimens. The wings show a conspicuous dark
band and are kept half open when at rest.

The eggs of Chrysops are deposited upright in a single layer, on
leaves and stems of plants above or near water, or on exposed rocks
in streams. :

The larvae and pupae resemble those of Tabanus except that in
the larvae the last antennal segment is longer than the segment
which immediately preceeds it, while in the pupae the antennae
project beyond the head.

CHRYSOPS DISCALIS (Williston) (FIG. 25)

This is an American species which has been implicated in the
spread of tularaemia in Utah. (Chap. XXXI.) The fly has been

 

F16. 25.—Chrysops discalis. (From Stitt’s ‘Practical Bacteriology, Blood Work and
Animal Parasitology ’’ 7th. Edition.)

reported from Utah, Idaho, Montana, Wyoming and Colorado. It
is rather large, 1o to 11 mm. long, with a prominent hyaline space in
SUBORDER ORTHORRHAPHA 59

the discal cell. (Fig. 23.) In the female there are various sized
hyaline spots in all of the wing cells except the costal, marginal and
fourth posterior. The axillary cell is almost entirely hyaline. The
ventral surface of the abdomen is gray with three rows of black spots.
The male is much darker than the female.

CHRYSOPS FULVASTER (Osten Sacken)

This is another American species abundant over a number of
Western states. It may be distinguished readily from C. discalis
by the enlarged first antennal segment. The female but not the
male may have a hyaline spot in the discal cell as in C. discalis.

Family Leptidae

A few members of this family have been reported as biting man,
one, Symphoromyia grisea Meigen, in Italy, and another, Symphoro-
myia hirta Johnson, in Colorado. The latter is said to inflict painful
bites throughout the day in sunny weather.

SECTION BRACHYCERA HETERODACTYLA

The tribe is not of great importance from the standpoint of
preventive medicine as few of its members bite man nor are
their usual habits such that they would become

a menace.
One of the Phoridae, Phora femorata is found

in houses occasionally. Another, A phiochaeta ferru- pig. 26. — Wing of

ginea of India, West Indies and Central America, 4#piochacta (Phori-
- dae). (From Stitt's

has been reported as a cause of intestinal and “Practical” Bacteri-
van ology, Blood Work
and Animal Para-

pinus fenestralis or “window fly” is a household fly sitology” 7th. Edi-
which is not a menace to health. id

Members of the family Asilidae have been called ‘robber flies”
because they prey on adult insects frequently other flies.
CHAPTER VIII

SUBORDER CYCLORRHAPHA
SECTION ASCHIZA

Description.—This section is of little practical importance in
preventive medicine. In the Aschiza a lunula may be seen but the
ptilinal suture is absent; the third segment of the antennae is simple
and has an arista which is either terminal or dorsal; the third vein
is never forked; there are never more than three complete posterior
cells and the empodium is never pulvilliform.

Family Syrphidae

Larvae of Eristalis tenax (Drone fly) (Fig. 27) a member of the
family Syrphidae, have been reported as causing intestinal myiasis,
in some instances with severe symptoms.
The larvae of this fly are known as ‘“‘rat
tailed” larvae because of their long breath-
ing tube. Eggs are laid in liquid manure

or in filthy liquids in chambers, privies,

Fi16. 27.—Wing and rat- . . . :

tail larva of Eristalis (Syr- highly polluted ditch water and the like.

pase). Or DO iis The family Syrphidae is characterized by

LL Sa Suse the presence of a spurious vein simulating a

: ” longitudinal vein and caused by a thicken-

ing of the membrane of the wing between the third and fourth
longitudinal veins. The antennal grooves are absent.

 

SECTION SCHIZOPHORA

The section Schizophora is of great importance in preventive
medicine because it contains a number of flies, of which, some bite,
some like the house fly carry disease mechanically, while the larvae
of some may cause myiasis in one or another of its forms.

Description.—In the Schizophora the lunula is distinct and the
frontal suture is present; the antennae are three jointed and simple;

the arista may be plumose, pectinate or bare and is placed dorsally;
60
SUBORDER CYCLORRHAPHA 61

none of the longitudinal veins is forked and there are not more than
three posterior cells. ne

The Group is divided into two tribes, Acalyptratae and Calyp-
tratae. In the former the squamae are small at times rudimentary;
the thorax has no complete transverse suture and the subcostal
vein is often small or vestigial.

Muscoidea Acalyptratae

The family Sepsidae includes the cheese fly, Piophila casei
Linnaeus, which may cause intestinal myiasis, and the dung fly
Sepsis violacea, which may be found in houses.

Microneurium funicola de Meijere of the family Oscinidae is a
small fly of Java and Ceylon which hovers in front of the eyes and
is suspected of carrying the Koch-Weeks bacillus. Several species
of Hippelates found in the Southern United States dart at eyes and
other parts of the body in search of perspiration.

ave

137

 

Sem

Fic. 28.—Wing of Drosophila.

The Family Drosophilidae contains the Pomace flies, which breed
largely in decaying fruit. Drosophila melanogaster (= ampelophila)
is common. It may be attracted by excrement and therefore might
carry certain diseases of the intestinal type. Eggs are deposited on
overripe fruit in which the larvae develope. The larva is very small
and has projecting from the tail end two small fleshy processes
carrying the stigmal plates. No doubt these larvae are frequently
taken into the alimentary canal of man.

The Family Borboridae contains a small fly (Borborus equinus)
which may enter houses. It breeds in dung and other refuse.
CHAPTER IX

SUBORDER CYCLORRHAPHA (CONT’D)

MUSCOIDEA CALYPTRATAE

In the Calyptratae the squamae are well developed; the thorax
has a complete transverse suture and the auxiliary vein is normal.
These are collectively known as the Muscoidean flies included among
which are such important Families as Muscidae, Sarcophagidae and
Calliphoridae. It is therefore advisable before going further to
give some attention to their anatomy.

Adult Anatomy. The Head. (Fig. 29).—For the purpose
of more easily locating and describing the various parts and bristles
of the head it is convenient to regard it as having a superior and
inferior region, two lateral regions and an anterior and posterior
region.

The superior region, the highest part of the head, is known as
the vertex. Here are located the simple eyes or ocelli, usually three
in number. They are placed in a definite triangular space the
ocellar triangle or plate. The bristles arising from this plate are
called the ocellar bristles of which there are two groups the greater
and lesser ocellars. The former are a pair of bristles arising just
back of the most anterior ocellus. They diverge and point forward.
The latter consist of a varying number of pairs of bristles extending
backward from the insertion of the greater ocellars. The last pair
are sometimes called the post vertical bristles.

At the vertex of the head between the ocellar triangle and the
eye more or less behind its inner and upper corner are four bristles,
two on each side. The inner pair are known as the inner vertical
bristles. These are usually the larger of the two pairs and are
erect or convergent. The outer pair, those nearest the eye, are the
outer verticals and are erect or divergent. :

The anterior region of the head has been divided into two parts
an upper and a lower. The upper part is known as the front or
frons and is that area lying between the eyes and limited above by

the ocellar triangle and below by the arch of the ptilinal suture.
62
SUBORDER CYCLORRHAPHA 63

The rest of the anterior region extending downward from the front
to the cheeks laterally and to the lower margin of the head in the
middle line, is the face.

The area occupying the middle of the front between the ocellar
triangle and the arch of the ptilinal suture is known as the frontalia.

ocellr

t outer ocellars
!

inner vertical bristles

  
 
     
 
 
  

Sronfalia---. pia of outer vertical bristles

ad frontal bristles
i frontal orbital bristles
parafrontal ~. ’

Jurnufa.-.......

Chee ooeen--- Noor

havstellom

  

Jabellae

Fic. 29.—Head, front view, of a Muscoid fly to show anatomical parts. (Semidia-
grammatic.)

On either side of the frontalia i.e. between it and the compound eyes
are the parafrontals or gemovertical plates which extend upward
over the vertex to the epicephalon of the posterior region, and extend
downward to a level somewhat below the roots of the antennae to
become continuous with the parafacial areas. A row of bristles
extending downward on either side of the frontalia are known as the
frontal bristles or fromtals. Outside of the frontal row, that is
64 INSECTS AND DISEASE OF MAN

between the frontals and the eye and anterior to the vertical bristles,
may be seen one or more bristles which are termed the fronto-orbitals.
Other bristles lower down and not quite in line with the fronto-orbitals
are called the lower fronto-orbitals.

The ptilinal suture has been mentioned several times and as
it is a very important and characteristic feature of the Muscoid
flies it would be well to study it before going on to a description of
the face. This suture arches over the base of the antennae extending
downward on each side at times almost to the lower border of the
head. It has the shape of an inverted U. It is sometimes called
the frontal suture or frontal fissure, and it is the scar resulting from
the closure of the fissure through which the ptilinal sac was thrust
to force the cap off of the pupal case and thus permit the fully devel-
oped fly to emerge.

The ptilinal suture marks off an area in the middle of the face
which is known as the ptilinal area. In this area lie the three-jointed
antennae in the antennal grooves or foveae. They are separated from
the lateral arms of the ptilinal suture by the facialia, distinct ridges
which extend downward on either side to the lower margin of the head.
The lower end is prominent and is called the vibrissal angle. The
angle of each side has arising from it a prominent bristle—tke vibrissa.
~ Running along the facialia above the vibrissae are the facial bristles.
The lower median portion of the ptilinal area is the clypeus or facial
plate. This may extend upward as a ridge between the antennae.
Such a ridge is known as the facial carina. The clypeus is limited
below by the anterior border of the epistoma which surrounds the
epistomal orifice located in the inferior region of the head. It is
through this orifice that the mouth parts are projected.

Just above the roots of the antennae and bounded above by the
arch of the ptilinal suture is a small oval or crecentic depression,
the frontal lunule or lunula and between the roots of the antennae
is a small plate known as the antennal plate.

The area on the face between the lateral arms of the ptilinal
suture and the eye is the parafacial area or gena as it is also called.
It is limited below by the transverse impression and above becomes
continuous with the parafrontal area. Bristles arising from it are
called the facio-orbital bristles.

The transverse impression is a more or less distinct depression
which begins at the ventral arm of the ptilinal suture, runs across
the face and along the lower margin of the eye to its posterior or occipi-
Se

SUBORDER CYCLORRHAPHA ; 6

tal border. The cheek is that area between the lower border of the
eye and the oral margin. It is limited by the occiput behind and in
front merges into the face. Hairs arising from it and from the lower
border of the occiput comprise the beard. The term bucca is not quite
synonymous with cheek for the bucca is an area below the transverse
impression, under the eye, extending downward to the epistomal
orifice and backward to the great foramen.

The posterior region of the head, the occiput, contains the occipital
or great central foramen into which is inserted the neck. The area
above the foramen which is formed of a ridge-like sclerite seemingly
a continuation of the parafrontals, is called the epicephalon or para-
frontal-occipital ridge. The area below the foramen is the metacepha-
lon which is outlined by a distinct suture extending from the foramen
outward and downward on either side. Laterally the area is known
as the paracephalon or paracephalic plates. A pair of bristles placed
high up and back of the verticals are known as the occipito-centrals
while the small bristles in a row along the occipital border of the eye
are called the cilia of the posterior orbit, the orbit being the narrow Space
immediately contiguous to the eyes.

The lateral portion of the head is occupied by the eyes and cheeks.

The Proboscis.—The mouth parts are adapted to biting and
sucking or to suction only. In the latter case the proboscis of the
house fly may be taken as the type. (Fig. 30.) In those Muscoids
which suck only and which are of importance in Preventive Medicine
—the nonbiting Muscidae, the Sarcophagidae, the Calliphoridae etc.—
the proboscis is built on the same general principles only differing
in the details of construction.

The proboscis is divided into a proximal part, the rostrum, a middle
part, the haustellum; and a distal part the labellae.

The Rostrum.—The rostrum contains the buccal cavity and the
aspiratory pharynx together with the muscles which operate it, and
is that part of the sucking apparatus which in insects like mosquitoes,
horse flies, fleas etc. is permanently located within the head cavity.
In the house fly however it is capable of being extruded from and
drawn back into the head at will. The overlying integument is
attached above to the margins of the epistomal orifice and is continu-
ous below with the integument covering the haustellum. In the
accompanying figures to illustrate the mouth parts, the softer tissues,
muscles, integument and the like, have been dissolved out with
caustic leaving only the chitinous structures.

5

 
66 INSECTS AND DISEASE OF MAN

The most prominent structure in the rostrum is the fulcrum
which in shape has been likened to a Spanish stirrup iron. It serves
as a protection and gives attachment to the muscles which operate
the aspiratory pharynx. The fulcrum forms the posterior wall of
the aspiratory pharynx which runs along its entire length. The
anterior wall of the pharynx is composed of a thin chitinous plate

FuLcrRUM

  
 
 

 

LABRUM-=-EPIPHARYNX,
HYPOPHARYNX

   

ASPIRATORY
fo oonn PHARYNX

YSCAL _ .......
2 ere

   

.Buccat Caviry

FRESTOMAL...
TEETH

 
  
   

=e FURCA :
: %
i 9)
Couriring PART OF EXTERNAL WALL J

FSEUDOTRACHEAL
MEMBRANE

  

FiG. 30.—Proboscis of Musca domestica.

thickened down its centre to give better insertion to the muscles
which operate it. The aspiratory pharynx begins below at the buccal
cavity and ends above in the oesophagus.

The anterior wall of the buccal cavity and the distal extremity of
the epipharynx are connected by a short membrane. A similar
membraneous connection exists between the posterior wall of the
buccal cavity and the hypopharynx. The buccal cavity is therefore
in direct connection with the food canal in the haustellum. The
single jointed palpi are not attached to the fulcrum but arise from
the integument.
SUBORDER CYCLORRHAPHA 67

The Haustellum.—The haustellum begins below the buccal
cavity. It is the haustellum which is folded up under the head and
entirely or partially concealed when the rostrum is drawn into the
head. The haustellum is analogous to the fleshy labium of the
mosquitoes and horse flies. Its posterior wall is composed of a
plate of chitin, broad and slightly convex in its posterior aspect.
This is the mentum. Anteriorly there is a long much narrower
chitinous plate, convex in its posterior aspect forming a gutter—the
labial gutter—in which rest the labrum-epipharynx and the hypo-
pharynx. The mentum and labial gutter are connected by mem-
branous tissue and between them are the soft parts, muscles, labial
salivary gland etc. The gutter is thickened at each edge forming
the lateral rods, which articulate distally with the discal sclerite.
The labrum and epipharynx are closely attached to each other and
freely movable and when apposed to the Aypopharynx which lies
beneath them, form a channel through which the fluid food passes
when sucked up by the action of the aspiratory pharynx. The
hypopharynx is not freely movable but is attached to the labial
gutter throughout most of its length. It is channeled to carry the
salivary juice.

On each side of the proximal end of the labrum-epipharynx there
is articulated a chitinous rod—apodeme—which passes upward into
the rostrum outside of the fulcrum. The apodemes serve for the
attachment of muscles which are concerned with the movements of
the haustellum and more particularly the labrum-epipharynx.

The Labellae.— The labellae begin at the discal sclerste. This
is a somewhat V-shaped slender piece of chitin articulating about the
centre of each of its arms with the lateral rods of the labial gutter
at their distal extremities. It surrounds the mouth or stoma into
which empty the large ducts which collect the fluid food from the
smaller channels in the pseudotracheal membrane,—the most con-
spicuous structure in the labellae. Surrounding the mouth and
arising from the discal sclerite are a number of very small weak teeth
known as the prestomal teeth. These are not sufficiently stout to
abrade the skin but in the biting Muscidae are greatly modified so
that they are adapted to cutting as will be seen later on. The
labellae are articulated to the haustellum through the discal sclerite
above and another sclerite, the furca, below. These two articulations
permit of the free movement of the labellae.
68 INSECTS AND DISEASE OF MAN

This sucking proboscis has been evolved from the proboscis
of the biting Muscoidean flies. Following the evolution backwards
one should next study the proboscis of Philaematomyia, a genus
not found in the United States. (Fig. 31.) In this Genus the
similarity of parts as compared to the proboscis of the house fly can
be readily seen but there is a marked change in size, shape and density
which adds rigidity and increases strength, for at least one member
of this Genus can actually scarify the skin and draw blood.

As in Musca the rostrum can be drawn into the head and the
haustellum folded up beneath but the latter has become narrower

INTER DENTAL
ARMATURE

 

PSEUDO TRACHEAL MENBRANE |

Fi1G. 31.—Proboscis of Philaematomyia.

and more prominent posteriorly because of the greater convexity and
deepening of the mentum. The labial gutter has become narrower
and the labial rods thickened and strengthened. The discal sclerite
is markedly thickened and its articulation with the lateral rods much
firmer. The prestomal teeth have been reduced in numbers to about
eight and each is increased in size and strength. Between them
may be seen a number of very small blade-like processes, the inter-
dental armature. The pseudotracheal membrane is reduced as
compared to Musca but functions in the same way collecting the
blood or serum which exudes following the scarifying action of the
prestomal teeth.

The next example of a proboscis forming a true biting apparatus
may be learned from a study of the mouth parts of Stomoxys. (Fig.

32.)
INTEROENTAL

ARMATURE

SUBORDER CYCLORRHAPHA 69

Like Musca the rostrum can be drawn into the head but the
haustellum has become greatly elongated and highly chitinized so
that it sticks out prominently in front of the head when the proboscis
is at rest. The labellae are greatly reduced in size and the pseudo-
tracheal membrane has practically disappeared. A closer study

  

.....AspIRATORY
PHARYNX

Apoeme

LABRUM-EPIPHARYNX

    

 

HvpoPuARYNX

  
 
 
 
 
  

LABIAL GUTTER

   

DISCAL SCLERITE MENTUM

 

wel’
SUT FuRcA
 PRESTOMAL TEETH

Fi1G. 32.—Proboscis of Stomoxys calcitrans.

shows that the mentum is narrowed and elongated, tapering towards
the distal extremity and bulging towards the proximal end. It and
the labial gutter are closely connected by a narrow strip of membrane.
The hypopharynx is freely movable. The discal sclerite is power-
fully built forming a strong collar around the stoma. The prestomal
teeth are sharp pointed cutting teeth each one having a secondary
cutting point towards the base. They are united to each other at
their bases where they are attached to the discal sclerite and between
them may be seen the interdental armature made up of tiny leaf-like
blades. In addition there is a series of very small rod-like processes,
a pair for each tooth, which are probably sensory in function.

 
 
  
 
70 INSECTS AND DISEASE OF MAN

In biting the prestomal teeth are everted and partially rotated
which operation acting repeatedly and with great rapidity bores a
way into the skin.

Except for the Genus Philaematomyia which has already been
mentioned the proboscis of all biting Muscidae is constructed on
the same general principle but differs in details in the various Genera.
The proboscis of Glossina is probably the most highly specialized
of the entire group.

Svblateral Row

Humeral callus.
¥ MHumeral

  
  

0 ——@-r—gp-f-----

 
  
   

 

 

 

 

0, ...Post Hunieral
Aterior dorso- central.
Anizrior acosticlial.. .4..... . ©... .\.....
; ..-Presulural

Prealar callus... . |]. --.Notoplevral
PoSIErior aetostichal Jo onus. covdpinnnd 50k fT NY Supra-alar
Posterior dorso -certral |. ............]

2 I ntra-alar

..-Postalar
Postalar callus. ......\E
Bi Prescutellar
WEE | he Marginal
Discal scutelbars =~ “Subapical

= “Apical
F16. 33.—Dorsal view of thorax of fly of the Muscid type to show grouping of macro-
chaetae (bristles) (Semidiagrammatic).
The Thorax. (Figs. 33 and 34).—Itseems unnecessary toattempt
a detailed description of the thorax as a study of the illustrations
will prove much more satisfactory. Suffice it to say that the meso-
thorax is by far the largest segment of the thorax. Dorsally it is
divided by a transverse linear impression, (a depressed line) the
transverse suture, into an anterior and posterior portion, the pre-
SUBORDER CYCLORRHAPHA . 7%

scutum and scutum respectively. Posterior to the latter is the scufel-
lum, more or less triangular shaped and marked off from the scutum
by another transverse linear impression.

The bristles of the scutellum may be margina i.e. when they are
borne on its edges. They may be discal when they are placed on
the surface of the scutellum away from its margins. They may be
apical when they are located at the tip of the scutellum and sub-
apical if they are just anterior to the tip. When present, there is
usually not more than a pair of either apicals or subapicals.

Qnfterior and posterior dorsg-central
Qnterior and posterior acrostickal + *

  
  
    

 

Scutellvm,

Homeral ......{... 5x0. saline
Griferior spiracle 5 pe spiracle
Proplevr a. -«w-uv-enen

Mesoplevral ..-* -. Hypoplevral

Proplevral pt

Anterior sterno pleural re Al Comp

Preropleiral..... # S
‘Posterior sterno plevral

Fi. 34.—Lateral view of thorax of a Muscoidean fly to show bristles and other anatom-
ical parts (Semidiagrammatic).

The Wings. (Fig. 35).—A few words in connection with the
illustration will suffice. Particular attention should be paid to the
first posterior cell which lies between the third and fourth longitudinal
vein; the discal cell which is bounded by the fourth and fifth longi-
tudinal veins and the posterior cross vein. The locations of the
basal cells should be noted.

The fourth longitudinal vein should be studied with regard to its
degree of angulation or bend and the degree to which it closes the
first posterior cell. The point on the wing margin at which the
costal vein ends should be noted. It will be remembered that unlike
the costa of mosquitoes the costal vein in the flies under considera-
tion does not extend all round the wing margin. The presence or
72 INSECTS AND DISEASE OF MAN

absence of the auxiliary vein should be noted. The stem vein should
be studied. The stem vein is a thick vein toward the base ot the
wings which is the basal section of the first longitudinal vein and
separated from the rest of the vein by a suture about opposite the
humeral cross vein. It may carry a row of hairs when it is said to
be ciliated. In some flies a costal spine is present. This is a stout
bristle on the costal vein near the end of the auxiliary vein.
Costar VEIN

HUMERAL CROSS VEIN rid
AUXILIARY VEIN i 157 LONGITUDINAL

STEM VEIN

2%P LONGITUDINAL

 
 
 
  
 

382 LONGITUDINAL
i A™LoNeIruDINAL

- «ooo TIP OF WING

"5 LONGITUDINAL

6™ LoNGITUDINAL OR ANAL VEIN

Imm

Fi16. 35.—Wing of Liuicilia.

The squamae (calypters) are a pair, an upper and a lower, of
membraneous expansions from the root of the wing extending
backward over the halteres. The squamae may be provided with:
a fringe of cilia. Two scales at the extreme base of the costa may be
present in some flies and are known as the epaulet (tegula) and
subepaulet (basicosta). The latter which is the outer is easily seen.
The former may be so close to the body as to be seen only with
difficulty. The vestiture and color of these may furnish valuable
diagnostic points. The subcostal sclerite is a more or less triangular
structure on the lower side of the wing at its base.

The Abdomen.—The number of segments that can be recognized
as such externally varies considerably—from four or five to seven.
The terminal segments, have been greatly modified to form structures
concerned with reproduction that is, the clasping organs of the male
and, in certain flies, the ovipositor of the female. The clasping
organs (Fig. 48) have great taxonomic value as they differ in
shape and size in the different species. The external genitalia of
the female can not be used in differentiating species as they do not
SUBORDER CYCLORRHAPHA 73

posess distinctive characters. The extent of their development
depends upon the breeding habits of the insect. The house fly for
instance has an ovipositor made up of the last four segments of the
abdomen forming a long narrow tube large enough to admit the
passage of an egg. When in use it is thrust out of the body and
directs the egg to a favorable location in the breeding material.
When not in use it is drawn inside of the abdomen, one segment
telescoping into the other. In those flies which give birth to a living
larva the ovipositor may be very inconspicuous or may be no more
than a mere slit at the end of the abdomen.

Bristles on the abdominal segments may be marginal or discal.

Alimentary Tract.— The alimentary canal is longer than that of
the mosquitoes or Tabanidae because of the elongation of the mid-
gut or stomach. There is no dilated portion as seen in the Orthor-
rhapha, but the capacity and absorptive surface are maintained if
not increased by the greater length. A proventriculus serves as a
valve between the fore-gut and the mid-gut. The oesophagus is
short. It passes through the brain and the neck into the thorax
where it is in communication with the proventriculus ventrally.
Here the duct of the crop begins. The crop is a large thin walled
sac which is filled when the fly is feeding, its contents being passed
on slowly to the stomach. It lies beneath the stomach and when
full occupies quite a large part of the abdomen.

A curious structure is the peritrophic membrane, a thin walled
tube within the lumen. of the mid- and hind-gut, having its origin
at the proventriculus and terminating at the anus. There is thus
an inner tube separating the contents of the gut from the epithelium
lining the gut. It is in contact with the lining cells but is not
attached to them. The Malpighian tubes empty into the alimentary
canal at about the junction of the mid- with the hind-gut. These
are four in number the two on each side emptying into the gut by a
common duct. The kind gut is not elongated. It empties into the
rectum which has four rectal papillae.

The salivary glands are found in the thorax extending into the
abdomen. They are long and tubular, sometimes coiled, lying free
in the body cavity (the haematocoele) bathed in the blood and at
places in contact with the walls of the gut. The ducts from the two
sides unite in the head to form a common duct which passes down the
rostrum outside of and posterior to the fulcrum to become continu-
ous with the salivary canal in the hypopharynx. In flies having a
74 INSECTS AND DISEASE OF MAN

pseudotracheal membrane, salivary glands are also located in the
haustellum—the labial salivary glands. They are at its lower end
lying near the anterior surface and empty on the internal or oral
surface of the labellae.

The Larva. (Fig. 36).—The larva of the Muscoidean flies is
an active, voracious, legless, wormlike creature, without a distinct
head (acephalous). It is usually tapering, the small end being the
anterior or head end while the posterior end is broad. From the
anterior end project two dark hook-like processes, the mandibles,
which are sometimes fused into one. Above these are two papillae.
The second segment from the anterior end has on each side, project-
ing hand or fan-like structures with a varying number of terminal

STIGMAL
FIELD

ApicaL
SPINES :

 
  
 
 

ANTERIOR
SPIRACLES

    

VENTRAL ‘Fusirorm AREA AE
Hooks” %

Z Fusi REA 3
ANAL TUBERCLE LATERAL FUSI FORM ARE: PrRb1aE

Fi1G. 36.—Larva of a Muscoidean fly to show certain parts used in identification.

divisions depending on the species. These are the anterior spiracles.
The posterior, expanded end of the larva has on its posterior surface
two chitinous plates each with three slits which vary in appearance
according to the species and are only truly characteristic in fully
matured larvae. They are the stigmal plates. The area carrying
these plates may be sunken to form a pit and may or may not be
surrounded by small fleshy tubercles. There may be a rounded
protuberance or button at the base of each plate. The stigmal plates
may also be observed in the pupal stage on the posterior end of the
pupal case. The roughened areas to be seen on each segment are
known as the fusiform areas. If ventrally situated, the ventral
fusiform areas; if laterally, the lateral fusiform areas. The roughened
area may extend completely around a segment. The roughening
is due to the presence of minute spines or hooklets. Some larvae
may be provided with spinous processes or fleshy processes other
than the tubercles already mentioned.

The Pupa.— When fully grown the larva seeks a suitable place to
pupate, usually loose soil. Here pupation takes place by a contrac-
SUBORDER CYCLORRHAPHA ; 7%

tion and hardening of the larval skin producing a puparium. Such a
pupa is said to be coarctate. The puparium is rounded, elongate-
ovoid in shape and varies in color from dark gray or yellowish to
dark brown. The pupa is quiescent and takes no food. The adult
emerges from the pupal case through an opening made by forcing
off a small circular cap in the head end.

Family Oestridae

The Oestridae are the “bot” or “warble” flies. They are very
hairy and the mouth parts are rudimentary. The antennae are
inserted into round pits.

Larvae of these flies are parasitic and spend their existence either
under the skin, in the nasal or pharyngeal cavities or in the alimentary
canal.

The following simple key will serve to distinguish the more tuner

tant genera of the adult Oestridae
1. Fourth longitudinal vein straight or curved towards hind margin of wing;

first posterior cell widely open; arista bare. ................. Gastrophilus
Fourth longitudinal vein bends towards anterior margin of wing; first pos-
terior cell closed or narrowed........... a LE a aE 2

2. Fourth longitudinal vein joins the 3rd. vein before the termination of the
latter, entirely closing the 1st. posterior cell which is petiolate.

Oestrus

First posterior cell more or less narrowed but not closed. ................ 3
3. Arista bare; proboscis rudimentary... ....o.i bv svi ian ane Hypoderma
Arista haired on upper side; proboscis well developed................... 4
4: Tarsiislender not haley. oo... von Ul ae ned BERR 00 Cas Dermatobia
Mars broad, fattened, Dalry... ... Ii. . ohne vas ale vs inva sisate Cuterebra

Genus Hypoderma
(Warble flies)

Hypoderma bovis de Geer, may be mentioned as an example of
dermal myiasis. The eggs of this fly are deposited on the skin of
cattle attached to the hairs. Hatching requires about a week.
It was thought that the larvae were then licked off and swallowed
thus reaching the oesophagus where they remained a considerable
time between the mucous and muscular coat, finally making their
way to the subcutaneous tissue of the back where further growth
took place producing lumps in the skin. Later investigators say
76 INSECTS AND DISEASE OF MAN

that the larvae perforate the skin near where the eggs are laid and
then migrate to the subcutaneous tissues of the back, and that lick-
ing by the animal’s tongue destroys more eggs than it introduces into
the mouth. When ready to pupate the larva emerges through a
small opening which it makes in the skin, and then drops to the ground
which it enters to become a pupa. The pupal stage last from three to
five weeks.

Another warble fly of cattle in the United States is Hypoderma
lineata Vill. :

The warble flies are of importance commercially. The presence
of the larvae not only interferes with the nutrition of the animal but

 

Fic. 37.—Stigmal plates of Hypoderma bovis.

causes the hide to become of inferior quality. At times great finan-
cial loss is sustained. Both species are reported for man.

A somewhat similar condition is occasionally observed in man
giving rise to what has been called “creeping eruption’ because the
larva moves from place to place in the subcutaneous tissues. It is
rare in the United States.

Other flies of the Genus Cuterebra attack squirrels and chipmunks
(C. emasculator) and rabbits (C. cuniculi).

’

Genus Dermatobia

The larva of Dermatobia hominis, a fly of tropical and subtropical
America, occassionally gains access to the subcutaneous tissues of
man where it grows producing an abscess. When fully grown it
emerges to pupate in the ground. Itis thought that the eggs of this
fly are attached to the ventral surface of the abdomen of a mosquito
(Psorophora) or to other flies or to ticks and that when ready to
SUBORDER CYCLORRHAPHA 77

/

hatch they are left on the skin at the site of the wound made by the
bite. The larva (Fig. 38) is pyriform in shape and the thoracic
segments are armed with hook-like spines pointing backwards.
These larvae are normally found in the subcutaneous tissue of lower
animals and their presence in man is accidental, but in some regions
not uncommon.

 

 

Fi1G. 38.—Larva and stigmal plates of Dermatobia hominis.

Genus Oestrus
(Bot flies)

As an example of nasal infestation mention may be made of
Oestrus ovis Linnaeus, the sheep bot-fly, which lays its eggs around
the nasal cavities of sheep. After hatching the larvae make their
way into the nose and enter the sinuses where they grow attached to
the mucous membrane. When fully grown they leave the nostrils
and drop to the ground which they enter to become pupae. This
larva has been found in the nasal cavities of man.

Genus Gastrophilus
(Bot flies)

As an example of intestinal myiasis mention may be made of
Gastrophilus equi Fabricius, which deposits its eggs on the hairs of
horses. Licking by the horses tongue keeps the eggs moist and has-
tens hatching. The larvae are licked off and swallowed thus enter-
78 INSECTS AND DISEASE OF MAN

ing the stomach where they attach themselves to its walls and grow.
When fully grown they pass out of the intestines with the excrement,
enter the ground and pupate. (Fig. 39.) Gastrophilus hemorrhoid-
alis Linnaeus is another horse bot fly. Both species are common in
the United States.

Fic. 39.—Stigmal plates of Gastrophilus equi.

A separate Family has been made for Gastrophilus, namely Gastro-
philidae. It is here mentioned under the Oestridae because of its
habits.
CHAPTER X °
MUSCOIDEA CALYPTRATAE (CONTINUED)

FAMILY MUSCIDAE

Key to Some of the More Important Genera of the Muscidae

. Proboscis completely retractile and capable of being flexed back under the
head and completely or partially concealed; labellae well developed;
haustellum not forming a conspicuous, elongated, tapering projection
in'front:ol the head (Figs. 30:& 37)... oo viv nh ns 2

Proboscis only partially retractile, not capable of being concealed under
the head; labellae absent or vestigial; haustellum forming a conspicu-
ous projection in front of the head (Fig. 32).......... chu. duu un 5

. Proboscis capable of being only partially concealed under the head; mentum
always plainly visible as a strongly convex, chitinous plate; minute
examination shows that the prestomal teeth are not numerous, are
thickened and elongated and arranged in one row, that the pseudotracheal
membrane is present and functional and that the hypopharynx is free
from the labial gutter (Fig. 31).

Philaematomyia Austen, 1909 (Page 86)

Proboscis capable of being entirely concealed under the head; mentum
not prominent; minute examination shows that the prestomal teeth
are numerous, weak and arranged in three rows, that the pseudotracheal
membrane is well developed and that the hypopharynx is only partially

freeiromthelnblal gutter... |. cui a a ar a LS 3
. Dark grey to black flies, never metallicincolor................c....... 4
Thorax, abdomen, cheeks and vertex shining green, lustrous..............

Cryptolucilia (Page 85)
. Fourth longitudinal vein bends sharply; 1st. posterior cell almost closed
(Fig. 40); thorax marked with four longitudinal stripes or bands (some-
times fewer) of about equal length........ Musca Linn (Page 80)
Fourth longitudinal vein bends gradually; first posterior cell widely open
(Fig. 41); thorax marked with two short, black stripes and two fainter
Inveral styipes: 0. ln do ln eR a Muscina (Page 83)
. Arista with branched bristles on its upper side; 4th. longitudinal vein with
two angles and discal cell “cleaver” shaped (Fig. 43); pupa with two
characteristic protuberances behind. ..... Glossina Wiedemann (Page 87)
Arista with simple bristles on one or both sides; fourth longitudinal vein
not as above; discal cell normal in shape (Fig. 40); pupa without pro-

tuberances behind, resembling the pupaof Musca..................... 6
. 1 Arista: with bristlesronupper side only... 0 ul Ld oi i an 7
Arista with bristles on both upper and lower side...................... 9

79
8o INSECTS AND DISEASE OF MAN

7. Palpi very short much shorter than proboscis, entirely concealed when
rostrum 1s retracted; haustellum long projecting well beyond head;

1st. and 3rd. longitudinal veins ciliated at base (Fig. 42).
Stomoxys Geoffry (Page 86)
Palpi as long or longer than proboscis, always visible when proboscis is at

8. First longitudinal vein nude, 3rd. longitudinal vein ciliated at base; palpi
club shaped, as long as proboscis and somewhat curved upwards; pro-
boscis short and blunt; first posterior cell narrowed; medium sized,
zobugh esr abo tas ra tlk Cn ST eRe Stygeromyia Austen

First and 3rd. longitudinal veins nude at base; (Fig. 47) palpi straight and
longer than proboscis; proboscis long and pointed; first posterior cell
widely open; small flies. ...Haematobia Robineau-Desvoidy (Page 88)

9. First and 3rd. longitudinal veins ciliated at base; fourth longitudinal vein
feebly curved; 1st. posterior cell widely open; palpi as long as proboscis,
feebly club-shaped; sexual dimorphism marked.

: Lyperosiops Townsend (Page 88)

First and 3rd. longitudinal veins nude at base........................ 10

10. Palpi strongly spatulate; 4th. longitudinal vein feebly curved; 1st. posterior
cell widely open; sternopleurals 2.

Bellolarynx Austen 1909

JPalpi feebly spatulate; 4th. longitudinal vein strongly curved; 1st. posterior

cell narrowly open; sternopleurals 2, the anterior small and at times

SEN eel Haematobosca Bezzi 1911

~The Non-biting Muscidae
Genus Musca

Members of this Genus have their mouth parts adapted to suc-
tion only.

The Genus Musca has been divided into two groups, the non-
blood sucking species and the blood sucking species (haematopha-
gous). In the first group fall the domestic species which live on all
kinds of animal and vegetable foods. This group includes Musca
domestica Linnaeus.

The second group includes the wild species of Musca, which
while they can not bite, they suck the blood which exudes from the
bites of biting flies like Tabanus and Stomoxys, or serum which
exudes from sores. This group includes Musca autumnalis. Mem-
bers of this group breed in dung and probably not in human excre-
ment and therefore would not be so important as the truly domestic
Musca which may breed in human excrement. :
MUSCOIDEA CALYPTRATAE

 

 

   

1F POSTERIOR CELL

4 | ONGITUDINAL
VEIN

FiG. 41.—Wing of Muscina stabulans.

 

 

Fi1G. 43.—Wing of Glossina morsitans.

 

81
82 INSECTS AND DISEASE OF MAN

MUSCA DOMESTICA LINNAEUS

The thorax of the house fly or “typhoid” or “filth” fly as it is
sometimes called, has four equally broad stripes on the dorsum,
running longitudinally. * Dorsally on the abdomen there is a median
brown line and laterally a large yellow area. The arista is feathered
dorsally and ventrally. The fourth longitudinal wing vein bends
with a decided angle distally and the first posterior cell is almost
closed. (Fig. 40.)

Life History.—The house fly lays its eggs, 120 or more in a batch,
preferably in fresh stable refuse, but it may breed in human feces,
garbage or other organic matter. It is not unlikely that a house
fly which has actually bred in human excreta is a much greater
menace to health than one which developes in manure and then
merely rests on the surface of human excreta to feed or oviposite.
The egg hatches within one or two days into a larva or maggot, a
worm-like creature, which reaches its full development by succes-

 

Fi1G. 44.—Larva of Musca domestica.

sive moulting, in five to fourteen days. The larva (Fig. 44) is very
active. When full grown it migrates to the bottom and towards the
edge of the pile of organic matter, where it burrows into the ground
if the soil is not too hard, to become a pupa inclosed in a hard, brown
case. This is a typical coarctate pupa. In this stage which lasts
from three to five days the insect is quiescent. The fully developed
adult fly emerges through a circular split in the head end of the
puparium or pupal case. Complete development from the time
the egg is laid until the adult emerges requires from 10 to 20 days
depending upon atmospheric temperature, and four days after
complete development the females are capable of laying eggs.

Eggs are not laid in manure after fermentation has well begun,
probably not after the first twenty four hours as the high temperature
in the centre of the manure pile is inimical to the life of the larvae.
Sunlight and drying are also unfavorable to their development. In
order to pupate larvae will burrow into old manure if earthy
material is not available or where the soil is too hard.
MUSCOIDEA CALYPTRATAE 83

Extermination.—The logical way to exterminate flies is to elimi-
nate their breeding places. Such procedure should go hand in hand
with the screening of foods and of human habitations and privies.

Manure should invariably be collected from stables not less
than every seven days, or before the larva has had an opportunity
to pupate. If there be no connection with the ground development
does not progress satisfactorily. Therefore a tight platform on
which to pile the manure is advisable.

Where it is not possible to have frequent collections a light-tight
manure bin should be constructed with a tight fitting cover, screened
ventilation openings, and drainage into a sewer if available. The
bin should have a concrete floor. In order to catch any flies which
may develop within the bin it has been suggested that a fly trap
made of fine wire mesh be constructed on the top, communicating
by a small opening with the interior of the bin. As the fly is helio-
tropic it will naturally seek the light and pass from the dark interior
to the trap outside. The trap may be detached from time to time
and submerged in a pail or tub of water.

The use of chemicals, such as borax, petroleum, chloride of lime,
etc., to prevent the breeding of flies in manure does not seem to
produce the practical results that were expected. According to the
United States Department of Agriculture, sodium borate or crude
calcium borate are perhaps the best chemicals for the purpose, used
in quantities of 0.62 pound borax or 0.75 pound crude calcium borate
to every 8 bushels of manure, and applied immediately upon its
removal from the stable. The chemical should be sprinkled par-
ticularly around the edge of the pile, and then wet with two or three
gallons of water. This treatment must be repeated with each
addition of fresh manure. The chemical in the amounts recom-
mended does not destroy the fertilizing properties of stable manure.

The Richmond Health Authorities, taking advantage of certain
factors in the life history of the fly, have developed what they
have called a ‘“maggot” trap. This depends for its efficiency upon
the fact that larvae will crawl downward in the pile of manure in
an effort to reach the ground to pupate and that the adult female
will not lay her eggs in manure after fermentation has well begun.
The maggot trap is essentially a manure bin without a cover and
with a bottom of coarse mesh heavy wire. After the eggs develop
larvae make their way downward and passing through the wire
mesh fall into a concrete basin below which is kept full of water.
84 INSECTS AND DISEASE OF MAN

Here they drown. A film of oil should be kept on the surface of the
‘water to prevent mosquito breeding. Two bins are usually in use,
one in process of filling while the other, already full, is awaiting the
migration of the larvae before the contents are removed.

Where possible it is sometimes best to burn stable refuse with
the help of crude oil if necessary, thus effectually destroying eggs and
larvae. It may be burned in windrows, or placed on a grating
of heavy iron such as railroad iron, laid across a small gully, forming
an improvised incinerator.

Manure may be spread in a thin layer on the ground so that
sunlight may reach it and fly development will not take place. It
may afterwards be plowed under as a fertilizer.

Remedial measures directed towards the eradication of flies
after they have developed are rather hopeless. It then becomes
necessary for individuals to protect themselves against the pest by
an adequate screening of domiciles, privies, and food thus breaking
the vicious circle of flies, feces, food and persons. Chemicals can
be used in privies.

A swat-the-fly campaign after the insect has multiplied in great
numbers is futile, although it may be possible that killing adult
flies in the early part of the breeding season when there are but few
and before they have had an opportunity to oviposite, may help to
eliminate the pest. Various schemes have been devised to trap
the adult fly with more or less success. The general principle
involved is that a fly will enter a receptacle where food is present
guided by the sense of smell, and will emerge because of its tendency
to seek the light. This point may be taken advantage of in the
construction of window screens. A space of one fourth of an inch
should be left between the upper wooden strip of the frame and the
screening material. A fly gaining access to the house through open
doors etc., will crawl upward and out through this opening. In
localities where mosquitoes are also a nuisance or a danger, screens
should be made of No. 16 to 18 mesh. Where flies only are to be
excluded a coarser mesh will serve the purpose. A fly-swatter is a
convenient implement to have available. Fly traps are also
useful.

Sticky fly paper is an excellent means of catching flies. A sticky
substance which may be spread on paper, on spiral wire or on a
wire coil, is made by dissolving 20 pounds of clear resin in 5 quarts
of castor oil. Heat and stir until a clear solution is obtained. For
MUSCOIDEA CALYPTRATAE 85

household purposes proportionately smaller amounts should be
made up. ; :

Garbage should be stored in water-tight, closely covered, metal
receptacles, both rat proof and fly proof, and should be collected
and incinerated at least twice a week.

Genus Muscina

Muscina stabulans, known as the non-biting stable fly, is a more
or less common fly and may come into the house. It breeds in dung
and decaying animal and vegetable matter but unlike the house fly
its larvae are mainly carnivorous feeding on other larvae in the
decomposing material.

 

 

ANS EE FR, OY

 

 

 

F1G. 45.— Insects in which the adult stage is important. (1) Stomonys calcitrans;
(2) S. calcitrans, larva; (3) Tabanus bovinus; (4) Tabanus larva; (5) Glossina palpalis;
(6) G. palpalis, side view; (7) G. palpalis, pupa; (8) Glossina, palps and arista. (From
“‘Stitt’s Practical Bacteriology, Blood Work and Animal Parasitology,” 7th Edition.)

Muscina assimilis is another member of the genus. Its legs,
palpi and antennae are wholly black, whereas in the case of Muscina
stabulans the legs are in part yellow, the palpi are yellow and the
antennae are brown.

Genus Cryptolucilia

Cryptolucilia (Pseudopyrellia) caesarion Mg. is a common fly
breeding in cow manure. , Its thorax, abdomen, cheeks and vertex
are bright shining green.
CHAPTER XI

THE BITING MUSCIDAE
Genus Philaematomyia Austin, 1909

These flies somewhat resemble Musca domestica. They are
greyish in color with longitudinal dark stripes on dorsum of thorax.
They may be recognized by their peculiar proboscis which is
described elsewhere. Eggs are laid and hatched in cow dung.
Pupation takes place in the ground. Time from oviposition to
emergence of adult about 6 or 7 days. The adult feeds on cattle
only occasionally attacking man. There are but three known
species of which P. insignis is the commonest. These flies are
not known in the United States.

Genus Stomoxys Geoffry

Flies of the genus Stomoxys resemble rather closely the common
house fly but the long, tapering, chitinized proboscis adapted for
biting will immediately differentiate them from Musca domestica.
There are a number of species in the genus Stomoxys but the common
one of the United States is Stomoxys calcitrans Linn. This fly is
cosmopolitan in its distribution.

Stomoxys calcitrans Linn.

The arista is feathered dorsally. The palpi are slender and short,
less than half the length of the proboscis. The fourth longitudinal

 

Fic. 46.—Larva of Stomoxys calcitrans.

vein curves so as to merely narrow the first posterior cell which is
therefore broadly open. (Fig. 42.) The first and third longitu-
dinal veins are bristled at their proximal end. In the resting posi-

tion the head is raised, the proboscis projecting forward. The legs
86
THE BITING MUSCIDAE 87

are black the abdomen is grey, the thorax is marked with clear black
~ stripes and the abdomen with regular dark spots.

Eggs are laid on moist hay and straw, grass heaps, horse manure
and decaying vegetable matter. Never in cow dung. They will
breed in marine plants washed up on the beach. From egg to adult
requires from 235 to 35 days. Egg stage 2 to 3 days, larval stage 14
to 21 days, pupal stage about 10 days.

The adults bite many different species of mammals including man
and may come into the house before a rain. No disease in man nor
animals has been traced to this fly.

To prevent the breeding of this fly care should be taken to prop-
erly dispose of rotting hay and straw and manure.

Genus Glossina Wiedemann
(Tsetse Flies)

These flies are confined to tropical Africa and Arabia and are
of great interest because they carry sleeping sickness (Trypanoso-
miasis). One species Glossina palpalis Robineau-Desvoidy carries
Trypanosoma castellanii and one, Glossina morsitans Westwood carries
Trypanosoma rhodesiense. There are about 17 known species in the
Genus. :

The Glossinae have narrow bodies, they are dull colored greyish
or yellowish brown, with the wings closed flat one over the other and
projecting when at rest considerably beyond the abdomen. The
palpi are as long as the proboscis and enclose it. The proboscis pro-
jects forward and its base is bulbous. The arista is feathered with
branched bristles dorsally only. The fourth longitudinal vein has
two sharp bends. The discal cell is cleaver shaped, a characteristic
point. The first posterior cell is narrowly open.

Glossina palpalis is a dark medium sized fly with the thorax
bluish gray to olive gray and marked with brown stripes. The
abdomen is dark brown marked with pale and dark triangular areas.
The hind tarsi are entirely dark and the third joint of the antenna is
dusky brown to black. It is the insect host for Trypanosoma gam-
biense, its distribution corresponding to the area in which the North-
ern form of sleeping sickness is endemic. ;

Glossina morsitans is a light colored medium sized fly with a light
grey streaked thorax. The abdomen is buff colored with spots and
bands. The last two joints of the fore and midtarsi have sharply
defined dark brown or black tips.
88 INSECTS AND DISEASE OF MAN

Glossinae live in jungles or bushes along the banks of lakes or
streams, although G. morsitans is not so restricted in its range as
G. palpalis. They suck the blood of many of the large wild animals
of the locality. They bite principally during the middle of the day.

The female deposits a single fully developed larva which has been
nourished within its uterus, growth taking about eight or ten days.
The larva immediately seeks a place under ground, usually near the
roots of shrubs and trees, and in a few hours becomes a pupa which
develop into the fully formed adult in about six weeks. This
period depends more or less upon atmospheric temperature. The
larva bears on its last segment two prominent rounded granular black
projections between which is a pit bearing two stigmal plates.

Genus Haematobia Robineau-Desvoidy
(Horn Flies)
(Synonym Lyperosia)

These flies are very troublesome to cattle. They are about one-
half as large as the common house fly. They resemble Stomoxys
but are smaller and have straight feebly clubbed palpi longer than the

 

~~»
OSTERIOR CELL
2 2™ | ONGITUDINAL

VEIN
Fi1G. 47.—Wing of Haematobia irritans.

   

proboscis. The arista is haired dorsally only. The fourth longi-
tudinal vein is feebly curved and the first posterior cell is widely
open. The common horn fly of the United States is Haematobia
wrritans.

The female lays her eggs in fresh cow manure. Darting from the
animal as soon as the dung is passed, she deposits her eggs hurriedly
and immediately returns to the host. The length of time to develop
from egg to adult is about two weeks. Pupation takes place in the
soil.
THE BITING MUSCIDAE 89

Genus Lyperosiops Townsend

This Genus is one proposed by Townsend to take the place of
Haematobia as used in most books. Haematobia is the exact syno-
nym of Lyperosia as shown by the type irritans. Haematobia takes
precedence over Lyperosia.

The type of Lyperosiops is stimulans. It is a European and
Oriental fly not found in the United States. The species of Lypero-
stops are distinguished by the arista having 5 to 8 bristles above and
3 to 4 below. The fourth vein is feebly curved and the first posterior
cell is widely open. There is marked sexual dimorphism.
IO.

CHAPTER XII

OTHER NON-BITING MUSCOIDEAN FLIES

FAMILY SARCOPHAGIDAE
Key to the Genera (J. M. Aldrich, 1916)*

. Abdomen wholly shining black; arista long-plumose (tropics).

Phrissopodia Macq.

Abdomen with three rows of shining black spots on the second, third and
fourth segments; these are sometimes confluent, but at least the inter-
vening angles are densely pollinose; arista pubescent (widespread north)

(Page bog). hn Th EE Wohlfahrtia B. and B.
Abdomen pollinose, at most the hinder part of the segments shining black
in certain lights, tessellated in others... ..... nn UL 0 2

. Veins 1, 3, and 3 hairy; first posterior cell closed and short petiolate (trop-
Seal eS LE TR LE Johnsonia Coq.
Neinmalways bare... oo aha, aire LS J ms RE 3

. Male with one orbital bristle, proclinate (the uppermost frontal sometimes
simulating another, Dut 1eCliNAle).. vs oi isn coh dunihis se oid tines siete 4
Male without (orbital. i i des dis daa in oie Se vw obese ahs 6

. Front protuberant; vibrissae approximated and high above oral margin
TE a Ne SR REE Se ha Camptops Aldrich
Front not protuberant, vibrissae as usual... ioe di sini saerioivn vaio 5

. Metacephalon greatly developed, hence the lower edge of head remarkably
long, produced backward (tropical)........... Sarothromyia B. and B.
Metacephalon not greatly developed (tropical)... .. Sarcophagula V. d. W.
sATistaishort=plumese. 00 co LG ra RI BRL Le DU 7
Arista Iong-plumiose, Lo ri Sw eee en MLL REC 10,

. Parafacial with a single macrochaeta below, proclinate (Louisiana, Texas.

Camptopyga Aldrich

Paraincial with o pow of WalrS. cies «bv sie winiie's sala ivi 103 ereiubeis ta (4 ieidis 8

. No costal spine (widespread north).................../ Agria Desvoidy.

Costal spine strongly developed. ......... oo coin, vn TU 9

. Back of head with only black hair; anterior acrostichals very large (north-

ROTI ie A i eR Harbeckia Aldrich
Back of head with some pale hair; no anterior acrostichals (widespread).

Hypopelta Aldrich

Two large posterior dorsocentrals, two equally large anterior ones (tropical).
: Notochaeta Aldrich
Generally three or four posterior dorsocentrals, if only two the anterior
ones are-mUchEeQueed.. ur es te ia ia hia ss mbes WAR Het II
* Sarcophaga and Allies. Published by the Thomas Say Foundation.
90
OTHER NON-BITING MUSCOIDEAN FLIES 91

11. Vibrissae approximated and high above the oral margin (the distance

equaling the length of the second antennal joint) (widespread).
Emblemasoma Aldrich
Vibrissae normal, or if somewhat approximated they are not strikingly
removed fromithe oral margin... oa 0d at hh eh ars 12
12. Parafacials quite bare; first vein hairy (Louisiana). . Sthenopyga Aldrich
Paraficials with hairs, sometimes delicate.... i... A... hlLL LLL 13
13. Ocellars absent; frontal rows not noticeably divergent below, reaching base
of antennae (tropical)............. Bd tap Harpagopyga Aldrich
Ocellars present; if absent, the frontal rows are abruptly divergent below
and reach about to the middle of second antennal joint................ 14
14. Fifth sternite of male undivided; epaulet yellow; back of head with only
black hair(northeastern). ... .... 0 LG. hd Thelodiscus Aldrich

Fifth sternite of male deeply divided (widespread) (Page 93).

Sarcophaga Meig.

Description.—The Sarcophagidae have large bodies. The arista
is feathered dorsally and ventrally in the basal half but is naked and
hair-like in the distal half. The legs are stout. The abdomen is
grey with whitish or silvery, tesselated or changeable spots. The
fourth vein ends considerably before the apex of the wing with an
almost angular bend. The parafacials are hairy. There are no
discal bristles on the abdomen and not more than a single pair of
discal scutellar bristles. The palpi are well developed. Theeyes
are never hairy. The proboscis is of the sucking non-biting type
similar to that of the house fly. The abdomen has four main seg-
ments—four tergites and four sternites. Because of the fact that
the first and second sternite are united, the last visible sternite is
really the fifth. This sternite is forked behind and may have brushes
of short spines, blunt processes etc. which are of specific importance.

As in many other Diptera, a study of the accessory organs of
generation is ‘of value in determining the species. (Fig. 48.) Ter-
minating the abdomen; just back of the fourth segment in the male are
two small segments which together are known as the hypopygium
or genital segments. They serve to protect and give attachment to
the accessory organs, which consist of two forceps, two accessory
plates and a pair each of anterior and posterior claspers. These
organs can not be studied unless the end of the abdomen is drawn out
as far as possible without tearing the tissues. Dried specimens
should be kept in the relaxing chamber at least 24 hours before this
is attempted. The penis lies in the middle line in front of the for-
ceps and between the claspers. The anus is located at the end of
the second segment of the hypopygium.
92 ; INSECTS AND DISEASE OF MAN

 

g

Fi1G. 48.—Male genitalia of some of the Sarcophaga. (a) S. communis; (b) S.
assidua; (c) S. bullata; (d) S. haemorrhoidalis; (e) S. quadrisetosa; (f) S. sarracenioides;
(g) Dorsum of abdomen of Wohifahrtia meigenii (left) and Wohlfahrtia vigil (right).

(From Aldrich, ‘“Sarcophaga and Allies in North America.” The Thomas Say Founda-
tion.)
OTHER NON-BITING MUSCOIDEAN FLIES 93

Larva.—The Sarcophagidae are larviparous. The larva is
tapering. (Fig. 36.) There are two great hooks at the small,—the
head,—end. The stigmal plates have no button and lie at the
bottom of a pit. (Fig. 49.) The slits of the stigmal plates are not
sinuous, they are slender and are subparallel to each other. The
slits in one plate are subparallel to those in the opposite plate. The
fusiform areas completely encircle the segments. There are dis-
tinct tubercles above the anal area and around the stigmal field.

Habits.—In habits the larvae range from scavengers to parasites
of warm blooded animals. They have been reared from human and
animal excrement, from carrion and
from dead insects. Some are also para-
sites of living insects.

Genus Sarcophaga

Most of the members of the Family
belong to the Genus Sarcophaga. A
common species in North America
is Sarcophaga communis Parker which
breeds in carrion and will breed in :
human excrement. It is abundant in BS jr.
the North but in the South it is
replaced by a variety, Sarcophaga communis var. ochracea Aldrich.
Another common species in the United States is Sarcophaga haemor-
rhoidalis Fallen. This is cosmopolitan in its distribution. It is
also a scavanger and has been bred from human excrement and
has been passed in the stools. It is quite likely that this species is
not infrequently a cause of intestinal myiasis and the larvae seem to
be capable of developing within the intestinal canal of man. The
following species have also been bred in human excreta: Sarcophaga
quadrisetosa Coquillett, Sarcophaga assidua Walker, Sarcophaga
sarracenioides Aldrich, a variety of S. tuberosa Pandelle, S. pachy-
proca Parker and S. bullata Parker.

Sarcophaga carnaria, a European species may be the cause of
nasal, intestinal or cutaneous myiasis. It normally breeds in tainted
flesh.

 

Genus Wohlfahrtia

The Genus Wohlfahrtia is also of interest because it may be a
cause of nasal and cutaneous myiasis. A European form is, in
04 INSECTS AND DISEASE OF MAN

habits, similar to the North American Screw-Worm fly, Cochliomyia
macellaria Fabricius. Two species are found in the United States,
a Western form, Wohlfahrtia meigenii Schiner and an Eastern form,
Wohlfahrtia vigil Walker. Larvae of the latter have been taken
from beneath the skin of infants. The western form may have the
same habit.

In W. meigenii the abdomen is mostly pollinose, its black spots
small. In W. vigil the black spots are large and confluent, the
pollinose part not being very conspicuous.

Key to the More Common and Widespread Species of the Genus Sarcophaga
in the United States. (Condensed from Aldrich’s Key)

I. Three distinct postsutural dorso-central bristles.
Group A. Hind tibiae with villosity (with erect hairs); both segments of
hypopygium black.

1. Middle tibiae with a patch of yellow hair covering the apical third of
thefrontaider. i... ou in a i EE sinuata Meigen

Group B. Hind tibiae with erect hairs; at least the second segment of the
hypopygium red.

1. First vein bare; front without orbital bristle in male; legs black; hind
femora on outer side with a median row or part of a row of longer
bristles than the upper and lower rows; sternites 1—4 not successively
narrowed; anterior acrostichalspresent..............ccovenvnn.. 2

Same but anterior acrostichals absent... .......... 0 vveivildon, 3

2. With an almost complete median row of bristles on hind femur.
cimbicis Townsend
With only the distal end of the row present; the accessory plate slender,
finger-like. ........ date met le BSE latisterna Parker

3. With a complete median row of bristles on hind femur.. . bisetosa Parker

Group C. Hind tibiae not with erect hairs, at the utmost with a few appressed
hairs; hypopygium wholly black.

1. Blrst vein haley. oo oh vain andi asin od SR ae 4

Biri welnibare.. con be a a RI Ek a 2

2. Male without orbitals; frontals extending below bise of antennae 3
anterior acrostichals large; arista short-plumose; hypopygium
lagge. a nl A Agria  affinis Fallen

3. Second segment of hypopygium opaque; palpi yellow; forceps slender
largely yellow and having a protuberance on the attached part on
which is a striking tuft of long straight black hair, which is invisible

Inatepose. boi EL hunteri Hough
Same but forceps not with such tuft; Distal segment of penis thickened
fromi its hase, = LL a a es opifera Coquillett

4. Second abdominal segment with erect median marginal bristles; distal
segment of penis full and globular, flat behind. . melampyga Aldrich
OTHER NON-BITING MUSCOIDEAN FLIES 95

Group D. Hind tibiae not with erect hairs; at least the second segment of
hypopygium red or reddish yellow.

I.

10.

II.

12.

Wirstiveln hafry. oll rs dh coding RR 14
Firsbovein Dare. 0. Jon i eat ie dae LL Lp LR 2
Palptiyellow oo 2h. Coad byt Goan i ne Le Le 3
Palpiiblackl ios iii DU a A i a i (oS 4
. Legs black; outer vertical bristles absent in male; first segment of

hypopygium with row of bristles at apex, often indistinct; small
species; forceps with a pair of processes in the basal attached part
which bear a striking tuft of long straight black hair, concealed in
FEROS... i eh A ee fel ae hunteri Hough
Same but forceps not with such processes or tufts. .opifera Coquillett

. Arista long and thin, short-plumose; hypopygium large, second

segment red with long upcurved bristles. . Hypopelta scrofa Aldrion
Arista normal; both segments of hypopygium reddish yellow. ........ 5

. Frontal rows of bristles not strongly divergent below; epaulets yellow.

peniculata Parker
Frontal rows suddenly diverging in the last two or three bristles;

epamletsiblack. ccd nmin pS a, I 6

. Anterior acrostichal bristles well developed; parafacials gray; penis
with a pair of erect recurved hooks on the back near apex... .... 7
Same but penis not with hooks onback.............. di 00 0 8

. Accessory plate at least twice as long as wide; not excised; distal

segment of penis slender narrowed at tip........ alcedo Aldrich

. Distal segment of penis in the form of a long tube, incurved at the end

and forming a loop that can be seen through in profile beyond the
lateral processes. i... .ouine esl isnt ile g ie reversa Aldrich
Distal portion not forming a loop that can be seen through. ......... 9

. Distal segment of the penis on its apical half with lateral thin expanded

margins which are whitish or transparent somewhat like a ruffle.. . 10

Penis: not with rufile-like expansion. . i... .cuuus rss vuusivsivvains 13
Distal segment (beyond the hinge) evidently divided into two subseg-

TREIIES  ateisrs iain ih viie mints 6 mera ients Be Pettit as so a Fira wil fi a Tura le ae II
Distal'segmentinot so'divided. ........ oh Col 2

The division of the distal segment is near the tip, which is divided into
two delicate processes attached to the fringe. marginata Aldrich

The division is just beyond the middle, the apex broadly and deeply
cleft into two strong but flat claws which are not connected with
Fhe TrInge. iin cn is le ete Mire falciformis Aldrich

The chitinous distal segment is notched into two sharp points at apex;
a pair of erect median marginal bristles on second abdominal
SEQIRENE. J cer ss Soniye a td il ee eS setigera Aldrich

The distal segment is swollen and whitish near end, not perceptibly
notched; rarely with median marginals on second abdominal
SEegent. Ll eaten LL I coloradensis Aldrich
96 INSECTS AND DISEASE OF MAN

13. Second abdominal segment without median marginals; front at least
.16 of head width; the stout divergent prongs at the tip of the penis
cover and conceal the minute incurved copulatory tube or at most
have a V shaped opening....... 000. oho. aculeata Aldrich

14. Tibiae black; first segment of hypopygium very large, flat behind,
giving the abdomen a truncated appearance; acrostichals well
developed col...» oh hr ie aR Ses pachyprocta Parker

* Tibiae black; first segment of hypopygium retracted almost invisible;
anterior acrostichals hardly differentiated from hairs.
helicis Townsend
II. Four post-sutural dorsocentral bristles or else the anterior ones of the post-
sutural series indistinct, hardly differentiated from hairs.
Group E. Hind tibiae with erect hairs; hypopygium entirely black.

1. Front about as wide as one eye; middle tibiae with long dense hairs on
distal half of inner side; very robust species. = (Atlantic seaboard
from Massachusetts to Texas.)............v..... johnsoni Aldrich

Group F. Hind tibiae with erect hairs; at least second segment of hypo-
pygium red. :

1. First vein bare; legs black; first segment of hypopygium black at

leaston apical half... .c.. 0 ik sony Cun si Dear 2
Same but first segment yellow at least on apical half................ 5

2. Prescutellar bristles absent; forceps nearly straight in profile witha
notch behind nearbase.............. ves haemorrhoidalis Fallen
Prescutellar bristles present. ...... bl hae Tinta Bos Lenn 3

3. Middle tibiae with out erect hairs, with a single row of black hairs
behindithe eve... i... ou Wl se me securifera Villeneuve
‘With more than one row of black hairs... noo Losl eis 4

4. Forceps in profile with an emargination behind followed by a hump.
falculata Pandelle

Forceps not with a hump; penis with four slender processes at tip.
tuberosa var. exuberans Pandelle
5. Middle tibiae without erect hairs; at most with appressed hairs as
long as the tibia is wide; parafacials gray or with but little yellowish
tinge and with distinct hairs; the row of bristles on the fourth abdom-
inal segment entirely marginal; anterior acrostichals not differen-
tiated at most faintly discernible at front edge of thorax; third
abdominal segment with median marginal bristles; forceps with
nearly parallel front and back edges and an apical tooth formed by
an excision of the front edge............ sarracenioides Aldrich
Same but forceps tapering to a sharp point; distal segment of penis
short and very broad and blunt, a curved horn-like process at each

outerapicaliangle..... .... 0 ua bullata Parker

Group G. Hind tibiae without erect hairs; both segments of hypopygium
black.

so Bist vein hairy). fol Ln sahara  R salva Aldrich

Group H. Hind tibiae of male without erect hairs; at least the second seg-
ment of hypopygium red.
OTHER NON-BITING MUSCOIDEAN FLIES 97

ro Fhst vein hairy ov a ea a 7
BIrsbvelDaYe. Jv Lh a i Shh ae re aE 2

2. Epaulet largely yellow; frontals not or but little divergent anteriorly;
scutellum without a pair of small apical bristles in male......... 3
Epauletsblack 00 LR GR 4

3. Palpi and legs black; front about half as wide as one eye; evidently
narrowed below the ocelli; parafrontals and parafacials gray,
pollinose; first segment of hypopygium black (very common
north) se US CL A communis Parker

Same but parafrontals and parafacials yellow, pollinose; first segment
of hypopygium red (very common south).
communis var. pchracea Aldrich

4. Vibrissae not farther above the oral margin than half the length of
second antennal joint, generally not unusually approximated;
palpi black; one or two pairs of strong erect anterior acrosthicals,
several times as large as adjacent hairs; anterior dorsocentrals
also large and erect. Forceps with barb like projection behind.

kelly: Aldrich
Same but acrostichals either undifferentiated or but little larger than

AAIcent Ralvse oo oi drain shat atta a id a eae es 5
5. Scutellum with a pair of small apical bristles between the large
makina. a Ls BR Se 6

Scutellum without small apicals; front much narrower than the width
of one eye; fifth sternite with the sides not diverging; forceps in
back view decidedly diverging at the tip, very small; hind tibiae not
hairy; anterior claspers long not very stout... .assidua Walker

6. Back of head with two rows of black hairs behind eye; large stout
species without median marginals on third abdominal segment.
plinthopyga Wiedeman

Back of head with three rows of black hairs behind eye; frontal rows -
suddenly divergent at lower end; outer vertical present; forceps
with dense erect short hair almost at tip........ utilis Aldrich

7. Lateral vertical bristles generally present; forceps divergent.
latisetosa Parker

Lateral vertical bristles absent; stalk of penis very long, on the front
side just before tip with a flat yellow transverse plate projecting
FOLWARd: es, hia oe ia bisa al fel aterab eT quadrisetosa Coquillett

FAMILY CALLIPHORIDAE

Description.—Members of the Family Calliphoridae have the
mouth parts well developed and adapted to suction only, as typified
in the house fly. Hypopleural bristles are present; notopleural bris-
tles 2; sternopleurals 2:1 or 1:1, never 1:1:1; post humerals usually
laterad of presutural, sometimes in line with presutural, rarely

absent, never mesad of presutural; hind coxae bare behind above
7
98 INSECTS AND DISEASE OF MAN

base of hind femur; wing venation of the Muscid type. The abdomen
or the abdomen and thorax is usually of a bright metallic color but
sometimes yellowish or blackish.. The thorax is usually without
stripes or bands.

Habits.— These flies are commonly known as blue or green bottle
flies. They are scavangers breeding in fresh or decaying meat or
human or animal excrement and may be the cause of myiasis in its
several forms.

 

 

 

 

 

 

F1G. 50.—Insects in which the larval stage is important. (1) Cochliomyia macel-
laria; (2) C. macellaria, larva; (3) Dermatobia hominis larva, early stage; (4) D. hominis
larva, later stage; (5) Dermatobia hominis; (6) Auchmeromyia luteola; (7) A. luteola,
larva; (8) Sarcophaga magnifica; (9) S. magnifica larva; (10) Anthomyia pluvialis;
(11) A. pluvialis larva. (From Stitt’s ‘Practical Bacteriology, Blood Work and Animal
Parasitology,” 7th Edition.)

Larva.—The larva is tapering and has two great hooks at the
small or head end. The slits in the stigmal plates are not
sinuous, they are slender and directed rather transverse to the
body. The plates are provided with a button and are not placed at
the bottom of a pit as in Sarcophagidae. There are tubercles about
the anal area and processes around the stigmal field. The roughened
area may encircle the segments.

Among the Calliphoridae which are not some metallic shade of
blue or green are the Genera Pollenia and Melanodexia, greyish and
OTHER NON-BITING MUSCOIDEAN FLIES 90

nonmetallic in coloration. In these genera the sternopleurals are
1:1; the prosternum and propleura are bare and the parafacials are
hairy down to the lowermost margin of the eye. In all other Calli-
phoridae, American at least, the prosternum and the propleura are
hairy.

Other nonmetallic genera which may be mentioned, are the
yellowish or brownish yellow—testaceous—Calliphoridae, Mesem-
brinella (blow flies of South American) and Awuchmeromyia and
Bengalia both African genera of medical interest.

Key to the Genera of Calliphoridae (R. C. Shannon, 1923)*

1. Prosternum and propleura bare; sterno-pleurals 1:1; parafacials hairy down
to lowermost margin of eye. (Subfamily Polleninae.)
A. Thorax with abundant deciduous pile; two sublateral bristles; post-

humeralsipresent (Page 106). 0a. Lt Sia Pollenia
AA. Thorax without deciduous pile; one sublateral bristle; post-humerals
Se rs i LES SL Melanodexia

2. Prosternum and propleura pilose; sternopleurals 2: 1.
A. Upper side of stem of first vein ciliated; subcosta sclerite with small
black bristles. (Subfamily Phorminae.)
B. Face yellow with yellow pile; anterior portion of lower squama pilose;
one post-humeral bristle.

C. Palpi normal with well scattered bristles; three or four propleural
bristles; post-thoracic spiracle light-colored with a row of black
hairs along its lower margin (Chrysomyia fulvipes Macg. (wheeler:
Hah: syn. by Aldrich)... 0... Compsomyiops Townsend

CC. Palpi about one-third normal size with bristles placed on outer

third; post-thoracic spiracle darkened. (Chrysomyia macellaria

Fab.) see Footnote} (Page 105)....... Cochliomyia Townsend

BB. Face black with black hairs; lower squamae bare; usually two post-
humeral bristles.

C. Disc of upper squama bare; anterior acrostichals well distinguish-
able from surrounding hairs.

D. Four intra-alars; six or more marginal scutellars; prothoracic
spiracle dark orange to black (metallica Tns.) (Page 106).

Protocalliphora Hough

DD. Two intra-alars; four marginal scutellars; prothoracic spiracle

distinctly light orange colored (regina Mg) (Page 103).
Phormia Robineau-Desvoidy
CC. Disc of upper squama thinly pilose; anterior acrosticals not distinct
from surrounding hairs; prothoracic spiracle black.

* Genera of nearctic Calliphoridae, blow flies, with Revision of the Calliphorini.
Insecutor Inscitiae Menstruus, Vol. XI, 1923, Nos. 7-9, pp. 106-110.
1 Where there is only one North American species it is noted in parenthesis.
I00 INSECTS AND DISEASE OF MAN

D. Aristal rays closely applied to arista; face much produced below,
making the head as high as broad; prothoracic spiracle notice-
ably larger than third antennal joint. (aristatus Ald. & Snn.
(Phormia coerulea Mall., preoc.)....Boreélus Ald. & Snn.

DD. Aristal rays well separated; face moderately produced below,
noticeably broader than high; prothoracic spiracle about size
of third antennal joint. (ferraenovae Desv.) (Page 105).
Protophormia Townsend
AA. Upper side of stem vein bare; subcosta sclerite faintly pubescent; one
post-humeral bristle. (Subfamily Calliphorinae.)
B. Upper surface of lower squama bare; a small chitinized hairy patch
present on posterior end of the membrane between lower squama
and lower margin of the post-alar declivity (caesar, et al) (Page 104).
Lucilia Desvoidy
BB. Upper surface of lower squama distinctly pilose; above mentioned
patch absent.
C. One sublateral; two bristles near middle on exterior surface of
front ‘tibia (Page ooo). i... i. hv us vido Cynomyia Desvoidy
CC. Two or three sublaterals; one, rarely two, bristles midway on
exterior surface of fore tibia.
D. Two sublaterals (Acrophaga BB.)...... Steringomyia Pokoray
DD. Three sublaterals.

E. Last section of fourth vein straight or but very slightly curved;
antennae black, small, third joint only as long as dorsal bristle
of second jJolnt............ 0. Ln, Onesia Desvoidy

EE. Last section of fourth vein with a decided bend; antennae nor-

mal in size, third joint much longer than bristle of second
Jolt a Calliphora Desvoidy

Synopsis of Calliphorini (R. C. Shannon)

Males

A. Outer forceps very elongate; inner ones rudimentary; one sublateral.
Cynomyig

B. Entire front of head, bright golden yellow with silvery pruinosity.
mortuorum Linne
BB. Facial plate dark, genae reddish brown............ cadaverina Desvoidy
AA. Outer forceps not very elongate; inner ones well developed, being nearly

as long to longer than outer; two or three sublaterals.

B. Lobes of fifth sternite very prominent, obtusely rounded apically;
twoisublaterals, >. oc Co a ATL Steringomyia
C. Narrowest width of front much broader than width of parafacials;
bristles on parafrontals continue all the way to the inner verticals;
lower half of parafacials distinctly reddish brown; inner forceps
longer than outer; squamae white......cvui.ennvivvay alpina Zett
OTHER NON-BITING MUSCOIDEAN FLIES I0I

CC. Narrowest width of front not broader than parafacials; bristles on
parafrontals and below level of anterior ocellus; parafacials black;
squamae darkened.

D. Parafacial broader than narrowest width of front; inner forceps
as long as outer, much broadened basally, flat, in outline pear-
Shaped. Lh ll ce a ts a bie eine is alaskensis Shannon

DD. Parafacials of same width as narrowest part of front; forceps very

slender, about two and one half times as long as combined width;

inner ones much shorter than outer......... aldrichia Shannon

BB. Lobes of fifth sternite inconspicuous, appressed, except elongata which
has them truncate; three sublaterals.

C. Last section of fourth vein straight or only slightly bowed inward;
third antennal joint small, about as long as dorsal bristle of second
antennal joint; forceps small... ..... 0... na Onesia

D. Third antennal joint distinctly longer than width of parafacial;
wings and squamae smoky; forceps very small, outer ones rounded
apically, their basal halves overlapped by hypopygium.

‘ aculeata Pandell

DD. Third antennal joint slightly shorter than width of parafacial,

wings and squamae very slightly tinged; forceps not unusually
small, outer ones pointed, thick and irregular in outline; inner
ones more deeply inset than outer............... agilis Meigen

CC. Last section of fourth vein with a decided bend; third joint normal
sized, much longer than bristle of second joint. ...Calliphora

D. Front of head bright orange with silvery pruinescence; pair fronto-
orbitals; only five pairs of frontals; forceps moderate, of equal
development, slender and curved apically; squamae white.

elongata Hough

DD. Front of head partly black; no fronto-orbitals; squamae darkened.

E. Narrowest width of front over twice as broad as parafacial;
a well differentiated pair of secondary ocellars placed immedi-
ately behind post-ocelli; forceps very small; outer ones nearly
bare; inner ones very hairy on post-aspect. . . .latifrons Hough
EE. Narrowest width of front much less than twice width of parafacial;
secondary pair ocellars not well differentiated from surrounding
hairs.
F. Three intra-alars; basicosta black; outer forceps well provided
with long, loose hairs.

G. Narrowest width of front broader than width of parafacial;
bucca mostly reddish; outer forceps regular in outline,
obtusely pointed. .......L000. 0a coloradensis Hough

GG. Narrowest width of front less than half the width of para-
facial; bucca black; outer forceps suddenly curved at apex,
sharply pointed... oii. Bh ne. viridescens Desvoidy

FF. Two intra-alars. :

G. Basicosta yellowish; outer forceps with long, loose hairs,
broad, obtusely rounded at apex; bucca red.

erythrocephala Meigen
102 INSECTS AND DISEASE OF MAN

GG. Basicosta black; bucca black.

H. Parafacials black; outer forceps straight, comparatively
broad, gradually tapering to obtuse point, clothed with
short cstiffbalrs.. Soop bos ni Gn morticia Shannon

HH. Lower half of parafacials red; outer forceps gently curved,
very slender, sharply pointed, nearly bare.

vomitoria Linne

Yo Beard zed: ..... divas dog. ni esa vomitoria vomitoria

I. cBeard'black ... .. v.50, vomitoria nigribarba Shannon

Table of Females

A. One sublateral; two bristles about midway on exterior side of fore tibia.

Cynomyia

‘B. Entire front of head bright orange yellow........ mortuorum Linne

BB. Frontand facial plate black... ......... onan cadaverina Desvoidy
AA. Two or three sublaterals; one bristle midway on outer side of fore tibia.

B. Two sublaterals; slender species. ..... .. vee vu veanvis .Steringomyia

C. Plumosity of arista two-thirds normal length; squamae white.
popoffana Townsend
CC. Plumosity normal; squamae darkened.
D. Lower fronto-orbital on level with fifth frontal; disc of fourth
segment with strong bristles and sparse, short hairs.
aldrichia Shannon
DD. Lower fronto-orbital on level with sixth frontal; disc of fourth
segment conspicuously haired, bristles weak. Probably female
GL LR i alaskensis Shannon
BB. Three sublaterals, usually robust species.

C. Last section of fourth vein very slightly bowed inward; antennae black,
small, third joint only as long as bristle of second joint; frontal vitta
twice as long as broad; rather small species. ...Onesia agilis Meigen

CC. Last section of fourth vein with decided bend; antennae of normal
size, partly red; frontal vitta less than twice as long as wide.

Calliphora
D. Post-margin of second tergite without long bristles except at sides;
squamae white; basicosta yellow. ............. elongata Hough

DD. Post-margin of second tergite with appressed long bristles extending
across; squamae darkened.

E. A strongly differentiated pair of secondary ocellars placed imme-
diately behind post-ocelli; bristles on facial ridges well devel-
oped, lower ones longer than width of parafacial.

latifrons Hough

EE. Secondary ocellars hardly differentiated from surrounding hairs;
facial ridge bristles much smaller.
F. Three intra-alars; basicosta black.

G. Bucea ved... nl a na a A coloradensis Hough

GG. Bucea Black... 5.0 Lila Saloni, viridescens Desvoidy

FF. Two intra-alars.

G. Basicosta yellowish; bucca reddish... .erythrocephala Meigen
OTHER NON-BITING MUSCOIDEAN FLIES 103

GG. Basicosta black; bucca black.
H. Head as high as broad; parafacials normally black.
morticia Shannon
HH. Head broader than high; lower half of parafacials reddish.
vomitoria Linne
Li: Beard reddish. is bali Coss S280 0 vomitoria vomitoria
HT. Beard black. ......0. cv. vomitoria nigribarba Shannon

Kep to the Tribe Luciliini (R. C. Shannon, 1924)*

Table of Males

A. Arista brevi-plumose, the dorsal bristles of first antennal joint being of
equal length; two sublaterals (third sublateral absent), threeintra-alars
(Genus Francilia Shannon)... ove ovo oa. alaskensis Shannon

AA. Arista of normal plumosity; three sublaterals; two intra-alars (first one
absent) (Genus Lucilia).
B. Basicosta black.
C. Palpi yellow; two post acrostichals; subcostal sclerite with black setae
caesar Linne
CC. Palpi dark brown to blackish; three post acrostichals; subcostal sclerite
WItHOUL SETAE: i. oie ais wide esis dint lbwiadety bata fate sylvarum Meigen
BB. Basicosta yellow.
C. Two post acrostichals.
D. Beard black; parafrontals very narrow, contiguous; second tergite
with post margin concolorous with rest of segment.
australis Towns. and unicolor Townsend.
DD. Beard mostly yellow; parafrontals separated by width of a para-
frontal; second tergite with post margin bluish black.
pilater Hough
CC. Three post acrostichals.
D. Hypopygium conspicuous; lobes of fifth sternite prominent, ligulate,

with dense long hairs... ..... 0. i ono pallescens Shannon
DD. Hypopygium nearly concealed, lobes of fifth sternite inconspicu-
ous, appressed, with shorter, stiffer hairs. ..... sericata Meigen

Table of Females

A. Basicosta black.
B. Three post acrostichals; palpi dark brown to black. : . . sylvarum Meigen
BB. Two post acrostichals; palpi yellow (caesar), or brownish (elongata).
C. Subcostal sclerite with small black setae; post margin of second tergite

with weak appressed bristles...... Lo. .0 uo ak caesar Linne
CC. Subcostal sclerite without setae, post margin of second tergite with
strong erect bristles... cin Jilin sali, elongata Shannon

* Nearctic Calliphoridae, Luciliini, Insecutor Inscitiae Menstruus, Vol. XII, Nos.
4-6, 1924, Pp. 73-74
104 INSECTS AND DISEASE OF MAN

AA. Basicosta yellow.
B. Two post acrostichals; front above antennae no broader than length”of
third antennal joint.
C. Beard black; facialia setae arranged in a single row.
australis Towns. and unicolor Towns.
CC. Beard mostly yellowish; facialia setae arranged in several irregular
TOWEL he LT a RR Ue pilates Hough
BB. Three post acrostichals; front above antennae much broader than length
of third joint.
C. Parafacial broader than parafrontal................. sericata Meigen
CC. Parafacial as broad as parafrontal............... pallescens Shannon

Genus Calliphora
(The Blue Bottle Flies)

These are scavenger flies which deposit their eggs on fresh or
decaying meat or on meat which has been cooked. Also on human
and animal excrement or in open wounds.

The thorax is bluish black but not lustrous; the abdomen blue
and lustrous with white changeable spots.

These flies will come into the house seeking food on which to
deposit their eggs. The complete life cycle from egg to adult requires
on an average about 22 days; egg stage about 24 hours, larval stage
about ten days and pupal stage about eleven days. Pupation takes
place in loose earth.

There are several common species of which the Calliphora vomi-
toria and the Calliphora erythrocephala are the best known.

Genus Cynomyia

The Genus Cynomyia has habits similar to Calliphora and closely
resembles it but the abdomen is uniformly shining blue without
the whitish changeable spots. Cymomyia cadaverina Robineau-
Desvoidy is a common carrion fly.

Genus Lucilia
(The Green Bottle Flies)

These are also scavenger flies which deposit their eggs on fresh
and decaying meat, human and animal excrement and in open
wounds.

The thorax and abdomen are metallic green or bluish green and
lustrous. The complete cycle of development from egg to adult
OTHER NON-BITING MUSCOIDEAN FLIES 105

requires about two weeks; egg stage one day, larval stage eleven
days, pupal stage about twelve days.

Two very common species of Lucilia are Lucilia caesar and Lucilia
sericata. The former has a more northern distribution than the
latter.

Members of this Genus do not come into the house as frequently
as those of the Genus Calliphora.

Lucilia sericata and L. caesar have been called the ‘sheep mag-
got” flies because of the habit of laying their eggs in wounds of
sheep or in the soiled wool of sheep especially those having diarrhoea.

Genus Phormia and Genus Protophormia

These flies are also metallic greenish in coloration.

Phormia regina is not unlike Lucilia in appearance and habits.
Protophormia terraemovae has a northern distribution. It is the
common scavenger fly of Alaska and also occurs in Greenland and
Northern Europe.

Genus Cochliomyia
(The Screw Worm Fly)
(Synonym, Pycnosoma, Chrysomyia)

Cochliomyia (Chrysomyia) macellaria Fabricius has a blue-green
body, a yellow front to the head and three black lines dorsally on
the thorax. It is larger than the common house fly.

It is a danger to man and animals, for although it can not bite, it
may deposit its eggs in wounds or in the nostrils or ears, attracted
by foul discharges. Sleeping men who have offensive catarrh are
especially liable to attack by this fly. The larvae develop quickly
and are very destructive eating away the tissue rapidly. Gaining
entrance to the frontal sinuses death may result. Several hundred
eggs are deposited in rotting flesh, wounds or in body cavities, in
the space of a few moments, and several batches may be laid. Eggs
develop within a few hours and the larvae grow to maturity rapidly.
They pupate in the ground.

This fly is found in tropical and temperate North and South
America. In the southern United States it is most prevalent from
July to October and is of considerable economic importance as pest
of cattle. The larvae have twelve segments with rings of minute
spines.
106 INSECTS AND. DISEASE OF MAN

The common means of propagation is probably in the carcasses

of dead animals. Proper disposal of such material would go far to

eliminate the fly in places where it is a menace.
To dislodge them from the sinuses and ears chloroform is valuable
used as a wash of 109, to 259%, chloroform in milk.

Genus Bengalia
(Synonym Ochromyia)

The larva of this fly burrows under the skin producing a lesion
with a central opening somewhat resembling a boil. When mature
it drops out and pupates in the ground. Men, monkeys and dogs
may be affected. Two species, both African, are known, Bengalia
anthropophaga and Bengalia rodhaini. The larva of the former is
known locally as “ver du Cayor.”

Genus Auchmeromyia

Auchmeromyia luteola Fabricius is of interest because its larvae
live in cracks and crevices in the floors of native huts in tropical and
subtropical Africa, coming out at night to suck the blood of persons
sleeping on or near the ground. The larva is called the ‘Congo
floor maggot.” The adult fly can not bite although it may be a blood
feeder. The larva is not known to carry disease.

Genus Protocalliphora

. These flies in the larval stage are blood-sucking parasites of
nestling birds.

Genus Pollenia

Pollenia rudis is a more or less common fly which breeds in earth
worms as a true parasite of the living worm. There are on the thorax
a number of soft appressed yellow hairs mixed in with the bristles.
CHAPTER XIII
FAMILY ANTHOMYIIDAE

To this family belong several genera known to be more or less
troublesome to man. The arista is naked or pectinate, the first
posterior cell is completely open and abdominal bristles are often
absent. Eggs are laid on decaying vegetable matter, excrement or
on living plants the larvae developing in the roots.

Three genera may be mentioned as follows:

I. Arista bare........................Fownia (Homalomyia)
2 AMS pIIINGSe - Fe IRE Hylemyia
Sa Arista pubescent. oC ENE SELS  C Hydrotea

   

Le ii

4™ LONGITUDINAL VEIN

F1G6. 51.—Wing of an Anthomyiid fly.

Common species are Fannia canicularis or ‘‘little house fly”
and Fannia scalaris or ‘“latrine fly.” Superficially these flies resemble
the “house fly” but they are smaller and there are but three dark
stripes on the thorax instead of four as in Musca domestica. They
can be differentiated from each other as follows:

1. Sides of second and third abdominal segments translucent

yellow in themale Cols ur aut R A canicularis
2. Sides of abdomen blackish, midtibia with a tubercle beyond
themiddle.. «ot anak Gl em iy scalaris

The larvae of Fannia are provided with long lateral and dorsal
spinous processes which in F. scalaris are feathered. (Fig. 50.)
Larvae of Fannia canicularis have been passed from the intestines
of man, and larvae of Fannia scalaris have been passed in the urine.
107
108 INSECTS AND DISEASE OF MAN

Anthomyia radicum a root maggot fly of Europe has also been the
cause of intestinal myiasis. Because of the habit of developing with-
in roots it is likely that such larvae are frequently taken into the ali-
mentary tract of man when vegetable roots such as radishes are con-
sumed in the raw state. In the United States two of the common
root maggot flies are the cabbage root maggot (Hylemyia brassicae)
and the onion maggot (Hylemyia antigua).

Hydrotea meteorica Linnaeus attacks the eyes and nostrils of
animals and man.
CHAPTER XIV

KEY TO THE LARVAE CAUSING MYIASES (ADAPTED
FROM BANKS)*

. Body with spinous or fleshy processes laterally and dorsally or terminal 2
Body without spinous or fleshy Processes. ....... «cuca ons innensans 3

. Body with long lateral and dorsal spinous processes. . . . Fannia (Homalomyia.)
Body with long tail-likeprocess........... 000... insite din. Eristalis.
Body ending in two small fleshy processes, rather small species, the processes
bearing the stigmal plates, body about 5 mm. long........... Drosophila.
Same but processes not bearing the stigmal plates, body about ro mm. long.
Piophila.

. Body robust, ovate, cylindrical, rounded at ends, slightly depressed, or body
PYEformi alan LL ie RAL SA LG Oestridae.
Body truncate broadly rounded at one end and tapering at the other (head)

. But one great hook, posterior stigmal plates with winding slits; no distinct
lateral fusiform areas, tip of body with few if any conical processes.

; . Muscinae

With two great hooks; slits in the stigmal plates not sinuous............... 3

No tubercles about anal area; no distinct processes around stigmal field... . . . 6

Distinct tubercles above anal area; often process around stigmal field; lateral

fusiform areas wenglly: distinct... on. Talila wl a seo 7

. Stigmal plates on black tubercles, lateral fusiform areas distinct. . Ortalidae

Stigmal plates barely if at all elevated, lateral fusiform area indistinct, stigmal

plates often contiguous or nearly so; slits long and subparallel. . Trypetidae

. Slits in Stigmal plates rather short and arranged radiately............... 8
Slits'slender and 'subparallel to each other... ..... ........ 0.0 coo. 9

. Two tubercles above anal area; stigmal field with distinct fleshy tubercles
aroundiiti on ee Anthomyiidae (except Faunia)
Four or more tubercles above anal area; slits of stigmal plates usually
pointed ationeiend...... i. nl Sasi LL a Muscina

. A button to each stigmal plate; slits rather transverse to body. . Calliphoridae
No button to stigmal plates; slits of one plate subparallel to those in opposite
plate; plates at bottom of a pit... v0 darn i Sarcophagidae

* The Structure of Certain Dipterous Larvae with Particular Reference to Those in

Human Food by Nathan Banks, 1912, U. S. Department of Agriculture, Bureau of
Entomology. Technical Series No. 22.

109
II0 INSECTS AND DISEASE OF MAN

 

FiG. 52.—Stigmal plates of (1) Musca domestica; (2) Sarcophaga; (3) Stomoxys
calcitrans; (4) Auchmeromyia luteola; (5) Bengalia anthropophaga; (6) Calliphora.
(4 and 3 are from Stitt and are drawn to a smaller scale than the others; only one plate
is shown.)
CHAPTER XV
SUBORDER PUPIPARA

To this Suborder belong certain more or less degenerate blood
sucking Diptera with the body depressed dorso-ventrally; the pro-
boscis is concealed, the antennae are reduced; the wings are present
or absent when present they may be dropped or very rudimentary;
the legs are armed with stout claws and the integument is leathery.
Additional claws are often present. The females do not deposit
eggs but extrude a larva so far developed that it becomes a pupa in a
short time. Some are parasitic on birds and bats, some, the Hippo-
boscidae, are parasitic on domestic and other animals. A very
familiar example of the parasite on a domestic animal is the socalled
sheep “tick” or “louse,” Melophagus ovinus Linnaeus which is a
wingless fly almost as dependent on its host as a louse. An example
of a winged Hippoboscid is Hippobosca equina Linnaeus the forest
fly or horse tick as itis sometimes called although itis not a tick at all.

117
CHAPTER XVI

ORDER SIPHONAPTERA
(Fleas)

Fleas are insects belonging to the Order Siphonaptera. They are
wingless and flattened laterally (compressed). The mouth parts
are adapted to piercing the skin and sucking blood. The
antennae are three-jointed and are carried in a groove on either side
of the head; eyes are simple sometimes absent or vestigial. The
metamorphosis is complete there being four distinct stages of
development, egg, larva, pupa and adult (imago).

Fleas are found on warm blooded animals and birds and in their
nests. With certain exceptions each animal has its own particular
species of flea, which will only seek the blood of another species of
animal when compelled by necessity. Adult fleas subsist on blood
and both the males and females bite. The insect infests its host
for the purpose of feeding. Copulation may also occur on the host.
The eggs develop in the nest, not on the animal, and much of the
life history takes place in the nest where temperature and humidity
conditions are particularly suited to complete development.

Adult Anatomy. (Fig.s53 and Fig. 54).—Like all insects the body
of a flea is divided into a head, thorax and abdomen. :

The Head.—The head is divided by the antennal grooves into an
anterior and a posterior portion known as the froms and occiput
respectively. The lateral lower portion of the head beneath the
eye and extending from the anterior angle of the head to the antennal
groove, is known as the gene and its prolongation backwards as the
genal process. This process may extend so far backwards as to
meet the occiput thus closing off the antennal groove, or it may be
short and widely separated from the occiput thus leaving the anten-
nal groove open behind.

The frons may be notched or tuberculated in front forming the
so called frontal notch or tubercle.

The antennae, two in number, one on each side, lie when at rest

in the antennal grooves. They are capable of being erected and are
112
ORDER SIPHONAPTERA II13

divided into three parts, the distal part or ¢/ub having nine segments.
In some species this segmentation does not extend completely around
the club.

Just posterior to the anterior inferior angle of the head arises a
pair of four-jointed maxillary palpi and posterior to them, one on

   

Lateral spines of 3

5th tarsal jointee..-... £9

Lateral portion of £2
8th abdominal segment

   
   
   
  
    
  
 
 
 
  
  
 
 

Movable process
of claspersSare......
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each side are the maxillae,—triangular shaped chitinous processes
which serve as a protection to the perioral ring located between
them and through which project the mouth parts having their

movable articulations attached to its borders.
8

 

Fic. 53.—The external anatomy of a male flea.
114 INSECTS AND DISEASE OF MAN

The mouth parts consist of an epipharynx (labrum-epipharynx),
two mandibles, a labium and two labial palpi (labellae). The labial
palpi serve as a sheath to protect the epipharynx and mandibles
which are the true biting organs. They arise from a common basal
joint (the labium) which is attached to the posterior margin of the
perioral ring. They are segmented, normally having five pseudo-
joints, but the number of segments varies with the species. The
labium and labial palpi taken together form the rostrum.

The epipharynx or pricker is a slender, hollow organ, stylet shaped
at its distal extremity. It has an anterior and posterior surface and
has at its margins delicate expansions which interlock with similar
expansions on the mandibles to form the blood canal. The distal,
stylet-like end is closed but the hollow interior communicates proxi-
mally with the hoemocoele. The epipharynx is continuous with
the anterior wall of the buccal cavity and the dorsal wall of the
aspiratory pharynx.

The mandibles are triangular on section and have their distal
ends serrated. Each is grooved on its inner surface so that when
apposed a canal is formed which connects with the salivary pump.
This is the salivary canal. The mandibles are connected just within
the head to the lateral margins of the perioral ring, through the
mandibulo-basal articulations. Thus a joint is formed giving them
an up and down movement and bringing into play the saw-like action
of their serrations.

Alimentary Tract. (Fig. 54).—Within the head, above the inser-
tion of the mandibles is the buccal cavity. Its posterior wall is
thickened and represents the hypopharynx. This is concave ven-
trally and serves as an attachment for the muscles which operate
the salivary pump.

Just above the hypopharynx, and connecting it to the aspiratory
pharynx, is a thinning and reduplication of the lining chitinous
membrane, which serves as a valve. Here begins the aspiratory
pharynx which leads into the oesophagus at the oesophageal com-
missure of the large nerve ganglion (brain) in the head. The
muscles operating the aspiratory pharynx draw it open aspirating
the blood from the wound in the skin. When these muscles relax
from before backward, the pharynx collapses by reason of the
elastic properties of chitin and the blood is forced through the
oesophagus and gizzard into the stomach. The muscles have their
origins from the inner surface of the dorsal wall of the head.
ORDER SIPHONAPTERA.

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116 INSECTS AND DISEASE OF MAN

The oesophagus opens into the stomach through the gizzard
(proventriculus). This is provided with a number of chitinous
finger-like processes which when apposed form a tight valve prevent-
ing regurgitation from the stomach. The stomach is capable of
great distension and active peristaltic movement. It is not lined
with chitin. It empties into a short intestine which in turn empties
into the rectum. The intestine receives the excretions from the
Malpighian tubules. The rectum is provided with the so-called
rectal glands the function of which is unknown.

The salivary glands, four in number, lie two on each side of the
anterior end of the stomach. They are simple ascinous glands and
their ducts unite into two main ducts which empty into the salivary
pump in the head. The ducts are lined with chitin spirally arranged.

The Thorax.—The three thoracic segments are known as the
pro, meso and metathorax. Each is formed of a dorsal portion the
notum or tergite, and a ventral portion, the sternite. The prosternite
is undivided but the lateral portions of the meso- and metasternite
are divided by an internal rod-like thickening of the chitin extending
upward from the insertion of the coxa, into an anterior and a posterior
part, the stermal and the meral portion or epimerum. The sternal
portion is further divided into a lower part the sternum and an
upper part, the episternum. The epimerum of the metathorax is
broad, overlapping the abdomen and supplanting the sternite of
the first abdominal segment. There is a breathing spiracle on both
sides of each thoracic segment the third being located at the upper
edge of the metathoracic epimerum.

The Abdomen.—The abdomen is made up of ten segments.
Each consists of a dorsal portion or fergite and a ventral portion or
sternite. On each side of abdominal segments 2 to 7 is a breathing
spiracle, located in the pleural membrane connecting the tergite
with the sternite.

The seventh tergite usually has on or near its apical margin
(dorsally) on each side, one or more stout bristles sometimes arising
from a cone-like process. These are known as the antepygidial
bristles. Posterior to them is a sensory organ known as the sensory
plate or pygidium. It is present in both males and females and its
function is unknown. It is carried on the dorsal portion of the
ninth tergite. It is separated from the seventh tergite by the dorsal
part of the eighth tergite which contains the eighth or last breathing
spiracle. The lateral portion of the eighth tergite is expanded on
ORDER SIPHONAPTERA 117

each side into a broad lobe which in the female conceals the ninth
segment in relation to the genital orifice.

The clasping organs of the male which are developed from the
ninth abdominal segment are characteristic of the species and are
therefore of great taxonomic value. They are divided into the
upper and lower claspers. In general the upper claspers, which are
evolved from the gth. tergite, consist of a pair of movable processes
each articulated to a more or less broad irregularly shaped plate. The
plate consists of a body and a long process extending caudoventrad
and known as the manubrium. Above and anterior to the insertion of
the movable finger or expodite, the body is usually prolonged into a
more or less cone-like process (sometimes two) which may be termed
the immovable process. In some species, there may be two or more
movable processes, as in Pulex irritans in which the claspers resemble
a pair of pincers covered by a hairy movable flap; or, as in Xenopsylla
where there are three processes, two movable and one immovable.
These correspond to the jaws of the pincers and the flap of P. irritans.
The lower clasper is evolved from the gth. sternite. In general it
has the shape of a boomerang on side view. It is made up of an
external horizontal arm and an internal vertical arm. The latter
extends upward to the base of the manubrium lying on its outer side.
The horizontal arm may project distally from the end of the abdomen
and is sometimes fused with its fellow of the opposite side. It is
between the upper and lower claspers that the male organ is pro-
jected during the act of copulation.

The vulva of the female is also found between the gth. tergite
above and the gth. sternite below. The anus in both sexes is found
between the oth. tergite and the roth. sternite. The latter are
seen as two small flaps posterior to the pygidium. The upper flap
or 1oth. tergite of the female has a small bristled process known as
the style.

In the female certain of the accessory organs of reproduction
are, in shape, as characteristic of the species as are the clasping
organs in the male. This is especially true of the spermatheca or
receptaculum seminis which is the resevoir in which the spermatozoa
are stored until the egg is in a position to be fertilized as it passes
down the egg canal. The spermatheca is readily recognized as a
highly chitinized organ located in the posterior part of the abdomen.
It is made up of a body and a tail. The body connects by an elon-
gated, tortuous tube, the ductus receptaculi seminis, to the bursa
118 INSECTS AND DISEASE OF MAN

copulatrixz, which in turn opens into the vagina. Just posterior to
this opening are the colleterial glands which by their secretion give
hardness to the egg.

Legs.—The flea, as other insects, has three pairs of legs.
The hind legs are noticeably the largest. Each is composed of a
coxa, trochanter, femur, tibia and a five-segmented tarsus, the last
tarsal segment terminating in a pair of claws.

Fleas are provided with spines, or spinelets and setae (bristles or
hairs). They vary in number and arrangement and are important
structures in identification. The spines are frequently disposed so
as to form a ctenidium or comb on the head, thorax or abdomen.

The Egg.—The egg is a tiny, elongated, white, glistening body,
viscous or dry depending on the species. Blood seems to be neces-

 

FiG. 55.—A flea larva (Ctenocephalus canis).

sary before oviposition can take place. Blood of the normal- host
seems to be most conducive to egg laying. High temperatures as
body temperature prevent hatching; low temperatures either
delay or prevent it. The length of time required to hatch therefore
varies with the temperature as well as with the humidity and there-
fore varies under different climatic conditions. Observers in India
found that the incubation period for eggs of the Indian rat flea
was 2 days. In San Francisco, California, it was found to be g
to 13 days at room temperature. In the same place and under
similar conditions it was found that the eggs of the human flea took
6 days to hatch, eggs of the dog flea about 4 days, eggs of the Cali-
fornia ground squirrel flea 7 to 8 days and of the European rat
flea 5 to 6 days.

Larva. (Fig. 55).— The larva emerges from the egg by making a
circle of gashes in the egg shell with a wedge-shaped horny structure
ORDER SIPHONAPTERA 119

on its head. The larva is a slender, legless, worm-like creature with
masticatory mouth parts. Larval fleas feed on the organic matter
in the dust of the floors, carpets, etc. or in the nest of the animal.
An important source of food supply seems to be the excreta of
adult fleas.

Pupa.—After a period varying from one to four weeks during
which time it undergoes three moultings, the larva spins a cocoon
and becomes a quiescent pupa, which in from one to four weeks
becomes the fully grown and fully developed adult flea.

CLASSIFICATION

The Order Siphonaptera is divided into two Suborders,—the
Fracticipita and the Integricipita. In the Suborder Fracticipita
(Figs. 56 and 357) the frons and occiput are separated dorsally by

 

.

Fic. 56.—Head of a bat flea (Ischnopsyllus octactenus).

a sulcus through the chitinous envelope of the head, extending from
the top of the antennal groove of one side, across the vertex to the
antennal groove of the other side. A joint is thus formed which
permits of some motion between the frons and occiput, the former
overlapping the latter above. The antennal groove is a part of the
occiput and its thickened posterior margin after contouring the
groove above turns abruptly towards the vertex.

In the Suborder Integricipita (Figs. 61 and 65) the frons and
occiput have fused together, the line of union or suture being often
visible as a chitinous thickening extending to the top of the head.
120 INSECTS AND DISEASE OF MAN

This thickening is known as the falx. The anterior and posterior
margins of the antennal groove have also coalesced above. :

There are certain genera which seem to represent a transitional
stage (connecting link) between the two groups,—from the Fracticipita
to the Integricipita—the former being the primitive form. Fusion
between the frons and occiput has progressed to a more or less
degree and the joint is vestigial. Under such circumstances there
might be a difference of opinion as to which group a given specimen
should be assigned so that in using the following key it would be
well to try both Suborders when one has failed to produce results.

The Order is also subdivided into a number of families, including
Tungidae, Pulicidae, Ceratophyllidae, Leptopsyllidae, Hystricho-
psyllidae, etc.

 

FiG. 57.—Head of a Fracticipite flea (Corypsylla ornatus).

Key to the Genera of the Siphonaptera

1. Frons and occiput separated above by a sulcus extending from the top
of the antennal groove of one side, across the vertex to the antennal
groove of the other side; anterior and posterior margins of antennal
groove not fused above the root of first antennal segment; lateral apical
spines or spinelets often present on some of the abdominal segments,
extending to or almost to the stigmata. ...... (Suborder Fracticipita). .46

Frons and occiput not separated by a sulcus; falx often present; anterior
and posterior margins of antennal groove fused above root of first antennal
segment; apical spines never present, apical spinelets when present
usually dorsal rarely extending to the stigmata (Suborder Integricipita).. . 2

2. The three thoracical tergites together always shorter than the first abdominal
tergite; no comb present; the rostrum consists of three, or fewer, feebly
chitinized segments; genal edge of head in all cases produced downwards
into a triangular lobe situated behind the mouth parts................3
ORDER SIPHONAPTERA 121

Thoracical tergites together longer than the first abdominal tergite; combs
of spines frequently present; rostrum more or less strongly chitinized,
consisting of four or more segments (rarely less); lower edge of head rarely
produced into a triangular lobe behind the mouth parts............... 5

3. Hind coxa without a patch of spinelets on the inner side................ 4

Hind coxa with a patch of spinelets on the inner side (Fig. 59).

* Echidnophaga ONiff (1886) (ambulans)t
4. Hind femur simple without a large tooth-like projection near the base
(Page srso¥ii ionic, * Tunga Jarocki (1838) (penetrans)

Hind femur with a large tooth-like projection near the base.

* Hectopsylla Frauenfeldt (1860) (psittaci)

5. Abdominal tergites two to seven with but one row of bristles............ 6
Abdominal tergites two to seven with at least two rows of bristles... ..... 22

6. With a row or patch of spinelets on inner side of hind coxa; antepygidial
bristles one on each side; four (rarely three) pairs of lateral plantar bristles

on fifth tarsal segment of all legs. U0. -. oe nn En JE Ae
Without a row or patch of spinelets on inner side of hind coxa.......... 18
ye absent, ral ph NRT a Rooseveltiella Fox (1914) (georychi)
Bye presenton lh cr eR EL Rd ERs 8

8. No:pronotalicomly. 1h... it elim as elm) Bd a 9
Pronotal comb present, of few or numerous teeth. ..................... 14

9. Anterior angle of genal edge produced intoalobe..................... 10
Anterior angle of genal edge not produced into a lobe.................. II

10. Frons with very small frontal tubercle near the vertex; anterior angle of
genal edge of head produced downwards into a triangular lobe; pronotum
shorter than metanotum. ......... Moeopsylla Rothsch. (1908) (sjoestedii)

Frons without tubercle; anterior angle of genal edge of head produced
backwards into a triangular lobe; pronotum longer than metanotum.
Pariodontis Rothsch. (1908) (riggenbachi)

11. Mesosternite very narrow, with but one internal rod-like incrassation which
extends from the insertion of the coxa forward to the anterior border
(Big iGo). ould iss * Pulex Linnaeus (1758) (irritans)

Mesosternite with two internal rod-like incrassations, one extending from
the insertion of the coxa forwards and one extending upwards........ 12

12. Frontal tubercle present; frons strongly angulate in male more evenly

rounded in female........ Ornithopsylla Rothsch. (1908) (laetitiae)
No frontal tubercle; frons not angulate, strongly rounded in both sexes. .13

13. Fifth tarsal segment of all legs with three pairs of lateral plantar bristles;

club of antenna plainly segmented all around.
Actenopsylla J. & R. (1923) (suavis)
Fifth tarsal segment of all legs with four pairs of lateral plantar bristles;
club of antenna distinctly segmented only on hind side (Fig. 61).
: * Xenopsylla Glink. (1907) (cheopis)
* A star in front of the generic name indicates that the genus is found in the New
World.
1 The specific name following the date is the type of the genus.
122 INSECTS AND DISEASE OF MAN

14.

16.

17.

13.

19.

20.

21.

22.

23.

24.

. With a comb of spines on the pronotum only (Fig. 64).

* Hoplopsyllus Baker (1903) (anomalus)
With a comb of spines on the pronotum and the gena................. 13

. Spines in genal comb numerous (more than three)..................... 16

Spines in genal comb reduced to three or less; pronotal comb also reduced.
Archaeopsylla Dampf (1908) (erinacer)
Genal comb running horizontally along lower border of gena; teeth of comb
consisting of about seven rather long, pointed spines (Fig. 63).
* Ctenocephalus Kolenati (1839) (canis)
Genal comb running across gena obliquely. .......................... 17
Mandibles large, strongly serrated; frons tending to be obtusely angled in
front * Spilopsyllus Baker (1903) (leporis)
Mandibles not enlarged; frons rounded.
Nesolagobius J. & R. (1922) (callosus)
Pronotal combipregent iil nh oS fais el REE 10
Pronoizbicombiabsent. ui oi an Se 20
Labial palpus of five segments, the last segment very long, slightly curved
at the apex, much more produced posteriorly than anteriorly
*Megarthroglossus J. & R. (1915) (procus)
Labial palpus of four segments, not as above; second segment of antenna
widened on outside, covering one-third of the club
*Callistopsyllus J. & R. (1915) (terinus)
Eyes absent; fifth hindtarsal segment with four pairs of lateral plantar
bristles; one antepygidial bristle on each side; vestiture of body greatly
reduced Jol ine een *Anomiopsyllus Baker (1904) (nudatus)
eS DTeRen i i SS el ei 21
Frons with a tooth-like tubercle; antennal groove closed behind; antepygidial
bristles absent in both sexes; fifth tarsal segment of all legs with six
(rarely five) pairs of lateral plantar bristles.
Lycopsylla Rothsch. (1904) (novus)
Frons truncate with no distinct frontal tubercle; antennal groove open
behind; antepygidial bristles two on each side, a long and a short one;
fifth tarsal segment of all legs with five pairs of lateral plantar bristles;
two receptacula seminis; claws of tarsi with basal tooth. |
Coptopsylla Rothsch. (1908) (lamellifer)

Genzlcombipresents. +, ovo ral 0 a SC A I is ES 23
Genalcomthialsent. (i nn ba aC i Le 29
Eye present but not always strongly pigmented; spines of genal comb two
either parallel or crossing each other... 0 si Co anh 05, 27
Eye absent or vestigial; spines of genal comb three (rarely two) or fiveor
SE IIIT OE i oo ea Ti Vedio ta oe a Ta a air a 1 ee das 24

Metasternite not divided; 5 spines in genal comb, the third one pale and
overlapping the second; a small flea.

* Micropsylla D. & P. (1923) (peromyscus)

Metasternite normally divided; none of the genal spines overlapping;

labial palpus with a curved bristle posteriorly near the tip............ 25
25.

26.

27.

28.

29.

30.

31.

32.

33-

ORDER SIPHONAPTERA 23,

Spines of genal comb three (rarely 2); fifth hind tarsal segment with three
pairs of lateral plantar bristles and a fourth pair on the ventral surface
in between the first lateral pair (rarely four pairs of lateral bristles).

* Ctenophthalmus Kolenati (1856) (bisoctodentatus)

Spinesefigenal combiifive.. ©... 26

Fifth tarsal segment of all legs with four pairs of lateral plantar bristles.

* Rhadinopsylla J. & R. (1912) (musculana)

Fifth tarsal segment of all legs with six pairs of lateral plantar bristles.

* Actenophthalmus Fox (1925) (heiseri)

Genal spines two crossing each other; fifth tarsal segment of all legs with four
pairs of lateral plantar bristles; antepygidial bristles one on each side.

Chiastopsylla Rothsch. (1910) (numae)

Genal spines two parallel to.eaclh other. 0 ULL Lilo LL a 28

Bristles on posterior border of tibiae mostly unpaired, numerous, forming
a kind of comb; spines in pronotal comb deflected; pronotum much wider
above than at the sides.......... Caenopsylla Rothsch. (1909) (mira)

Bristles on posterior border of the tibiae mostly in pairs; spines of pronotal
comb not deflected; blunt; eye large; apical margin of pronotum incurved.

Mesopsylla Dampf (1910) (eucta)

With a row or patch of spinelets on inner side of hind coxa............. 30

Without a row or patch of spinelets on inner side of hind coxa.......... 3%

Without oblique rows of bristles on occiput; eye present; fifth tarsal article
of all legs with five pairs of lateral plantar bristles.

* Odontopsyllus Baker (1903) (multispinosus)

With oblique rows of bristles on occiput; eye vestigial; fifth article of fore
and mid-tarsus with four pairs of lateral plantar bristles and a proximal
ventral pair in between the first lateral pair, fifth tarsal segment of hind
leg with four pairs of lateral plantar bristles, the ventral pair being
absent or represented at the most by one bristle.

* Catallagia Rothsch. (19153) (charlottensis)

Fifth tarsal article broadly dilated and lengthened beyond the fourth pair
of lateral spines where on each side there is a hair, a bristle and a hair,
there is also a pair of subapical bristles; fifth tarsal segment of fore leg
as long as rest of tarsus; on all legs the claws are nearly as long as the fifth
segment; fore coxa nearly nude with but few long bristles; fore tibia armed
on posterior border with a few large black tooth-like bristles or a few

heavy bristles... ....... * Malacopsylla Weyenbergh (1881) (grossiventris)
Yessmot aeabove.. 0 LL, oo en SN a Rn i 32
Frontal notch or tubercle present; with or without eye.................33
Ne distinct frontal notch or tubercle; eye present... .................. 41

Fifth tarsal segment of all legs with four pairs of lateral plantar bristles,
never with a pair of proximal ventral bristles; antepygidial bristles o or
1; no:pronotal comb; eye present... ana RAS 0 LE 34

Fifth tarsal article of all, or at least some of the legs, with five pairs of plantar
bristles, all lateral, or four lateral and a proximal ventral pair........... 37
124 INSECTS AND DISEASE OF MAN

Fifth tarsal segment of all legs with six pairs of lateral plantar bristles all
in line except the third pair which is dislocated towards the median line;
pronotal comb present; one antepygidial bristle on each side.

* Dasypsyllus Baker (1905) (perpinnatus)
34. Antepygidial bristles none; an eye row of four or five long bristles; claspers

broad and deep, disc-like; species usually very hairy................. 33
Antepygidial bristles one on each side; an eye row of three bristles or less;
claspers large, triangular; species not especially hairy................. 36

35. Club of antenna short, symmetrical, not much longer than broad; labial
palpus of about eleven segments; body of pregnant female elongate.
Vermipsylla Schimk (1885) (alacurt)
Club of antenna long; labial palpus of from five to seven segments; gena
often dark, blending with eye.
* Trichopsylla Kolenati (186 2 (penicilliger Kolenati)
36. Club of antenna short, not symmetrical, the proximal segments sloping
backwards; segmental incisions most marked on hind side; genal process
with only two bristles behind eye, one at some distance above other.
* Rhopalopsyllus Baker (1905) (luizi)
Club of antenna long, symmetrical; segmental incisions marked on both
sides; genal process with several bristles along lower margin or at least
one or two bristles close behind eye.
* Parapsyllus Enderlein (1903) (longicornis)
37. Maxillary palpus very long and slender reaching beyond the apex of the
fore coxa and being longer than the labial palpus which is five segmented;
the bristles of the postmedian row on the abdominal segments and metano-
tum are long, generally of nearly the same width to near the tip or even
slightly widened distally, the tip not drawn out into a long thin point;
antepygidial bristles one; eye vestigial.
Xiphiopsyllus J. & R. (1913) (hippia)
Maxillary palpus not reaching beyond the apex of forecoxa; bristles of
abdomen and metanotum normal in contour (drawn out into a fine point).
38
38. Frons with a large spade-shaped tubercle; eye small, behind same a bristle-
like spine; some spinelets on first five abdominal segments.
Listropsylla Rothsch. (1907) (agrippinae)
Frontal tubercle present but not so prominent; no bristle-like spine back of
eye; with or without dorsal spinelets on abdominal segments. ........ 39
30. Antepygidial bristles 4 or 5 (rarely 3) on each side; a lower genal row of five
bristles; eye absent; five pairs of lateral plantar bristles on fifth tarsal
segment of all legs, the first pair somewhat dislocated towards the median
line; especially prominent in the male is a median caudal extension of the
seventh tergite between the two groups. of antepygidial bristles; occiput
with an oblique row of bristles.
* Dolichopsylla Baker (1905) (stylosus)
40.

41.

42.

43.

44.

45.

ORDER SIPHONAPTERA 125

Antepygidial bristles three on each side, in the male one or two of them
frequently reduced in size; a lower genal row of about three bristles. ..40
Head with three rows of bristles across frons and occiput; eye reduced;
bristles of second antennal segment short in both sexes; hind margin of
pronotum slightly incurved; mid- and hind tibiae with two to four single
dorsal bristles in between the postmedian and subapical dorsal pairs;
bristles of tarsi short, fifth segment with the first pair of plantar bristles
moved on to the ventral surface; clasper of male without a bristle at the
insertion of the movable process; ventral arm of ninth sternite without a
sinus; eighth sternite large, in the female with an oblique vertical row of
brstles.Cn oh * Amphipsylla Wagner (1909) (shelkovnikovi).
Bristles on occiput rarely tending to form oblique rows; one or two rows of
bristles on frons; eye present (rarely absent); some of the bristles on the
second joint of antenna frequently as long as or longer than the club;
hind margin of pronotum not incurved; most of the bristles on hind margin
of tibiae in pairs; some of the apical bristles on second hind tarsal segment
often long at times reaching well to the fifth segment; five pairs
of lateral plantar bristles on the fifth tarsal segment of all legs, the first
pair at times bent or dislocated towards the median line or even moved
well on to the ventral surface; clasper of male with two bristles at the
insertion of movable process; ventral arm of ninth sternite with a sinus;
eighth sternite small, and in the female with no distinct vertical row of
bristles (Fig. 65)............, * Ceratophyllus Curtis (1832) (hirundinis)
No antepygidial bristles; ventral margin of head dilated behind the palpus
into a rounded lobe projecting downwards; genal process immediately
behind eye dilated into a truncate flap which partly covers the club of the
antenna; pronotum almost hammer-shaped; episternum of metathorax
larger than sternum; eye large. . . . Uropsylla Rothsch. (1905) (fasmanicus)
Two antepygidial bristles on each side; head and thorax not as above;
pygidium usually convex; species hairy... .........cv eh oii uvaniais 42
Pronotal comb absent; antennal groove open behind.
Notiopsylla J. & R. (1914) (kerguelensis)
Pronotal comb present; antennal groove closed behind; eighth abdominal
sternite of minle very large... . un cana Sl LL ral 43
Pronotum with one row of bristles; hind tibia with one lateral row on outer
surfage ak a nL a se Choristopsylla Rothsch. (1922) (och)
Pronotum with at least two rows of bristles... ....................... 44
Comb incomplete, reduced to a small number of spines.
Bradiopsylla Rothsch. (1922) (echidnae)
Comb complete, with more than sixteen spines on the two sides together. . 45
Frons without a pair of short stout spines in the first row of bristles; expodite
(movable process) of male very long, curved down at the apex; female
with conspicuous process dorsally between the two pairs of antepygidial
bristles: tr lt iar ny nn) Stivalius Rothsch. (1922) (akalae)
Frons as in Stivalius; expodite of male curved up at apex; female without
dorsal process between antepygidial bristles.
Pygiopsylla Rothsch. (1906) (killi)
126 INSECTS AND DISEASE OF MAN

46.

47.

48.

49.

Frons with two short, stout, curved spines in the anterior row of bristles.
Acanthopsylla Rothsch. (1922) (rothschildi)
Head with two chitinous flaps Merion on each side (the bat fleas)

(Fig. 36) .. ers 270
Head without these Taps but olten with a gonad comb of strongly hitinized
SPANBRRCE Sl NEL eal ee Re LR Sr a7

A comb of numerous spines on the frons placed around the border of a
“cap” or “crown” which is divided off from the rest of the frons by a

marked suture; genal comb present or absent....................... 48
No such arrangement of frontal spines; with or without genal comb. . . . . .. 50
Cap vertically placed or nearly so; genal comb present.................49

Cap horizontally placed; genal comb absent.
Stephanopsylla Rothsch. (1911) (thomasi)
No row or patch of spinelets on inner side of hind coxa; maxilla elongate,
IARGUIRTL ior in Serio Stephanocircus Skuse (1893) (dasyuri)
A patch of spinelets on inner side of hind coxa; maxilla irregularly elongatel,
ovate, tip somewhat pointed... *Craneopsylla Rothsch. (1911) (wol ffhuegeli).

. With lateral apical spines or spinelets on some of the abdominal segments

reaching to or almost:to the stigmata... oven Ls 51
Without lateral apical spines or spinelets on the abdominal segments;
dorsal apical spinelets frequently Present... .... ois. ii ive niviels oa 57

. Eye present or somewhat reduced; abdominal combs of spines or spinelets

not so conspicuous; bristles on posterior border of tibiae mostly in pairs. . . 52
Eye absent or vestigial; abdominal combs of spines or spinelets usually
conspicuous; some of the bristles on posterior border of hind tibia in
groups of three (or four), or at times single forming a kind of comb;
notch at apical end of hind coxa usually very pronounced.............. 53

. Genal comb of five or six spines; labial palpus of four segments; eye well

definedi. ie. inl nan enh Typhloceras Wagner (1903) (poppe)
Genal comb absent; labial palpus of six to eight segments; eye reduced.
*Atyphloceras J. & R. (19135) (multidentatus)

. Genal process broad and obtuse and separated from the oral edge by a deep

sinus; frontal spines arranged along the anterior edge of antennal groove;
first segment of antenna large, as long as the club, second segment short
except on the anterior side where it is much produced distad; bristles on
posterior border of tibiae mostly single forming a kind of comb; one
receptaculum seminis....... Dinopsylla J. & R. (1913) (ellobius)
Genal process not separated from the oral edge by a deep sinus; first and
second segments of the antenna not as above; some of the bristles on posterior
border of hind tibia in groups of three (or four); a comb of spines along
ventral edge of gena and at times along the anterior border of antennal
groove; receptaculum seminis frequently double..................... 54

. Five pairs of lateral plantar bristles on fifth tarsal segment of all legs;

labial palpus of four or five segments; two receptacula seminis..........53
Four pairs of lateral plantar bristles on fifth tarsal segment of all legs with
a ventral pair placed in between the first lateral pair; labial palpus with
one or 11 to 13 segments; receptaculum seminis one or two............. 56
56.

59.

60.

61.

ORDER SIPHONAPTERA I27

. Frons rounded as far down as first genal spine; a comb of spines along ventral

edge of gena; abdominal tergites with two rows of bristles.
* Ctenoparia Rothsch. (1909) (inopinata)
Rounding of frons stopping well above first genal spine; a comb along ventral
edge of gena the middle spine being the longest; abdominal tergites with

three rows of bristles... ... * Hystrichopsylla Taschenberg (1880) (talpae)
Labial palpus of one segment; a comb of spines on ventral border of gena;
one receptaculum seminis. . . .. * Stenoponia J. & R. (1911) (tripectinata)

Labial palpus of 11 to 13 segments; a comb of spines along ventral border
of gena as well as along antennal groove; chitin of occiput internally
thickened at about the middle; two receptacula seminis of unequal size.

Macropsylla Rothsch. (1905) (hercules)

. Mandibles and labrum-epipharynx very broad particularly the former;

labial palpus but feebly chitinized and showing but three distinct segments;
six genal spines in vertical row; one antepygidial bristle; row of spinelets
on inner side of hind coxa. ...Chimaeropsylla Rothsch. (1911) (potis)
Mandibles and labrum-epipharynx slender; labial palpus well chitinized and
distinely showing four or more segments... ... cc. oni. 58

. Frons often narrowly rounded (subangulate) in front; bristles on posterior

border of tibiae mostly single forming a kind of comb; four pairs of lateral
plantar bristles on fifth tarsal segments of all legs with or without a ventral
pair in between the first lateralipalr.... .. . 0 ivi. ven iithin iin 59
Bristles on posterior border of tibiae mostly in pairs and not forming a kind
elcome ce itt 61
Frons subangulate with short stout spiniform bristles near anterior margin;
with or without genal comb; eye absent or vestigial................. 60
Frons not subangulate. and without spiniform bristles near anterior margin;
genal comb vertical with the teeth of the comb rounded at the tip and
somewhat overlapping anterior edge of antennal groove; eye near base
of antenna; a comb or patch of small spiniform bristles on inner side of
hind coxa; four pairs of lateral plantar bristles on fifth tarsal segment of all
fogs. cit mL Hypsophthalmus J. & R. (1913) (campestris)
Genal comb present, vertical, of from two to numerous teeth; frons sub-
angulate in’ front, with two or three spine-like bristles near the angle;
labial palpus of five segments; four lateral pairs of plantar bristles with a
pair of ventral bristles in between the first lateral pair (Fig. 67).
* Leptopsylla J. & R. (1911) (musculi)
Genal comb absent; frons strongly subangulate with tubercle at the angle;
a row of spiniform bristles parallel with margin of frons from oral corner
to base of antennal groove; second segment of antenna widened apically
into a broad rounded lobe covering in the male one-third the club, in the
female one-half; labial palpus of four segments.
* Stenistomera Rothsch. (1915) (alpina)
With two combs of spines on the head a frontal and a genal, the frontal
comb not placed around the borders of a cap or crown which is divided
off from the rest of the frons by a suture; frons strongly reclining back-
wards; two antepygidial bristles on each side; occiput with an internal
dorsal incrassation before the centre.
Cleopsylla Rothsch. (1914) (lownsendi)
128 INSECTS AND DISEASE OF MAN

With but one comb.of spinesonthe head. ........ ..... co 000i 00, 62

62. Genal comb of two spines either parallel or crossing each other......... 63

Genal comb of three spines, quite small and pale; no genal process; ante-

pygidial bristles one on each side placed at some distance from the apical
margin of the seventh tergite; eye strongly reduced.

Agastopsylla J. & R. (1923) (box)

Genal comb of four spines. ris hry Bal una E Nn el hr 65
Genal or frontal comb of five or six spines. ......... 000 000 anh 67
03. Genal spines crossing-each other... .... 0... nil a si iis 64

Genal spines parallel to each other; eye reduced, not pigmented; frons
produced into a kind of snout at a short distance from the maxillary
PAIDUS. ah e, Acropsylla Rothsch. (1911) (episema)

64. Frontal tubercle absent; without dorsal spinelets on the abdominal segments;
fifth segment of tarsi on all legs with four pairs of lateral plantar bristles
and a ventral pair in between the first lateral pair; hind coxa with a row
or patch of small bristles on the inner surface.

* Phalacropsylla Rothsch. (1915) (paradisea)

Frontal tubercle present, small; with dorsal apical spinelets on some of the
abdominal segments; five pairs of lateral plantar bristles on fifth fore and
mid-tarsal segment, on the fifth hind tarsal segment the proximal pair
placed ventrally between the first lateral pair or, the proximal pair ven-
trally placed between the first lateral pair on all legs; a patch of spinelets
or thin bristles on inner side of hind coxa.

* Neopsylla Wagner (1902) (bidentatiformis)

65. First spine of genal comb almost completely covered by second; antepygidial
‘bristles two on each side; eye without pigment.

Neotyphloceras Rothsch. (1914) (rosenbergi)

First spine of genal comb not covered by second. .... Ea CEN 66

66. Labial palpus of four segments; the genal spines of almost equal length,
second from above not sharply pointed; two or three antepygidial bristles
onteach side... ..... 0. * Doratopsylla J. & R. (1912) (dasycnemus)

Labial palpus of five segments; second spine from above long and tapering
toa sharppoint. ..0.0050 Ga. i Palaeopsylla Wagner (1902) (minor)

67. Hind coxa with a row or patch of spinelets (or spiniform bristles) on the
gnaerside.. lo UL a Re Ln LL 68

Hind coxa without a row or patch of spinelets on inner side; no frontal
notch or tubercle; head rounded; fifth tarsal segment of all legs with four
pairs of lateral plantar bristles and one ventral pair in between the first
lateral pair; genal spines similar to Nearctopsylla. (See 69.)

Chiliopsylla Rothsch. (1915) (allophyllus)

68. Eye present placed high up in head near base of antenna; genal process
deep with a vertical genal comb of about five spines extending from eye to
ventral border of head; one long antepygidial bristle accompanied by two
very small ones; fifth segment in all tarsi with four pairs of lateral plantar
bristles. ........ co. a Hypsophthalmus J. & R. (1913) (campestris)

EVE aADSENt. oi vhs edie air dni tan eat Baubles i To es Rede eye 69
60,

70.

71.

72,

73.

74.

75

76.

77-

78.

ORDER SIPHONAPTERA 120

Genal spines six, all more or less elongated, the fourth from top dilated at
the tip; abdominal tergites 1 to 7 with an internal thickening dorsally;
frons subangulate; genal process, short, truncate. (Fig. 57.)

* Corypsylla Fox (1908) (ornatus)

Genal spines five, the upper one short, broad and triangular, the next three
lanceolate, the fourth (2nd. from below) the longest; abdominal tergites
without dorsal internal thickening; frons rounded; pronotal comb curved

frontad ventrally............ * Nearctopsylla Rothsch. (1915) (brooksi)
Meaziliniacuminate. vl. oo um a a LL OLR SE 71
Mazillatpanente. oho, sri LL Che la 75
One or more of the abdominal tergites with a comb of spines........... 72

Abdominal tergites without combs, with a pair of dorsal spinelets; eye bristle
present; antepygidial bristle present; genal process acuminate.
* Sternopsylla J. & R. (1921) (fexanus)
Head very short, semicircular; first abdominal tergite with comb; prothorax,
apart from comb, extremely short; bristles on posterior border of tibiae
of an even length forming a kind of comb. ]
Thaumapsylla Rothsch. (1907) (breviceps)
Head elongate, distinctly longer thandeep................ccvvvuun... v3
Frons with distinct tubercle; first abdominal tergite with small comb, tergites
II to VI and metanotum with a few short apical teeth; bristles on posterior
border of tibiae in pairs not forming a kind of comb; fifth tarsal segment
with first pair of plantar bristles replaced. by small ventral bristles.
* Ptilopsylla J. & R. (1921) (leptina)
Frons without tubercle; eye bristle absent; abdomen with four combs. . ..74
Second segment of antenna enlarged exteriorly covering about half the club;
antepygidial bristle present... ... * Hormopsylla J. & R. (1921) (fosteri)
Second segment of antenna not as above; antipygidial bristle absent;
seventh abdominal tergite with false comb; all species have five combs
(including the prothoracic) but in one (IN. dictenus), the three middle have
only one pair of very short teeth.
Nycteridopsylla Oudemans (1906) (pentactenus)
Abdomen with five or Seven combs. . ...... 0 Jal ll un 76
Abdomen with false combs, also metathorax, composed of the thickened
bristles of the submedian row which are placed close to the apical edge of
the tergite because of the border being sinuate dorsally.
Myodopsylla J. & R. (1911) (insignis)
Abdomen without combs «.. ox lei de Sh Fal ne 3
Abdomen with seven combs. . . .Ischnopsyllus Westwood (1833) (elongatus)
Abdomen with five combs. . Hexactenopsylla Oudemans (1906) (hexactenus)
Epimerum of metathorax with comb; first abdominal tergite small.
Chiropteropsylla Oudemans (1908) (aegyptius)
Epimerum of metathorax without comb... ...... 00 man To ao 78
Posterior margin of occiput behind antennal groove, with four or more short,
strong, pointed, spine-like bristles; metepimerum higher than long.
Araeopsylla J. & R. (1921) (scitulus)

Posterior margin of occiput with only the usual bristles.................. 79
9
130 INSECTS AND DISEASE OF MAN

79. Occiput with about six dorsal incrassations, thorax with similar structures,
bases of abdominal segments with one such incrassation.
Largaropsylla J. & R. (1921) (signata)
Occiput and thorax without incrassations.
Rhinolophopsylla Oudemans (1910) (unipectinaia)
Synonyms:
Ceratophyllus = Stenonotus = Monopsylla
Ctenophthalmus = Spalacopsylla
Doratopsylla = Stenopsylla
Leptopsylla = Clenopsylla
Malacopsylla= Megapsylla
Notiopsylla = Goniopsylla
Rhopalopsyllus = Rothschildiella
Trichopsylla = Chaetopsylla = Oncopsylla
Xenopsvila = Loemopsylla
Echidnophaga = Argopsylla = Xestopsylla
Hectopsylla = Rhyncopsylla
Tunga = Sarcopsylla = Rhynchoprion

FAMILY TUNGIDAE
Genus Tunga Jarocki (1838)

Description.—Labial palpi pale, consisting of one segment; head
not divided by a groove or, an internal thickening from the antennal
groove upwards; prosternite not produced posteriorly into a distinct
conical tooth; hind coxa produced anteriorly at the apex into a tooth,
no patch of spines on the inner side; hind femur simple; tibiae with
three pairs of dorsal bristles; tarsi very slender, some of the apical
bristles on segments 2, 3 and 4 of hind tarsi very long and thin;
sth. segment linear about eight times as long as it is broad with a few
long and thin hairs; claws slender without basal projection; female
without anal style and without stigma on first, second and third
abdominal tergites.

Three species of this genus are known, namely:

Tunga penetrans Linnaeus (1758) with eyes distinct.

Tunga caecata Enderlein (1901) with eyes vestigial.

Tunga caecigena Jordan and Rothschild (1921) with eyes com-
pletely absent. :

Tunga Penetrans

This is a flea of tropical and subtropical America and has been
introduced into Africa. It is known locally as the jigger or chigoe.
ORDER SIPHONAPTERA I3I

The hind legs are not well developed as in other fleas, for part of its
life history is spent as a fixed parasite on man and the lower ani-
mals. The mandibles are very stout. The female fixes her mouth
parts in the skin and the resulting irritation
produces a swelling which encompasses the
insect except for a small opening at the end
of the abdomen. Through this opening she
is enabled to secure air and to lay her eggs
which drop to the ground and hatch similarly
to other: fleas’ eggs. At the termination of
the egg laying period the adult dies. The pi. 55. —Tunga penctrans,
skin between the toes is oftenest attacked. egg-distended female. (From

\ J ... Stitt’s ‘Practical Bacteri-
Infection may follow producing a dermatitis ology, Blood Work and Ani-
and pustular conditions. The flea is more Penton igi
~ prevalent when the weather is warm and dry.

Genus Echidnophaga Olliff (1886)

Description..—Labial palpus consisting of one segment; head angu-
late in front and divided by a groove or an internal thickening from
the antennal groove upwards; abdominal segments 2 to 8 with a

 

 

Fic. 59.—Head and thoracic nota of Echidnophaga gallinacea.

stigma in both sexes; hind coxa anteriorly produced at the apex into a
broad tooth and bearing on the inner side a patch of spinelets; hind
femur simple; anal segment of female with style.

There are eight species of this Genus found in Asia, Africa, Europe
and Australia. Only one, E. gallinacea, has been introduced into
America.
132 INSECTS AND DISEASE OF MAN

Echidnophaga gallinacea Westwood. (Fig. 59)

In this flea the fifth tarsal segment has two ventral apical bristles
and there is a small lateral lobe at hind margin of head. It is a
flea of chickens and has been taken off other domestic animals and
rats. It will attack man.

FAMILY PULICIDAE
Genus Pulex Linnaeus (1758)

Description.— Frontal notch absent; eye present; club of antenna
short distinctly segmented only on the posterior side; antennal

 

 

F1G. 60.—Head, prothorax, mesothorax and genitalia of Pulex irritans (male).

groove closed behind, the genal process separating the antennal
groove from the fore coxa; no spines on gena, at times a small tooth
at genal edge of head slightly behind lower oral corner; two bristles
on gena, an ocular and an oral; labial palpi of four segments; tip of
rostrum asymmetrical; mandibles broad, short and densely serrate;
hind coxa with a comb of spinelets on the inner surface anteriorly
and a number of hairs posteriorly; fifth tarsal segment with four
lateral bristles besides the subapical hair; an antepygidial bristle on
each side separate from the apical edge of the 7th. tergite; pronotum
without a comb of spines; mesosternite very narrow, without internal
rod-like incrassation from the insertion of the coxa upwards, claspers
with two movable processes forming a kind of pincers which is cov-

|
ORDER SIPHONAPTERA 133

ered by a third process in the shape of a large hairy flap, all processes
conspicuous.

~ Two species of Pulex have been described. The common, well
known, widely distributed species is Pulex irritans the type of the
genus. (Fig. 60.) Baker has reported another from Mexico,
Pulex dugesi. This differs from P. érritans mainly in the length of
the rostrum, which in P. irritans reaches to about half the length of
the anterior coxa and in P. dugesi to about three fourths the length
of that coxa.

Genus Xenopsylla Glinkewicz (1907)

Description.—Frons without a notch or tubercle; eye present;
genal process almost completely closing the antennal groove, separat-
ing it from the prosternum and being pointed behind; anterior angle
of genal edge of head not produced into a triangular lobe; no spines on
head; club of antennae short, distinctly segmented only on the
posterior side; eye present; two bristles on the gena, one in front of
the eye and one near the lower genal border, labial palpi with four
segments; tip of rostrum asymmetrical, no spines on prothorax;
hind coxa with a comb of small teeth (spinelets) on the inner side;
fifth tarsal segment with four lateral bristles besides the subapical
hair; an antepygidial bristle on each side separate from the apical
edge of the 7th. tergite at times placed on a tubercle; mesosternite
with a rod-like incrassation from the insertion of the coxa upwards;
claspers with two or three small processes, manubrium narrow, upper
internal portion of the gth. sternite not very sharply defined.

XENOPSYLLA CHEOPIS ROTHSCHILD (FIG. 61)

This is the Indian rat flea and very likely the true plague
flea. Cragg has pointed out that in parts of India where this
rat flea predominates, epidemics of plague are not uncommon
while in those parts of India where other rat fleas predominate
epidemics of plague are rare or absent. X. cheopis is cosmopolitan
in its distribution and is present on the East, South and West coast
of the United States. Whether it is present in the interior of the
United States is not known. It has been carried from port to port
by ship rats most of which are black rats (Rattus rattus).

The labial palpi reach to the apex of the fore coxa; the median
saggital incrassation of the occiput has an even contour; the epi-
sternum and sternum of the metathorax are separated from each
134 INSECTS AND DISEASE OF MAN

other by a suture; the episternum bears one bristle, the sternum 1,
and the epimerum 10 to 17 in two rows (5 to 8, 5 to 7); the meso-
sternite bears 5 bristles; the hind femur has a tooth ventrally at its
widest portion, a row of 5 to g bristles on the inner surface and two

 

Fic. 61.—Head, prothorax, mesothorax and genitalia of Xenopsylla cheopis (male);
(A) oth sternite of X. astia.

subapical bristles on the outer surface; the antepygidial bristle
is not on a cone like process; the longest apical bristle of the second
hind tarsal segment reaches to the middle of the fifth segment; there
are two movable processes, to the claspers, one narrow and more or

  

B C
Fi1G. 62.—Receptaculum seminis of (A) Xenopsylla cheopis; (B) X. brasiliensis; (C)
X. astia.

less straight, the other with rounded contour its upper border being
more convex than the lower and containing along its edge a number
of bristles; the ninth sternite is club shaped gradually but distinctly
expanded towards the end; receptaculum seminis as in (Fig. 62A).

Xenopsylla astia Rothschild. This is also a rat flea of India,
Ceylon, Philippine Islands etc. It can be distinguished from
ORDER SIPHONAPTERA 135

X. cheopis by the ribbon-like ninth sternite (Fig. 61A), the “keel”
shaped contour of the median sagittal thickening of the occiput in
the male and the shape of the receptaculum seminis in the female.
(Fig. 62C.)

Xenopsylla brasiliensis Baker is a rat flea of India, Africa and
South America. This can be distinguished from the others by the
different shape of the receptaculum seminis (Fig. 62B) and by
the antepygidial bristle which in the male is carried on a cone.

Genus Ctenocephalus Kolenati (1859)

Description.— Frontal notch absent; eye present; labial palpi
four segmented; club of antenna distinctly segmented only on pos-
terior side; two bristles on gena an ocular and an oral; a comb of
spines on lower edge of gena; a comb of spines on the prothorax;
one antepygidial bristle on each side; minute teeth (spinelets) on
inner side of hind coxa; fifth tarsal segment of all legs with four
bristles on each side besides a thin and long subapical hair.

CTENOCEPHALUS CANIS CURTIS (FIG. 63)

This is the dog flea. The labial palpi reach to two-thirds of the
anterior coxae; there are seven stout pointed spines along the lower

 

Fi. 63.—Head, prothorax, mesothorax and genitalia of Ctenocephalus canis (male).

margin of the gena; the posterior angle of the gena usually ends in
a small tooth; there is a ctenidium of from 14 to 16 spines on the
prothorax; one of the apical bristles of the second joint of the hind
136 INSECTS AND DISEASE OF MAN

leg reaches nearly to the middle of the fifth joint; the stigmata are
large; the manubrium of the claspers is short and narrow; the
movable finger is short, thick, swollen at its middle, bluntly rounded
at its distal extremity and contains on its rounded border numerous
hairs. Ct. canis has been reported as the intermediate host of
Dipylidium caninum, Hymenolepis diminuta, Dirofilaria immilis;

Leishmania donovani and L.

infantum.

CTENOCEPHALUS FELIS BOUCHE

This is the cat flea.

The differences between this and the dog

flea as pointed out by Rothschild are not marked but constant.

They may be studied from the following tabulation.

C. felis has

been reported as intermediate host for Dipylidium caninum and

Dirofilaria tmmitis.

 

Clenocephalus canis

Ctenocephalus felis

 

Bristles on hind tibia between fifth
and apical dorsal pairs.
Abdominal stigmata..............
Mid-tarsus.. 00. asa
Eighth tergite of female

Bristles on metathoracic episternum
Bristles on metathoracic epimerum.

Bristles on inner side of hind femur.
Movable finger

Manubrium

 

Shorter in canis.

Shorter and more
rounded especially in
female.

Two in number.

Larger in canis.

3.0r 4.

1st. row, 7 to 11.

2nd. row, 7 to 9.

10 to 1 3.

The ventral edge is much
straightened.

Anterior portion con-
siderably broader than
the posterior.

 

Longer and more pointed
especially in female.

A single bristle and a
‘minute hair.

Slenderer in felis.
More rounded at apex,

style more slender
than in canis.
2 Or 3.

1st. row, 5 to 8.

2nd. row, 5 to 7.

710 10.

A few more hairs on the
surface; the dorsal edge
is more rounded and

- produced further along
the ventral edge.

Almost the same breadth
along its entire length.

 

Genus Hoplopsyllus Baker (1905)

Description.— Frontal notch absent; eye present; labial palpi
with four segments; two bristles on gena an ocular and an oral; no
ORDER SIPHONAPTERA 137

spines on head; club of antenna segmented only on posterior side;
no oblique rows of bristles on occiput, a comb of spines on the pro-
thorax; two antepygidial bristles, one on each side; a row of spinelets
on inner side of hind coxa; fifth tarsal segment on all tarsi with four
bristles on each side besides a thin and long subapical hair.

It will be noted that the foregoing genera of the Pulicidae, have
many points in common but differ in certain outstanding features
such as the presence or absence of ctenidia and the type of clasping
organs.

HOPLOPSYLLUS ANOMALUS BAKER (FIG. 64)

A flea of the California ground squirrel (Cifellus beecheyi). The
mandibles reach to scarcely half of the anterior coxae; the pronotum
has a ctenidium of about ¢ spines; the bristles on the second joint

 

F16. 64.—Head and prothorax of Hoplopsyllus anomalus (male).

of the antenna are considerably longer than the third joint; one of
the apical bristles on joint 2 of hind tarsi is longer than joint 3 and 4
together; the lateral portion of the ninth tergite is a large sclerite,
rounded above, with a stout tooth at the posterior upper angle and
numerous bristles along the upper margin; the movable finger has
the shape of an elongated, inverted plowshare with the point directed
cephalad and with a few weak hairs on the posterior border.

FAMILY CERATOPHYLLIDAE
Genus Ceratophyllus Curtis

Description.—Frontal tubercle present; eye present occasionally
vestigial; head of female evenly rounded, of the male flattened on
138 INSECTS AND DISEASE OF MAN

top; club of antenna segmented all round; no spines on head; labial
palpi five segmented; a comb of spines on the pronotum; three ante-
pygidial bristles on each side in the female, often fewer in the male;
pygidium not convex; no spinelets on inner side of hind coxae; fifth
joint of all tarsi with five bristles on each side, all in line or only the
proximal pair dislocated towards the median line; claspers with
one movable process; outline of claspers distinct; inner vertical
portion of ninth sternite distinct, external horizontal portion broad-
ened, membranous with a sinus in its posterior border.

CERATOPHYLLUS FASCIATUS BOSC. (FIG. 65)

The European and North American rat, flea. The labial palpi
reach not quite to the apex of the anterior coxae; there are three

 

Fic. 65.—Head, prothorax and genitalia of Ceratophyllus fasciatus (male).

bristles in the lower genal row, evenly spaced; the upper row is
represented by three small bristles along the edge of the antennal

groove, the lowermost frequently paired in the male; the second joint
of antenna contains about five hairs about as long as third joint;
there are about 18 spines in the pronotal ctenidium; there are two
rows of bristles on the abdominal sternites, a posterior of about 12
or 14 and an anterior of smaller less numerous bristles; on the inner
ORDER SIPHONAPTERA 130

side of the hind femur is a row of 3 or 4 bristles; on outer side of
hind tibiae there are 8 to 12 lateral bristles; none of the bristles at the
apex of the hind tibia is longer than the next succeeding joint; the
" lateral bristles on the fifth tarsal joints of all legs are in a uniform
row; the finger of the claspers is short extending to a little beyond
the immovable process, its distal edge is convex, its proximal edge
angulate, from the distal edge there are two large and two small
bristles alternating; the ninth sternite is broad and thin with a
deep sinus in its posterior border and its surface containing numerous
hairs; in the female the sternite of the seventh abdominal segment is
never distinctly sinuate; receptaculum seminis as in (Fig. 68F).

CERATOPHYLLUS ACUTUS BAKER (FIG. 66)

This is a flea of the California ground squirrel. There are three
bristles in the lower genal row the middle bristle close to the upper;

27,

 

Fic. 66.—Head, prothorax and genitalia of Ceratophyllus acutus (male).

the upper genal row is represented by one or two small bristles at the
edge of the antennal groove; the labial palpi are long extending well
beyond the trochanters; the longest bristle opthe second joint of
hind leg extends to the middle of the- jt: the hind femur has a
row of 4 or 5 small bristles on the inner side; the bristles on the mar-
gins of the fifth tarsal joint are in a uniform row; the finger of the
claspers is very long and slender. It is shaped like the blade of a
scythe and extends well beyond the tip of the immovable process;
receptaculum seminis as in Fig. 68E.
I40 INSECTS AND DISEASE OF MAN

FAMILY LEPTOPSYLLIDAE
Genus Leptopsylla Jordan and Rothschild (1911)

Description.—The head is subangulate in front; eyes absent;
club of antenna segmented all round; a comb of spines on posterior
border of gena; oblique rows of bristles on occiput; a comb of spines
on the prothorax; bristles on posterior border of tibiae mostly single
and in a close set row forming akind of comb; inner side of kind coxae
without spinelets; the last tarsal joint on all legs has on each side
four birstles with a proximal pair situated between the first lateral
pair.

LEPTOPSYLLA MUSCULI DUGES (FIG. 67)

This is the mouse flea and a flea of rats. It can be readily identi-
fied by the four genal spines together with the two short thick spine-

 

Fic. 67.—Head, prothorax and genitalia of Leptopsylla musculi (male).

like bristles anteriorly at the most prominent part of the frons which
are characteristic of the genus; receptaculum seminis as in
(Fig. 68A).

Eradication

Eggs, larvae and adults may be removed from rugs, carpets etc.
by the vacuum cleaner. The dust should be burned.

Dogs may be bathed in a 39% solution of creolin or liquor
cresolis compositus or in an emulsion consisting of equal parts
of kerosene anda 39% solution of the above. These insecticides
should be permitted to act for not less than five minutes and
followed by a bath in soap and water. Washing should begin at
ORDER SIPHONAPTERA I41

 

Fic. 68.—Receptaculum seminis of (A) Leptopsylla musculi; (B) Echidnophaga
gallinacea; (C) Pulex irritans; (D) Ceratophyllus niger; (E) Ceratophyllus gous; F)
Ceratophyllus pose,
142 INSECTS AND DISEASE OF MAN

the head. Cats which are prone to lick themselves after such a bath
may be made sick so that it is perhaps better to dust well with pyre-
thrum powder, first placing the animal on a large piece of paper.
The fleas will be stupified and will drop off. The paper with its
contents should then be burned.

The animal’s bedding should be burned weekly or soaked in
5% cresol solution. .

When practicable floors should be mopped with kerosene paying
particular attention to cracks, base boards etc. or sprinkled with
napthalene. Cellar floors may be white washed.

Ground which has been exposed after a search for rat breeding
and harboring places should be soaked with a 5% solution of cresol
or one of the cresol preparations.

Fumigation with sulphur, three pounds to rooo cubic feet, may
be practiced. The inclosure to be fumigated should be tightly closed
and exposed to the gas for 6 hours. It must be kept in mind that
sulphur may tarnish metals and may be destructive to fabrics, paint-
ings, etc.

Cyanide fumigation is efficatious but dangerous and should be
used only by one thoroughly trained in the procedure.
CHAPTER XVII

ORDER ANOPLURA
(Lice)

The term lice is commonly applied to two different groups of
wingless insects which resemble each other more or less closely but
are never-the-less distinct. One group (the biting lice) called the
Mallophaga is comprised of the lice which are more especially found
on birds and which have masticatory mouth parts and feed on epi-
dermal scales and feathers. They do not attack man and are there-
fore of little interest from the standpoint of preventive medicine.
The other group (the sucking lice) is called the Anoplura and is com-
prised of those lice having suctorial mouth parts and which dwell
upon warm blooded animals including man and subsist upon blood.
These are the lice of special interest in preventive medicine.

The Anoplura are degenerate parasitic insects. They lack
wings. They are flattened dorso-ventrally. Their mouth parts are
adapted to piercing the skin and sucking blood and are retracted
inside the head when not in use. The metamorphosis is incomplete
in that the young and adults have a similar form and eat the same
food and there is no pupal or quiescent stage in the life history.
Three moultings occur before the adult stage is reached and the sexual
organs are distinct. ;

Adult.—Anatomy.—Like all insects the body is divided into a
head, thorax and abdomen. There may be two small but distinct
simple eyes or ocelli, one.situated on each side of the head at
its broadest part. In front of these, one on each side, is a three to
five jointed amfenna. At the most anterior part of the head is
located the mouth opening which is surrounded by a ring of tissue,
the haustellum, bearing a number of hooklets (prestomal teeth). At
rest the piercing organs are withdrawn into the head by an invagina-
tion of the integument. The stylet is composed of three parts.
These when protruded from the head and apposed form a tube
through which the blood is drawn up by the action of the aspiratory -
muscles. In the act of biting the haustellum is placed against the

143 ;
144 INSECTS AND DISEASE OF MAN

skin where it is held firmly by the hooklets, forming an air tight
ring. The stylet or stabber is then inserted, the saliva injected and
the blood withdrawn. During the operation which may last more
than 30 minutes, the blood may be seen to pass into the digestive
system and the waves of contraction of the aspiratory apparatus and
of the alimentary canal may be observed. As in other degenerate
parasites the ejection of feces often accompanies feeding. The body
louse usually clings to fibres of the clothing while feeding. Feeding
normally takes place 4 or 6 times a day and most of the biting is
done where the clothing is tightest (around the neck, waist, back etc.).
The blood first passes into the buccal cavity, then into the pharynx
and then backward into the oesophagus and stomach. The lateral
thickenings of the buccal cavity are known as the fuliurae. The
stomach is provided with two lobes or pockets anteriorly lying on
either side of the oesophagus. From the stomach the digested food
passes into the intestine or hind gut at the beginning of which empty
four Malpighian tubules. There are two pairs of salivary glands,
one pair (trouser-shaped)lying on either side of the stomach, and
one pair (kidney-shaped) lying on either side of the oesophagus
between the anterior lobes of the stomach.

The thorax does not show complete segmentation. A sternal
plate may be observed. It is located in the middle of the ventral
surface.

The abdomen is made up of nine segments but the number may
be reduced in some species. The tergites and sternites are usually
only thinly chitinized but laterally the pleurae may be densely
chitinized forming the pleural plates. The ninth segment in the
female is notched behind forming two flaps, the felson. On the
ventral surface of the eighth segment are two triangular plates
bristled on their edges and known as gonopods. These are used to
grasp a hair while oviposition is taking place, holding it firmly as the
egg is being cemented to it. The ninth segment in the male is
rounded, not notched. At the posterior end of the male abdomen
may be seen a pointed chitinous organ, composed of two parts, used
to dilate and hold open the genital opening of the female allowing
the insertion of the penis during the act of copulation.

Breathing occurs through spiracles located on each side of the
mesothorax and of the third to eighth abdominal segments. The legs
are robust and adapted to clinging. They are made up of five
joints; a coxa, trochanter, femur, tibia (often provided distally with a
ORDER ANOPLURA : I45

’

thumb-like process) and a tarsus terminating in a large movable claw
which when apposed to the thumb-shaped process of the tibia permits
the louse to grasp a hair or fibre of clothing. In some species there
is a small plate between the tibia and tarsus known as the prefarsal
sclerite.

Eggs of the louse are elongate-ovoid with a granulated cap known
as the operculum. The young lice resemble the adults except for
their small size and absence of genital organs.

FAMILY PEDICULIDAE

The lice which infest man belong to the Family Pediculidae,
subfamily Pediculinae. The Pediculinae have five-jointed antennae;

       

  

ENA Magn
Sr ANTE
wah §

   

Fic. 69.—Pediculus humanus, dorsal and ventral view (female).

there is but one pair of spiracles on the thorax; there is no tubular
prolongation in front of the head; the eyes are simple, black and
prominent; the thumb-shaped process on the hind tibia is present;
the legs are suitable for clinging and the tibiae and tarsi are stout.
There are three members of this subfamily, Pediculus humanus
Linn. 1758 (= capitis) or head louse (Fig. 69). Pediculus corporis
de Geer 1778 (= vestimenti) (Fig. 70) or body louse and Phthirus
pubis Linn. 1758 or crab louse. (Fig. 71.)

10
146 INSECTS AND DISEASE OF MAN

Anatomical differences between the head and body louse are very
slight. They differ in habit or location but very little in structure.
The head louse is smaller than the body louse and the lateral con-
strictions between the abdominal segments are shallower. They
will interbreed readily and it is believed by some observers that it
would probably be more exact to regard them as varieties of the
same species, i.e. Pediculus humanus variety humanus and Pediculus
humanus variety corporis. On the other hand crab lice are readily
distinguished by their different shape.

HAUSTELLUM

ANTENNA

  

py iy
1 4 Ly Wr 7
RIN 111A

     
 

F1G. 70.—Pediculus corporis, dorsal and ventral view (female).

Habits.—The head louse inhabits the hairs of the head attaching
its eggs with the operculum uppermost near the base of the hairs
by means of a cement which is formed in a special gland. As the
hair grows the nits are carried farther and farther away from the
scalp. Around the ears and the occipital region are favorite loca-
tions for oviposition. Children are more likely to be infested and
especially girls with their long hair: also old people.

The body louse inhabits the clothing especially at the seams, at
arm pits and fork of trousers, attaching its eggs to the fibres of the
cloth. Woolen clothing is particularly liable to become lousy on
account of the wool fibres to which the eggs may be easily attached.
ORDER ANOPLURA 147

Cotton and silk are much less likely to harbor lice. There is also a
tendency to change woolen clothing, which is mostly worn in winter,
less frequently than cotton or silk. Occasionally eggs of the body
louse may be found attached to the hairs of the body.

The crab louse inhabits the hairs of the pubic region but at times
in badly infested individuals it may extend to the hairs of the body
and even to the beard and eyebrows.

we 7
&, AO

 

| |

Fi1G. 71.—Phthirus pubis, ventral view, female.

Pediculus corporis

Man and his clothing are the chief disseminators of body lice
and only occasionally will they be found in blankets and mattresses
and practically never in rooms, beds, trenches etc. apart from their
normal host. However the temperature of the surroundings has
a marked influence on their movements and vitality so that when the
temperature of the environment approximates that of the body, as
while in bed, lice will very likely wander from one person to another
148 INSECTS AND DISEASE OF MAN

or when the skin becomes hot as in a fever, lice show a tendency to
leave the body and migrate more rapidly to another. They also
leave the body at the death of the host. They are very sensitive to
heat and are best adapted to a temperature of between 86 and go
degrees F., the temperature which exists between the skin and clothing.
At 104 degrees they are very active. At 98 degrees they are active
and without food die on about the second day. At 6o to 65 degrees F.
their activity is not marked and even without food they may live 4 or’
5 days. At still lower temperatures they become moribund and die
slowly. If, after a delousing process, there is complete absence of
peristaltic action in the lice examined, it may be assumed that they
are actually dead and will not revive.

In general it may be said that the average life of a louse (body)
after reaching maturity is 34 to 40 days. Away from the human
body and unfed they die in 3 or 4 days, at most 7 days. The female
louse reaches maturity in about 12 days and oviposition begins the

second day after the last moult.

Eggs.—Eight to ten eggs a day are laid for about 30 days. They
are cemented to the fibres of the clothing, the operculum pointing
upward. Under favorable humidity conditions eggs will hatch in
8 or 9g days when kept at a temperature of 87 degrees F. Such
conditions exist between the skin and the clothing when constantly
worn. At 98 degrees they will hatch in 5 days. Below 72 degrees
F. none will hatch. Eggs may hatch as long as 35 days after laying
if kept cold, so it is possible for eggs to lie dormant in discarded
clothing up to 35 days and still hatch. A fertile egg may be told by
observing the reddish or brownish eye spot in the embryo.

When fully developed the nymph emerges. from the egg shell by
first forcing open the lid or operculum. This permits only a partial
escape and to complete the process the larva swallows air which is
then emitted from the rectum into the lower part of the shell so
that gradually a pressure is obtained sufficient to force the insect
completely out of the covering.

Nymphs.—The young look very much like adults except for their
smaller size. If not fed they die in 24 to 48 hours. If fed they
moult in from 4 to 6 days to enter the 2nd. nymphal stage.

The 2nd. nymphal stage moults in about four days (or 8 days
after emergence from the egg) to enter the 3rd. nymphal stage which
in another four days (or 12 days after emergence from the egg)
moults to become the fully formed adult.
ORDER ANOPLURA 149

! Pediculus humanus

The life history of Pediculus humanus is similar except perhaps
that the number of eggs laid is fewer and the life of the insect shorter.

Phthirus pubis

Phthirus pubis (Fig. 71) is about as long as broad while the body
and head louse are each about three times as long as broad. In the
pubic louse the first pair of legsis slender. In the others the first pair
of legs is relatively stout and terminate in strong claws markedly ser-
rated on the inner edges. The head is larger than in the other species
and there is less demarcation between the thorax and abdomen.
Three protuberances bearing hairs may be seen on each side of
the abdomen, and the insect is more hairy than the other species. The
crab louse usually infests the pubic hairs but may be found on
other hairy parts including the hairs of the legs and body, the beard
and eyebrows and rarely the head. The eggs of the crab louse can
be differentiated from the eggs of the head and body louse by the
different appearance of the cap or operculum which in the crab
louse is more conical with larger more prominent nodules. Eggs
hatch in from 6 to 8 days. Three moultings over a span of 14 days
are required to reach maturity after which the adult lays about two
eggs a day for another 14 days when it dies. Crab lice are very per-
sistent feeders and adhere closely to the skin. They are spread
from person to person during coitus and by means of the eggs attached
to hairs shed in toilets or by the use of clothing which has been worn by
others.

Diseases Transmitted by Lice.—It is known that the body louse
is the carrier of typhus fever (see Chapter XXXIII), trench fever (see
Chapter XXXIV) and European relapsing fever (see Chapter XXXV).
Urticaria and melanodermia (vagabond’s disease) may follow from
the irritation of the bite and cutaneous pyogenic conditions from the
scratching. The head louse may carry typhus fever and it is said
that this louse may also carry favus and impetigo. The pubic louse
so far as known, is not responsible for the spread of any disease,
although it is certainly a potential carrier and great irritation of the
skin under the pubic hairs may follow its bite.

CLASSIFICATION

Many lice besides those infesting human beings are known to
science. Each has for its host a particular species of warm blooded
150 INSECTS AND DISEASE OF MAN

animal and it is not common to find one on an animal other than its
normal host and then usually on a closely related species. Neither
do lice survive for any length of time away from a host. Just why
they are so dependent upon one species of animal is not known.
It may be body temperature, serum reaction, thickness of skin or the
size of the hairs to which they cling. Certainly they are very sus-
ceptible to temperature and humidity conditions. These remarks
are equally true of the biting lice, the Mallophaga.

Monkeys.—The lice of monkeys and apes belong to the
Family Pediculidae. In fact the louse of apes is in the Subfamily,
Pediculinae, but can be told from the man-infesting species of Pedi-
culus in that some of its pleural plates have lateral lobes. Most of
the lice of monkeys belong to the Subfamily Pedicininae, the members
of which have three-jointed antennae.

The Dog (Canis familiaris)—The sucking louse of the dog is
Linognathus piliferus Burmeister. It is not often encountered.

The genus Linognathus is characterized by having five-jointed
antennae; the middle and posterior pairs of legs are nearly equal in
size and larger and stouter than the anterior pair; the abdomen is
without chitinized tergal, sternal, and pleural plates; each abdom-
inal segment has two or three rows of rather long hairs; eyes are
absent; the head is rather slender and the thorax small and elongated.

Two species of biting lice have been recorded from dog, Hetero-
doxus longitarsus and Trichodectes latus. The former is a kangaroo
louse on the dog only by accident. The latter is found with more or
less frequency.

The Domesticated Cat (Felis domesticus) —The cat has no sucking
louse. The Mallophagan louse of the cat is Trichodectes subrostrata.
This has also been recorded from the wild cat.

The Horse (Equus caballus)—The sucking louse of the horse is
Haematopinus asini Linne which is also reported from the donkey.

In the genus Haematopinus the head is very. broad posteriorly
with the temporal angles very prominent; the antennae are five-
jointed; the thorax is broad and the sternal plate well defined; the
legs are nearly all of the same size; pretarsal sclerite is present;
pleural plates are strongly developed from third to eighth segment;
there is but one row of bristles on each abdominal segment; the ter-
gites have many small chitinized plates but these plates may be
absent.
ORDER ANOPLURA 151

The biting lice of the horse are Trichodectes equi and T'. pilosus.
The latter has not been reported from the United States.

The Domesticated Hog (Sus scrofa domestica) — The sucking louse
of the hog is Haematopinus suis Linne (= urius Nitzsch) which passes
temporarily to man. No biting lice have been recorded from hogs.

The Domesticated Cow (Bos taurus). — The sucking lice of cattle
are, Haematopinus eurysternus Nitzsch, the “short nosed ox louse,”
Linognathus vituli Linne ‘‘the long nosed ox louse” and Solenopotes
capillatus. The biting louse is T'richodectes scalaris.

Domesticated Sheep (Ovis aries). —The sucking louse of sheep is
Linognathus pedalis Osborn. It occurs on the legs and feet below
the long wool. Itisnotcommon. Biting lice havenotbeenrecorded
from sheep.

The Domesticated Goat (Capra hircus) —The sucking louse of the
goat is Linognathus stenopis Burmeister. Two different biting lice
have been taken from the Angora goat, I'richodectes climax and T.
hermsi. The latter is much larger than 7. climax and has on its
head and abdomen numerous short, spiny hairs irregularly disposed.

The Rabbit.—The common sucking louse of the rabbit in the
United States is Haemodipsus ventricosus Denny. It may be taken
from wild or tame rabbits.

The genus Haemodipsus is characterized by having a short head,
broader posteriorly; the abdomen is without chitinous plates or else
the pleural plates are extremely small; the abdominal segments have

a single row of rather closely spaced very long hairs; the anterior
legs are more slender and smaller than the others; eyes are absent;
antennae are five-jointed.

In H. ventricosus the thorax is narrow and the sternal plate hexa-
gonal all of its margins being nearly equal in size; pleural plates are
present on the third to sixth segments but they are very small and
tooth-like with the base attached to the body and the point free.

The Domesticated Guinea Pig (Cavia cobaya) —Sucking lice have
not been recorded from this animal. Two forms of biting lice are
common, Gliricola porcelli and Gyropus ovalis. The latter can be
readily distinguished from the former by its very broad abdomen,
almost twice as broad as long.

Domestic Rats.—Polyplax spinulosa Burmeister is the common
sucking louse of the rat. (Fig. 72.) At times P. serratus, a mouse
louse, may also be encountered. Two other forms also have been
taken off rats, P. miacanthus and Hoplopleura acanthopus which
152 INSECTS AND DISEASE OF MAN

probably has as its normal host, a field mouse (Microtus). In
the United States H. acanthopus is represented by a variety, ameri-
cans. :

In the genus Hoplopleura, the antennae have five joints, similar in
male and female; the first pair of legs is small with slender claws, the
second pair larger with broader claws, the third pair very large and
stout with very broad, blunt claws; on the hind tibia there is usually

SL] or J)

og JL 2
wi)! Uo TR =
>) Ln =

Food

BT 7)
|r
TTT,
A i
TFT
oI ITT]
Al 1 [ TF 2

Pp TTT TTT Te)
A ey I IR

 

0
i Hi og 4
if

wd

Fic. 72.—Polyplax spinulosa. (Left) female; (right) male.

a short, pointed process on the anterior margin; pleural plates are
present on the first to eighth segments, they are well developed,
large, overlapping, with the posterior margin variously toothed;
tergites and sternites of abdomen well chitinized, in the female,
‘tergites four to seven and sternites three to six are transversely
divided into three distinct plates, the remaining segments with
either one or two plates, each plate having a transverse row of
spines; the males have a smaller number of plates; in both sexes the
ORDER ANOPLURA 153

anterior sclerite of the third sternite has 4 or 6 very long conspicu-
ous spines.

The genus Polyplax is characterized by having five-jointed anten-
nae and no eyes; the anterior pair of legs is small, the middle and
posterior pairs large; tergites and sternites of the abdomen are well
chitinized and some at least are divided transversely into two distinct
plates, with one row of hairs on each plate (two rows to each abdom-
inal segment); pleural plates are present on the first to the eighth
segments; in the male the 3rd. joint of the antenna usually has a
projection apically.

~ California Ground Squirrel (Citellus beecheyi).—The common
sucking louse of this squirrel is Linognathoides montanus Osborn
(= columbianus). This species may also be found on other squirrels.

The genus Linognathoides resembles Polyplax except that there
are no defined well chitinized tergal and sternal plates and the
third segment of the antenna of the male has no process.

Another species of sucking louse has also been taken off Citellus
beecheyi namely Enderleinellus osborni Kellogg and Ferris.

In the genus Enderleinellus the antennae are five-segmented;
the posterior pair of legs is large and heavy with a stout claw, the
anterior and middle pairs are much smaller and each has a slender,
pointed claw; the abdomen is without chitinized tergal and sternal
plates or with these plates weakly developed; pleural plates are
present on the second to fifth or sixth segments; most of the abdom-
inal segments have one row of hairs; on the third abdominal
segment is a pair of widely separated chitinous plates. Another
member of this genus, Enderleinellus suturalis Osborn, has also
been found on a ground squirrel. Both of these species have a
transverse suture running across the head just behind the antennae.
In suturalis the abdominal segments 2 to 7 each have a transverse
row of from 18 to 24 long, slender, bluntly pointed hairs arranged in
three groups; in osborni the abdominal hairs are much fewer and
much shorter and: stouter.

Key to the Families, Subfamilies and Genera of the Anoplura (Adapted from
Kellogg and Ferris) *

1. Body with spines or hairs in definite rows, never with scales; occurring exclu-
sively on land mammals... ot Sa Al a  ahetore 5

* The anoplura and mallophaga of North American Mammals. Published by Stan-
ford University, California, 1915.
154 INSECTS AND DISEASE OF MAN

IO.

IT.

12.

13.

Body with short stout spines or with spines and scales; occurring exclusively
on marine mammals (seals, sea-lions and walruses)
Family Echinopthiriidae. . 2

. Antennae five-segmented, thorax and abdomen bearing scales.

Genus Antarctophthirus Endeirlen (ogmorhini)*
Antennac-four-segmented..). coi ii dnl rei A sels a al 3

. Thorax and abdomen bearing scales.

Genus Lepidophthirus Enderlein (macrorhini)
Thorax ‘and abdomers Without SCales. .c. ui. hie voi leis sis oie bois iebvisiesiets 4

. Head thorax and abdomen beset with long, heavy spines.

Genus Echinophthirus Giebel (phocae)

Body clothed with long hairs and short spines, first pair of legs greatly
reduced, without tibial thumb and in no way adapted to clasping.

Genus Proechinophthirus Ewing (fluctus)

. Head much elongated (tubularly produced anteriorly), cylindrical in shape;

tibiae without a thumb-like process opposing the claw.
Family Haematomyzidae
(Containing but one genus, Haematomyzus, occurring exclusively on
elephants) (elephantis)
Head not elongated; tibiae with a thumb-like process opposing the claw.....6

. Eyes extremely rudimentary or entirely lacking

Family Haematopinidae. .11
Eyes present, usually well pigmented (Page 145)..... Family Pediculidae. .7

. Antennae distinctly five-segmented (Page 145)... Subfamily Pediculinae. .9

Antennae distinctly three-segmented or indistinctly five-segmented (on
MORKBYSY or ils a TE en hs wih Subfamily Pedicininae. .8

wes all of sameislze. ......0 duals Genus Pedicinus Gervais (ewrygaster)

Middle and posterior legs larger and stouter than anterior.
Genus Phthirpedicinus Fahr. (micropilosis)

. Legs all of same size (Page 145).......... Genus Pediculus Linn. (capitis)
Amnteriorlegs smaller than the others. o.oo iii ssn vie ales vie 10
Abdomen long, segments two, three and four distinct each bearing a pair of

spiracles in the normal lateral position.
Genus Phthirpediculus Ewing (propitheci)
Abdomen greatly shortened, segments two, three and four strongly com-
pressed so that the spiracles are crowded together and appear to be in one

Segment (Page TAG). . Lo. vn wave ini iv sh Genus Phthirus Leach (pubis)
Antennae fivessesmented. ... ori an LS a SR Ce 13
Antennae three-segmented............. Subfamily Euhaematopininae. .12

Posterior legs with stalked, disk-shaped appendages on femur and tibia.
Genus Euhaematopinus Osborn (abnormis)
Posterior legs without appendages.
Genus Haematopinoides Osborn (squamosus)
Anterior legs smaller and with slenderer claws than posterior at least.
Subfamily Linognathinae. . 14
Legs and claws all of same size (Page 150).
Subfamily Haematopininae (One genus Haematopinus Leach (suis))
* The specific name in parenthesis is the type of the genus.
14.
x5.

16.

17.

18.

19.

20.

21.

22.

a3:

24.

25.

26.

ORDER ANOPLURA 155

Anterior tarsi with two joints. ... .. Genus Hypophthirus End. (notophallus)
Anterior tars] withibut one Joint... il ums mind i Care ios 15
Anterior pair of legs with two claws. . ..Genus Scipio Cummings (aulacodi)
Anterior pair of legsiwith but'one claw... ...... in LoL Go, 16
Abdomen with well developed pleural plates.......................... 20
Abdomen entirely without pleural plates......................cc00.us 17

Abdominal spiracles large, tubular, projecting from the body wall.
Genus Solenopotes
Abdominal spiracles small, not projecting from body wall............. 18
Gonopods of female long or moderately long.......................... 19
Gonopods very short; head broad, considerably widened behind the anten-
nae; infesting rabbits; abdomen with but one row of hairs or spines on each
segment (Page 151).
One species of the Genus Haemodipsus End (lyriocephalus) (in part)
Gonopods long, frequently reaching beyond the extremity of the body;
head usually slender, but little widened behind the antennae; abdomen
with more than one row of hairs or spines on each segment; for the most
part infesting Ungulates (Page 150).
Genus Linognathus Enderlein (piliferus)
Gonopods moderately long, behind each gonopod a stout, flat, spine-like
process, abdomen with but one row of hairs or spines on each segment.
Genus Cervophthirus Mjoberg (tarsandi)
Tergites and sternites of the abdomen for the most part with more than one

transverse row of halrsor bristles...) J. nis. ola 25
Tergites and sternites of the abdomen for the most part with but one row of
hajrsiorbristlen oi Se dp et Ll ee ne 21
Leg 1 smaller than either II or IIT and with smaller and more slender claw.
23

Anterior and middle pairs of legs of the same size or subequal, smaller than
the posterior pair which are large and stout........................ 22

Pairs of pleural plates five or less (Page 153).

Genus Enderleinellus Fahr. (sphaerocephalus)
Pairs of pleural plates seven. ...Genus Proenderleinellus Ewing (africana)

Abdomen with a pair of chitinized plates on the second or third sternite.
Genus Fahrenholzia Kell. & Fer. (pinnata)
Abdomen Without such Plates... ..cah oi oss ins mish as wisi 24
Occiput deeply sunk into the thorax; rostrum surrounded by denticles;
pleural plates quite large. . . Genus Eulinognathus Cummings (denticulatus)
Occiput not deeply sunk into the thorax; rostrum not surrounded by

denticles; pleural plates minute. ..... Genus Haemodipsus (in part)
Abdominal tergites and sternites with not more than two rows of hairs or
Pristlegs... a a a Ln RN TE Ee 27

Abdominal tergites and sternites in part with three rows of hairs or bristles. . 26
Pleural plates with posterior margin variously toothed, second pair of
plates of same type as others (Page 152).
Genus Hoplopleura Enderlein (acanthopus)
Second pair of pleural plates enormous and wing-like.
Genus Pterophthirus Ewing (alata)
156 INSECTS AND DISEASE OF MAN

27. First antennal joint with a stout spine at the distal post-axial angle or on the

posterior margin.......... Genus Neohaematopinus Mjoberg (sciuropteri)
Firstiantennal Joint not.S0: ass oon hia hms So ah ie aw Arn 28

28. Abdominal tergites and sternites with distinct chitinized tergal and sternal
plates (Page x53)... La, Genus Polyplax End. (spinulosa)

Abdominal tergites and sternites without distinct chitinized plates in the
female and with these absent or extremely reduced in the male (Page 153).
Genus Linognathoides Cummings (citelli)

Eradication

Nits and lice are destroyed within thirty minutes by hot water
or dry heat at 55 degrees C., even when protected by a covering of
khaki cloth. If the temperature is raised to 6o degrees C. 15 minutes
will suffice. If, during the process of washing or drying garments,
they are subjected to the temperatures and periods given above,
chemical solutions are unnecessary. The evidence seems to establish
the fact that steeping for 20 minutes in a 29, watery solution
of equal parts of crude carbolic acid and soft soap (lysol) is effective
provided the temperature of the solution i is not below so degrees F.
(Bacot and Lloyd).

Both lice and nits can be destroyed by the immersion of vermin-
ous garments in gasoline, benzine, kerosense, turpentine, dichlor-
ethylene, or tetrachlorethane. The latter two are non-inflammable.
Danger from fire when gasolene or benzine is used may be avoided
by the use of a bath and extractor as employed in “dry cleaning.”

Fabrics such as bed clothes, underclothing, and outer garments
may be baked, boiled or steamed. Both lice and nits are killed by
dry heating to 70 degrees C. (158 degrees F.) for 10 minutes. Dry
heat at 100 degrees C. (212 degrees F.) will kill nits and lice in about
one minute, while boiling water requires but 3o seconds. Care must
be exercised to make sure that the desired temperature has actually
penetrated to the center of the material to be disinfested. Dry
. heat does not penetrate readily.

Where a double jacketed steam chamber is available, it should
be used for cotton or woolen articles. To insure penetration a
vacuum should be produced before the steam is admitted. Cyanide
gas may also be applied in a steam chamber. This is an excellent
method for destroying lice and their eggs in bundles of clothing and
~ bedding or in baggage. Use from 143 to 285.7 ounces to Tooo cubic
feet. Produce an initial vacuum of 26 inches and expose to the
cyanide for at least 30 minutes. For baggage an exposure of one
ORDER ANOPLURA 157

hour is better. After removal bundles should be opened and aired
as some of the cyanide in poisonous quantities may remain in the
meshes of the cloth even though a second vacuum has been produced
to assist in the removal of the gas from the chamber. Articles made
of leather, such as shoes, gloves, hats, etc. may be disinfested by
cyanide or immersed in gasoline or kerosene.

In the case of male persons infested with Pediculus capitis the
hair should be clipped short. In the case of females the hair should
be treated by a thorough application of a mixture of equal parts of
kerosene oil and vinegar, covered with a towel for one half hour and
then thoroughly washed with warm water and soap.

Body lice are to be found in the clothing particularly the seams.
They attach their eggs to the fibres of the cloth. Rough cloth like
woolen material, is therefore favorable to their propagation, while
smooth stuffs like silk and cotton are not.

In addition to the treatment of the clothing of infested persons,
it is well to wash the body with liquid soap made by boiling soap
chips 1 part in 4 parts of water, and adding 2 parts of kerosene.
After this mixture jellies, use by mixing 1 part with 4 parts of warm
water.

Ironing clothes, particularly along the seams, with a hot iron is
useful in the eradication of body lice.

Equal parts of kerosene and a 39% solution of cresol make an
emulsion which is destructive to vermin.

A good remedy for pubic lice is a wash composed of 1 fluid ounce
of Acetic acid (C.P.) and 3 fluid ounces of 1 to 3000 solution of
bichloride of mercury.
CHAPTER XVIII

ORDER HEMIPTERA
(The True Bugs)

This is a large order of insects many of which feed on the juices
of plants and may be serious plant pests; some are aquatic; some
feed on insects harmful to man; some are blood suckers and are
extremely annoying or even dangerous to man.

The Hemiptera have a suctorial proboscis arising from the front
part of the head and folded back under the head when at rest; the
labium is segmented; wings are four in number but may be wanting
or vestigial, when present the hind wings are membranous and the
fore wings or hemelytra, are thickened at the basal half, the apical
half being membranous; the fore wings form a protecting cover to
the hind wings which when at rest are folded under them? the meta-
morphosis is incomplete.

The blood-sucking Hemiptera which attack man are found in
only two Families, the Cimicidae or true bed-bugs in which the wings
are absent or vestigial, and the Reduviidae or false bed-bugs,—
winged members of the Order. Closely related to the Cimicidae is
the Family Polyctenidae, the so-called ‘many combed bugs” which
are parasitic on bats.

There are some very familiar examples of Hemiptera which do not
bite man but which may be very destructive to vegetation. These
include the “stink bugs’ (Family Pentatomidae), the ‘squash bugs”
(Family Coreidae), the ‘“‘chinch bugs” (Family Lygaeidae), the
“water boatmen” (Family Corixidae), the “giant water bugs”
(Family Belostomatidae), etc.

FAMILY CIMICIDAE

These are degenerate parasitic forms of insect life belonging to
several genera of which three are found in the United States, namely,
Cimex, Oeciacus and Haematosiphon. In Cimex the proboscis is
short reaching to about the fore coxae and the anterior margin of

the pronotum is deeply sinuate. In Oeciacus the proboscis is similar
158
ORDER HEMIPTERA 150

in length to Cimex but the anterior margin of the pronotum is only
slightly sinuate. In Haematosiphon the proboscis is long reaching to
the posterior coxae.

Several species of the Genus Cimex have been described of which
Cimex lectularius Linn. and C. hemipterus Fabr. (the Indian bedbug)
are parsites of man subsisting on man’s blood and living and breed-
ing in his domicile. Cimex boueti Brumpt also is said to bite man.
Two other members of the genus which are found on bats are C.
pipistrelli Jenyns, a European species and C. pilosellus an American
species.

Oeciacus hirundinus Jenyns and O. vicarius Horv. are found in
swallows’ nests in Europe and America respectively.

Haematosiphon inodorus Duges is a bug of poultry in Southwestern
United States and Mexico. Itis the only representative of the genus.

Genus Cimex

The two species closely associated with man are widely distributed
members of the genus. They are domestic in their habits feeding on
the blood of man and living and breeding in the cracks and crevices
of beds and other furnitures, and in the walls and floors of houses.
Their wings are purely vestigial and their range of movement is there-
fore limited. Neither do they live permanently on the host like the
more parasitic insects, the lice, and are therefore only accidentally
transferred from place to place in laundry or on man’s clothing.
Occasionally they may travel on foot from one house to another in
search of food,—a matter of some yards. They ordinarily feed at
night and in the absence of human blood will suck the blood of the
lower animals. ' Occasionally they infest the animal house of a
laboratory.

It is believed that the bed-bug may transmit Kala-azar. It has
been incriminated in the spread of European relapsing fever and it is
possible that it may rarely carry plague bacilli from man toman giving
rise to small circumscribed outbreaks of the disease. In labora-
tory experiments plague and tuleraemia have been successfully trans-
mitted by the bite of the bed-bug. This bug by reason of its habits
must have many opportunities to take into its stomach microorgan-
isms that may be circulating in the blood of the host, but because of
its rather limited range of movement it is not so likely to give rise to
widespread epidemics, such as might be produced by blood-sucking
insects with more migratory habits, as for instance, mosquitoes,
160 INSECTS AND DISEASE OF MAN

flies and fleas, or lice which are continually being transported from
place to place on the body of the host. Bedbugs are important
factors in destroying sleep and therefore contribute to nervous strain.

The Adult. Anatomy. (Fig. 73).—The body is flattened dorso-
ventrally and, as in other insects, is divided into a head, thorax and
abdomen.

In Cimex lectularius the head anteriorly is bluntly pointed. It is
widened out behind and broadly attached to the thorax, there being
no distinct neck visible. At the broadest part of the head, one on
each side, are the compound eyes and just anterior to these are the
four-segmented antennae. The basal segment of the antenna is
stout and much shorter than the others; the third segment is the long-
est and the fourth or terminal segment the most slender.

The proboscis at rest is carried folded back under the head and
prothorax. Itis composed of a labrum, two mandibles, two maxillae
and a labium. The labrum is a small flap arising just dorsad of the
proboscis and apparently serving as a protection to that organ at its
origin. The labium is long and four-segmented, the last segment
terminating in a blunt point. It serves as a sheath to protect the
mandibles and maxillae which are concealed in a groove (the labial
gutter) running throughout the entire length of its anterior surface,—
that is its inferior surface when at rest. The mandibles are the true
biting organs. They lie outside of the maxillae and closely invest
them. They are articulated to a chitinous rod which runs backwards
to the posterior part of the head. Distally their ends are pointed and

“armed with a row of recurved teeth. The maxillae play no part in
making the wound in the skin but form when apposed to each other,
two canals, one for the passage of the salivary juice and one for the
passage of the blood which is drawn up by the action of the aspira-
tory pharynx. The latter is composed of two chitinous plates
located in the head. It is operated by the contraction of the aspira-
tory muscles which arise from the inner surface of the exo-skeleton
of the head dorsally and laterally and which when in action draw
the dorsal plate away from the ventral plate thus sucking the blood
up from the wound in the skin.

The prothorax is the most conspicuous of the three thoracic seg-
ments. Its anterior margin is concave. Its lateral borders where
the tergite and sternite meet are thin and sharp, strongly convex
and are produced forwards into prominent angles which reach on each
side to or almost to the eye. This segment is convex dorsally and
IT

  

Corpouno eve ‘
“ CLYPEUS

ANTENNA

 

1 AeoominaL
 STERNITE

   
  

 
  

=+-I3T ABDOMINAL
TERGITE
. 2% ABDOMINAL
STERNITE

ORIFICE OF THE ..cznen
ORGAN OF BERLESE

P16. 73.—Cimex lectularius, female, ventral and dorsal view.

VIZLAINTH YIaTI0

191
162 INSECTS AND DISEASE OF MAN

flattened ventrally. The mesonotum may be observed just back of
the pronotum as a small triangular area. - Behind this is the metano-
tum which is almost concealed by the elytra, the vestiges of the first
pair of wings. The elytra are articulated to the lateral portions of
the mesothorax and contain many feathered hairs. Ventrally the
mesosternite can be seen as a smooth transverse plate back of which
is another plate, the metasternite. At the posterior border of this
sternite one finds the opening of an organ of special sense. The stink
glands which lie ventrally and posteriorly in the thoracic cavity,
open on each side of the thorax between the bases of the second and
third legs.

The legs are composed of a coxa, trochanter, femur, tibia and
three tarsal segments of which the first is very small. The last
segment terminates in a pair of claws. At the apical end of the
tibiae is a tuft or comb of fine hairs. The lines of demarcation
between the tarsal joints are not well marked.

The abdomen is rounded and is made up of ten segments, only
eight of which are plainly’ discernible. It is widest at about the
third segment. The female abdomen is more rotund and less
pointed posteriorly than the male. The gth. and roth. segments
are greatly modified because of their relation to the genital orifice
and the anus. Each consists of two small sclerites situated ven-
trally. Between the screrites of the goth. segment is the genital
orifice and between the sclerites of the 1oth. segment is the anal
orifice.

Some authorities believe that the genital orifice is used only in
oviposition and not in. copulation. In the fourth sternite, to the
right of the median line, may be seen a triangular incision which
indicates the position of the opening of the organ of Berlese or
copulatory pouch. This may be the opening into which the penis
is inserted during copulation and the spermatozoa injected.

The body of a bedbug is generously supplied with small serrated
hairs and there is a stigmatic opening on each side of the unmodified
abdominal segments.

Alimentary Tract.—Blood coming up the food canal first enters
the buccal cavity, a small membranous pouch, and then, passing
through the aspiratory pharynx, enters the oesophagus which joins
the stomach at the posterior end of the thorax. There is no proven-
triculus. The stomach is in two parts of which the anterior portion
or cardia is the wider and contains a number of constrictions. It
ORDER HEMIPTERA 163

passes backwards to the posterior end of the abdomen where there is
a marked constriction serving as a valve and marking the beginning
of the second portion of the stomach which is longer than the cardia.
Its diameter is variable and it lies coiled in the posterior part of the
abdomen. The hind gut is short and ends in a relatively large
rectum at the anterior end of which empty separately the four
Malpighian tubules,—an unusual arrangement. There are no
rectal papillae. ;

There is one pair of salivary glands located at the anterior end
of the stomach. After leaving the glands each duct communicates
with a salivary reservoir lying on either side of the oesophagus, and
then passes forward to the salivary pump.

Eggs and Immature Forms.—The eggs are white and oval with
a small projecting rim at one end surrounding the operculum. They
are cemented to the surface on which they are deposited. One
female may lay as many as 150 eggs or more in batches of from 6
to so. Itrequires 7 to ro days for the eggs to hatch in warm weather.
Longer periods are required in cold weather. The metamorphosis
is incomplete. There is no pupal stage and the young from the time
of emergence from the egg resemble very closely the adult forms
except that they are pale in color, smaller and the various regions of
the body differ in proportions. The young grow to adults after
five successive moultings over a period of 7 to ro weeks or more,
the color becoming darker and darker until fully grown. Bedbugs

are capable of living perhaps for a year and for long periods without
food.

CLASSIFICATION

Family Cimicidae.— The head is short and broad; the proboscis
is carried in a groove on the ventral surface of head and thorax;
ocelli are absent; wings are vestigial; the elytra are short and broad
leaving most of the abdomen uncovered; the tarsi are three jointed:

To this Family belong the following Genera: Cimex, Oeciacus,
Cacodinus, Haematosi phon and Loxaspis.

Genus Cimex :
(Synonyms,—Acanthia, Klinophilos, Clinocoris) =

In this genus the head is short and broad; the antennae are four-
jointed the last two joints slender; the prothorax is concave in front
164 INSECTS AND DISEASE OF MAN

with its anterior angles considerably extended; the elytra are rudi-
mentary and overlie the metathorax; the abdomen is uncovered and
consists of eight visible segments, the legs are slender; the anterior
tibia are more than twice as long, the posterior tibiae three times as
long as the tarsi, which are three jointed.

Cimex lectularis —In this species the lateral projections anteriorly
are rounded and extend up to the eyes; the dorsum of the prothorax
is convex in the middle portion with the outer lateral portions flat-
tened; the abdomen is widest at the third segment.

This insect is cosmopolitan in its distribution although in tropical
countries it may be replaced by the next species. ;

Cimex hemipterus.—In this insect the convexity of the prothorax
extends to the margins, the lateral flattened area being inconspicu-
ous; the abdomen is less orbicular and is widest at the second abdo-
minal segment.

This is a common bedbug of the tropics and subtropics.

FAMILY REDUVIIDAE

The Reduviidae are winged Hemiptera called “assassin bugs”
because they are predacious, sucking the blood of other insects.
Some however prefer the blood of warm-blooded animals including
man and are therefore important from the standpoint of preventive
medicine. ;

All members of the family have a long, narrow head with a
distinct neck; the antennae are long, slender and four-segmented;
the eyes are large and prominent; ocelli are usually present; the
proboscis is three-segmented, bent, and folded back under the head
when at rest as in the other Hemiptera; the legs are long and the
tarsus three-jointed, the prothorax is strongly developed and wings
are present.

The genus Conorhinus (cone-nosed bugs) contains the blood-
sucking species.

Reduvius personatus is of interest because it preys upon the bed-
bug thus securing the blood of man indirectly and in a manner less
irritating to the human host.

A familiar example of the family Reduviidae is the “wheel bug”
(Arilus cristatus) which has a prominent dorsal projection on the
prothorax somewhat the shape of a cog-wheel.

No doubt all of the members of the family can bite if given the
opportunity but most of them do so only through accidental contact.
ORDER HEMIPTERA 165

Genus Conorhinus
(Synonym—T'riatoma)

Conorhinus megistus.— This is a large bug of Brazil. It is 23
mm. or more in length, black in color with regularly arranged red
markings on wings, prothorax and abdomen. It is domestic din its
habits laying its eggs in cracks and holes in walls of inhabited houses.
Eggs hatch in from 25 to 50 days. The young are wingless. Com-
plete growth takes almost a year. The adults are powerful fliers.
All stages bite man. They bite at night principally on the face.
Children are most frequently bitten. C. megistus is a carrier of
Schizotrypanum cruzi which is the cause of South American trypo-
nosomiasis (Chap. XXX). This trypanosome passes part of its
life history within the body of the insect.

Conorhinus sanguisuga.—This is the Mexican or Texas bedbug.
It is 20 to 25 mm. in length. It has become a vicious biter of man
although it seems that in the past it preferred to suck the juices from
the common bed-bug and so has acquired a taste for human blood.
It is a dark brown bug with pink markings.

Conorhinus rubrofasciatus is a bug of India which has spread to
South America. It has been suggested as a carrier of kala-azar.
It is dull brown in color with markings on the pronotum and with
dusky yellow or brick red elytra.

Eradication

Bedbugs are very frequently difficult to exterminate, especially
in situations where there are numerous cracks and crevices in which
they may lurk. These are frequently overlooked, or it may be
difficult to reach the bottom of the crevice with the insecticide.
Perseverance, however, will usually produce the desired results.
The insecticide should be applied several times at intervals of 3 to
4 days, so that any young which may have escaped destruction in
the eggs will be subsequently killed.

Fumigation with either cyanide or sulphur is efficacious, but the
former is dangerous and should only be used by one experienced in
the process. Sulphur may be used without danger but it must be
remembered that sulphur gas in the presence of moisture is liable to
tarnish metals, discolor painted surfaces or bleach and weaken
fabrics. Mattresses and bedding should be hung in the room.
166 INSECTS AND DISEASE OF MAN

Bureau drawers should be opened. All cracks around doors should
be sealed and windows tightly closed.

Four pounds of sulphur for each thousand cubic feet should be
burned in a pot surrounded by water in a tub. The pot, however,
may be placed directly on an iron deck. The exposure should be
about six hours.

Many solutions have been suggested for the extermination of
bedbugs, and probably all of those mentioned are satisfactory pro-
vided they are applied thoroughly. Both kerosene and gasoline
are effective against the insects and their eggs. These may be
applied by a brush or an atomizer, always keeping in mind their
inflammable nature.

Mixtures of equal parts of kerosene and 959, phenol or kerosene
containing 59% of cresol will give satisfactory results when properly
applied.

A mixture of equal parts of turpentine and 95% phenol has
been used successfully. All mixtures must be applied lavishly with
paint or varnish brushes, using a small brush for cracks in woodwork.

Bunk or bed springs and pipe frames may be thoroughly heated
by gasoline torch. Boiling water is efficacious if it reaches the right
spot. Mattresses may be treated with flowing steam applied with a
steam hose on deck or on a fireroom or engine-room grating. After
this treatment they should be dried in the sun and treated liberally
with a strong solution of bichloride of mercury (saturated solution),
which should be applied especially to the seams and ticking holes
and allowed to dry.

It must be remembered that the cracks in walls and floors may
harbor bedbugs as well as the bed or other furniture.

Other formulae which are recommended as agents to kill bedbugs
are as follows:

Oil of mirbane, 34 ounce.

Crystallized carbolic acid, 114 ounces.

Kerosene (or benzine), 32 ounces.

Add the oil of mirbane to the kerosene; stirring slowly; liquefy
carbolic acid crystals by standing container in hot water. Then add
to the mixed oils, stirring rapidly.

This mixture should be introduced into all crevices with feathers,
small brushes, or small spray syringe, as a rosebush syringe, which
may be purchased at a seed store. A cheap atomizer gives very
satisfactory results.
ORDER HEMIPTERA 167

For use in mattresses and beds the following may be used:

Sodium chlorid (common salt), 14 ounce.

Bichloride of mercury (corrosive sublimate) 14 ounce.
Water, 2 ounces.

Alcohol, 2 ounces.

Spirits of turpentine, 6 ounces.

Steam disinfection is the best treatment for mattresses. If a
strong solution of corrosive sublimate is used as an expedient it should
be borne in mind that the amount of mercury volatilizing from the
bichloride at room temperature may be sufficient to cause symptoms
of mercurial poisoning.

It is reported from the Sanitary Corps of the Army that bedbugs
have been eradicated from officers’ barracks by the use of heated
air. The barracks building should be treated as a whole. All out-
side doors and windows should be tightly closed and inside doors
left open. Thermometers should be placed here and there in the
room on a level with the eye so that the temperature may be deter-
mined. The steam radiators should be turned on and the heat from
this source supplemented by small oil stoves placed in each room.
Fans, installed near the ceiling and pointed downward should be
allowed to revolve at slow speed so that as much of the heated air as
possible will be kept at the lower level where it is needed. A tem-
perature of 140° F. can be reached in the lower parts of the room while
at the ceiling it is much higher. It has been found that a tempera-
ture of 125 to 130° is sufficient to kill bedbugs and their eggs. Occa-
sionally the procedure will have to be repeated. Mattresses, bedding
and clothing should be distributed so that penetration of heat will be
facilitated. Nothing should be hung near the stove because of the
danger of fire. Anticipating such an occurrence fire extinguishers
should be at hand and any material particularly inflammable should
be removed. The exposure should be six hours. Naturally, in
summer the required temperature is more easily reached than in
winter.
CHAPTER XIX

ORDER ORTHOPTERA
(Roaches)

Roaches are insects belonging to the order Orthoptera, family
Blattidae. There are a number of genera coming within this family,
the members of which are mostly wild. They are related to the
crickets. At least four species, have become domesticated and have
been household pests for many years; all are found in the United
States. The domesticated species are as follows:

The oriental roach (Blatta orientalis). This is a common roach
in Europe as well as in this country. It is a large species, very dark
in color, and sometimes called in Europe the “black beetle.”

The German roach, or Croton bug, A European species, small
in size (Blaitella germanica).

~The Australian roach, a native of Australia (Periplaneta austra-
lasiae). This may be differentiated from the others by the brighter
and more definitely limited yellow band on the back between the
head and wings and by the yellow markings on the sides of the upper
wings.

The American roach of subtropical and tropical America (Peri-
planeta americana).

Cock roaches are brown or dark brown in color; the body is
rather broad and flattened dorso-ventrally; the head is bent under the
body and the mouth parts are directed backward, the eyes downward.
The antennae are very long and slender. The insects have two pairs
of wings, the outer pair being leathery. = In some species the females
are almost wingless, notably the oriental cock-roach. The mouth
parts are well developed masticatory organs. Metamorphosis is
incomplete. The eggs are not laid separately, but are gathered
together within the abdomen and inclosed in a horny capsule, which
is then deposited in dark cracks and crevices. When the eggs
develop the capsule is split and the young emerge. The egg capsule
is often carried by the mother until the eggs are about ready to

hatch. Newly-hatched insects resemble the adult forms very closely,
168
ORDER ORTHOPTERA 169

and pass through a variable number of molts. It probably takes
from six months to a year to reach full development, depending upon
the species. :

Roaches of different species are rarely found together, although
roaches of the same species live together on very amicable terms.

Ordinarily not more than one generation per year is produced.
Reproduction occurs principally during the warm weather, as roaches
are particularly sensitive to cold. The abundance of roaches is

~ apparently not accounted for so much by rapidity of multiplication
as by very unusual ability to preserve themselves from ordinary
means of destruction.

They are nocturnal in habits and their numbers are often not
realized unless they are surprised in their midnight feasts. During
the day they conceal themselves wherever protection from natural
enemies and from light is afforded. Because of their shape they
can squeeze into very small crevices. Occasionally they migrate
and this accounts in part for the way in which new houses and
offices are invaded. They are also transported with supplies. When
surprised they seek shelter with a scurrying gait, and usually escape.

They are practically omnivorous. The mouth parts and jaws
are strong, enabling them to eat all sorts of substances—dead animal
matter, cereals, and in fact any form of food material; woolens,
leather, and cloth or leather bookbindings. Occasionally they
turn cannibal. Probably dead roaches frequently ‘disappear in
this way.

Anatomy of the Mouth Parts. (Fig. 73).—Heretofore all of
the insects studied have had in the adult state, suctorial mouth
parts. The roach is provided with masticatory mouth parts and it
is probable that the specialized proboscis of the sucking insects
like the Diptera has evolved from the masticatory type.

A study of the mouth parts of the roach shows it to be made up of
three pairs of appendages namely, mandibles, maxillae (1st. maxillae),
and labium (2nd. maxillae), which are adapted either to cutting or
to holding solid food in the act of mastication.

The anterior flattened prolongation of the head is known as
the clypeus, articulated to which is a flap-like process—the labrum—
really an extension of the integument covering the clypeus.

Behind the labrum are two stout, curved mandibles. They are
broad, serrated blades attached to the gena (the lateral part of the
head beneath the eye) by a joint which permits of free movement
170 INSECTS AND DISEASE OF MAN

towards the median line. When they are brought together they
serve as a pair of powerful jaws. In the Orthorrhaphous flies like
the Tabanidae, the mandibles have become specialized into elon-
gated, flat cutting organs. In the Cyclorrhaphous flies the mandi-
bles have disappeared.

Behind the mandibles are the maxillae (1st. maxillae) which are
attached to the inferior margin of the head. The basal joint—the
cardo—is elongated and directed transversely to the axis of the head.
The second joint—the stipes—is articulated to the first at right

 

Fic. 74.—Mouth parts of a cockroach, Parcoblaita pennsylvanica (the common
wood-roach of the United States). A, labrum; B, mandible; C, hypopharynx; D,
maxilla; E, labium; c, cardo; g, (of maxilla), galea; g (of labium), glossa; 1, lacinia;
1p, labial palpus; m, mentum; mp, maxillary palpus; p, paraglossa; pf, palpifer; pg,
palpiger; s, stipes; sm, submentum; B, D and E are in ventral aspect. (From Folsom’s
‘‘ Entomology,” 3rd. Edition.)

angles. Its outer distal angle bears a five-jointed palpus—the
maxillary palpus. Terminating the stipes are two processes. The
anterior and outer—the galea—is soft and probably sensory. in
function. The posterior and inner process—the lacinia—is a cutting
blade with a toothed inner edge. The piercing maxillae of the
Orthorrhaphous flies together with their palpi, are homologous with
the 1st. maxillae of the cockroach. In the Cyclorrhaphous flies the
1st. maxillae have disappeared, and the proboscis has evolved from
the labium or 2nd. maxillae.
ORDER ORTHOPTERA 171

In the roach the labium (2nd. maxillae) is composed of two
median plates, incompletely separated. The plate behind is known
as the submentum, that in front, as the mentum. Terminating the
mentum is a bilobed piece—the ligula. Each lobe again divides
longitudinally into two portions the outer of which is known as the
paraglossa. Between the mentum and the ligula, on each outer
edge, there arises a three-jointed palpus—the labial palpus. It is
from the labium that the proboscis of the Cyclorrhaphous flies has
principally developed. It is also retained, greatly modified, in the
Orthorrhaphous flies, as the labium and labellae.

The mouth opening of the roach lies between the labrum above, the
labium below and the mandibles and 1st. maxillae laterally. The
mouth leads into the buccal cavity, the roof of which is formed by
the epipharynx, and the floor by the hypopharynx. A chitinous
elevation in the hypopharynx is known as the lingua and beneath
this is the opening of the salivary duct.

In the insects previously studied the long, slender labrum-
epipharynx and hypopharynx are merely prolongations of the
homologous structures in the roach.

Internal Anatomy.—The oesophagus which communicates with
the buccal cavity by a small opening, passes through the neck
and thorax, gradually widening into a crop which lies in the abdomen.
The proventriculus which separates it from the stomach, is a thick
walled, pear-shaped organ. Its chitinous lining is elevated into
six broad teeth between which are smaller tooth-like ridges. The
stomach or ventriculus is a wide, elongated tube, the anterior end of
which is provided with seven or eight diverticula. The Malpighian
tubules, 20 or more in number, empty into the intestine at its junction
with thestomach. Theintestine has been divided into the lium, colon
and the rectum in which may be seen the six socalled rectal glands,—
ridges projecting into its interior and well supplied with tracheae.

The salivary glands two in number lie on either side of the oesoph-
agus and crop. They are about one fourth of an inch long. Their
ducts unite beneath the suboesophageal ganglion into a common
duct which empties into the floor of the buccal cavity beneath the
lingua. There are also two salivary receptacles which are elongated,
oval sacs situated at the end of a long duct. The ducts from the
sacs unite with each other and then with the ducts of the salivary
glands to form the common duct. The ducts of glands and receptacles
are lined with chitin arranged spirally.
172 INSECTS AND DISEASE OF MAN

Roaches by preference infest bakeries, kitchens, pantries, store-
rooms and toilets. They follow water and drain pipes.

Roaches are a sanitary menace, because they are potential car-
riers of infection mechanically by means of their feet and bodies.
They soil everything they come in contact with, leaving a nauseous,
roachy odor. It is thought that the roach is the intermediate host
for a tape worm (Davainea madagascariensis) which has been found
in man. Roaches also act as the intermediate host of the Nema-
tode Gongylonema, which is associated with cancer of stomach of
rats.

The total elimination of roaches is difficult. Scrupulous cleanli-
ness and the keeping of food and food remnants in places inaccessi-
ble to the roach is of prime importance. All unnecessary corners,
cracks and imperfections in the structure of the building which favor °
breeding or furnish hiding places must be eliminated or treated with
roach poison.

Eradication

The best poison is sodium fluoride. Sodium fluoride powder
must be liberally sprinkled or blown by means of a powder blower
into corners, drawers, closets and other places of concealment.

It must be distributed in such a way that it will not be swept up or
removed. It should be allowed to remain and act for weeks at a
time. It can be sprinkled along the back parts of shelves and out of
the way in the recesses of drawers, in file cases, etc. This substance
is not injurious to books or other materials. It forms the basis of
most roach powders on the market. The roaches walk in it and then
lick it off their feet.

Large numbers of roaches may be destroyed in places heavily
infested by means of traps. A simple form of trap consists of a deep
smooth basin or jar with a stick leading up to the top as a runway
from which they slip into the trap. The trap may be baited with
mucilage or sweetened meal or other food material.

A dish containing 1 part of dry and thoroughly powdered pliites
of paris to 3 or 4 parts of flour well mixed may be placed near a dish
of water. The insects eat the mixture, become thirsty and drink.
The water sets the plaster of Paris which then clogs the intestines.

These expedients will destroy large numbers of roaches in suitable
places, but gradual elimination of the insects by means of sodium
fluoride properly distributed is the most effective measure in the long
run and the one most generally practicable.
ORDER ORTHOPTERA 173

Arsenic does very little good, as roaches are wary and shun the
poison bait. Phosphorus has been used successfully in the shape of a
paste. This may be purchased as a proprietary preparation. Pure
borax is at times used with great success. It may be used alone or
in a mixture consisting of 1 part of powdered borax and 3 parts of
finely pulverized chocolate, freely sprinkled around infested places.
Fumigation by hydrocyanic-acid gas or by sulphur dioxide will
* destroy roaches. Fumigation, however, may not destroy the eggs,
which subsequently hatch making a second fumigation necessary.

Carbon bisulphide is also of value as a gaseous insecticide, but it
must be used with caution as it, like hydrocyanic-acid gas, is poison-
"ous to human beings and domestic animals.

Flowers of sulphur used in the same way as sodium fluoride will
act as a repellant but is not nearly so satisfactory as the fluoride.
CHAPTER XX
CLASS ARACHNIDA

To this Class belong the spiders, scorpions, mites and a few other
less important groups. The spiders and scorpions are not parasitic
and are only troublesome to man by reason of the bite or sting which
they may be capable of giving through the mouth parts (chelicerae),
or a special stinging apparatus as in the tail of the scorpion. The
members of the class which are far more important from the stand-
point of medical entomology belong to the Order Acarina, or mites, a
number of which are parasitic and cause disease through infestation or
by actually carrying the causative agent of disease from one animal
to another. In the following table only those mites are mentioned
which in one way or another produce pathological reactions in man
with more or less frequency. It must be remembered, however,
that there are other mites which will occasionally be found on man
and which may actually bite him.

SUPERFAMILY FamiLy GENUS AND SPECIES
Ornithodoros moubata
Ornithodoros savignyi
Ornithodoros turicata |
Ornithodoros talaje |

Ixodidae. .......- Dermacentor andersoni (Rocky Mountain
spotted fever tick)
Demodicoidea. . Demodecidae. . . . Demodex folliculorum (Follicle Mite)
Sarcoptidae...... Sarcoptes scabet (Itch mite)
Tarsonemidae... . Pediculoides ventricosus (Straw itch mite)
Glyciphagus domesticus (in sugar, cause of
grocers itch) also

Tyroglyphid mites in flour and other food
stuffs.

Liponyssus bacoti (a rat mite)

Dermanyssus gallinae (a poultry mite)

Microtrombidium  pusillum (a chigger of
Europe)

Trombidoides. -Trombidiidus. . Trombicula akamushi (Tsutsugamushi fever
mite of Japan)

Trombicula irritans (Chigger of Mexico and
the United States)

Eupodoidea. . . . Eupodidae. . . ... Tydeus molestus (may attack man similar to

chigger)
174

Argasidae. .. .. (Relapsing fever ticks)

Ixodoidea... .

 

Sarcoptoidea .
Tyroglyphidae.

Parasitoidea. . ..Dermanyssidae
(Gamasoidea)

 
CLASS ARACHNIDA 175

ORDER ACARINA
(The Mites)

In this Order there is little differentiation between the head and
thorax and these are therefore spoken of together as the cephalo-
thorax. This is broadly united to the abdomen with often no clear
line of demarkation. There are no antennae. The abdomen usually
shows no evidence of segmentation. In their life history the acarines
typically pass through four stages —egg, larva, nymph and adult.
The adult and nymph have four pairs of legs, the larva has but
three pairs.

While the mites vary greatly in size, shape and color, the points
which are common to all acarines are usually sufficiently charac-
teristic to group them without great difficulty.

Mites are found everywhere if one will only look for them. Some
are parasitic on animals, many are not. Some live on the juices of
plants or insects; some produce galls; some live in water—fresh and
salt; some live in humus and may be found in rotting leaves. Others
live on fruits, in cheese, flour, sugar etc.; others prey upon their own
kind. Some are parasitic on insects, birds, mammals and reptiles;
some eat the epidermal scales or feathers or hairs, others burrow under
the skin, some live within the follicles, others suck blood. They
have been found in the bronchial passages of monkeys, in the air
sac of snakes, in the bark of trees and in the dust from the floor.

External Anatomy.—The anatomy may be described briefly as
follows; (Fig. 75).

In many mites the back is covered in whole or part by a corneous
shield known as the scutum. At the anterior edge of this may be
seen a small, subtriangular or rectangular piece known as the capit-
ulum, which can not always be detected with ease. It supports the
mouth parts. The mouth parts consist of a pair of mandibles or
chelicerae—often styliform or needle-like,—sometimes chelate or
clawed,—and a pair of palpi. A lip or labium may be formed by a
union of the basal joints of the palpi. In many species additional
mouth segments can be seen. There may be a central piece known
as the hypopharynx which is a prolongation of the aspiratory
pharynx; an upper plate known as the epistome and an under plate
spoken of as the Zypostome. The latter is especially marked in
the ticks. It isin two halves and in the ticks is covered with small
recurved teeth. The palpi are never more than fivejointed. They
176 INSECTS AND DISEASE OF MAN

are sensory organs, although in some species they are modified for
clasping. The last joint may be hairy or it may terminate in a
spine, hook, or claw.

One or more pairs of simple eyes (ocelli) may be present on either
side of the cephalothorax or the scutum. Rarely there may be only
a median pair of eyes.

The adult mite usually has four pairs of legs composed of from
three to seven segments. The following segments can usually be
‘seen ;—beginning with the segment attached to the body they are,
coxa, trochanter, femur, patella, tibia and tarsus. The legs are haired
or spined to a greater or less degree and the last joint or tarsus
terminates in one to three claws or ungues and a sucker (pulvillus

 

Fic. 75.—A mite (semidiagrammatic) showing the external anatomy. (After
Banks.) Dorsal view: 1. Leg I. 2. Leg II. 3. Leg III. 4. Leg IV. 5. Abdomen.
6. Cephalothorax. 7. Palpi. 8. Mandibles. 9. Capitulum. 10. Eyes. Ventral
view: 1. Claws. 2. Tarsus. 3. Tibia. 4. Patella. 5. Femur. 6. Trochanter.
7. Coxa. 8. Beak. 9. Genital plate. 10. Genital aperture. 11. Anal aperture.
12. Anal plate.

or caruncle), at times a pulvillus and no claws. In some species
the two posterior pairs of legs are located so far removed from the
two anterior pairs that they appear to arise from the abdomen.

Many of the mites are softbodied. In addition to a dorsal shield
or scutum some are provided with chitinous plates or shields ventrally.
The body is usually supplied with hairs, bristles or scales arranged
in a manner characteristic of the species. The anal aperture is
located on the ventral surface near the tip of the abdomen. The
genital aperture of the male (epiandrum) as well as of the female
(vulva or epigynum) is usually on the ventral surface anterior to
the anal opening usually between the fourth pair or hind legs (leg
IV). In some species the genital segment is pushed so far forward
that the genital aperture is close to the mouth.
CLASS ARACHNIDA 177

Internal Anatomy.—The alimentary canal is composed of a
pharynx or aspiratory organ to which are attached the aspiratory
muscles; an oesophagus; a stomach with its coeca; a narrow iniestine
and a rectum. The two malpighian tubules empty into the rectum.
Salivary glands are located in the cephalothorax.

The breathing or fracheal openings in some species are wanting.
In others the spiracles are located on each side of the cephalothorax,
while in others the respiratory system opens into the coxal cavities
(acetabula), or by an orifice in what is known as a stigmal plate
located on each side near the fourth coxae.

Life History of Mites.—In the life history of mites there are
typically four stages—egg, larva, nymph and adult. Most mites
deposit eggs, some are viviperous and one, Pediculoides ventricosus,
-gives birth to adult males and females.

The larva which emerges from the egg is active, has but three
pairs of legs, and no genital orifice. After feeding awhile it becomes
quiescent. A fourth pair of legs develops, usually the hind pair,
and the larva after a moult then becomes a nymph with four pairs of
legs and breathing spiracles but no genital orifice. During the
nymphal stage the mite grows by moulting one or more times, then
becomes quiescent, and finally, after undergoing a final moult
becomes the fully formed adult.

There is often a curious nymphal stage in the life history of some
mites, especially the Tyroglyphidae, in which the body becomes
hard and chitinous, there is an absence of a mouth orifice and distinct
mouth parts, the legs are short and poorly adapted to walking and
an arrangement of sucking discs develops on the ventral surface
near the tip of the abdomen. By the aid of these discs the Hypopus,
as it is called, clings to an insect until it is transported to a place
favorable to its development into an adult mite.

Ticks.—Of all mites, the ticks or giant mites are most familiar.
They are all temporary parasites of warm blooded animals and of
birds and have been taken from snakes and tortoises.

The body is leathery and in the female is capable of great dis-
tension when engorged with blood and full of eggs.

In most of the ticks a dorsal shield or scutum is present. This
in the male covers the entire back but in the female only a small
part in front. Just anterior to the scutum may be seen the capit-
ulum which is composed of the basal part or basis capituli and the

mouth segments. These are, two four-jointed palpi; two mandibles
12
178 INSECTS AND DISEASE OF MAN

with their sheaths, and a hypostome. The mandibles, mandibular
sheaths (lying dorsal to the mandibles) and the Aypostome together
form the proboscis or haustellum. At the tip of the mandibles
are two processes known as the digits or apophyses. The under
surface of the hypostome is furnished with stout teeth. The mandi-
bles and hypostome are the piercing organs which are inserted into
the skin when the tick feeds. The food channel is formed by the
dorsal surface of the hypostome and the ventral surface of the
mandibles.

The inner surface of the palps is more or less concave. The palpi
vary in length and shape. The first and last joints of the palpi are
not always easily seen, as the first or basal joint is short and broad,
and the last joint is very small indeed, located at the end of the third
joint, often in a depression. The shape of the palpi and the shape of
~ the basis capituli are both of taxonomic value. On the dorsum of
the capitulum of adult female Ixodid ticks may be seen two depressed
pitted areas known as the porose areas. Their function is unknown.
They are seen only in the female adult forms of the Ixodidae—never
in the larval or nymphal stages.

The posterior edge of the body is frequently marked by furrows
giving a lobed or festooned appearance. The scutum is often orna-
mented with whitish, silvery or yellowish streaks or spots, when
without, the tick is said to be inornate. It has two longitudinal
grooves known as the cervical grooves. On the dorsum of the abdo-
men about the middle there may be seen in some genera two small
circular or oval plates called the dorso-submedian porose plates or fovea.
Their purpose is unknown.

On the ventral surface, the genital opening may be seen located
anteriorly well towards the capitulum. Posteriorly, towards the
tip of the abdomen, is the anal.opening. The ventral surface is
marked by grooves. In some forms there is a post-anal groove. In
others a groove anterior to the anal opening. In all ticks it is usually
possible to detect a groove on each side of the anal aperture. Ven-
tral plates or shields are present in the males of some genera. These
plates may be closely applied to the body and level with the integu-
ment when they are spoken of as non-salient plates, or, they may
project more or less from the body.

Each leg has six joints namely,. coxa, trochanter, femur, tibia,
metatarsus and tarsus. The tarsus terminates in two claws and a
pulvillus, or the pulvillus may be rudimentary or absent. The first
coxa is often bifid. One or more of the coxa may be spined.
CLASS ARACHNIDA 179

On the upper surface of tarsus I (the tarsus of the first or most
anterior leg) may be seen a pit known as Haller’s organ possibly an
organ of hearing.

Above and behind the last or hind coxa (or in front of this coxa
in the Argasid ticks) may be seen the stigmal plate (one on each
side) which contains the stigma, or tracheal orifice or breathing spiracle.
The shape and the minute structure of the stigmal plates have
taxonomic value. A section of the stigmal plate of the genus Der-
macentor, for instance, is, according to Stiles, composed of three
layers. Chitinous, goblet-like structures are to be observed, the
stem of the goblet forming the internal layer, the rim and upper part
forming the external layer and the lower part of the bowl of the goblet
forming the middle layer. Interspersed between these goblet-like
structures are smaller, supporting, chitinous structures of circular to
elongate form. On surface view the stigmal plate has the appear-
ance of being granular. The larger granules are the goblet-like
structures seen on cross section. They vary in size and number
according to the species. The smallest granules are the small,
chitinous, supporting structures.

Internal Anatomy.—The mouth which is located between the
hypostome below and the mandibles above, after passing backwards
for a distance as the buccal cavity, ends blindly. A V-shaped opening
in its floor communicates with the aspiratory pharynx and on each
side posteriorly there is the opening of the salivary ducts. The
pharynx is continuous with a narrow oesophagus which opens into the
floor of the midgut or stomach. This is the central food reservoir
which gives off diverticula, anteriorly, posteriorly and laterally.
The stomach-is connected to the rectum by a very fine, practically
functionless, #nfestine. The rectum is saccular and has emptying
into it, the two, long, fine, convoluted Malpighian tubules. Thus it
would seem that the rectum serves more as a uninary bladder than
as a true fecal reservoir.

The salivary glands, two in number, lie over the bases of the
first pair of legs. Other unicellular salivary glands may also be
present. Their ducts empty into the main salivary duct.

Dermal glands are present and there is a socalled cephalic gland in
the head and coxal glands in the second coxal joint which empty
through a minute pore in the first coxal joint.

Lying behind the midgut is a single ovary. There are two coiled
oviducts connecting with a spermatheca and ending at the genital
orifice.
180 INSECTS AND DISEASE OF MAN

In their metamorphosis ticks like other acarines, pass through
the four stages of egg, larva, or “seed” tick, nymph and adult. All
stages after hatching feed on blood.

Classification of Mites

The Acarina have been classified in several ways. Canestrini has divided
them into suborders according to the location of the stigmatic opening, as
follows:

Astigmatic:—Those which have no stigmatic openings but breathe through

the skin. (Tyroglyphid and Sarcoptid mites.)

Prostigmatic:—Those with spiracles at the sides of the beak. (Trombidioi-

dea and Eupodoidea.)

Mesostigmatic:—Those with a spiracle above and slightly in front of the

fourth coxa, with a peritreme extending forward. (Parasitoidea.)

Metastigmatic:—Those with a spiracle located above and behind the fourth

coxa. (Ixodoidea—the ticks.)

Cryptostigmatic:—Those with tracheal openings into the acetabula of the

legs. (The Oribatid mites.)

Hydracarina:—The water mites.

Nathan Banka has classified the Acarina by dividing them into eight super-
families. His key to these and to the families is as follows:

Synopsis of Superfamilies (Nathan Banks)*

1. Abdomen annulate, prolonged behind; very minute forms; often with but
Bon daa nr A ah ah Demodicoidea
Abdomen not annulate nor prolonged behind; always with eight legs... ... 2

2. With a distinct spiracle upon a stigmal plate on each side of the body (usually
below) above the third or fourth coxae or a little behind; palpi free; skin

often coriaceous or leathery; tarsi often with a sucker... ................ 3
No such distinct spiracle in a stigmal ‘plate on this part of body... 4
3. Hypostome large, furnished below with many recurved teeth; venter with
furrows; skin leathery; large forms, usually parasitic. ....... Ixodoidea

Hypostome small, without teeth; venter without furrows; body often with
coriaceous shields, posterior margin never crenulate; no eyes.
Parasitoidea
4. Body usually coriaceous, with few hairs; with a specialized seta arising
from a pore near each posterior corner of the cephalothorax; no eyes;
mouth parts and palpi very small; ventral openings of the abdomen
large; coxae all close together; never parasitic; tarsi never with a sucker.
Oribatoidea

Body softer, without such specialized seta. ........ 00h ivnvannernannsn 5

* This key and others by Nathan Banks, from The Acarina or Mites. Report No,
108, Dec. 1915, Bureau of Entomology, U. S. Department of Agriculture.
CLASS ARACHNIDA 181

s-Divingin water... ol... cL dS ala a Hydrachnoidea

Not lvinginawater.. La cn lL i v0

6. Palpi small, three-jointed, adhering for some distance to the lip; ventral

suckers at genital opening or near anal opening usually present; no eyes;

tarsi often end in suckers; beneath the skin on the venter are seen rod-like

epimera that support the legs; body often entire; adult frequently parasitic

Sarcoptoidea

Palpi usually of four or five joints, free; rarely with ventral suckers near

genital or anal openings; eyes often present; tarsi never end in suckers;

body usually divided into cephalothorax and abdomen; rod-like epimera

rarely visible; adulis:ravely parasiiie. 0. ol ha a aa 7

‘7. Last joint of palpi never forms a “thumb” to the preceding joint; palpi
simple, or rarely formed to hold prey; body with but few hairs.

Eupodoidea
Last joint of palpi forms a thumb to the preceding, which ends in a claw
(a few exceptions); body often with many hairs........ Trombidioidea

Synopsis of Families

Demodicoidea

‘With but four legs, of five joints each; living on plants, often in galls.
Eriophyidae
With eight legs, of three joints each; living in skin of mammals. . . . Demodicidae

Sarcoptoidea

1. With tracheae; no ventral suckers; legs ending in claws; body divided into
cephalothorax and abdomen; the female with a clavate hair between legs

I and II; not parasitic on birds or mammals. ........... Tarsonemidae

Without tracheae; no such clavate hair... Luda ins a iitnds in sieiais ain toi 2

2. Genital suckers usually present; not parasitic on birds or mammals; skin

usually without fine parallel Hines... ol. bu dL on be ned) 3

Genital suckers absent; parasitic on birds or mammals; skin with fine parallel

Hines. in, rr ESE a 4

3. Legs short, without clavate hair on tarsi I and II; living on insects.

Canestriniidae

Legs longer, with clavate hair on tarsi I and II; not parasitic (except on bees).

Tyroglyphidae

4. Possessing some specially developed apparatus for clinging to hairs of mam-

TRAE RE ee ad Listrophoridae
Without such apparatus......... 2. Sadie an a 5

sr ldvinz onplulnage of Died. . 0. oc oniieh se hi Analgesidae

Not on plumage of birds, but on ving tissues. . ...... vc. ivi vanviainis vin nis 6

6. Vulva longitudinal; in skin and cellular tissue of birds... ... Cytoleichidae

Vulva transverse; in skin of mammals and birds. ............ Sarcoptidae
182 INSECTS AND DISEASE OF MAN

Parasitoidea

1. Palpi with the last joint enlarged; a spiracle situate above coxa III.
Holothyridae
Palpi not enlarged at tip; spiracles situate behind coxa r11............... 2
© 2. Genital aperture near the anus; mouth parts retractile within a large buccal
cavity, which is situated in an anterior part of the body separated by a

suture from therestoithebody. ..:... ue, Spelaeorhynchidae

Genital aperture not or scarcely behind the hind coxa; no anterior part of

body ‘separated by a suture... o.oo anni se 0 Parasitidae
Oribatoidea

1. No division between cephalothorax and abdomen... ... Labidostommatidae

A suture between cephalothorax and abdomen................1 re eens.. 2

2. Cephalothorax movably attached to the abdomen; palpi four-jointed.

Hoplodermidae

Cephalothorax not movable; palpi five-jointed.............. Oribatidae
Ixodoidea

1. No scutum; no ventral shield; mouth parts of adult not prominent from above;

no pulvillus to tarsus in adults... .... 0. ..h oan oo cs ae Argasidae

Scutum present; sometimes ventral shields; mouth parts of adult prominent

from: above; pulvillus to tarsus of adults... .... Lo Ixodidae
Trombidioidea

1. Legs I and II with processes bearing spines; skin with several shields; coxae

CONLIGUONS. ceo Fin mim tai tie wie ft» Caeculidae
Legs I and IT without such processes; few, if any, shields................ 2

2. Mandibles chelate or uncinate, that is a basal rather thickened part, with a
clawmnearBiailip. se es SI 3
Mandibles stylate (needle-like), and retractile; coxae in two groups... .... 4

3. Tarsal joint of leg I usually enlarged; usually a crista metopica on cephalo-
thorax; coxae in widely separated groups..............:. Trombidiidae
Tarsal joint of leg I not enlarged, often long; no crista metopica; coxae
usually’ in ‘one group, CONLISUOUS.... .\..c.iivissiie nin ante aati ‘Anystidae

4. Tarsi enlarged; usually a dorsal groove; adults free.......... Erythraeidae
Tarsinotl enlarged: nodorsal groove... 00 LUG an 5

5. Phytophagous occurring on plants; often spinning threads: palpi simple;.
leg 1 never ending in long hairs; all legs with claws; bristles usually simple
Tetranychidae
Predaceous or parasitic, often on birds or mice; palpi often enlarged at base
and forming a forceps; claws often absent from one or more pairs of legs;
often with pectingte bristles... 0... Lo da ool ou Cheyletidae
CLASS ARACHNIDA 183

Eupodoidea

Palpi simple; mouth parts hidden by a hood; no apparent division of body,
and no bristles above; last joint of leg I but little longer than preceding.
Cryptognathidae
Palpi often geniculate, or else fitted for grasping prey; mandibles large and
snout-like; cephalothorax with four long bristles above, two in front,
two behind; last joint of leg I longer than preceding joint, often
WICC aS IONE. STN 5 shies sa ls pea ee eae ctr ll Bdellidae
Palpi never geniculate, not fitted for grasping prey; beak small; cephalothorax
with bristles in different arrangement; last joint of leg I shorter or but little
longer than preceding joint; eyes, when present, near posterior border.
Eupodidae

Hydrachnoidea

(Water Mites)

Mouth parts carried upon a distinct beak; no ventral suckers; living in the

BO a a ee a Halacaridae
Mouth parts not carried upon a beak; usually suckers near the genital
openings; usually infresh water... ..... din omeiiminnss Hydrachnidae

Superfamily Ixodoidea Banks 1894
(The Ticks)

The Ixodoidea are acari having their breathing spiracles located
near the fourth coxae (Metastigmatic). They are characterized
by having a movable false head or capitulum which is composed of a
basal portion or basis capituli, a pair of four-jointed palpi, protrusible
mandibles terminating in two or three serrated digits or apophyses,
and a rigid hypostome toothed on its under surface. All subsist
on the blood of animals. Most of them will probably bite man
under the proper conditions, many of them have been known to
bite man, and a number of them transmit certain diseases of man
and animals, including relapsing fever of Africa, Persia, Central
America and South America; Rocky Mountain spotted fever;
piroplasmosis and spirochaetosis of animals and birds.

The superfamily has been divided into two families, the Argasidae
and the Ixodidae. The differences between them have been tabu-
lated by Nuttall as follows:
184

INSECTS AND DISEASE OF MAN

 

Argasidae

| Ixodidae

 

Sexual dimorphism
Capitulum:

Festoons. .
Eyes Gen present).

Spleacles ivr oo. LG,

Legs:

Barely, or eS

Pad (pulvillus)

 

Slight.

Ventral in camerostome.

No porose areas in female.

Leg-like with subequal
articles.

Absent.

.| Absent.

Lateral,
folds.
Very small, more anterior.

on supracoxal

Unarmed.
Without ventral spurs.

Absent or rudimentary.

Marked.

Anterior; porose areas in
female.

Relatively rigid, of varied
form, 4th. article rudi-
mentary.

Present.

Generally present.

Dorsal, on the sides of the
scutum.

Generally large, well be-
hind coxa IV.

Generally armed with
spurs.

Generally armed with one
or two ventral spurs.

 

Always present.

 

Key to the Genera of the Family Argasidae

. Margin of body flattened,

sharp-edged

Margin of body thick, rounded, not clearly defined (Fig. 77)...Ornithodoros
Key to the Genera of the Family Ixodidae

. Venter showing a groove surrounding the anus in front and extending back-

wards to hind margin of abdomen; no festoons; no eyes; palpi of variable

form without projecting transverse ridges or sharp angles; stigmal plates

nearly circular; venter of male with nonsalient plates (Fig. 78).

Ixodes Latreille 1795 (ricinus)*

Venter with a distinct groove behind the anus but none in front, at times this
groove vestigal or absent; usually with festoons present in male more or
less distinct in female; eyes present or absent; stigmal plates rounded
to comma-shaped; palpi long or short, smooth, ridged or angled on sides;

ventral plates present or absent in male
. Palpi short, relatively broad, second article not especially longer than wide. 3

Palpi long, relatively slender, second article distinctly longer than wide... .7

. Palpi with acute transverse ridges dorsally and laterally; festoons absent or

only faintly indicated; stigmal plates rounded or oval; male with ventral
plates; post anal groove very faint or obsolete (Fig. 79).

Boophilus

Curtice 1891 (annulatus)

Palpi not ridged as above; festoons practically always present in male;
more or less distinct in female; stigmal plates rounded to comma-shaped;

post anal groove distinct; male with or without ventral plates

4. Second article of palpi acutely produced outwardly at base extending beyond
basis capituli; eyes absent; male without ventral plates (Fig. 81).
Haemaphysalis Koch 1844 (concinna)

* The specific name in parenthesis is the type of the genus.
CLASS ARACHNIDA 185
Second article of palpi not so produced; eyes present; with or without ventral

. Basis capituli rectangular dorsally; usually ornate; coxa IV in male much
the largest; male without ventral plates or shields (Fig. 82).

Dermacentor Koch 1844 (reticulatus)
Basis capituli hexagonal dorsally having prominent lateral angles; usually
fnorante.. Loni hn Luin ie a a SL RE 6

. ‘Coxa IV much the largest; male without ventral plates or shields.
Rhipicentor Nuttall and Warburton 1908 (bicornis)
Coxa IV normal; male with ventral plates and may show a caudal protrusion

le a Rhipicephalus Koch 1844 (sanguineus)
BYE PYeBEnl. . a a SES Se 8
Eye absentior-vestigial. uh hum ae ag SR La, 9

. Eyes within scutal margin; ventral shields present in male and two posterior
abdominal protrusions capped by chitinous points; basis capituli subtri-
angular dorsally; with or without ornamentation; with or without festoons.

Hyalomma Koch 1844 (aegyptium)

Eyes marginal; ventral shields absent except occasionally small plaques are

present close to the festoons; festoons always present; usually ornate

(Plg: 86)... Te Amblyomma Koch 1844 (cajennense)
. Similar to Amblyomma but body frequently very broad; eyes absent or
vestigial oi vo (Subgenus) Aponomma Neumann 1899 (gervaisi)

Boophilus Dermacentor

 

Rhipicephalus Amblyomma

FiG. 76.—Capitulum of the more important genera of Metastriatic Ixodidae.

FAMILY ARGASIDAE
Genus Argas Latreille 1796

In this genus the body is flattened and oval or rounded, with a

flattened, sharp-edged margin which is distinct even when the tick is
186 INSECTS AND DISEASE OF MAN

replete; the capitulum is entirely invisible from above; there are
numerous symmetrically arranged oval or rounded discs on the
dorsum and the venter, disposed in radial lines; the integument is
minutely wrinkled; eyes are absent.

Argas persicus Oken is the ‘“Miana bug” of Persia. It may
live in houses and is found on fowls. It is said that severe symptoms
may follow its bite. This tick is found in many parts of the world.
In the United States it is known under the name of Argas miniatus
Koch. Itis quite common on chickens and has a more Southern dis-
tribution. In Brazil, the Soudan and in other parts of the world it
transmits a spirochaetosis of chickens.

Argas reflexus Fabricius is a pigeon tick of Europe which has
been known to bite man.

Another genus, Caris, has been suggested for those Argas ticks,
which are parasitic on bats and which have a body as broad or
broader than long and a transverse groove behind the anus.

Genus Ornithodoros Koch 1844

In this genus the body is flat in the unfed tick but decidedly
convex when fed; the margin is thick and not clearly defined; the
anterior end is bluntly pointed and hood-like; the anterior portion of
the capitulum is often visible from above; when discs are present
they are not arranged radially; grooves and folds are present on the
venter; eyes may be present or absent.

Some of the ticks in this genus are responsible for the trans-

mission of relapsing fever. They are tropical and subtropical in
their distribution and at least four are found in America. These
ticks as well as those of the genus Argas are more like bugs in their
habits.
Ornithodoros moubata Murray (Fig. 77) is the carrier of relapsing
fever of Africa, or African tick fever as it is sometimes called. It
also possibly transmits Filaria perstans (Chap. XXXV.) These ticks
live in the cracks and crevices of walls and floors or in the gravel
floors of native huts and rest houses, coming out at night to feed.
The larval stage is passed in the egg, a nymph emerging after
an incubation of about twenty days. The adult ticks moult several
times and may live for at least a year.

Ornithodoros savignyi Audouin is common in Africa, India, Persia
and Aden. It will attack man and is responsible for the transmission
of Persian relapsing fever. (Chap. XXXV.)
CLASS ARACHNIDA 187

Ornithodoros talaje Guerin-Meneville is the carrier of relapsing
fever of Panama. (Chap. XXXYV.) Itisfoundin Central and South
America, Mexico and the Southern United States. It also lives in
houses its habits being similar to those of O. moubata. Because of
the presence of a lateral flap on each side of the mouth parts which
other members of the genus Ornithodoros do not have, a subgenus,
Alectorobius, has been proposed for this species.

Ornithodoros megnini Dugés is the ‘““spinose ear tick” of Mexico
and the United States. It is found on cattle and other domestic
animals, rabbits, etc., and occasionally on man. The adult rarely
feeds and its mouth parts are weak but the nymph takes enough

 

{Hina

F1G. 77.—Ornithodoros moubata, dorsal and ventral view. (From Stitt’s ‘‘Practical
Bacteriology, Blood Work and Animal Parasitology,” 7th. Edition.)

food to last through the adult state. When replete it drops to the
ground. The last moult, mating, and ovipositing occur off the host
in cracks and crevices in trees, walls, fence posts and the like. After
laying her eggs the female dies, but until she has been fertilized
may live for many months. After emerging from the egg the larval
ticks await the opportunity to attach themselves to an animal
preferring the inside of the ear as a feeding ground,—hence the
common name ‘‘ear tick.” This tick, unlike others of the genus,
has a spiny vestiture and for this reason as well as because of the
modifications in its life history, some authorities have placed it in a
subgenus, Ofobius.
188 INSECTS AND DISEASE OF MAN

Ornithodoros turicate Dugés is another tick of the Southern
United States, Mexico, Central and South America. Itattacks hogs,
small mammals and man and may be found in houses. It is the
carrier of South American relapsing fever. (Chap. XXXYV.)

Ornithodoros coriaceus Koch is found in Califorhia and Mexico

and will bite man. Its bite is followed by a severe reaction.

The Following Key May Be Used to Identify the American Species of
Ornithodorus (After Banks)

1. Body provided with many short, stiff bristles; hind tarsi scarsely three times
as long as broad at base, with one subterminal hump above; anterior tarsi
also with one subterminal hump; body rounded in front; no eyes.

0. megning
Body without bristles, but covered with rounded tubercles or granules;
hind tarsimore lenders... iii, fbi widuiviio vs vareaidie sms Adis ina alate wien 2

2. Two pairs of eyes present on each side above coxae 11; tarsi IV with a promi-
nent subterminal spur above; front of body conical in the middle; leg I

strongly roughened... oo. Ls i alii ed ie te ante O. coriaceus.
No'eyes: no such spur-on hind tarsl.. «.btini vies sisal ssivvinnice is 3

3. Front of body conical in middle; tarsi r without humps above; a lateral flap
on:each side of MOuTh DATED: Ji us vals i ha a Bids divbeisiabaial dikes 0. talaje
Body rounded in front; tarsi and metatarsi each with three humps; no lateral
flaponieach side of mouth parts... ....... ce ouios0 ou 0. turicala

FAMILY IXODIDAE
Genus Ixodes Latreille 1796

This genus is characterized by being inornate, without eyes and
without festoons; the spiracles are round or oval; the anal groove
surrounds the anus in front; the shape of the palpi and basis capituli
is variable; the tarsi are without spurs; the venter is covered by
nonsalient plates as follows, one pregenital, one median; one anal,
two adanal, and two epimeral. (Fig. 78.)

In general the palpi of most Ixodes are rather slender, the third
joint is longer than broad and tapers towards the tip. They are
also narrow at the base so that there ordinarily is a distinct interval
on each side between them and the base of the hypostome. The
basis capituli is usually not angulate at the sides. For a group of
ixodes which has the basis capituli slightly angulate at the sides and
the third joint of the palpi shorter than broad and broadly rounded
at the tip, another genus, Ceratixodes, has been adopted by some
CLASS ARACHNIDA 189

authorities. A few species have been described from sea birds
living in Arctic and Antarctic regions. For another group of Ixodes,
“on bats and which have the legs unusually long, the genus Haema-
lastor has been suggested.
A number of species of Ixodes have been reported from the
United States among them being Ixodes ricinus Linn. which has a -

PREGENITAL
PLATE

   
   
   
 
  
  

.. GENITAL
ORIFICE

.... MEDIAN
© PLATE

-.. EPiMERAL

PLATE

tr
GENITAL
GROOVE

 

PREANAL GROOVE ! ianaL mate
Anus

Fic. 78.—A tick of the genus Ixodes, male, ventral view.

wide distribution and in Scotland is believed to be responsible for
the spread of a disease of sheep.

It has been taken from a variety of domestic animals as well as
from deer and some of the smaller wild animals and birds. It will
bite man.

This tick drops to the ground between each one of its successive
stages, thus each time it is compelled to seek a new host.
100 INSECTS AND DISEASE OF MAN

Genus Boophilus Curtice 1891

This genus contains the well known Texas fever tick, Boophilus
annulatus Say (bovis Riley) (Figs. 79,-80) which transmits Texas or
red water fever among cattle. The disease is caused by a blood
parasite, Babesia bigemina, which is ingested with the blood when the
tick feeds and is transmitted by the adult female tick to her
offspring. Thus even young ticks which have not fed may carry
the disease.

The genus is characterized by being inornate and without
festoons; eyes are present; the palpi are short and ridged dorsally
and laterally; coxa I is bifid; the scutum is small; the anal groove

 

F1G. 79.—Boophilus annulatus, male, dorsal and ventral view.

absent or only faintly indicated; spiracles rounded or oval; the male
is provided with adanal and accessory adanal shields (Fig. 79).

The adult female tick when engorged is greatly swollen. She
drops to the ground to lay her eggs. After hatching, the young
or “seed ticks” climb on to a blade of grass or low foliage and attach
themselves to passing cattle. From this on growth takes place on
the same animal, the tick not leaving the host until fertilized by the
male and ready to deposit eggs. This tick or closely allied species,
perhaps only varieties, occurs in many parts of the world where
Texas fever may also occur. For instance in Australia and the
Philippine Islands there is a variety known as Boophilus australis
Fuller.
CLASS ARACHNIDA 191

In this genus the small size of the male as compared to the
engorged female is very striking.

The Genus Margaropus was made for winthemi Karsch, a tick
which has a preanal shield and the hind pair of legs in the male,
greatly swollen.

 

F16. 80.—Boophilus annulatus, female, dorsal and ventral view.

Genus Haemaphysalis Koch 1844

This genus is characterized by being inornate and without eyes;
festoons are present; the palpi are usually short and conical, with the
base of the second joint projecting outwardly beyond the basis
capituli; the basis capituli is rectangular dorsally; there is a dorsal
process on the first trochanter and the ventral surface of the male is
without plates or shields. (Fig. 81.)

Only a few species have been described from the United States of
which Haemaphysalis leporis palustris (Fig. 81) is common on
rabbits and widely distributed. H. chordeilis Packard has been
taken from birds. H. expositicius has been found on cattle in
Canada. The latter is an imported European tick. Haemaphysalis
leachi Audouin is a South African dog tick and is a spreader of
canine piroplasmosis.  H. puncrata isreported as causing fatal paraly-
sis in a child in Australia.
102 INSECTS AND DISEASE OF MAN

 

Fic. 81.—Haemaphysalis leporis-palustris, male, ventral view.

Genus Dermacentor Koch 1844

This genus is characterized by being usually ornate and with eyes
and festoons present; the palpi are rather short and broad and the

 

Fi1G. 82.—Dermacentor andersoni, male, dorsal and ventral view.

basis capituli is rectangular; coxa IV is much the largest; there are no
ventral plates or shields. (Figs. 82, 83.)

There are some ten species reported from the United ‘States.
Dermacentor variabilis Say (electus Koch) is the common “dog” tick or
“wood” tick of the Eastern States. On the Pacific Coast the com-
CLASS ARACHNIDA 103

mon “dog” tick is Dermacentor occidentalis Neumann. Both of

these ticks may be found on other animals and on man.
Dermacentor andersoni Stiles (Figs. 82, 83) is the tick of the

Bitter Root Valley, Montana, and the North West and is the carrier

Pass
Basis Capituli

 
   

 

Fi1G. 83.—Dermacentor andersoni, female, dorsal and ventral view.

of Rocky Mountainspotted fever. (Chap. XXXVI.) This tickinall
of its, stages feeds upon the blood of various warm blooded animals
both domestic and wild. It will bite man. It has been taken from

dogs, cattle, horses, swine, sheep, deer, mountain goats, bears, bad-
13
104 INSECTS AND DISEASE OF MAN

gers, coyotes, squirrels, chipmunks, rabbits, weasels, martens, por-
cupines and field mice. Larval and nymphal stages are only found
on small mammals, adults on larger animals. Mating takes place on
the host. When engorged the female drops to the ground and in
about two weeks egg laying begins. Several thousand eggs may be
deposited after which the tick shrivels and dies.

Under favorable conditions—summer temperature, out of direct
sunlight—the eggs develop in from 30 to 50 days into larval or “seed ”
ticks, with but six legs. Colder weather may delay hatching for
several months. The larva is very small at first, pale and soft but
soon develops a hard, brown integument. The larva climbs upon a
blade of grass or a twig and waits for a warm blooded animal to pass
by. Once attached it becomes fully engorged in from three to five
days. It then drops to the ground, becomes dormant for a period of
from two to eight weeks and then moults into the eight-legged
nymph. Many ticks never succeed in obtaining a host and perish
for want of food.

The nymph again waits for a host on which to feed, upon which it
remains for a period varying from four to eight days. It then drops
off, remaining active for two to four weeks depending upon the tem-
perature, then becomes quiescent and finally undergoes a last moult-
ing, the fully formed adult emerging from the nymphal skin. The
interval elapsing between larva and adult may be long—perhaps
four or five years.

The adult then attaches itself to a warm blooded animal and the
life cycle starts anew. One female produces but one brood. Ticks in
all stages of development hibernate during the winter. Extremely
low temperatures—3o0 or 4o degrees Fahrenheit below zero—will
not kill them, nor will such temperatures destroy the virus of
Rocky Mountain spotted fever in the body of an infected tick.

D. andersoni is the common wood tick of the Bitter Root Valley
and is closely related to D. venustus of Texas and D. occidentalis of
California.

Genus Rhipicentor Nuttall and Warburton 1907

In this genus eyes and festoons are present but there is no orna-
mentation; the palpi are short and the basis capituli is hexagonal
dorsally having prominent lateral angles; coxa IV is much the larg-
est; there are no ventral plates or shields; the male resembles Derma-
centor ventrally and Rhipicephalus dorsally.

This genus is not reported from America.
CLASS ARACHNIDA 195

Genus Rhipicephalus Koch 1844

In this genus eyes and festoons are present; there is usually no
ornamentation; the palpi are short and the basis capituli is hexagonal

   

i
Accessory’)
Plates  Adanal Plates

F1G. 84.—Rhipicephalus sanguineus, male, dorsal and ventral view.

 

dorsally with lateral angles more or less prominent; the male is pro-
vided with ventral shields and may show a caudal protrusion when
replete. (Figs. 84, 85.)

 

Fi1G. 85.—Rhipicephalus sanguineus, female, dorsal and ventral view.

Rhipicephalus sanguineus Latreille (Figs. 84, 8s), the type
species, is a widely distributed species now more or less common in
the Southern United States. Itis a dog tick but may occur on other
hosts. TItis the only member of the genus found in the United States.

 
 

196 INSECTS AND DISEASE OF MAN

This tick is responsible for the transmission of Piroplasma canis
and Haemogregarina canis. In the first instance the parasite is
acquired by the adult tick and is transmitted in the nymphal and
larval stages. Little is known as to how the tick transmits H.
canis.

Genus Hyalomma Koch 1844

In this genus ornamentation may be absent or present; eyes are
present within the scutal margin and there are usually festoons; the
palpi are long and the basis capituli subtriangular dorsally; the male
is provided with shields ventrally and has two posterior abdominal
protrusions capped by chitinous points; the female is more like
Amblyomma.

This genus has not been reported from America.

Genus Amblyomma Koch 1844

This genus is usually ornate, with eyes marginal and with fes-
toons; the palpi are long especially the second article; the basis capi-

 

Fi1G. 86.—Amblyomma cajennense, male, dorsal and ventral view.

tuli is of variable form; the male has no ventral shields although there
may be small ventral plaques close to the festoons. (Figs. 86, 87.)

The subgenus Aponomma differs from typical Amblyomma in
that the eyes are absent or poorly developed and the body is fre-
quently broad. This subgenus occurs on Reptilia.

There are many species of Amblyomma a number coming from
Tropical and Subtropical America. The “lone star” tick, Ambly-
omma americanum Linn., is more or less common on cattle in the
Southern States especially Texas and Louisiana. The female has a
single bright, silvery spot at the tip of the scutum. The male which
   

CLASS ARACHNIDA 197

is much smaller has several bright, silvery spots on its brownish
scutum.

Amblyomma cajennense Fabricius (Figs. 86, 87) is a common
tick of tropical America and extends up into Texas. The scutum in
both sexes is yellowish with irregular silvery streaks and marks.
A few other species are, Amblyomma tuberculatum from Florida from
tortoise (gopher); A. maculatum is more or less common in certain
localities on the Gulf Coast. Unlike others of the genus this tick
has but one prominent spine on the fore coxae, others have two.

physes, Mandible
poe. Su, Auli etic) ai pslome

      
   

   

( Ciel oe erfure ts it
po} i 5
“Stigmal Plate f
’ Claws Pulyillus

A B

Fic. 87.—Amblyomma cajennense, female, dorsal and ventral view.

A. habraeum Koch disseminates heart water fever among sheep and
calves in South Africa.

Key to a Few Species of American Amblyomma (After Banks)

1. Coxa 1 with but one spine, metatarsi (except 1) with two thickened spurs at
tip; second joint of palpus not twice as long as third; porose areas elongate;

shield brown, with silvery marks........... oe Lb oa ii, maculatum
Coxa 1 with two spines; metatarsi without stout spurs at tip; only slender
Rade. cis Jann) oo LL Sn Be hn le le 2

2. Projections of coxa 1 blunt and short; porose areas elongate; second joint
of palpus not twice as long as third; coxa IV of male with only a tubercle
behind; largespecies.... loci lh dB pd tuberculatum

Projections of coxa 1 longer, and at least one of them sharp pointed; second
joint of palpus twice as long as third; coxa IV of male with a long spine;
gmallerepecies. 0 cL a a a Gc 3
198 INSECTS AND DISEASE OF MAN
3. Porose areas nearly circular; shield of both sexes pale and yellowish, with
some silvery streaks and marks, and some reddish spots; shield of female
agibroadaglong. in ou A ee cajennense
Porose areas elongate; shield brown, in female with an apical silvery mark,
in male with two small apical and two or four other silvery spots; shield
of female llongerthan broad... hs di va ih 0, americanum
CHAPTER XXI
SUPERFAMILY EUPODOIDEA

FAMILY EUPODIDAE

These mites are small, soft bodied and move rapidly. They live.
mostly on the ground but some are found on the leaves of trees.
They like cold, damp places and are common in high altitudes and
are frequently found in caves. Many are predaceous, feeding on
other mites and small insects; some are found on snails and occa-
sionally on insects. One, Tydeus molestus Moniez has been reported
as attacking man.

FAMILY BDELLIDAE -

These are the “snout mites.” They are predaceous feeding on
other mites and small insects. They are most common in cold
countries and prefer a cold, damp environment. One species Bdella
cardinalis Banks has been taken from Rattus norvegicus in New York
City. They do not suck blood and were probably on the rats acci-
dentally or to prey upon their ectoparasites.

Superfamily Trombidioidea
FAMILY CHYLETIDAE

These are very small mites, typically with large palpi attached to
a distinct beak. They are predaceous and some are parasitic. They
may be found on birds, insects or mammals where they are present
to feed on other mites. Some live in the quills of birds or in the hair
follicles where they form tumors.

One genus, Myobia, is based on a species, Myobia musculi, from
the house mouse, Mus musculus. All legs are short and thick but the
first pair is particularly heavy and adapted to grasping a hair. Other
species have been reported from rodents and bats.

FAMILY TETRANYCHIDAE

These include the familiar “red spiders’ so destructive to cul-

tivated plants. Many of them can spin a thread hence the common
199 :
200 INSECTS AND DISEASE OF MAN

name ‘‘spinning mites’ is frequently applied to them. They feed
on the living plant sucking the juice from the leaves. They are
found on cotton, alfalfa, clover, orange, lemon and other trees, moss,
green house and out-door cultivated plants etc. When clover is
grown close to the house, it is reported that the clover mite (Bryobia
praetiosa Koch), upon the approach of cold weather, may enter for
shelter and greatly annoy the occupants.

FAMILY TROMBIDIIDAE

These are the “harvest mites.” Most of the species are red or
reddish in color. The six legged larvae are parasitic on insects and
~ mammals including man. However it is probable that man serves
only as an accidental host. Nymphs and adults probably live chiefly
on small insects.

The family is characterized by the body having two distinct divi-
sions, the anterior or cephalothorax bearing the two anterior pairs of
legs, the palpi, the mouth parts and the eyes of which there are two
on each side; the posterior portion or abdomen bearing the two pos-
terior pairs of legs. The mandibles are provided with a distinct
jaw (hence chelate) or curved spine-like process; the palpi are five
jointed, prominent, often swollen in the middle, the next to the last
joint terminating in one or two claws, the last joint acting as a thumb
to the preceding joint; the body is clothed with bristles or feathered
hairs. A dorsal groove along the median line of the cephalothorax
may be present. This is called the crista or crista metopica. Eggs
are laid and hatched in or on the ground and it is likely that except
when on a host, the larval mite spends its existence on the ground,
not climbing up on vegetation as do the ticks.

The harvest mites are wide spread and in the larval stage cause
much annoyance to man by reason of the reaction following the bite.
One, the Kedani mite of Japan, is responsible for the transmission of
Tsutsugamushi or Japanese River fever. (Chap. XXXVII.) This
mite, Trombicula akamushi, in its life history does not differ materially
from other mites of its kind. The larva is very small and bright red
or orange in color. The nymphal and adult forms do not bite but
live on vegetable juices. Blood is obtained by the larvae usually
from the small rodents of the locality, especially the field mouse
(Arvicola hatanedzumi) on which they congregate about the ears.
The larva develops into an octopod nymph which after one, or per-
haps more moults becomes the fully formed acarine which may be
SUPERFAMILY EUPODOIDEA 201

found under fallen leaves or decayed vegetable matter in areas
which have been subjected to inundation.

There are at least three European forms of chiggers as well as
species in other parts of the world. According to Ewing the chigger
of the United States, Trombicula irritans, is the same as the Mexican
chigger, Trombicula tlalzahuatl Murray. It is widely distributed in
the United States from Long Island to Central Mexico and from the
Atlantic Coast to the Rocky Mountains.

The chigger mites have been known for many years under the
name of Leptus,—Leptus autumnalis in Europe and Leptus irritans
or americanus in the United States. This was before their proper
place in the acarine world was recognized.

The chigger of the house fly is Trombidium muscarum Riley. At
times many of the flies areseen to have these small red mites attached
to them. Euthrombidium trigonum is more or less common on locusts
and grasshoppers or other Orthroptera both in the United States and
parts of Europe. :

Key to Some of the Genera in the Family Trombidiidae (Adults) (After Banks)

wiNoeristametopien.c.. 00 LL Ren Ce a Trombella
Crista metopica present...... dR PL a EL 2
2.i:Sides: of tbody with ‘projectionsi..o.t0 wl edi nn Jr] Chyzeria
Body without projections. ...i + .Lic nis ii him bn Boh i Fes 3
3. Claws with a pulvillus; eyes pedunculate; one claw at tip of palpus.
Allothrombidium
Nopllvilllcs ow won i en Sis TS sa Nr 4
AriNoeyes. ©... SD ST Re RS ei A ee 5
Eyes present... un anti cana hit ia on Lr JR RE SL 6
rig. Crista’enlarged mear middle .o.. i 00 iva vai a vals Typhlothrombidium
Crista enlarged at end: ic) lL nasties nt Lee Trombicula
6. Eyes sessile; palpus with two claws at tip......... ooh id cold, 7
BEyespedunculate........ ...5. 0 od a Li hh a eh 10
7: Cristatenlarpedibutonee: uv. ov ul WEES pl Cn 8
Crista enlarged twice. ian saab g an aN aL ET Gn 0
8. Enlarged only at end; abdomen higher than the cephalothorax.
Microthrombidium
Enlarged only near middle; abdomen and cephalothorax of same height.
Tanaupodus
9. Crista enlarged at middle and at end..... Aen Re Euthrombidium
Crista enlarged twice near the middle. ................. Diplothrombidium
10. Crista enlargedineapmiddle. 0. nL L0G deh oi ae ae IT
Cristasenlarped nearend. .. 0b. rnin Bo a Ja a 12

11. Eyes long pedunculate; no teeth at the base of the palpal claw.
Dinothrombidium
202 INSECTS AND DISEASE OF MAN

Eyes short pedunculate; teeth at the base of the palpal claw.

Podothrombidium

12. Crista enlarged near anterior end; eyes long pedunculate; no teeth near
palpaliclaw: legs rather short... .. 0.0... a vn. ok Trombidium
Crista enlarged near posterior end; eyes short pedunculate; teeth near
palpaliclaws legs vervilong 00 dane aed Johnstoniana

Superfamily Parasitoidea (Gamasoidea)

This superfamily has been divided into three families of which
Parasitidae is the best known and contains some familiar examples.

FAMILY PARASITIDAE

Many of these mites are parasitic on insects and vertebrates.
Eyes are absent; the mouth parts are retractile; the mandibles are
either clawed with the fingers of the claw toothed, or they are
adapted to piercing; an epistome and a hypostome (not provided
with teeth as in the ticks) may be present, together with a long
fleshy part, the lingula, between the points of the bifid hypostome;
the palpi are usually five-jointed; the legs six-jointed; the venter is
provided with plates or shields; the breathing spiracle is located on
each side above and slightly in front of coxa IV (Metastigmatic) and
is surrounded by a chitinous ring, the peritreme, which extends
forward for a varying distance in a more or less sinuous line.

Banks divides the Family Parasitide into five subfamilies as
follows: :

1. The spiracle and peritreme (nearly or quite) on the dorsum; legs short and
very bristly: all with large caruncles....... nc inch Spinturnicinae
Spiraclesiand periiremes ventral. (ine. tne se we wr a Shane 2

2. No shield or chitinous surface about the anus; parasitic within mammals.
Halarachinae
A shield or chitinous surface about anus; not parasitic in mammals.......... 3
3. First pair of legs inserted within the same body opening (camerostome)
as the oral tube; dorsum of body projects beyond the camerostome; genital
apertures in the sternal plate; often occurring on insects. . . . . Uropodinae
First pair of legs at one side of the mouth opening; dorsal surface of body
does not project in front of the camerostome; male genital opening usually
on the anterior margin of the sternal plate (sometimes in the middle)... . . . 4
4. Jaws of mandibles without teeth, often stylate or needle-like; parasitic on birds,
mammals, or reptiles; tarsus 1 with claws or caruncles; leg II of male never
with processes; anus in female usually at the front end of the anal shield;

all the chitinous shields rather weak, and often not evident.

Dermanyssinae
Jaws of mandibles toothed; rarely stylate or needle-like; usually not found
on animals, except insects.......... AT A iy Parasitinae
SUPERFAMILY EUPODOIDEA 203

Of the above, the Spinturnicinae are mostly parasitic on bats,
some on sparrows, swallows, the domestic fowl and other birds.

The Halarachninae include but two genera, Halarachne which
has been found in the bronchial passage of seals, and Preumonyssus,
which has been found in the lungs of monkeys.

The Uropodinae are frequently found on insects. They are
not necessarily parasitic but often use the insect as a means of
transportation. They live in decayed wood, humus, manure etc.
and probably feed in part at least on bacteria and fungi.

The Dermanyssinae contains members some of which are well
known. Ewing regards the Dermanyssid mites as constituting
a family which is characterized as follows;—‘‘ Mouth parts adapted
for piercing, the chelicerae being either devoid of one or both of the
chelae or of all true teeth, but however, recurved ‘‘hold-fast” hook-
like structures are sometimes present. Integument somewhat
leathery and distensible, but covered to a large degree by one or
more dorsal shields and one or more ventral plates. Each tracheal
trunk opening through a peritreme situated on the side of the
body. Sexual dimorphism evident and at times marked. Parasitic
in habits and on vertebrates.”

Ewing separates them as follows:

Key to the Subfamilies and Genera of Dermanyssidae (Ewing, 1922)*

. Chelicerae adapted for both piercing and attachment, being provided with
recurved barbs or hooks.
bt. Both chelae of chelicera present, the fixed one SE with a single
recurved barb and the movable one falciform; hypostome without
recurvedihooks.i...... |... rR Subfamily Entonyssinae
Containing but one genus... ... Ss smesasiensnni es Entonyssus Ewing
b2. One chela of chelicera lost, the remaining one provided with several
recurved hooks; hypostome with a pair of recurved hooks.
Subfamily Ixodorynchinae
Containing but one genus. .......... 0.00 0... Ixodorhynchus Ewing
a2. Chelicerae provided only for piercing, hence without hooks or barbs.
b'. Chelicerae shear-like in both sexes, never needlelike.
Subfamily Liponyssinae
ct. Body of both sexes entirely covered above by dorsal shield, sternal
plate of female large and reaching to the third coxae.
Tetragonyssus Ewing
c%. Body not entirely covered above by dorsal shield in either sex.
d!. Female with a divided dorsal shield.

* The Dermanyssid Mites of North America by H. E. Ewing. No. 2459 Proceed-
ings of the U. S. National Museum, Vol. 62, Art. 13, 1922. ;
204 INSECTS AND DISEASE OF MAN

el. Posterior dorsal shield large, covering much of the abdomen above;
first segment of palpus of female with a horn-like process.
Ceratonyssus Ewing
e?. Posterior shield minute; sternal plate with only four setae; first
segment of palpus of female without any horn-like process.
Serpenticola Ewing
d2. Dorsal shield of female entire.
el. Legs stout; tibia 1 and 11 less than one and one half times as long
as broad; femora 1 and 11 spined above. .Ichoronyssus Kolenati
e% Legs not so stout, especially the first and second pairs, tibia T more
than one and one half times as long as broad; femora 1 and 11 not
spined above.
fl. Body of female with a constriction and incomplete transverse
groove behind the insertion of the last pair of legs.
Leiognathus Canestrini
f2. Body of female without constriction and incomplete transverse
GROOVE. =. ios viiv vimana he ia a Be Liponyssus Kolenati
b2. In the female, chelicerae needle-like; in the male; variously modified but
always with both arms present.......... Subfamily Dermanyssinae
cl. Dorsal shield of female entire; anus situated in posterior part of anal
late... a CY eae sy ie Dermanyssus Dugés
c%. Dorsal shield of female divided; anus situated centrally in anal plate.
: Allodermanyssus Ewing

Of the above genera, Liponyssus and Dermanyssus are perhaps
of the most interest to the medical entomologist as they contain a
common rat mite, Liponyssus bacoti Hirst, and a common chicken
mite, Dermanyssus gallinae Redi, both of which have been known
to bite man and may be of great annoyance. The peritreme of D.
gallinae is long and sinuous and extends beyond the second coxae.

The subfamily Parasitinae contains many genera, some of which
are parasitic on insects and some on mammals. Many of them
although predacious, feeding on other mites or small insects, do not
attach themselves to the host but live in moist soil, fallen leaves,
refuse, etc.

The genus Laelaps is important because it occurs on small mam-
mals and in their nests. In this genus there is a stout bristle at the
apex of the anal plate and one on each of the coxae. Laelaps echid-
ninus Berlese. (Fig. 88) is the common mite of rats in all parts of
the world. Three other species have been taken from rats, Laelaps
agilis, L. stabularius, and L. hawatiensis. They are not known to
bite man. The latter is a small species. L. stabularius may cause
a puritus without skin lesions.

Raillietia auris Leidy lives in the ears of cattle.
SUPERFAMILY EUPODOIDEA 205

The genus Parasitus (formerly and better known as Gamasus)
includes numerous species which are not parasitic on vertebrates
and not often on insects. They are found among fallen leaves or in
refuse or debris and a few inhabit sea beaches.

 

Fi1G. 88.—Laelaps echidninus, dorsal and ventral view.

Superfamily Oribatoidea

These mites can be distinguished by the presence of a hair arising
from a pore near the corner of the cephalothorax on each side. They
are not parasitic on animal or vegetable life and are therefore of
little economic importance. They feed on vegetable matter but do
no harm.

Superfamily Sarcoptoidea

FAMILY TARSONOMIDAE

These mites are of great economic importance as many of them
are destructive to vegetable life, tea, rice, grasses, pineapple, fruit
trees, green house plants, etc. One, Pediculoides ventricosus,
(Fig. 89) infests grain for the purpose of attacking insects which may
be upon it. When feeding on injurious insects its presence is bene-
ficial. On the skin of man it produces a dermatitis, ‘‘straw itch” or
“grain itch” which may be extremely annoying to those working in
the fields or sleeping on fresh straw mattresses and may occur in
epidemic form. Pediculoides brings forth adult offspring.
200 INSECTS AND DISEASE OF MAN

The Tarsonomid mites usually can be distinguished by the
presence of a small organ bulbous at the end, arising between legs
I and II. (Fig. 89 A.) A capitulum is present; the chelicerae are
slender and needle-like; the palpi are minute; the posterior legs
are remote from the anterior.

Ewing gives them rank of a superfamily and proposes the follow-
ing key to the families and genera.

 

Fi1G. 89.—Pediculoides ventricosis, female, dorsal view.

The Classification of the Families and Genera of the Tarsonemoidea (Ewing,
1922) *

A. Both sexes provided with four pairs of functional legs.
B. Females with elongate bodies; capitulum and first two pairs of legs
not covered by any projecting cephalothoracic shield.
C. Posterior legs of female each ending in a pair of claws and caruncle.
Species usually ovoviviparous..................... Pediculoididae
D. Female with a large capitulum, showing a rostrum and rudimentary
palpi; segments of abdomen distinct.
E. Larval stage represented by octopod deutovum stage; gravid
female with only the tip of abdominal wall swollen.
Pediculoides Tar-tpz.
EE. Larval stage normal; most of the dorsal wall of abdomen distended

ingravidfemale... ......0...... 00 000 Pediculopsis Reuter
DD. Female with capitulum reduced to a cephalic papilla, and abdomen
indistinctly segmented.................. Pigmeophorus Kram.

* Canadian Entomologist, May, 1922.
SUPERFAMILY EUPODOIDEA 207

CC. Posterior legs of female devoid of claws and caruncle. Species ovi-
Porous. salt ne nt aL SE Tarsonemidae
D. Female with pseudostigmatic organs and very slender posterior
pair of legs, which in the male are somewhat enlarged.
Tarsonemus C. &F.
DD. Female without pseudostigmatic organs and with short, stumpy
fourth pair of legs, which in the male are reduced.
Acarapis Hirst
BB. Females with subdiscoidal bodies; capitulum and first two pairs of legs
covered by the projecting cephalothoracic shield. . Disparipedidae
C. Females with posterior legs each composed of five segments and
provided with a pair of claws and caruncle.
D. Anterior legs of female each provided with a claw.
E. Segments IV and V of leg IV of female exceedingly slender,

cylindrical “and subcapillary. i... navn Imparipes Berl.

EE. Segments IV and V of leg IV of female short, stout, and V never
cylindrical. i... A EC Se Pygmodispus Paoli

DD. Anterior legs of female clawless.................. Diversipes Berl.

CC. Females with leg IV composed of four segments and without claws
and caruncles.
D. Anterior legs of female each provided with a claw.
Disparipes Mich.

DD. Anterior legs of female clawless.............. Variatipes Paoli
AA. Males hexapod; females in their final stage legless. ......... Podapolipidae
Contains the singular, degenerate genus. ....... Podapolipus Rov. & Gr.

FAMILY TYROGLYPHIDAE

These mites are injurious to food stuffs, roots and bulbs. In the
hypopial stage they may attach themselves to insects, or even small
mammals, in order to be transported from one place to another more
suitable locality. A species which was described by Banks as
Histiotoma tarsalis lives in the nests of rats and is carried around as
a hypopus by the rat flea.

Glyciphagus domesticus (Fig. go) infests sugar and is a cause of
grocer’s itch. In this genus the anal and genital openings are
large and some of the hairs of the body are feathered. T'yroglyphus
farinae is also a wide spread species most commonly found in flour
and grain. Carpoglyphus passularum infests dried fruits. A num-
ber of species are injurious to roots and bulbs.

The family Canestriniidae includes a few very small mites
parasitic on insects especially beetles.

The family Analgesidae are the bird mites occurring exclusively
on birds and feeding on the epidermal scales and feathers. Their
presence is apparently not harmful.
208 INSECTS AND DISEASE OF MAN

The family Listrophoridae are the ‘hair clasping” mites, living
upon small mammals. They are adapted to clasping a hair either
by the last tarsal joint or the under lip. They cling to and feed on
the hairs.

 

Fi16. 90.—Glyciphagus domesticus.

FAMILY SARCOPTIDAE

These are the “itch mites.” They are permanent parasites in
or on the skin of man, animals and birds, producing a condition
known as acariasis.

They are very small in size, with the surface of the body striated
transversely and provided with a few bristles some of them short and
strong; the palpi are small and three-jointed; the mandibles are
chelate; the beak is prominent; the male may have a pair of suckers
near the tip of the abdomen; the legs are short and stout and termi-
nate in a claw and a long pulvillus, or there may be only along bristle.

Key to the Sarcoptidae (After Banks)

1. Anal opening on the dorsum................ ni ao rN 2
Anabiopening below... i a aaa, 3,

2. On small mammals, not bats; third pair of legs in male without apical suckers.

Notoedres

On bats; third legs in male with suckers..................... Prosopodectes
SUPERFAMILY EUPODOIDEA . 200

3. Pedicle of suckers jointed; mandibles styliform and serrate near tip.

Psoroptes
Pedicle'not jointed; mandibles chelate... .. iv Ld eae La 4
4. No suckers to legs of females; parasitic on birds............. Cnemidocoptes
Suckers at least on legs 1 and 11; parasitic on mammals................. 5

5. Legs very short; in male the hind pair equal in size; body usually short.
Sarcoples
Legs more slender; in the male the third pair is much larger than the fourth;
body more elongate............... er SL En dA 6
6. Female with suckers to fourth pair of legs...................... Chorioptes
Pemale:without suckers to fourthlegs......, 0... 000 Lu nna ie 7
7. Hind part of male abdomen with two lobes..................... Caparinia
Hind part of male abdomen without lobes....................... Otodectes

 

  

 

 

«“L.AVERY=-

 

 

F16. g1.—Arachnoidea exclusive of ticks. (1a) Sarcoptes scabiei, female; (1b) S.
scabiei. male; (2) Demodex folliculorum; (3) Trombicula akamushi, hexapod larva
(Kedani mite); (4) Trombidium holosericeum larva (Leptus); (5) Dermanyssus gallinae;
(6) Tyreglyphus langior; (7a) Pediculoides ventricosus, male; (7b) P. ventricosus, young
female; (7c) P. wentricosus, impregnated female; (8) Porocephalus armillatus; (9a)
Linguatula serrata, female; (g9b)L. serrata, larva. Note: Figure not drawn to scale.
(From Stitt’s “Practical Bacteriology, Blood Work and Animal Parasitology,’ 7th.
Edition.)

Sarcoptes scabiei De Geer is the itch mite of man. The female
burrows under the skin, usually in the regions about and between
the fingers, hands, wrists, axillary folds, lower abdomen, genital and
anal regions. She lays her eggs in the burrow as she progresses,
until finally she has deposited from 10 to 40 eggs extending along the
burrow and interspersed with fecal matter and debris. The young

mite like other acarines is three-legged. About four moultings
14
210 : INSECTS AND DISEASE OF MAN

occur before the adult stage is reached. After mating the adult
female undergoes a final moulting and then starts a burrow of her
own but before doing so may migrate to another host. The females
die at the end of the burrow when oviposition has terminated. The
condition is attended by great itching and if not arrested is followed
by inflammation and pustule formation. The following is said to
be a good remedy:

Alcohol and water equal parts. To each fluidounce add one
dram of precipitated sulphur. Shake well before using. Apply
freely to affected area three or four times a day. Sulphur ointment
is a good remedy. Clothes and bedding should be sterilized.

Species of the genus Sarcoptes may also be found on domestic
animals.

* The genus Notoedres is the itch mite of cats, rabbits and rats.
It is found usually about the ears, eyes, nose and lips. It differs
from Sarcoples in having the anal opening situated dorsally.

The “scab mite’ of sheep is an itch mite which does not burrow.
It is known as Psoroptes communis var. ovis. It causes the formation
of papules which become vesicles and finally pustules. These coalesce
and in drying produce a yellowish, greasy, scaly layer under and
around the edges of which the mites may be found. As the disease
progresses this layer becomes thicker and more widespread gradually
healing in the middle. The wool has a characteristic rough look and
in places is stuck together in masses. Regions where the wool is
thickest and longest, especially along the back, neck, flanks and rump
are favorite sites for the mite to attack. Dipping is the proper
treatment. Tobacco dip, sulphur and lime, arsenical dips, 8 per
cent kerosene emulsion, are good. All should be applied thoroughly.
Trees, fence posts, stable walls, etc. against which infested sheep
have brushed, should be thoroughly white-washed.

The genus Chorioptes is another non-burrowing itch mite causing
the so called “foot scab’ of sheep. It may also attack the ears and
neck. Horses, cattle and goats may be attacked by their own partic-
ular species of Chorioptes. The condition is not so serious as that
produced by Psoroptes and is more easily cured.

The itch mites of poultry and other birds belong to the genus
Cnemidocoptes. C. mutans is the itch mite of fowls producing what is
known as “scaly leg.” C. gallinae is found at the base of the feath-
ers where it burrows.
SUPERFAMILY EUPODOIDEA 211

FAMILY CYTOLEICHIDAE

These are also mites of fowls. Laminosioptes occurs on or in the
skin where it produces a calcareous cyst. Cytoleichus is found most
commonly in theair passages. Species have been taken from turkeys.

Superfamily Demodicoidea

The family Eriophydae are plant feeders, many of them producing
galls or other deformations on the leaves and twigs of plants.

The family Demodicidae has but one genus, Demodex, which
lives in the sebaceous glands and hair follicles of man and other
animals.
cle

The following rodents have been found naturally plague infected:

CHAPTER XXII

RODENTS OR GNAWERS
VERTEBRATA. CLASS MAMMALIA. ORDER GLIRES

 

Sub-family Murinae
(old world and
domestic rats and
mice)

Genus Rattus

Rattus norvegicus (gray
or brown rat)

Rattus rattus (black

rat)
Rattus ~~ alexandrinus
(palm rat)

Rattus coucha (multi-

mammate rat)

G en us Arvicanthis
Arvicanthis  pumilio
(striped mouse)

Genus Gerbillus

Gerbillus teterona (ger-
bille)

Genus Mus

Mus musculus (house
mouse)

 

Sub-family Cri-
cetinae (Ameri-
can rats and
mice)

Genus Oryzomys
Oryzomys pulus-
tris (rice rat)

 

Family Muridae (rats and mice)

Sub-family Neo-
tominae (wood
rats)

Genus Neotoma
Neotoma fuscipes
(brush rat)

 

Sub-family
Microtinae
(field rats and
mice)

 

Family Sciuridae (squirrels and

marmots

Sub-family Sci-

urinae (true
squirrels and
marmots)

Genus Citellus

Citellus beecheyi
(California
ground squirrel)

Genus Marmota

Marmota  bobac
(Tarbagan or
Siberian  mar-
mot)

 

Sub-family Pter-
omyinea (flying
squirrels) -

Family Leporidae
(hares and
rabbits)

Genus Lepus
Le pus europaeus
(English hare)

Genus Pryctola-
gus

Pryctolagus cuwi-
culus (English)
wild rabbit)

 

 

Family Caviidae

Genus Cavia
Cavia cobaya
(guinea pig)

 
RODENTS OR GNAWERS 213

The scheme on preceding page indicates the position in zoological
classification of the various rodents which have been found naturally
infected with plague. Of these the domestic rats and mice and the
California ground squirrel are of the greatest importance in the United
States as harborers of plague bacilli.

Rodents have certain general characteristics which distinguish
them from other orders in the class of mammals. They are usually
small, furry, herbivorous animals with clawed digits and plantigrade
feet. The most characteristic feature of the rodentia is their den-
tition. The canine teeth are absent and the incisors are elongated,
curved and grown from permanent pulps. There are never more
than two incisors in the lower jaw and there are usually two in the
upper jaw. The fronts only are covered with enamel so that when
in use these teeth wear away on the inner surface and are thus
sharpened.

The members of the family Muridae, to which belong the rats and
mice, using these terms in their broadest sense, have no premolars
and the number of molars on each side of both jaws is three with
the exception of one genus, Hydromys, in which the 3rd. molars are
vestigial.

The Old world, true or domestic rats and mice (Murinae), may be
distinguished from the American forms (Cricetinae) by the arrange-
ment of the cusps on the unworn upper molars. In the Murinae
they are arranged triserially, i.e., in three longitudinal rows while in
the Cricetinae they are arranged biserially, i.e., in two longitudinal
rows, one on the outer and one on the inner margin.

- The common rats are characterized by narrow ungrooved incisors;
three small, rooted molars; soft fur mixed with hairs, occasionally
with spines; and a thumb provided with a short nail instead of a claw.
The tail is ringed with overlapping scales and is naked or nearly so;
the ears are large, the eyes are bright and prominent and the muzzle
pointed. The difference between rats and mice is mainly one of
size. Both have six foot pads. The last on the hind foot of rats
being elongated while in the mice it is usually circular. Contrary to
the belief held by some people mice are not young rats.

FAMILY MURIDAE
Sub-family Murinae

. Rattus norvegicus (Gray, Sewer, Brown, Wharf or Norway Rat).
This species probably came from Northern Asia, migrating into
214 INSECTS AND DISEASE OF MAN

Europe some time during the early part of the 18th Century. It has
since spread to all parts of the world. It is larger and heavier than
the following species, its muzzle is less pointed, its head is larger
and thicker, its ears smaller and its tail is shorter than the head
and body combined. In color it is grayish brown above with over
hairs tipped in black, it is whitish below. Its average length includ-
ing the tail is about 16.3 inches. The length of the hind foot
is 1.5 to 1.8 inches (38-46 mm.). The female usually has twelve
mammae, three pairs of pectoral and three pairs of inguinal.

The Norway rat is a powerful fighter and is ferocious among
mammals of its own size and kind. It can burrow readily and
lives within or near the ground, in burrows, sewers, basements,
between cellar or basement walls, in or under lumber piles or wooden
and concrete pavements and similar places favorable to hiding and
breeding. Itis especially attracted to places where food is abundant.
It can gnaw its way through wood and plaster and is a good swimmer,
but a poor climber. It is omnivorous. It can adapt itself to all
sorts of climates but is more abundant in temperate regions. Rats
breed the year round. The ratio of females to males is about 1.8
to 1. The period of gestation is three weeks. The average number
to a litter is eight. Rats produce from three to five litters a year.
The young females are capable of breeding when less than three
months old. Rats are great travelers, migrating from place to
place on foot as well as by ships and trains. The rat population, in a
given community, is hard to estimate but it is not unlikely that
usually there are at least as many as one rat to every person. Migra-
tion is prompted by varying conditions in the food supply and other
conditions in the environment inimical to the propagation of the
species.

Rattus rattus (Black, Ship, or Indian Rat).—The black rat is more
slender in build than the gray rat. Its head is longer) its muzzle is
more pointed, its ears are larger and wider and when laid forward
reach to the middle of the eye or beyond. The tail is longer than
the head and body combined. The fur is soft and thicker than that
of the brown rat and the color is blue black above and black or
slaty gray below (on the belly). Its average length is 14.9 inches.
The length of the hind foot is from 1.3 inches to 1.5 inches, (33-37
mm.). The females of both the black rat and the roof rat (alexan-
drinus) have ten mammae, two pairs of pectoral and 3 pairs of
inguinal. The black rat probably originated in Southern Asia,
RODENTS OR GNAWERS 4 215

migrating to Europe much earlier than the gray rat. It is the com-
mon rat in India, and is also found in many parts of the world
including the United States, more especially in seaport towns to
which it has been carried by ships. It is the rat common to ships.
Like the palm rat it is a good climber and is usually trapped in the
upper portions of the house. In fact it is rather distinctly urban
in its habits and its residence in houses brings it in rather intimate
‘contact with man. When introduced these rats are frequently
killed off by the more ferocious gray rat before they have oppor-
tunity to multiply. It has been noticed that there is both a relative
and absolute increase in the numbers of the black rat and the house
mouse following a decrease in the number of gray rats.

Although the black rat is the common rat of India, the gray
rat is more or less numerous in the seaport towns of that country
especially at and near the waterfront, having been introduced by
ships.

Rattus alexandrinus (Alexandrian, Palm or Roof Rat).—This
species is very similar in size and characteristics to the black rat
but its color is grayish brown above and white or yellowish white
below. The Alexandrian rat may have been a native of Egypt but
it is now found in many parts of the world, more especially in warmer
countries. It is a good climber, and in tropical or semitropical
countries lives in the Palm trees and is thus known as the palm
rat. It is more rural in its habits than the black rat but also takes
up its residence in houses. It is found in the United States, more
especially in southern seaports.

In general, the breeding and feeding habits of the last two
species are similar to those of the gray rat, but the number of young
to a litter is smaller. :

Albinos and spotted specimens of both the brown and black rat
are not infrequently observed. The white rat of the bird storeis an
albino of Rattus norvegicus.

Mus musculus (The House Mouse).—The house mouse is cosmo-
politan in its distribution. It resists extermination by the brown
rat and other enemies because of its diminutive size which enables
it to escape into places too small for its enemies to follow.

Diseases Other than Plague, Affecting Domestic Rats.—The
following are some of the pathological conditions which have been
reported as having been found in common domestic rats:
216 ; INSECTS AND DISEASE OF MAN

Rat leprosy Rat scabies (Notoedres alepis)
Leptospira icterohaemorrhagiae (cause of Tularaemia
Weil’s disease)
Trypanosomiasis (Trypanosoma lewisi) Trichinosis (Trickinella spiralis)
Spiroschaudinnia morsusmuris (cause of Spiroptera obtusa (Found in stomach)
rat bite fever)

Hymenolepis diminuta Hymenolepis nana
Hepaticola hepaticum (eggs and adults Gigantorhynchus moniliformis (In
in liver) small intestine. Intérmediate host

a beetle, Blaps mucronata)
Cysticercus fasciolaris (cat tapeworm, Pericardial effusion
Taenia crassicollis) seen as cysts in

the liver)
Multiple abscess of the lung Consolidation of the lung
Cirrhosis of the liver Fatty degeneration of the liver
Hernia Nephritis
Abscess of the kidney Atrophy of the kidney
Vesicle calculi Lipomas
Fibromas Sarcomas
Adenomas "Carcinomas
Cystic adenomas Fibro adenomas
Adeno-carcinomas Epitheliomas

Cancer of stomach due to Gongy-
lonema neoplasticum

Natural Enemies of Rats.—Important natural enemies of the
rat are larger hawks, owls, skunks, foxes, coyotes, weasles, minks,
ferrets, certain breeds of cats and dogs, especially small, well trained
Irish, Scotch and fox terriers, mongoose, alligators, and snakes.

Economic Considerations.—Aside from diseases such as bubonic
plague and trichinosis which may be spread by rats, these vermin
cause great damage to food stuffs of many kinds including grains,
growing and stored, poultry, eggs, fruits, vegetables, etc. It has
been estimated that the yearly losses from rats in Great Britian and
Ireland are $73,000,000. It would probably not be far wrong to
estimate the losses in the United States during a year at not less
than $2.00 per capita, if one takes into consideration the amount of
marketable food which they have either eaten or spoiled or which is
otherwise lost through their depredations, as well as the destruction
to property and the expense to which many persons are put to eradi-
cate them. The great economic loss which rats cause to a community
alone furnishes an excellent reason for their extermination.

Ectoparasites Which Have Been Found on the Genus Rattus
and Mus in the Western Hemisphere.—The following ecto-parasites
RODENTS OR GNAWERS 217

have been reported from rats in the Western Hemisphere by various
observers: many of these parasites have for their normal hosts ani-
mals other than rats, and sojourn on the rat is therefore purely
accidental:

Order Siphonaptera

Tunga caecata Enderlein 1901 (Brazil, accidentally on Rattus rattus).

Echidnophaga gallinacea Westwood 1875 (California, New Orleans and New
York City, a flea of fowls, accidentally on rats).

Pulex irritans Linn. 1758 (San Francisco, the human flea, cosmopolitan,
accidentally on rats).

Xenopsylla cheopis Rothsch. 1903 (California, Galveston, New Orleans,
New York, Boston, the common rat flea of tropical and subtropical
countries).

Xenopsylla brasiliensis Baker 1904 (Brazil, a rat flea of Africa and India).

Ctenocephalus canis Curtis 1826 (Nearly cosmopolitan, the dog flea, acci-
dentally on other hosts including rats).

Ctenocephalus felis Bouche 1855 (Cosmopolitan, the cat flea, accidentally
on other hosts including rats).

Hoplopsyllus anomalus Baker 1904 (California, a squirrel flea, accidentally
on rats).

Rhopalopsyllus gwyni Fox 1914 (From rats at a quarantine station, Georgia,
a South American flea).

Rhoplopsyllus adelus J. & R. 1923 (Brazil, on Rattus).

Ceratophyllus fasciatus Bosc. 1801 (Commonly found on rats in San Fran-
cisco, New York City and Boston, a European rat flea).

Ceratophyllus niger Fox 1908 (San Francisco, a flea of fowls, accidentally
on rats).

Ceratophyllus acutus Baker 1904 (San Francisco, a squirrel flea, accidentally
on rats).

Ceratophyllus londiniensis Rothsch. 1903 (San Francisco, a Mediterranean
species).

Ceratophyllus anisus Rothsch. (San Francisco, accidentally on rats).

Ceratophyllus wagneri Baker 1904 (Idaho, on a house mouse, a flea of the
white footed mouse).

Anomiopsylla nudatus Baker 1898 (Arizona, accidentally on Rattus).

Phalacropsylla paradisea J. & R. 1915 (Arizona, on Rattus, Mus and Mephi-
ts).

Ctenophthalmus pseudagyrtes Baker (Boston, accidentally on rats).

Leptopsylla musculi Duges 1832 (Cosmopolitan, a flea of Mus musculus and

Rats).
Order Anoplura
Polyplax spinulosa Burmeister (Cosmopolitan, the common rat louse).
Order Mallophaga

Philandesia foxi Ewing (New York City, accidentally on Rattus norvegicus)
218 INSECTS AND DISEASE OF MAN

Order Acarina

Boophilus annulatus Say (Dallas, Texas, on rat).

Laelaps echidninus Berlese (Widely distributed, a common rat mite).
Laelaps hawaiiensis Ewing (New York City, New Orleans).
Liponyssus bacoti Hirst (Widely distributed, on mice and rats).
Myobia musculi Schrank (On mice).

Notoedres alepis Railliet & Lucet (San Francisco, on Rattus).

Bdella cardinalis Banks (New York City, accidentally on rats).

FAMILY SCIURIDAE

(Squirrels and Marmots)

Plague is endemic among the ground squirrels of California,
Citellus beecheyi. The characteristics of this squirrel are as follows:
its upper front teeth are large and two in number, chisel shaped and
separated from the grinding teeth by a wide space, grinding teeth at
least 4 in each jaw; the fore feet are not modified for digging; their
claws are normal; eyes are prominent; ears large and prominent;
cheek pouches are present; the tail is well haired but not bushy and
is more than two thirds the length of the body; the nail of the thumb
is rudimentary; above, the color is mixed black and pale yellowish
brown. It is terrestial in its habits, living in burrows in the ground.
It breeds in February, March and April. The number of young to
a litter averages 8; the number of males to females is 1 to 1.4. Its
fleas are Ceratophylius acutus Baker and Hoplopsyllus anomalis
Baker, both of which feed readily on man’s blood. The louse of this
ground squirrel is Linognathoides montanus Osborne.

The Siberian marmot, Marmota bobac is related to the ground-hog
or wood-chuck and also has some other relatives in the United
States such as the ground squirrel. It is characterized as follows:
its upper front teeth are two in number, chisel shaped, both large,
and separated from the griding teeth by a wide space, grinding teeth at
least 4 in each jaw; ears large; forefeet not modified for digging, their
claws normal; the tail is short and less than one-half the length of
the body, bushy and not flattened; the thumb nail is broad and flat;
the fur is long, coarse and heavy; the skull is nearly straight causing
the head to appear flat above; the color is uniform being yellowish
brown above overlaid with black. It is terrestrial, living in burrows.
The flea of this rodent is Ceratophyllus silvantieri (Wagner) which has
been shown to bite man.
CHAPTER XXIII
A FEW NOTES ON TECHNIQUE

Collecting.—In collecting insects the medical entomolgist will be
most interested in those found in, on or around animals or those which
are found breeding in animal excrement; in those which bite or
otherwise annoy man or are found in his habitation or which breed
in human excrement, in carrion or other refuse, in food stuffs or in
water or damp places.

In collecting diptera a net made of bobbinette of still mesh, with
a handle, is necessary. It is well to rear the carrion breeders by tak-
ing some of the material on which the eggs or larvae are found and
some of the earth beneath (or some sand or loose soil), place it in a
shallow box covered by a frame to which is tacked mosquito wire
screening and thus permit the process of development to proceed to
the adult stage. For mosquitoes see page 247.

Lice and ticks should be collected directly from the animal or
bird, mites from the animal or bird or their nests. }

Fleas soon leave the host after it is dead. Therefore they should
be collected from live animals or perhaps better still from the nests
of animals or birds. The nest may be placed in a box with a piece of
moist blotting paper in the top to prevent drying. The larvae will
go on to development. Fleas may be obtained from the host by
searching through the hairs and picking off with forceps or they may
be stupefied with a tiny pledget of cotton on the end of a match
stick moistened with chloroform. The animal itself may be placed
in a jar and anesthetized. The fleas will then jump off and feeling
the effects of the anesthetic may be readily picked up with a pair
of small forceps. Combing with a fine-toothed comb is an excellent
means of dislodging fleas.

In collecting parasitic insects the host should be accurately
identified and noted on the label.

Killing.—For killing insects after capture, chloroform may be
used, or potassium cyanide (a deadly poison). Some small lumps
of the latter are placed in the bottom of a wide-mouth bottle, and
dusted with dry plaster of Paris. A soft paste of plaster of Paris

219
220 INSECTS AND DISEASE OF MAN

is then added so as to cover the cyanide for a depth of about 5 mm.
and allowed to dry. After drying the bottle should be tightly corked.
When ready for use a few strips of blotting paper placed in the bottle
will absorb moisture and prevent insects placed therein from being
shaken around and becoming mutilated. All cyanide not used
should be adequately disposed of by burying it deeply in the ground,
away from all possible contact with children or domestic animals,
as it is a deadly poison.

Chloroform is a useful killing agent but stiffens the muscles of the
insect. Itis quite volatile, but will last longer if prepared as follows:
some elastic (rubber) bands should be soaked in the chloroform and
then dropped into a wide-mouth bottle, and a piece of blotting paper
pushed down over the rubber bands to hold them in place.

The chloroform may be used on a pledget of cotton held in place
at the bottom of the bottle by a piece of blotting paper.

In the field, for small diptera, tobacco smoke may be used in the
absence of a better killing agent.

If caught alive insects like lice and mites may be killed by immer-
sion in water brought almost to the boiling point. This method
tends to keep the legs spread apart. Larva may bekilled inhot water
before placing in the preservative.

Mounting.—Small diptera may be preserved in alcohol, or
mounted on a slide in Canada balsam. As a general rule it is better
to mount diptera on entomological pins thrust through the thorax
dorso-ventrally a little to the right of the median line. Thirty-four
mm. black insect pins Numbers 1 and 2 are handy sizes. Some
prefer to mount insects on small triangular pieces of thin white
cardboard or heavy white paper, about 8 mm. long. The entomo-
logical pin is thrust through the base of the triangle and the point
of the triangle is fastened to the ventral surface of the insect by
some adhesive, a good one being white shellac dissolved in 95%
alcohol. This is a good method for small diptera; another is to
use very small entomological pins (micro-pins). These are useful in
mounting mosquitoes. The micro-pin is thrust through the thorax
of the insect and its point is then inserted into a small piece of cork
which in turn is pierced by the larger pin. :

After the insect is mounted, the label, or labels, should be pushed
up on the pin below the insect. The insect should never be pushed to
the top of the pin and it and the labels should be evenly spaced. For
this purpose a pinning block is useful.
A FEW NOTES ON TECHNIQUE 221

Diptera should be pinned while fresh. They are easily broken
when dry. If they have dried, they should be relaxed before han-
dling. A relaxing chamber (moist chamber) may be improvised by
placing moist blotting paper in a saucer which is then covered by
another saucer. Or, a jar containing a layer of moist sand can be
used. A piece of blotting paper under the cover will prevent con-
densed moisture from dripping on the specimens.

Fleas should be cleared and mounted on slides. The following
technique may be used:

1. KOH 109%, in water to dissolve the soft parts and to
decolorize the chitin. The solution may be used cold or warmed over
a water bath. Never use very hot or boiling KOH as it will distort
the parts. In fact some authorities dispense with it altogether. If
used it must not be allowed to act too long. The process must be
watched. A flea can be completely decolorized by the caustic and
this is highly undesirable.

2. Wash thoroughly in water to remove all of the caustic.

3. Dehydrate by running through the alcohols, 809% and 95%
each about 15 minutes, and then in two changes of absolute alcohol.

4. Clear in Xylol or Oil of Cloves.

- 5. Mount in Canada balsam.
An excellent dehydrating and clearing agent is carbolic acid crys-
tals dissolved in xylol to saturation. When this is used no absolute
alcohol is necessary.

In dried specimens the soft parts have practically disappeared
through dessication. If not mutilated such specimens make good
mounts and the caustic need not be used. If a specimen is con-
tracted it will expend if treated with H,O, before preparing to mount.

With lice, best results are obtained if they are stained before
mounting, as follows:

1. Treat until transparent with warm KOH (109%).

2. Wash thoroughly in water.

3. Stain with Acid fuchsin in water to which .0o8 HCI has been
added. The specimen should be over stained.

4. Run through the alcohols rapidly. The alcohol decolorizes
and therefore the process should be watched.

5. Clear in Xylol or one of the other clearing agents.

6. Mount in Canada balsam. Professor Herms uses weak
Magenta red for staining lice. For removing small insects from
222 INSECTS: AND DISEASE OF MAN

solutions or for pipetting off a solution to be replaced by another,
a medicine dropper is useful.

Preservation.—For preserving the pinned specimens a special
entomological box (Schmitt box) should be obtained. It should be
air-tight and light-tight, therefore it should have a well fitting cover.
It should have a soft inner bottom made of cork or pith so that the
pin carrying the insect can be easily pushed into it. Special pinning
forceps may be obtained.

Certain beetles and mites are pests to a collection and completely
destroy the specimens through their depredations. Therefore it is
well to fumigate occasionally, placing the specimen box in a larger
box and using carbon bisulphide. A repellant should also be kept
in the specimen box. Naphthelene is a good one. The flakes may
be tied in a small bag fastened to an inside corner of the box, or, a
pin may be heated and thrust head-first into a naphthelene ball
(moth ball). When cool the pin will be securely fixed in the naph-
thelene and can be pushed into the bottom of the box. Another
method is to melt the naphthelene, then tilt the box slightly and
pour the naphthelene into a corner or between the corners where the
bottom joins the sides.

Shell vials may be used for storing specimens. The pin bearing
the insect is thrust into the cork. The specimen should be allowed
to dry before the cork is put in place as moisture condensing inside
of the vial will favor the growth of moulds. The tip of the cork
may be dipped in melted naphthelene.

Formaldehyde in a 49, solution (x part of commercial
formalin to 10 parts of water), is a good preservative for fly and
mosquito larvae. Itis also a good fixing agent for tissues.

To preserve such arthropods as fleas, lice, ticks) bed bugs etc.,
709% alcohol is satisfactory. In this they may be kept indefi-
nitely. A very small amount of glycerine added to each vial will
prevent the too rapid evaporation of the alcohol: It will also
prevent drying even after the alcohol has evaporated. Homoe-
pathic vials make good containers.

All containers should be properly labeled with the name of the
specimen, host, date of collection, locality, name or initials of col-
lector and also the initials of the one who made the identification.

It is better to put the label inside of the vial with the specimen
rather than to paste it on the outside. It should be written in
A FEW NOTES ON TECHNIQUE 223

waterproof ink and immersed in alcohol before putting it in with
the specimen. Ordinary lead pencil may be used but will fade.

Examination.—A binocular microscope for entomological work
is almost indispensable for the examination of flies, mosquitoes,
ticks, etc., i.e., all insects that are not adapted to clearing and
mounting on a slide. Even with insects like fleas much can be
learned from the unmounted specimen by the use of a binocular
microscope. A good light from above is essential. Artificial
illumination and a good reflector or a focusing glass to direct light
on the field to be examined should be available. In lieu of a binocu-
lar microscope, a dissecting microscope can be used. For field work
a pocket magnifying glass should be carried. A half-inch lens is a
useful size.

For holding ticks, fly larvae, etc., or insects mounted on pins,
in any position desired for study under the microscope, plasticine or
modeling clay are useful. Or, a cork stopper may be used where
insects are mounted on pins.

Cleared specimens should be examined with the low power of a
compound microscope, and with the light coming from below. A
very bright light is not always desirable for this purpose. It should
be regulated to suit conditions. For details a higher powered lens
should be used.

When one has a long series of insects like fleas to examine it is
not necessary to mount all of the specimens. Take them from the
alcohol in which they are preserved, and, either cleared or uncleared
arrange them on a slide and examine with the compound scope.
Mount only those in which there is any doubt as to their identity.

Forwarding.—Diptera may be shipped in pill boxes. To prevent
them from being shaken around in the box, small pieces of loosely
crumpled tissue paper may be used. Never permit cotton to come
in contact with an insect as the setae will become entangled in the
fibres of the cotton, making it hard to separate them without
mutilation.

Insects that can be preserved in alcohol should be shipped in
Homeopathic vials well stoppered and surrounded by cotton.

In all cases a strong outside container should be used and if
sent by mail the regulations of the Post Office Department should
be followed.

Dissection and Staining. Mosquitoes.—For the internal organs,
fresh specimens should be used. First take off the legs and wings,

 
224 INSECTS AND DISEASE OF MAN

place the mosquito on a glass slide and remove all debris. If the
salivary glands and the alimentary tract of the same mosquito
are required the former should be dissected out first.

The thorax should be steadied by a needle held in the left hand,
then with another needle in the right hand, draw the head away
from the thorax and into a drop of saline solution by a series of gentle
pulls. The oesophagus and muscles will rupture and the glands with
their ducts will be drawn out of the thorax together with some
muscle fibres, fat body, nerve trunk and cervical tracheae. Cut the
mass loose from the head. The glands may be identified by their
highly refractile appearance and may then be separated from the
other tissues.

To remove the alimentary canal, steady the thorax as above and
then with a second needle gently crush between the last and next to
last segments of the abdomen dorsally and ventrally. Draw the
last segment away from the abdomen into a drop of salt solution by a
series of slow steady pulls as before. The alimentary canal up to
the oesophagus, and the reproductive system will be drawn out
of the abdomen and can be dissected away from each other and from
the tracheae which hold them in position. It may be necessary to
cut the main tracheae before the organs are entirely free from the
abdomen. The tracheae can be identified by their silvery
appearance. :

When the salivary glands of the same mosquito are not required,
it is better to decapitate by cutting, not pulling, before attempting to
take out the mid- and hind-gut. It is also better to wait until the
stomach is partially empty, before killing.

Ticks.—To dissect a tick one should slit around the edge or cut
away a thin slice of the integument from the edge, extending from
the level of one coxa to the coxa on the opposite side. The tick
should then be placed ventral side down and held by an entomolog-
ical pin thrust through the side of the basis capituli. The paraffine
trough devised by Christophers may be used. The tick being
fastened, the dorsal flap is lifted and the lateral incisions carried up
along the sides of the cephalo-thorax by a needle with a cutting
edge. This flap is then slowly reflected back over the capitulum.
The internal organs are then in view with the aorta uppermost.
The various organs can then be separated, but great care is neces-
sary. A medicine dropper may be used to wash away debris or
material from a ruptured intestine which obscures the field.
A FEW NOTES ON TECHNIQUE 225

The paraffin trough devised by Christophers is made by filling
a glass dish like a Petri dish, with about one-half inch of a mixture of
melted paraffine and lamp black which is then permitted to cool and
harden. Specimens may be fastened to this with entomological pins.

Francis has had good dissection results by holding insects in
place with a strip of surgeon’s adhesive plaster fixed to a thin piece
of wood.

Chitinous parts may be dissected apart in the clearing agent
(Xylol or Oil of Cloves) but it must be remembered that Xylol
and 959% or absolute alcohol tend to make chitin brittle.

In dissecting insects, practice alone makes perfect. This is
especially true in the case of small, chitinous insects like lice and
fleas. Many attempts must be made before one’s efforts are
successful.

Some form of dissecting microscope is necessary, together with
clean instruments, including fine pointed needles and needles which
have been ground to a sharp cutting edge on one side.

For purpose of study and demonstration it is well to stain and
mount the various organs. The technique used by Patton and
Cragg is briefly as follows: Flood with salt solution and remove all
parts not wanted and all debris. ;

Remove salt solution with a pipette or piece of filter paper and
arrange the organs in position on the slide.

When the specimen is just beginning to dry allow a small drop of
the fixing solution to come in contact with one edge and draw it
around the edges with a clean needle. As the material becomes
opaque add more of the fixing agent and finally immerse in a Coplin
jar full of it for one-half to one hour.

The fixing agent is Bless’ fluid composed of,

Formal: x 00) PE aR 7 parts
AlodholizoTs. Li 00 ah fn ie dey go parts
Glacial Acetic Acld...... 0. 00 J sda iey 3 parts

It should not be used more than ten days old.

This fixes the tissue to the slide and also is the fixing agent for
the cells of the tissue. :

From the fixing agent carry the specimen to 709%, alcohol where it
may remain until ready to complete the process. Then remove to
80% alcohol for 10 minutes, 95% alcohol for To minutes and absolute

alcohol for one hour. Reverse the process back to 45% alcohol
15
226 INSECTS AND DISEASE OF MAN

allowing a few minutes to each transfer and then overstain in haema-
toxylin. Staining usually requires several hours. Decolorize in
149% acetic acid or hydrochloric acid, watching the progress under
the microscope. When sufficiently decolorized carry through the
alcohols to absolute, to secure dehydration. Clear in oil of cloves
and mount in Canada balsam.

Borax-carmine may also be used as the stain in place of
haematoxylin.

To section insects or their tissues one requires a knowledge of
histological technique. The technique is the same except that with
insects one is dealing with material of very small size. It is better to
isolate the organ desired before preparing for section, although whole
insects may be sectioned with more or less success. For soft parts
only paraffin embedding is satisfactory. It will also answer for
mosquitoes. For insects like fleas where much chitin is present the
double embedding method (paraffin and celloidin) is better. The
celloidin should be allowed to act for some time but there should be
a minimum exposure to the paraffin as it tends to make the chitin
brittle.

Whole insects may be fixed in formalin solution or in a concen-
trated solution of bichloride of mercury in alcohol containing 5%
of glacial acetic acid. Fresh material should be used. The
wings and legs should be removed to permit of better penetration
of the fixing fluid. A small opening may be made in the abdomen
for the same purpose. Sectioning through chitin is unsatisfactory
and a number of sections may have to be made before obtaining good
ones. Stiles has had good success in sectioning heavy chitin by first
imbedding in paraffin. Before cutting a section paint the: top of
block with a solution of gum mastic (Mastixharz), using a camel
hair brush. Let dry, then cut. Mount section gum side down.
The chitin is softest in newly emerged insects. After fixing well, the
insect may be put into warm KOH solution (10%) or in Labarraque’s
solution for a short period.

Collateral Reading

MepicAL ENTOMOLOGY

Patton, Walter Scott and Cragg, Francis William. 1913. “A Text Book of Medical
Entomology.” (This book covers in a thorough manner, anatomy, life histories,
rearing methods and laboratory technique.)
A FEW NOTES ON TECHNIQUE 227

GENERAL ENTOMOLOGY

Folsom, Justus Watson. 1922. ‘Entomology with Reference to Its Biological and
Economic Aspect.” (Contains an excellent bibliography.)
© Comstock, John Henry. 1924. “An Introduction to Entomology.”

MEDICAL ENTOMOLOGY AND DISEASES

Byam, William and Archibald, Robert George. 1921-1923. “The Practice of
Medicine in the Tropics.” (This book includes chapters on medical entomology
by H. F. Carter, L. O. Howard, H. H. King, Ll. Lloyd, M. E. Macgregor, W. S.
Patton, W. D. Pierce, Cecil Warburton and: Malcolm Watson.)

Castellani, Aldo and Chalmers, Albert J. 1919. ‘Manual of Tropical Medicine.”

DIPTERA

Howard L. O., Dyar H. G. and Knab F. 1912-1917. The Mosquitoes of North and
Central America and the West Indies. (4 volumes) Published by the Carnegie
Institute of Washington.

Dyar, Harrison G. 1922. ‘The Mosquitoes of the United States.” Proceedings of
the U. S. National Museum, No. 2447, Vol. 62, Art. 1.

Williston, S. W. 1908. “Manual of the Families and Genera of North American
Diptera.” :

Aldrich, J. M. 1916. ‘‘Sarcophaga and Allies in North America.” Published by the
Thomas Say Foundation of the Entomological Society of America.

Banks, Nathan. 1912. ‘The Structure of Certain Dipterous Larvae with Particular
Reference to those in Human Food.” Technical Series No. 22 Bureau of Ento-
mology, U. S. Department of Agriculture.

Greene, Charles T. 1925. “The Puparia and Larvae of Sarcophagid Flies.” Pro-
ceedings of the U. S. National Museum, No. 2566, Vol. 66, Article 29.

ANOPLURA

Kellog, Vernon L. and Ferris, Gordon F. 1915. “The Anoplura and Mallophaga
of North American Mammals.” Published by Stanford University, California.
Lloyd, LI. 1919. ‘Lice and Their Menace to Man.”

ACARINA

Nuttall, George H. F., Warburton, Cecil, Cooper, W. F. and Robinson, L. E. “Ticks,
A Monograph of the Ixodoidea.” Published by the Cambridge University Press.
Banks, Nathan. 1915. “The Acarina or Mites.” Report No. 108, Bureau of Ento-
mology, U. S. Department of Agriculture.
CAUSATIVE AGENTS OF DISEASE

Stitt, E. R. 1923. “Practical Bacteriology, Blood Work and Animal Parasitology.”

COLLECTING AND PRESERVING INSECTS

Banks, Nathan. 190g. ‘Directions for Collecting and Preserving Insects.” Bulletin
No. 67, U. S. National Museum.
 

 

 

 
PART II

DISEASES OF MAN TRANSMITTED BY
INSECTS
 

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CHAPTER XXIV
INTRODUCTION

Arthropods may be divided into those which are parasitic and
those which are not. A parasite is an organism which lives wholly
or in part on the tissues or juices of another usually larger species,
the host. A flemporary parasite visits the host for the purpose of
feeding or breeding and remains with the host for a limited period of
time only (bed bug, mosquito, bot-fly etc.). Permanent parasites
remain with the host unless destroyed or removed. Parasites are
termed ectoparasites when they dwell upon or within the integu-
ment of the host, and endoparasites when they dwell within the
body.

An insect may be accidentally parasitic (pseudoparasitism) as for
example when eggs or larvae of flies are deposited in wounds, in the
nose, ears or sinuses, or are swallowed. This is sometimes the case
with the blow flies, the screw-worm fly etc. Although out of their
natural habitat these immature forms live and grow and by their
presence may constitute a disease which may lead to serious results.
This condition, where the larvae: of flies are involved, is known as
myiasis. Myiasis may also be a manifestation of true temporary
parasitism as typified in the bot-flies where part of the life history is
alway spent in an animal host.

An arthropod may be of medical interest without being parasitic,
the house fly for example. :

Non-parasitic arthropods may cause injury and disease in one of
four ways:

1. By serving as mechanical agents in the dissemination of infec-
tious material. :

2. By biting and stinging, and inoculating a venom.

3. By harboring a parasite which man may acquire through
accidental contact.

4. By pseudoparasitism.

The house fly preeminently illustrates the first of these principles.
It breeds in filth and feeds upon human filth which it carries in its
intestinal tract, on its proboscis and on its feet, back to man usually

231
232 : INSECTS AND DISEASE OF MAN

through contamination of his food. Thus it may carry diseases of
the intestinal type, notably typhoid fever and dysentery, both bacil-
lary and amoebic. In the latter case it is the encysted stage of the
Endamoeba histolytica which is transported in its intestines.

Certain non-parasitic arthropods although they may be incapable
of sucking blood are never-the-less capable of inoculating venom
through a bite or sting—spiders, scorpions, centipedes, hornets, bees,
wasps, etc. While such bites or stings are rarely fatal, serious symp-
toms may follow and certain individuals who have become sensitized
may exhibit anaphylactic phenomena.

The third method by which a non-parasitic arthropod may be
dangerous to man is illustrated by the Cyclops coronatus, a small
fresh water crustacean which harbors the embryos of the Guinea
worm (Dracunculus medinensis). Man becomes infested by swallow-
ing water containing the infected Cyclops which is destroyed by the
gastric juice and the embryo worm liberated.

The fourth way (pseudoparasitism) has already been mentioned.

Parasitic arthropods cause injury or disease in two principal
ways:

1. By their habits (burrowing or biting) which lead to irritation
and subsequent inflammation of the skin, frequently heightened by
scratching—Ilice, itch mites etc.; or the habit requiring them to spend
part of their life history in an animal host (bot-fly). :

2. By the withdrawal of infected blood from a patient and inocu-

lation of another person at a subsequent biting. The transfer of the
causative agent of the disease may be effected by,—(a) direct transfer-
ence of the microorganism without change or no change other than a
simple multiplication within the alimentary tract of the arthropod,
as in the case of the Bacillus pestis carried by the flea. (b) Cyclic-
ally, indirect or transference only after part of the life cycle of the
infecting organism has been completed in the body of the arthropod
host as in the case of the plasmodium of malaria.
Even though they carry no causative agents of disease, all biting
blood-sucking arthropods produce a reaction through the bite, because
of an irritating principle in the salivary secretion, the degree of reac-
tion depending upon the susceptibility of the individual bitten. The
permanent parasites, like the itch mites and pediculi, by reason of
their prolonged visitation, numerous bites or special habits, ordinar-
ily cause more or less severe irritation, loss of sleep leading to lowered
vitality, or secondary dermatitis.
INTRODUCTION 233

Some of the most prevalent as well as some of the more serious
diseases of man are transmitted by blood sucking arthropods, notably
yellow fever, typhus fever, bubonic plague, sleeping sickness,
malaria, Rocky Mountain spotted fever, filariasis, relapsing fever,
dengue, etc.

In studying a disease the mode of transmission of which is not
understood the epidemiologist must always bear in mind the possi-
bility that a blood sucking arthropod may play the principal role in
spreading the disease or in fact may be the only means by which it is
spread in nature.

If a disease is spread by a blood sucking arthropod the causative
agent must be circulating in the peripheral blood of the patient or
carrier, either in the plasma or in the cells, at the time of sucking the
blood. Conversely, if the causative agent of a disease circulating in
the blood stream is locked up in the body so that it does not escape
in any discharge from skin or mucous membrane, the disease can only
be spread in nature through the withdrawal of the virus by a biting
insect or other arthropod, which in due course of time is transferred to
another person. Such transference may take place in several
ways: —

First. The virus may gain access to the animal host by way of
the proboscis during the act of biting. If so, it may be present in
the salivary juices injected into the wound as in the transference of
malaria; it may be regurgitated from the alimentary canal as in the
transference of bubonic plague; it may pass down in the hollow of
the labium as in the transference of filariasis; or it may be by simple
contamination of the mouth parts of the arthropod, which having
recently sucked the blood of an infected person or animal, may be
contaminated for a brief period of time and so infect a susceptible
person, as is sometimes the case in sleeping sickness.

Second. An insect while engaged in biting may be crushed by
the hand and the contents of its body may be inoculated into the
skin by scratching, or by rubbing it into the wound made at the time
of biting. This occurs in the case of lice infected with the micro-
organisms of relapsing fever which penetrate the walls of the ali-
mentary tract of the louse and gain access to the body cavity.

Third. Contaminated feces from the arthropod may be depos-
ited at the site of the puncture made by the bite, the virus then being
rubbed in through scratching. This sometimes occurs in the trans-
mission of bubonic plague by the flea and may occur in other diseases,
234 INSECTS AND DISEASE OF MAN

including trench fever, typhus fever and tick-borne relapsing
fever.

It is possible that man may become infected with some micro-
organisms by ingesting an ectoparasite which is serving as the artho-
pod host for the microorganism. Among human beings this mode of
transmission could only occur accidentally as civilized man does not
intentionally eat his parasites, but it is known that white rats
become infected with an Hepatozoon through ingestion of the rat
mite (Laelaps echidninus) which transmits the organism from another
infected rat. The tape worm of dogs and cats (Dipylidium caninum)
has been rarely found in man. Infection in man is probably due to
the accidental ingestion of dog fleas or lice which harbor the larval
stage of the worm.

So far as known it is only in the case of a parasitic animal organism
that a definite stage in the life cycle of the organism does take place
in the body of the arthropod host. When such a stage in the life
history of the organism is necessary, a period of time must always
elapse between the withdrawal of blood from the patient or carrier
and the transfer of the infection to another person. This interval
of time is known as the extrinsic period of incubation. This period is
not always definite for much depends on atmospheric temperature
but until it has been completed the arthropod host cannot convey
the disease.

The host in which the sexual cycle of the microorganism occurs is
known as the definitive host. The definitive host is believed not to
be harmed by the presence of the organism. The host in which the
asexual cycle of the microorganism occurs is known as the infer-
mediate host. The intermediate host is harmed by the presence of
the parasite. As examples one may mention malaria in which the
mosquito is the definitive host for the malarial parasite and man is
the intermediate host; or filariasis in which the mosquito is the inter-
mediate host of the filaria and man is the definitive host.

In the case of those organisms known or believed to have a
definite stage of their life cycle in an arthropod host the development
of the organism is limited to one or at most a few species of the
arthropod concerned. For example, malaria can be transmitted only
by mosquitoes belonging to the anopheline group and of these only
the species of the Genus Anopheles serve as the insect carriers. Afri-
can trypanosomiasis is transmitted by but two species of tsetse
fly, Glossina palpalis and Glossina morsitans, and for that matter,
INTRODUCTION 235

each of these carries a different species of trypanosome. The
transmission of yellow fever is confined to one species of mosquito,
the Aedes aegypti. As a general proposition the arthropod remains
in a condition to disseminate the disease for a considerable period of
time, or even throughout its active life. In the case of pathogenic
microorganisms belonging to the vegetable kingdom, sojourn in
the arthropod is not essential. It is only through force of circum-
stances that they enter the intestinal tract of the arthropod and they
remain there until eliminated through defecation or regurgitation.
The body cavity, organs or tissue are not actually invaded. Multi-
plication of the microorganism may and usually does occur, but
ordinarily they are harbored only for a more or less limited period of
time, the tendency being for the gastrointestinal tract to clean
itself through peristaltic action. This occurs in the case of the flea
harboring the plague bacillus. Under such circumstances the mini-
mum period elapsing between the withdrawal of blood from an
infected person or animal and the inoculating bite is variable. It
may be short, since the mode of transmission is purely mechanical,
depending upon the degree of septicaemia in the animal or person
bitten as well as upon the rapidity and degree of multiplication in
the alimentary tract of the arthropod, the degree of peristaltic action
and the bactericidal action of the serum of blood ingested at sub-
sequent feedings.

The causative agent of tularaemia, Bacterium tularense, which is
regarded as a vegetable parasite, furnishes an exception to the
remarks made in the last paragraph. This microorganism seems to
be capable of infecting any of the common blood-sucking insects
and actually passes through the stomach walls and invades the body
cavity. The insect remains infective for long periods.

Some animal parasites in passing through the stage of the life
cycle for which an arthropod host is required, are transmitted to
the second generation of the arthropod. A classical example of this
is found in the case of Babesia bigemina, the causative agent of Texas
fever, a disease of cattle, which is transmitted by the second genera-
tion of ticks. The infected female leaves the infected animal and
deposits her eggs containing the microorganisms. The newly
hatched larvae seek new animal hosts and transmit the disease to
them. A long extrinsic period of incubation is thus required—40
to 60 days, 30 of which are required for development into the larva.
Such mode of transmission involving the second generation of the
236 INSECTS AND DISEASE OF MAN

intermediary host may take place in the case of Relapsing fever of
West and East Africa which is transmitted by a tick, and Rocky
Mountain Spotted Fever which is also transmitted by ticks. In
both of these diseases, however, the adult male and female ticks can
transmit the causative agents directly, the spread of neither disease
depending upon transmission to the next generation of ticks.

It is possible that some lesions in man attributed to insect bites
are, in reality, due to infection by the casuative agents of diseases
of lower animals, the germ not coming to full maturity in the human
host.

Much remains to be learned about the life histories of pathogenic
organisms, animal and vegetable, in their passage through arthropod
hosts. The examples cited will serve to indicate what is known of
the various ways in which arthropods may transmit disease, and the
possibilities which are to be borne in mind.

The above remarks have ignored the possibility that the virus
may leave the body of the patient or carrier by other means as well
as through the withdrawal of blood. If the causative agent of the
disease is present in any of the discharges there is, of course, the possi-
bility that there may be other modes of transference involved. It
may happen, however, that notwithstanding the presence of micro-
organism in one or more of the discharges, transmission in nature can
only occur by inoculation through the skin. Trench fever is an
example of this principle. The virus is contained in the blood of the
patient and also in the sputum and urine but the disease is only con-
tracted through inoculation into the skin, and it is highly improbable
that infection could be acquired in this way from urine or sputum
except under most unusual circumstances. The natural mode is
through the bite of an infected louse.

In studying the relation of a disease to a possible arthropod car-
rier the epidemiologist should consider the geographical distribution
and seasonal prevalence of the disease to ascertain whether these
factors correspond to the distribution and prevalence of any arthro-
pod which, in virtue of its life history and habits, could serve as an
intermediary host.

The points to be taken into consideration include, the time of
year at which the arthropod appears and disappears in relation to
the time of appearance and disappearance of the disease; the dis-
tribution of the arthropod, whether widespread or limited to cer-
tain areas; whether domestic or wild, i.e. breeding in or around
INTRODUCTION 237

houses or away from houses in woodlands, fields, marshes, streams,
mountainous districts, or lowlands, etc.; its habits of breeding and
the conditions (including temperature conditions) under which breed-
ing occurs. Does it invade the cities or is it limited to the country;
does it enter houses; is it present in large or comparatively small
numbers during its period of activity; do its habits bring it into con-
tact with man; does it suck blood and if so will it attack man or is it
confined in its feeding to other species; does it prefer one species to
another and what is its usual host; does it cling closely to its host or
move about actively? What distances are travelled by flight or
otherwise? Will it bite at all times or only within certain hours ; Is
there a history of a bite preceding the onset of the disease in human
beings, and is there any evidence of an epizootic among lower ani-
mals which may serve as hosts for the suspected arthropod?

When an arthropod is suspected of being a host, proof must be
sought through experimental laboratory work in attempts to dis-
cover whether the suspected arthropod, after having bitten a patient,
is capable of infecting susceptible animals or persons through biting;
or whether the salivary glands, or the crushed body of the arthropod,
or the contents of its gastro-intestinal tract, or its expelled feces,
are capable of transmitting the disease to susceptible animals when
inoculated. Arthropods which have been allowed to feed on the blood
of patients or diseased animals should be permitted to feed on experi-
mental animals for various lengths of time and at different intervals
after ingestion of the causative agent is presumed to have occurred.
One of the first things to be determined is whether laboratory ani-
mals are susceptible by inoculating them with blood, pus or dis-
charges from a diseased person or animal containing either the
known microorganism or the unknown virus as the case may be.
The possibility that arthropods of the second generation may trans-
mit the disease should be borne in mind. When searching for para-
sites of animals in an arthropod host it must be kept in mind that
insects harbor parasites which are peculiar to themselves and which
bear no relation to disease in man. As an example one might men-
tion Her petomonas pediculi, a louse parasite, which forms cysts in the
gut, and escapes with the feces deposited upon the human skin.
Other lice which feed at the contaminated site are infected through
ingestion. - Flagellates (Herpetomonas and Crithidia) are frequently
found in insects such as mosquitoes, horse flies, fruit flies, flesh flies,
blue bottle flies, the house fly, fleas, lice, etc., and at times it is only
238 : INSECTS AND DISEASE OF MAN

after careful breeding in the laboratory that such parasites can be
eliminated, thus avoiding confusion. Even yeast cells in the stom-
ach of mosquitoes have been confused with microorganisms patho-
genic to man.

Insects also have their external parasites. One frequently
observes fungi and mites parasitic on insects, as well as mites which
remain upon the insect to feed upon the juices of the parasitic mites.
CHAPTER XXV
MALARIA

Causative Agent.—Malarial parasites which are animal protozoan
blood parasites of the Class Sporozoa, Order Haemosporidia and
Genus Plasmodium. There are three species as follows:

Plasmodium vivax causing benign tertain malaria

Plasmodium malariae causing quartan malaria

Plasmodium falciparum causing aestivo-autumnal malaria.

Source of Infection. The blood of a person ill with malarial
fever or an infected anopheles mosquito. Man is the intermediate
host, the mosquito is the definitive host.

Mode of Transmission.—In nature malaria is transmitted
through the bite of certain species of infected Anopheline mosquitoes.
The disease can also be transmitted by inoculation of infected blood.

Period of Incubation.—About 14 days. Extrinsic period of
incubation ten to twelve days.

Period of Communicability.—As long as sexual forms of the
malarial parasite are present in the peripheral blood. Carriers in
the form of chronic cases are common in malarial sections and are
responsible in colder countries for carrying the disease over from
season to season. Although a certain number of female anopheles
survive the rigors of winter through hibernation, the malarial parasite
is carried over in human carriers and not in the mosquito.

Epidemiology.—Malaria is widely distributed over many parts of
the world; in the temperate zones as well as in tropics and sub-
tropics. In the United States it is prevalent in the southern states
and there are malarial centers in the New England States and on the
Pacific Coast of California.

! The mosquitoes known or believed to be implicated in the spread
of malaria in the United States are: ;

Anopheles quadrimaculatus, Say (by far the most important
vector).

Anopheles crucians, Wiedemann.

Anopheles punctipennis, Say.

Anopheles pseudopunctipennis, Theobald.

239
240 ’ INSECTS AND DISEASE OF MAN

Only the female of the species bites; she feeds on blood. The
male is a vegetarian. Feeding takes place at night. Anopheles
mosquitoes may be said to have two flights, the first beginning at
dusk in search of food; the second beginning at dawn in returning to
the place of rest or breeding place. Itis at dawn that the 4. quadri-
maculatus may be found on house screens. It is then easily killed
as it is sluggish when full of blood. Anopheline mosquitoes are much
easier to catch than the wary and active yellow fever mosquito.

Anopheles mosquitoes rarely breed in water which is polluted
with sewage or where decomposition of organic matter is taking
place to any great extent, or in water which contains trade wastes
like sulphuric.acid, coal gas or oil, soap or grease, etc., nor do they
breed in the rapidly flowing parts of streams, nor ordinarily in
deep water or water the surface of which is disturbed and ruffled or
which is covered by plants forming a dense film on the surface.
Fish, predacious water insects such as water boatmen, and tad
poles in large numbers may explain the absence of anopheles
larvae.

Where Anopheles larvae are found it does not necessarily follow
that they are actually producing mosquitoes, for where only young
immature specimens are collected it may mean that the conditions
are inimical to growth and that none is actually going on to full
development. On the other hand, where only large nearly grown
larvae are encountered it may mean that they were washed there
from elsewhere by heavy rains.

The breeding places of anopheles mosquitoes may be divided
into natural and artificial. The first are breeding places of choice,
the second are breeding places of necessity or accident. The
natural breeding places are shallow shady pools of clean water,
large ponds, especially near the edges, streams and ditches, more
especially in pockets at the edges, marshy areas containing small
pools, post holes, hoof prints, rice fields, and rarely street gutters,
etc., in general, clear quiet water,—ponds, swamps, pools, puddles,
lakes, lagoons. Aquatic plant life which furnishes shelter and
protection to the larvae promotes breeding. Plankton organisms
and organic matter furnish food to the larvae.

Among the artificial breeding places in which Anopheles mos-
quitoes may at times breed are puddles of clear fresh water where
some vegetation is present. Such puddles may result from drains
from ice plants, leaks from water pipes, fire plugs, pumps, overflows
MALARIA 241

from watering troughs, tanks, etc. Occasionally breeding takes
place in barrels, boats, fountains etc.

Anopheles quadrimaculatus.—This mosquito is rather fastidious
in its choice of a breeding place and much prefers, clean, clear, quiet
water, such as large ponds and grassy puddles. It will not breed in
sewage polluted water. It breeds especially in ponds of considerable
width and depth but when more favorable breeding places are
scarce it occasionally may be found in post holes, and rarely at the
edges of slow moving streams where there is practically no surface
flow. In ponds it is ordinarily found near the edge in shallow
water, sheltered and protected by water plants, but has been reported
from the middle of a large pond in 6 feet of water where floatage
(broken pieces of blades of wild celery and pollen) furnished pro-
tection by preventing any break in the waves, thus permitting only
long smooth swells, and also furnishing protection against fish.

A. quadrimaculatus enters occupied dwelling houses in large

numbers and therefore comes into intimate contact with people at
the time it is ready to feed. It may be guided into the house by
lights, even by light reflected up the chimney, and it may enter a
house by way of the chimney as well as through unscreened windows
and doors. It is also found in out buildings such as privies. Itmay
prefer the blood of man to that of animals. Probably most malaria
is contracted at night in the house from the bite of this anopheline.
This species may fly as far as 114 miles from its breeding place.
This is perhaps not usual, but from 14 to 1 mile is a common flight
for A. quadrimaculatus. The greater the amount of breeding the
greater the number that will be found at a distance from the
breeding place, and the greater the tendency towards long flights up
to the maximum. A. quadrimaculatus is an efficient carrier of P.
vivax, P. falciparum and P. malariae.

Anopheles crucians.—A. crucians is rarely found in inhabited
dwelling houses. It is not so widely distributed as either of the
other species. It is a porch biter and is commonly found under the
house or around the house, in outhouses, privies, stables,“etc., and
seems to prefer the blood of animals to that of man. Its maximum
flight distance is probably the same as that of A. quadrimaculatus.
It may be found breeding side by side with other Anopheles but may
adapt itself to brackish water, as in salt marshes, or water containing

small amounts of chemicals, conditions under which neither the
16
242 INSECTS AND DISEASE OF MAN

quadrimaculatus nor the punctipennis will breed. A. crucians is a
proven transmitter of P. falciparum and P. vivax.

Anopheles punctipennis.—This mosquito is more widely distrib-
uted and more numerous than either of the other species. It is most
in evidence in the early evening. Like crucians it is rarely found in
occupied dwelling houses but is a proch biter and is found under
houses and in outhouses, pig pens, and the like. It seems to prefer
the blood of animals to that of man. It does not fly far from its
breeding places which may be in streams and ditches as well as in small
ponds, marshy areas or other places where quadrimaculatus will breed.
Slight pollution of the water does not deter it from breeding.

A. punctipennis is a proven carrier of P. vivax and P. falciparum.

The two latter species of mosquitoes are less important dissemina-
tors of malarial infection than quadrimaculatus because the Anoph-
elines are shy, and biting outside while persons are moving about is
not a common occurrence.

Anopheles pseudopunctipennis—This mosquitoe is found in
the southwestern part of the United States, southern California, and
Texas, extending down through Mexico, and Panama into South
‘America. It may enter houses. It breeds in pools, ditches, edges
of streams, preferring clear, pure water. A. pseudopunctipennis is a
proven carrier of P. falciparum.

Some other anophelines which may carry malaria and which do
carry malaria in other parts of the world are:

Anopheles (Cellia) albimanus Wiedemann, (Panama, Brazil,
Virgin Islands)

Anopheles (Cellia) argyritarsus Robineau-Desvoidy, (Panama,
Brazil) ;

Anopheles (Cellia) tarsimaculatus Goeldi, (Panama, Porto Rico)

Anopheles minimus Theobald (Philippine Islands)

Anopheles (Myzomyia) Iludlowi Theobald (Philippine Islands,
Sumatra)

Anopheles fuliginosus Giles, (Philippine Islands)

Anopheles sinensis Wiedeman (Philippine Islands)

Anopheles (Myzochynchus) barbirostris Van der Wulp, (Philippine
Islands)

Anopheles (Myzomyia) culicifacies Giles, (India)

Anopheles (Myzomyia) funesius Giles (Africa)

Anopheles maculipennis Meigen, (Europe)

Anopheles bifurcatus Linnaeus, (Europe)
MALARIA 243

A. maculipennis is found in the Western United States and is
called A. occidentalis. A. albimanus and A. argyritarsus are also
found in the United States but have not been implicated in the trans-
mission of malaria in that country.

The life histories of those mosquitoes mentioned above as being
carriers of malaria in countries near or forming a part of the United
States are briefly as follows:

Anopheles argyritarsus.—Found in the Canal Zone, Brazil, etc.,
breeds in small collections of water such as seepage pools along hill-
sides, ditches containing only a small quantity of water, foot prints,
swampy pastures, and in artificial containers.

Anopheles albimanus.—Breeds in fresh or brackish water, even pre-
ferring brackish water, but not foul water. It is found in swamps,
hoof prints, wheel ruts, and even where there is a very thin film of
water, if algae are present. This mosquito enters houses in large
numbers.

Anopheles tarsimaculatus.— This mosquito breeds in fresh or brack-
ish water, but not in foul water. It has been taken from rivers,
swamps, ditches, small holes, hoof marks, and even artificial con-
tainers. The larval stage is prolonged to from 15 to 18 days.

Anopheles minimus—Found in the Philippine Islands, India,
etc. Breeds in pools and streams, and enters houses freely.

Anopheles ludlowi—Will breed in very fresh or salt water. It
has been taken from small pools, margins of running streams, marshy
grounds, and fish ponds. It enters houses freely.

Anopheles fuliginosus—Ordinarily found breeding in swampy
places and pools containing much vegetation. It enters houses freely.

Anopheles barbirostris—Breeds in shady pools and streams.
Feeds in the shade during the day. Rarely enters houses.

Anopheles sinensis—Breeds in swamps, rice fields and water with
much vegetation. Feeds by day. Not often found in houses.

Life History of the Malarial Parasite. (Fig. 92).— There are
two different cycles in the life history of the malarial parasites.
One takes place solely in the blood of the human host, requiring from
48 to 72 hours for its completion according to the species, and explains
the occurrence of the periodic attacks of chills and fever. This is
the non sexual cycle (schizogony). The other cycle has its beginning
in the blood of the human host but is completed only in the body of
the mosquito. This cycle is known as the sexual cycle (sporogony)
and without its completion malaria cannot spread.
244 INSECTS AND DISEASE OF MAN

In describing these cycles it is convenient to begin at the time of
biting when the falciform spore (sporozoite) from the salivary glands
of the mosquito is inoculated into the blood. The sporozoite then
bores its way into a red cell, assumes a spherical shape and enlarges,
finally showing division into spore-like bodies. The parasite is
then known as a merocyte. The merocyte ruptures, the spores
(merozoites) become free in the blood serum and then enter other red
blood cells and the cycle begins anew. This complete nonsexual
cycle takes from 48 to 72 hours depending upon the species of malar-
ial parasite. The cycle repeats itself until there are a sufficient num-

S g ~ Gametes~

— ©,

0°
30709 Schigogony
Show/rrng non
sexual cycle ]
in man (inter-\ ,
N o 7ediary 405t)00 50
~Jehizonts~ Wes
y Z

QO
©-@

F1G. 92.—Sexual (sporogony in mosquito) and nonsexual (schizogony in man) of
the malarial parasite. The sporogony diagram at the left shows in lower portion the
fertilization of the female gamete by the microgamete. The vermiculus stage of the
zygote is shown boring into the walls of the mosquito’s stomach later to become
the more mature zygote packed with sporozoites as shown in the upper diagram of
the developmental processes in the mosquito’s stomach. (From Stitt’'s ‘‘Practical
Bacteriology, Blood Work and Animal Parasitology,” 7th. Edition.)

    

   
     
 

: Sporogory
~ ern oi, Ye Sonal hl
nopheline mosquito (definitive
\. fost). Period ‘lasts 8-10days
= at 25°to 30°C. a

      
 

ber of merocytes rupturing simultaneously to produce symptoms.
This represents a period of about 14 days—the period of incubation.

By and by sexual forms (gametes) develop from some of the non
sexual forms of the parasite. The female, (macrogametocyte) contains
more pigment, less chromatin and stains more deeply blue. The
male (microgametocyle) contains less pigment, more chromatin and
stains greyish green rather than blue. These forms undergo no fur-
ther development within the human host, but when taken into the
stomach of a suitable mosquito host, the male gives off spermatozoa
like projections (microgametes) which break off from the parent
MALARIA 245

cell and enter a female parasite, which by nuclear changes and for-
mation of polar bodies has become a macrogamete. Thus the female is
fertilized, producing what is known as a zygote. The fertilized para-
site then penetrates the outer wall of the mosquito’s stomach (midgut) °
remaining within the stomach wall for about 10 days during which
time it enlarges until it becomes a cyst (oocyst) filled with hundreds of
falciform bodies (sporozoites). About the tenth day the oocyst
ruptures and the sporozoites are thrown off into the body cavity
from which they make their way to the salivary glands, and finally
into the blood of man. Thus the sexual cycle ends and a new cycle
begins. The essential formula is ten generations of the nonsexual
cycle in man alternate with one generation of the sexual cycle in the
mosquito. The total time necessary for development in the mos-
quito is about 10 or 12 days. (The extrinsic period of incubation.)
Low atmospheric temperatures delay development, and winter
weather stops it altogether.

Economic Considerations.—Malaria is a disease which though
not an important cause of death is responsible in districts where it is
prevalent for lowering the physical and mental efficiency of large
numbers of people to such a degree that economic conditions are
seriously affected, resulting in enormous financial loss to the com-
munity. In some localities practically entire communities are
sufferers from the malady in either its acute of chronic form. An
attack does not produce immunity.

Seasonal Prevalence. In the temperate zone malaria has its
highest prevalence and the greatest number of deaths occur rather
late in the season, August, September and October, after a consider-
able period of warm weather, for the malaria mosquito does not
ordinarily make its appearance in numbers until July and then
can do no harm until 10 or 12 days after it has bitten a patient.
When the temperature is below 60°F. mosquitoes do not carry
malaria. In the Tropics the malaria mosquito is present all the
year round. In the temperate zone it hibernates through the
winter neither feeding nor breeding. In the tropics it estivates
during the hot dry weather.

Epidemiological Study.—In an epidemiological study of malaria
both mosquito and human host must be investigated. A survey
to determine the prevalence and location of anopheline mosquitoes
will give what is known as the anopheline index to the prevalence of
malaria. This should include the collection of specimens and a
246 INSECTS AND DISEASE OF MAN

search for oocysts within their stomach walls and sporozoites within
the salivary glands in order that the percentage of infected mosqui-
toes among those examined may be determined.

Investigation of the amount of infection in human beings includes
a statement from local physicians as to the number of cases treated
in the current and previous years, study of the periods of greatest
prevalence, information derived from industrial plants relative to
loss of time on account of malaria, house to house visits for the
examination of all persons to determine the blood index, the history
index or the splenic index. The splenic index is sometimes investi-
gated when laboratory examinations are impracticable. It is deter-
mined by noting the percentage of persons among those examined
who have the enlarged spleen so characteristic of chronic malarial
infection. This is a valuable index of malarial infection in the
Tropics but it is not so useful in the United States. By the blood
index is meant determination of the percentage of persons examined
who show malarial parasites in the blood. The thick smear method
is better for this purpose as it furnishes a larger quantity of blood,
and malarial parasites are therefore more likely to be seen, even
though they may be few in numbers in the circulating blood. The
blood index is the best index of malarial infection in the United
States.

Method of Making Thick Smears and Staining for Malarial
Parasites.—1. Before making blood smears have slides and cover
glasses scrupulously clean and free of grease. It is well to flame
them before using.

2. About one-half drop of blood is smeared out over a surface
equaling the size of a cover glass.

3. Allow to dry thoroughly in air. This may take from one to
two hours at room temperature or 20 to 30 minutes in the incubator.
Protect from dust, flies, ants, etc.

4. Gently move slide about in a 29; solution of formalin to
which has been added 19, of glacial acetic acid, until laking is
complete.

Wash in glass of tap water to remove all acid.

Wash gently in distilled water.

Stain in weak Giemsa (1 drop to 1 cc.) for 20 to 30 minutes.
Wash in water.

Allow to dry without heat or use of blotting paper.

Togo Onn
MALARIA 247

Mosquito Survey.—To carry on a mosquito survey one needs:
1. One white enameled dipper with hollow handle so that its
* length may be extended by the insertion of a stick of wood.

2. One wooden extension to handle of above.

3. One medicine dropper with an orifice of about one-eighth of an
inch to be used in selecting larvae and pupae from the dipper.

4. One pair of entomological forceps.

5. One entomological bottle or a large test tube at the bottom of
which is placed cotton and rubber bands saturated with chloroform
covered with a paste board disk and corked. This is used as a
catching bottle for adult mosquitoes.

6. Six pill boxes in which to put adult mosquitoes when collected.

7. Six small preserve jars (Mason) in which to place specimens of
larvae collected, together with the water in which they were breeding
(about half full) covered with mosquito netting, these serve as
breeding jars. Small vials in which to place larvae may be taken
into the field, and the larvae transferred to the breeding jars in the
laboratory.

8. One notebook and pencil.

9. One pair rubber boots.

In making a survey for malarial mosquitoes it is well to collect
all kinds of mosquitoes as a matter of scientific interest. All possible
breeding places should be looked into even though the prospects of
securing Anophelines is remote. In looking for Anophelines the
dipper should be used for skimming the surface of the water or it
may be lowered into the water allowing the larvae to wash in.
Search must be made especially at the edges of ponds and pockets
at the sides of streams and where shelter is afforded by weeds,
rushes, etc. Before dipping wait quietly for a few moments. Note
the number of larvae per dipper and the size; also note the character
of the water, whether clear, muddy, stagnant or flowing; presence of
fish, tadpoles, water insects, water plants, algae, etc.

All such information should be recorded in the note book together
with the location of the mosquito breeding area. Spot maps or
charts are valuable. All specimens collected should be labeled with
date, time, and place collected, and initials or name of collector.

It is more or less difficult to bring Anopheles larvae to maturity
in breeding jars, therefore larger larvae or pupae should be taken
preferably.

Recognition of the Disease.—Malaria presents so many different
clinical manifestations, and the symptoms may be so variable even in
248 INSECTS AND DISEASE OF MAN

the same type of the disease that it is impraticable to discuss the
recognition of malaria from the clinical standpoint in a book of this
character. In regions where malaria prevails even the laity are more
or less familiar with the disease as it appears in the locality. For
the symptomatology of malaria a standard work on tropical medicine
should be consulted.

The blood examination is of prime importance. fresh and stained
films should be examined.

The following differential tables are taken from Stitt, Diagnosis
and Treatment of Tropical Diseases.

UNSTAINED SPECIMEN (FRESH BLOOD)

 

P. falciparum (malig-
nant tertian) (aestivo-
autumnal)

P. vivax (benign P. malariae
tertian) (quartan)

 

Character of the | Swollen and light in | About the size and | Tendency to .distor-
infected red cell. | color after eighteen | color of a normal | tion of red cell rather
hours. red cell. than crenation.
Shriveled appear-
ance. (Brassy color.)
Character of | Indistinct amoeboid | Distinct frosted |S m a 11, distinctly

young schizont. | outline. Hyaline. | glass disc. Very | round, crater-like
Rarely more than| slight amoeboid] dots not more than
one in red cell. Ac-| motion. one-sixth diameter
tive amoeboid move- of red cell. Two to
me nt. One-third four parasites in one
diam. of red cell. red cell common.

Sh ows amoeboid
movement un til
appearance of pig-
ment.
Character of | Amoeboid outline. No| Rather oval in|Only seen in over-
mature schizont. | amoeboid movement.| shape. Sluggish | whelming infections.
movement of pe-| Have scanty fine
ripherally placed| b 1a c k pigment
coarse black pig-| clumped together.

ment.
Pigment... ...... Fine yellow-brown, | Coarse almost black| Pigmented schizonts
rod-like granules | granules. Shows | very rare in periph-

which show active | movement only in | eral circulation ex-
motion in one-half | young to half-| ceptinoverwhelming

grown schizont. Mo-| grown schizont. infections. Tends to
tion ceases in full clump as eccentric
grown schizont. pigment masses al-

most black in color.

 

 

 

 
 

MALARIA

STAINED SPECIMEN

249

 

P. vivax (benign tertian)

P. malariae (quartan)

P. falciparum (malignant
tertian) (aestivo-autumnal

 

Character of in-

fected red cell.

Character of young
schizont.

Character of half-
grown schizont.

Character of ma-
ture schizont.

Character of mero-

cyte.

Character of mac-

rogamete.

Character of mi-
crogametocyte.

 

Larger and lighter pink
than normal red cell.
S ho ws ‘“Schuffner’s
dots.”

Chromatin mass usually
single and situated in line
with the ring of the irre-
gularly outlined blue
parasite.

Vacuolated or Fig. 8 loop-
like body with single
chromatin aggregation.
Schuffner’s dots.

Fine pigment rather evenly
distributed in irregularly
outlined parasite.

Irregular division into 15
or more spore-like chro-
matin dot segments.
Mulberry.

Round deep blue. Abun-
dant, rather coarse pig-
ment, chromatin at pe-
riphery.

Round, light green-blue,
pigment less abundant,
chromatin abundant and
located centrally or in a
band.

 

About normal size

and staining.

Rather thick round
rings which soon
tend to show .as
equatorial bands.

More marked band
forms stretching
across red blood cell.

Coarse pigment rather
peripherally
arranged in an oval
parasite.

Rather regular divi-
sion into eight or 10
merozoites. Daisy.

Round, similar to P.
vivax but smaller.

Round like P. vivax.

 

Shows distortion and some
polychromatophilia and
stippling. Rarely we
have coarse cleft-like red-
dish dots, Maurer’s spots.

Very small sharp hair-like
rings, with a chromatin
mass protruding from the
ring. Often appears on
periphery of red cell as a
curved blue line with
prominent chromatin dot.
Frequenly two chromatin
dots.

Not often found in periph-
eral circulation. Chro-
matin still compact.

Very rarely seen in periph-
eral circulation in ordi-
nary infection. Pigment
clumps early.

Sporulation occurs in
spleen, brain, etc. Rare-
ly in peripheral circula-
tion. Eight ‘to ‘lo
chromatin staining mero-
zoites. (In culture 32.)

Crescentic, deep blue, pig-
ment clumped at center,
chromatin scanty and in
center.

More sausage-shaped than

crescent. Light blue.
Pigment scattered
throughout. Chromatin

scattered and in greater
quantity but difficult to
stain.

 

Prevention and Control of Malaria

The prevention of malaria includes:

1. Measures directed toward the prevention of mosquito breed-
ing and the destruction of adult anopheline mosquitoes.

2. Measures -directed toward preventing anopheline mosquitoes
from becoming infected by detecting and controlling human carriers

and patients.

3. Protection of healthy person:
(a) Through quinine prophylaxis (immunization)
(b) By screening against mosquitoes.
250 INSECTS AND DISEASE OF MAN

Prevention of mosquito breeding and destruction of adult
Anopheline mosquitoes.

The breeding of mosquitoes may be combated by draining, filling,
oiling, use of larvacides, fishes and clearing.

Drainage.— Drainage may be of the usual horizontal type, or it
may be vertical. Hand in hand with drainage must go clearing
debris and plants, from the border of streams and ponds; straighten-
ing edges and deepening channels so that a free and more rapid
flow of water may be had.

Drainage is applicable to ponds, marshes, lakes, puddles and
ditches in which water has become stagnant. Temporary puddles
should be controlled by oiling; road side ditches should be cleaned
and channels leveled out; old wells, cisterns, etc. should be filled,
oiled, or treated by chemicals. Marshes, ponds, and lakes especially
require drainage. Streams may be straightened, cleaned and made
free of vegetation at the edges. All obstructions to the flow of water
should be removed.

The kind of ditching necessary to effect drainage depends some-
what upon the extent and kind of area to be drained.

Drainage ditches should have clean cut sloping edges, steep banks,
a uniform grade and width, a straight course, and should be free from
weeds, stones and sticks, or anything which may impede the flow of
water. When bends are necessary, sharp bends should be avoided.
The bottom should be narrow so that the flow of water will be rapid
rather than slow. As few ditches as possible should be dug. It is
best to start with the main ditch, then to build the laterals. Laterals
should enter the main ditch at an acute angle, or a curve to lessen the
deposit of silt or sand at the junction.

Earth ditches may be expensive to maintain, and to reduce the
ultimate cost of maintenance as well as to make drainage more effec-
tive, it may be advisable to give them a permanent lining of cement.
A rough base of concrete (1:3:5) may be laid on the bottom of the
ditch about 114 inches thick and extending for about 6 inches up the
side or 3 inches above the normal water line for small ditches. This
should then be covered with 14 inch of cement and sand (1:1).
The lining should be U shaped and not V shaped. In large ditches
24 inches or more in width, the lining of the side wall should extend
higher and should be thicker. The lining should also extend higher
at the bends or key walls should be built. Seepage holes should be
provided above the key wall. A lining of concrete 2 inches thick
MALARIA 251

reinforced with chicken wire is satisfactory, or a rough lining of flat
stones sealed roughly with cement mortar may be used.

Sub-soil Drainage is useful to lower ground water, thus permitting
surface pools to be absorbed more quickly. For sub-soil drainage
ordinary drain tiles are used, from 3 inches to 12 inches in diameter
and in 1 to 2 foot lengths. All drains should be spaced from 50 to
150 feet apart and laid up and down the slope. Drains should be
from two to four feet deep. The deeper it is the more area drained
and the fewer drains needed. They should have a grade of about 12
inches to 400 feet and should be laid so that each piece of pipe touches
the other. The joints of course should be loose. The drains should
be covered with earth.

When used as intercepting drains for seepage outcrops, the drain
must be laid at a right angle to the drainage flow. A grade of not
less than 12 inches per 200 feet is required in this case and the tiles
should be 14 to 14 inch apart. The drain should be covered with
stones, using small stones at the top, extending above the surface.

Drainage ditches may be utilized to intercept seepage outcrops.
They should be dug at a right angle to the seepage flow.

Sub-soil drainage has the advantage over surface drainage of
being more easily maintained, because it is self cleaning, needs little
attention, and no oiling; besides there is no water exposed in which
mosquitoes may breed. The outlet should be guarded by metal rods
to prevent entrance of small animals. Such drains should never
be used to collect house drainage or drainage in which there is much
sediment. :

In digging ditches dynamite has been found to be useful. Horse
drawn ditching machines are also valuable in constructing ditches
less than 3 feet'deep in open land, as well as in cleaning out roadside
ditches.

Vertical Drainage.— Vertical drainage is sometimes used. By
this is meant the draining of surface water into a well dug or bored
through the upper impervious stratum to a porous or water bearing
stratum below.

Filling.—Where drainage is not economical resort may be had to
filling. In using earth or clay as a fill no depression in which water
may accumulate should be left. It may be advisable to fill shallow
parts of ponds, thus making it easier to care for the deeper parts.

In a city, such parts of the city’s wastes as consist of ashes or rub-
bish make a satisfactory fill. Ashes and cinders are especially good.
252 INSECTS AND DISEASE OF MAN

It must be remembered in using old tins as filling material that care
be taken to cover them thoroughly with ashes, earth or similar
materials, so that no water may accumulate in them to breed mosqui-
toes. Sawdust and shavings when available may be used as a fill.
This should extend several inches above the ground. Wet areas due
to seepage outcrops can not be satisfactorily eradicated by making
shallow fills.

Clearing.— In order that there will be an unobstructed flow of
water in streams and ditches, and that there will be no stagnant
pockets in which mosquito larvae may breed, they must be kept
free of vegetation and should be kept at a proper grade and proper
width. Oil and larvacides should be used when necessary. To
kill algae, copper sulphate is efficacious. In dry weather a ditch
may become a series of stagnant pools. These may be eradicated
by digging small channels in the bottom of the ditch with a spade or
hoe. A phosphate drag is useful in clearing ditches of vegetation.

Low ground kept moist by seepage outcrops over which cattle
walk, leaving foot prints in which water accumulates, may be fénced
off. A barrel should be sunk in the ground at some point outside the
fence where it will fill with water and enable cattle to drink.

The use of drainage and fill to combat mosquito breeding fur-
nishes problems with which Sanitary Engineers should be more
familiar than Medical Officers. It is work which therefore should
be carried on by the former. A successful outcome depends upon
the way in which the work is planned and thorough supervision to
insure that ditches will have a proper grade and proper width and
are properly located, etc. Careful record should be kept of labor,
material, and cost.

Impounded Water.—In the season during which mosquitoes are
not breeding the level of the water should be kept as high as possible.
Before the mosquito breeding season begins the level of the water
should be lowered so that all brush and land vegetation which has
accumulated along the edges at high water will be killed up to the
high water level, and floatage and drift will be left at the high
water level when the water falls. During the breeding season water
should be kept at as low a mark as possible unless when to do so
uncovers growth otherwise submerged.

Oiling.—Oiling is a valuable means of controlling mosquito
breeding and oil must always be used for such areas as cannot be
treated otherwise. Oiling is not permanent like draining but must
MALARIA 233

be repeated once a week during the mosquito breeding season.
Kerosene will answer the purpose but it evaporates too rapidly.
An oil in consistency somewhere between kerosene and crude oil, or
fuel oil, is advisable in that it will spread evenly and rapidly and will
not evaporate quickly. A suitable mixture is one varying from
one part of kerosene to three parts of crude oil, up to 3 parts of
kerosene to one part of crude oil, depending upon the thickness of
the latter. The resulting mixture should be black in color and should
be slightly thicker than kerosene. Fuel oil ranging in specific
gravity from 36° to 38° Baumé and in viscosity from 34 to 38 drops
‘per minute is about right. Such oil does not burn readily. Oil that
has been drained from the crank cases of automobiles may be used.
It is cheap and satisfactory. Only a thin film of oil on the water is
necessary, but it should be an unbroken film which should remain
for at least 12 hours. It must be remembered that oil may not
spread satisfactorily where there is a barrier of vegetation and a
larger quantity of oil should be used in such places, or such vegeta-
tion may be removed by use of a submarine saw. Oil may be washed
away if applied just before a rain storm. Winds may blow an oil
film to one shore of a body of water. It is also a waste of oil and
of labor to oil where no mosquito larvae are to be found.

Coal oil kills larvae by plugging the breathing tube when they
come to the surface to breath, thus asphyxiating them. It also
acts as a chemical poison and as a deterrent against egg laying. The
amount of oil required to cover a given surface with a satisfactory
film varies greatly and depends upon the thickness of the oil, the
atmospheric temperature and the presence of water plants. About
1 gal. of crude oil will be required for 150 sq. yds. of clear surface.
A greater quantity of oil will be required where vegetation is present.

Oil may be spread by the so called knap sack pump, with the
nozzle adjusted to throw a fine spray, or better still with a cylindrical
pump which will throw a stream 25 to 30 feet. It may be thrown
on the surface of the water in the form of oil soaked sawdust. This
is a satisfactory means of spreading oil over the surface in the pres-
ence of water plants. The oil soaked sawdust may be encased
in a canvas bag or gunny sack and anchored to the bottom of the
body of water. The oil is gradually given off and spreads over the
surface. Oil soaked waste may also be used.

Drip cans are useful in applying oil especially to streams and
ditches in which the current is fairly rapid. The design of a drip
254 INSECTS AND DISEASE OF MAN

can varies according to the ideas of the operator. Ordinarily five to
ten gallon oil cans or drums answer the purpose. Dripping may be
brought about by means of a wick or a well fitting stop cock opened
slightly so that the desired number of drops per minute may be
obtained. The number of drops of oil will depend upon circum-
stances but in general it may be said that from 10 to 20 per minute
are required to treat the surface of a stream or ditch having an
average width of water surface of one foot. The object is to allow
a sufficient number of drops to form a continuous film. It will be
carried down stream and will accumulate on surfaces where no cur-
rent is present and where mosquitoes are most likely to breed. The
stop cock requires attention as it is liable to clog with sediment.
For use under water two stop cocks are convenient, one at the top
of the can and one at the bottom. A wick requires some attention
but it is an easy matter to squeeze the accumulated sediment from
it at the time the can is refilled. The wick should be fixed with one
end immersed in the oil and the other end in the water so that the oil
flows by capillarity. One type of can is placed on supports above the
water to be oiled. Another type is sunk to the bottom. Out going
oil rises to the top and spreads on the surface. A tiny opening must
be left so that as the oil drips out a corresponding amount of water
flows in. The surface drip can must also be provided with a means
of permitting air to flow into the can as the oil flows out.

A satisfactory drip can may be improvised by punching a hole
through the bottom of an ordinary 5 gallon oil can with a 2 or 3
inch round nail. A wad of loose cotton is then wrapped around the
nail just below its head and the nail pushed through the hole from
the outside. The can is then filled with crude oil.. The flow of oil

through the drip may be regulated by gently pushing the nail up or
down depending upon whether a greater or fewer number of drops
is required.

In using heavy oil as a drip the can should be elevated above the
stream at least 3 or 4 feet so that the drop of oil will fall on the
surface of the water with a splash thus breaking up and spreading
more rapidly.

Oiling may be discontinued before cold weather has perma-
nently set in. It must be remembered that when the temperature
is below 60° Fahrenheit, Anopheles do not carry infection. Either
the parasite does not go on to development within the body of
the mosquito, or it finally dies out. In the summer time eggs
MALARIA 255

must be deposited 28 days before the mosquito can infect, that is,
it takes 16 days from egg to adult, and the extrinsic period of incuba-
tion is 11 days, making 28 days in all. Now as the weather becomes
colder this time lengthens more than 50 per cent, making 42 days
instead of 28. Theoretically, therefore, it is permissible to stop
oiling 42 days before the atmospheric temperature is expected to
fall below 60° Fahrenheit. Practically, however, a factor of safety
should be allowed, so that oiling should proceed up to 21 days before
the advent of cold weather.

Larvacides.— The larvacide used in Panama is a good one. It is
phenol resin soap, and in the proportion of one part to 1000 parts of
water, kills larvae promptly. It mixes quickly with water and
tends to remain at the edges of the stream, and that which passes
down stream kills as it goes. It is only good for one day and there-
fore must be repeated once a week. In the same proportion it
may also be used in rain barrels and the like, at intervals of one
week. Any phenol preparation which has at least 159% of phenol
in the crude product is a good larvacide. It must be remem-
bered that phenol preparations are poisonous to fish and of course
should not be applied to water which is to be used for drinking or
cooking purposes.

To make about three and one half barrels of larvacide take

150 gallons of crude carbolic acid which must contain not less
than 159, phenol.

200 pounds of common rosin, finely crushed and sifted.

30 pounds of caustic soda dissolved in six gallons of water.

Heat the carbolic acid in an iron tank by means of a steam coil
with steam at 50 pounds pressure, or to 212°F. Dissolve the rosin
in the boiling acid and then add the solution of caustic soda. . The
whole must be thoroughly mixed. The product is ready in a few
minutes. This preparation may be used by spraying an emulsion
made by mixing one part of the larvacide to five parts of water.

Paris green has been tried as a larvicide, and has been found to be
successful in killing larvae of Anopheline mosquitoes. It does not
seem to be lethal to larvae of other forms of mosquitoes which are
not surface feeders. The paris green is diluted with a large propor-
tion of inert dust. Road dust, fine sand, flour, rotten wood dust and
the like may be used. The proportion is about 1o cubic centi-
meters of paris green in approximately one liter of dust. This
makes a very cheap larvicide. Danger of poisoning the water is
256 INSECTS AND DISEASE OF MAN

almost negligible. Larger proportions than the above may be used
without danger, and should be utilized where there is much high
grass, reeds, etc. It is used by casting it by hand into the air from
the edge of the pond in the direction of the wind, a gentle wind pref-
erably, and a sunny day. The dust settles on the surface of the
water. Such treatment is to be given every 1o days. There is little
danger of poisoning the operator, but naturally he would stand to
windward of the dust cloud, and must avoid inhaling the dust.
Not enough paris green is used in the water to injure fishes or domes-
ticated animals which may drink of it.

Another form of larvacide is nitre cake, an acid byproduct
obtained from the manufacture of high explosives. To kill all
larvae within 24 hours it must be used in the proportion of at least
one part of nitre cake to 100 parts of the water to be treated. A
0.5% solution in the water will destroy larvae in 3 days. It is fairly
efficient when used in old wells, abandoned cisterns, fire buckets,
small stagnant ponds, etc., where there is no danger of poisoning
people or domestic animals.

Fish Control.—Only a few fish have proved to be really effective
in the destruction of mosquito larvae. They are to be found among
the top minnows or mummichogs (Poeciliidae) the sun fishes (Cen-
trarchidae) and the minnows (Cyprinidae).

It must be remembered that certain fish, like the carp, which have
been suggested as useful in the destruction of mosquito larvae are
only of value when young, meaning that their usefulness would be
limited to the spring months. Carp have the added value that they
feed on the snails which act as vectors for certain important parasites
of cattle, sheep and goats.

To be effective, both old and young fish, must have the habit of
feeding on mosquito larvae. Also they should be of small size so
that they may go into the spaces between stems of water plants in
a search for larvae so to speak, as well as to find protection against
larger predaceous fish. They should multiply rapidly and should
beable to live under a great variety of conditions.

In places where fish control is tried, if only small larvae are
found, none large and no pupae, one may be certain that the result

is successful.
FAMILY POECILIIDAE. Top Minnows

Gambusia affinis—In the control of mosquito breeding by the use
of fish, the top minnow (Gambusia affinis) is the best for ordinary
MALARIA 257

purposes. This fish is especially suitable because it feeds on the
surface, it thrives under a great variety of conditions, it is very
prolific, and it will multiply in ponds containing predaceous fish
provided that there is shallow water for refuge. It lives in fresh
or brackish water. This fish is frequently encountered naturally
in water suitable to the breeding of mosquitoes, from Maryland to
Florida, in the Mississippi valley from Illinois to Louisiana, in Texas
and Mexico. It attains a length of from 114 to 214 inches. It
does not lay eggs but gives birth to young fish therefore special
breeding conditions are not necessary. It is cannibalistic. Chem-
icals in the water as those from certain trade wastes like sulphuric
acid, phenol larvacides, and oil will kill them. The water may also
be highly polluted so that mosquitoes such as Culex may breed but
the fish will not.

Plant growth in the water, especially when slightly submerged,
leaves and stems, or floating vegetable growth, afford protection to
larvae against the minnow. The greater amount of protection
afforded by vegetable growth the larger the number of minnows
required.

This minnow is essentially a still water or a pond minnow. It
does not seem to like even moderately running water and therefore it
is not worth much as an enemy of A. punctipennis.

Fundulus notatus is another top minnow that might be worthy of
mention because its range is somewhat farther north than Gambusia
affinis, it is good in mosquito work but not so good as Gambusia.

Lebistes reticulatus: (Guppy, Millions).—This little fish is a native
of Surinam, Venezuela, Trinidad and Barbadoes. The males are
beautifully colored and attain a length of one inch. The females
are somewhat larger'and are silvery yellow in color. They are very
active, very prolific and viviparous. The female brings forth every 4
to 6 weeks from 10 to 50 fry depending upon the age. Males are
ready for breeding when 8 to 10 weeks old, with females of the same
age or older. The young grow rapidly and a few hours after birth
are strong and active. The guppy is of value only as a means of
destroying larvae in warm countries as it would rapidly succumb
to the cold weather of the temperate zone. It hasbeen used success-
fully inthe Virgin Islands. It makes a good aquarium fish.

Two other species which are similar in habits and usefulness to
Gambusia afinis are Heterandria formosa (top minnow) and Mol-

lienisia latipinna. Their ranges, however, are more restricted.
17
258 INSECTS AND DISEASE OF MAN

The range of the former being from North Carolina to Florida and
the latter from South Carolina to Northern Mexico. Both of these
species were introduced into the Hawaiian Islands and are reported
to have been effective against mosquitoes.

The fishes in the United States destructive to the eggs and larvae
of mosquitoes may be grouped as follows: (Economic Circular No. 17,
Bureau of Fisheries, Department of Commerce).

North Atlantic division (south to New Jersey and Pennsylvania)

Fresh-water species—
Fundulus diaphanus (Killifish; Spring Minnow; Fresh-water Killy).
Enneacanthus obesus (Little Sunfish; Banded Sunfish).
Enneacanthus gloriosus (Spotted Sunfish; Little Sunfish; Speckled Perch).
Lepomis gibbosus (Pumpkin Seed; Sunfish; Tobacco-box; Common Sunfish).
Notemigonus crysoleucas (Roach; Shiner; Bream).
Carassius auratus (Goldfish).

Brackish or salt-water species—
Fundulus majalis (Minnow; Mayfish; Killifish; striped Killifish).
Fundulus heteroclitus (Mudfish; Mummichog; Minnow; Common Killifish).
Lucania parva (Rainwater Fish). :
Cyprinodon variegatus (Sheepshead Minnow; Variegated Minnow; Pursy
Minnow).

South Atlantic division.

Fresh-water species—
Gambusia affinis (Top Minnow).
Heterandria formosa (Top Minnow).
Enneacanthus obesus (Little Sunfish; Banded Sunfish).
Enneacanthus gloriosus (Spotted Sunfish; Little Sunfish; Speckled Perch).
Mesogonistius chaetodon (Black-banded Sunfish).
Centrarchus macropterus (Flier; Round Sunfish; Millpond Perch).
Lepomis gibbosus (Pumpkin Seed; Sunfish; Tobacco-box; Common Sunfish).
Notemigonus crysoleucas (Roach; Shiner; Bream).
Carassius auratus (Goldfish).

Brackish or salt-water species—
Fundulus majalis (Minnow; Mayfish; Killifish; Striped Killifish).
Fundulus heteroclitus (Mudfish; Mummichog; Minnow; Common Killifish).
Lucania parva (Rainwater Fish).
Cyprinodon variegatus (Sheepshead Minnow; Variegated Minnow; Pursy
Minnow).

North Central division.

Fresh-water species—
Fundulus diaphanus (Killifish; Spring Minnow; Fresh-water Killy).
Fundulus dispar (Top Minnow).
MALARIA 259

Fundulus notatus (Top Minnow).

Gambusia affinis (Top Minnow).

Lepomis cyanellus (Green Sunfish).

Lepomis gibbosus (Pumpkin Seed; Sunfish; Tobacco-box; Common Sunfish).
Notemigonus crysoleucas (Roach; Shiner; Bream).

Labidesthes sicculus (Brook Silverside).

South Central division.

Fresh-water species—
Fundulus dispar (Top Minnow).
Fundulus notatus (Top Minnow).
Gambusia affinis (Top Minnow).
Centrarchus macropterus (Flier; Round Sunfish; Millpond Perch).
Lepomis cyanellus (Green Sunfish).
Elassoma zonatum (Pigmy Sunfish).
Notemigonus crysoleucas (Roach; Shiner; Bream).
Labidesthes sicculus (Brook Silverside).

Gulf Coast waters.

Fresh-water species—
Fundulus chrysotus
Fundulus nottii (Star-headed Minnow).
Gambusia affinis (Top Minnow).
Mollienisia latipinna.
Centrarchus macropterus (Flier; Round Sunfish; Millpond Perch).
Elassoma zonatum (Pigmy Sunfish).
Elassoma evergladei (Pigmy Sunfish).
Notemigonus crysoleucas (Roach; Shiner; Bream).
Brackish or salt-water species—

 Fundulus grandis.
Fundulus similis (Killifish; Mayfish).
Lucania venusta.

Cyprinodon variegatus (Sheepshead Minnow; Variegated Minnow; Pursy
Minnow).

Goldfish are especially valuable to destroy mosquito larvae in
fountains, aquaria, small artificial ponds and the like.

Tadpoles when present in large numbers are also enemies to
mosquito larvae. :

For further information on the subject of the fishes which are
destructive to eggs and larvae of mosquitoes one should consult the
publications of the Bureau of Fisheries, Department of Commerce,
Washington, D. C.

Area to Be Controlled.—The width of the zone surrounding
human habitations in which mosquito control measures should be
260 INSECTS AND DISEASE OF MAN

instituted depends upon the amount of mosquito breeding. Where
heavy breeding is encountered this zone should be not less than one
mile in width, and perhaps a mile and a quarter, as this distance
represents the maximum flight of Anopheles quadrimaculatus and A.
crucians. Where only light breeding is encountered, from one half
to three quarters of a mile is ordinarily sufficient. This distance is
likewise sufficient in the case of A. punctipennis, the maximum flight
of this mosquito being less than that of 4. quadrimaculatus.

It has not been proved that A. punctipennis is really of great
importance as a disseminator of malarial infection. To eliminate
this mosquito much attention must be paid to streams and ditches
in which it breeds. If it could be shown that punctipennis was
of little importance much work could be avoided thereby saving con-
siderable expense. ;

Mosquito control measures should always begin well before the
mosquito breeding season, and every year before mosquitoes begin to
breed, streams and drainage ditches etc., must be putin proper condi-
tion to perform their functions well without permitting mosquitoes
to breed in them.

Partial control of anopheline breeding will do much towards the
control of malaria. :

Eradication of Adult Mosquitoes in and around Houses.— It is
very important that all Anopheles mosquitoes which have gained
entrance to the dwelling be killed before they are permitted to escape.
Careful search should be made for them on the screens, woodwork,
netting, etc., in the early morning when they are full of blood and
still sluggish. In this way many infected mosquitoes may be killed.

Land around habitations should be kept free of tall grass and
weeds which form resting places and harbor mosquitoes. Such care
also permits the ground to dry more readily under the heat of the
sun. The placing of land under cultivation is incidentally a means
of preventing the breeding of mosquitoes, since such land must be
drained except for the growing of rice. The rice paddy is a serious
problem because no practical means have been discovered to prevent
the breeding of anopheline mosquitoes in rice fields.

Preventive Measures Applied to Malaria Patients and Carriers of
Malaria Parasites

All malaria patients should be protected by mosquito bars and
treated promptly with quinine.
MALARIA 261

Treatment of Carriers.— Campaigns against malaria have been
carried on solely by treating carriers with quinine in the hope that
the carrier state will be overcome and that Anopheles mosquitoes even
though present will find no infected blood on which to subsist. The
treatment of carriers is logical but only when it is attempted, hand
in hand with mosquito control. In the absence of anopheline
mosquitoes the presence of a human case of malaria is obviously of
little moment from the community standpoint. On the other hand,
carriers who come into the community unknown to the authorities
may in the presence of anopheline mosquitoes, furnish the source
from which the community may become reinfected. Very intensive
epidemiological work is required for the detection of even a majority
of the carriers in a locality in which malaria is prevalent, and ordi-
narily the disease cannot be controlled by such methods alone, but
every carrier properly treated with quinine means one less focus of
infection and may mean the prevention of several cases of malaria.
Many carriers can be detected in the course of an intensive epi-
demiological study and these should be treated without charge.

In the routine work of a health department success in discovering
carriers must rest largely upon the cooperation of practicing physi-
cians; employers and others in referring suspected carriers for exam-
ination and treatment. The health department should provide an
approved mailing outfit for submission of blood specimens from
patients and carriers. Quinine should be administered to all car-
riers discovered by laboratory methods. Several methods of admin-
istering quinine have been advocated; 5 grains of the sulphate in
capsules, three times a day is, perhaps as useful as any or 10 grains
every night before retiring, for a period of 8 weeks. If acute symp-
toms are present at the time the patient is first seen they should be
treated by administering 10 grains of quinine sulphate by mouth
three times a day for four days followed by the 8 weeks course of
treatment.

Protection of Healthy Persons

Quin:ne Prophylaxis.— When quinine is circulating in the blood
many sporozoites inoculated by the bite of a mosquito will be promptly
killed before they have time to go on to development. This is the
theory of quinine prophylaxis. While quinine in prophylactic doses
does not always prevent the disease, visitors to malarious sections
should make use of it. For adults 5 to 7 grains may be taken each
262 INSECTS AND DISEASE OF MAN

morning. For children 2 to 3 grains will suffice; less for infants.
Prophylactic doses should be taken throughout the malarial season.
The quinine sulphate is preferable, administered in soft pills or in
capsules. Prophylactic doses of quinine do no harm, even when
taken for prolonged periods. Those who are peculiarly susceptible
to quinine can usually become accustomed to it.

It does not always kill all parasites in the blood, but even so will
prevent them from multiplying to the point where symptoms are
produced. Its use should be kept up for at least a month after cold
weather has set in and likewise after leaving a malarious section in
order to make certain the destruction of parasites which have sur-
vived. Again, to start the use of quinine early, say March or April.
may mean the prevention of a recurrent attack.

Screening.—All houses in malarious districts should be screened
against mosquitoes. Wire screening should have not less than 16
meshes to the inch when used to prevent the entrance of mosquitoes.
A no. 14 mesh if painted will also answer the purpose, and even
ordinary mosquito bar material can be made to serve. Galvanized
iron makes a good screen, resisting rust for several years. It is
cheaper but not as good as copper or bronze wire which lasts for a
much longer period without painting. After a couple of years
galvanized wire should be painted, care being taken not to fill the
meshes with paint to the point that air is excluded thus interferring
with ventilation. Common wire screening should be varnished or
painted as soon as put into use. Window screens should be kept
closed and screen doors should open outward and be provided with a
spring so that they will close automatically. Both should be made
of well seasoned wood. The lower half of the door and that part
which comes in contact with the hand or elbow when the door is
pushed open should be reinforced with heavy wire screening of
coarse mesh. Fire places with open chimneys should also be
screened as well as all other outlets in the house through which
mosquitoes may enter. Cracks in outside partitions may be sealed
with heavy paper. Open fireplaces may be sealed with muslin
held in place by strips of adhesive plaster.

Biologic Barriers.—Advantage is sometimes taken of the fact
that the malaria mosquitoes will suck the blood of animals, even
preferring animals’ blood to that of man. Piggeries may be estab-
lished well removed from human habitations, but between such
habitations and the source of mosquito breeding. In this way, many
MALARIA 263

of the mosquitoes seeking blood will be intercepted by the piggeries
and will not reach human habitations. Such a means of preventing
malaria is not by any means perfect, but plays a part in the general
scheme of malaria eradication. It is even possible to build pig
pens so that they will act as mosquito traps, that is, the mosquitoes
may enter but cannot leave, and they can be killed from time to
time by fumigation.

From observations made in Denmark, it has been suggested that
in a given locality malarial mosquitoes which may have once pre-
ferred human blood, may since have developed a taste for animal
blood. This might account for the great decrease in prevalence of
malaria in certain sections, even though the mosquito is still present.
However, it should be pointed out that a gradual but absolute
reduction in the numbers of insect carriers will account for the
gradual disappearance of the disease even though the insect carrier
may still be present. It may not be possible to exterminate a given
insect but it is possible to reduce it to a safe minimum.
CHAPTER XXVI
YELLOW FEVER

Causative Agent.—Leplospira icteroides described by Noguchi.*
This micro-organism will pass through bacteria-proof filters. The
temperature range favorable for its growth and multiplication is
from 18° to 37°C. (64.4 to 98.6°F.). The most favorable temperature
is about 26°C. It is present in the circulating blood of the patient
during the first three or four days of the illness. -

Source of Infection.—The blood of a patient ill with yellow fever.

Mode of Transmission.—By the bite of an infected Aedes
aegypti (Stegomyia fasciata) mosquito.

Period of Communicability.—During the first three or four days
of illness. :

Period of Incubation.— Three to six days.

Epidemiology.—The endemic centers of yellow fever are found in
tropical America, Mexico, Brazil, Ecuador, Salvador and on the
west coast of Africa. Epidemics within these endemic centers are
not uncommon. If once introduced the disease may become epi-
demic in any country where the suitable insect host is present.
Yellow fever has made its appearance a number of times in the
United States and, before the discovery of the method of transmis-
sion, created panics from time to time, especially in communities
bordering on the Gulf of Mexico. Its last appearance in the United
States was in New Orleans in 1905. The disease is unknown in the
Far East, probably because it has never been introduced.

There seems to be little natural immunity to yellow fever. One
attack confers immunity and second attacks are very rare. It is
less fatal in the younger age groups and in the negro race. Negroes
seem to have a certain degree of racial immunity. At least they
have the disease in milder form than whites, Indians or Chinese,
independently of previous attacks.

*In 1907 Stimpson of the U. S. Public Health Service, working with sections of
organs from persons who died from yellow fever, found a microorganism which he
termed Spirocheta interrogans. Thisis apparently the same microorganism as Noguchi’s
Leptospira icteroides.

264
YELLOW FEVER : 265

The disease is transmitted in nature only through the bite of an
infected mosquito, the Aedes aegypti, which is found in many parts of
the world; including Cuba, South America, Mexico, United States,
Hawaii, the Philippine Islands, Africa, India, etc.

In order to become infected the mosquito must withdraw blood
from the patient within the first three or four days of the illness after
which a period of extrinsic incubation must elapse. This period
never has been found to be less than 12 days and usually over two
weeks varying with the temperature. The lower the temperature
the longer the extrinsic period of incubation. Once infected the
mosquito apparently remains so during her active life, although in
the United States the organism dies out in the mosquito during her
period of hibernation so that it is not possible for yellow fever to be
carried over to another season. An outbreak during the following
year is accounted for by a new introduction of the disease. In coun-
tries south of the United States where the cold season is much shorter
and much warmer the inimical effect of low temperature on the organ-
ism within the mosquito might not be felt and so an infected mos-
quito might be active for a much longer period even into the next
warm season. Infection is not transmitted to the progeny.

Habits of the Yellow Fever Mosquito.—The yellow fever mos-
quito is a small brown mosquito with silver markings on the legs and
back. It is quick to avoid capture and to change its direction of
flight although it does not fly fast. It flies with its legs spread out
and has an annoying hum as it bites, preferring to bite the ankles,
under sides of the wrist and back of neck. It bites in daylight,
preferring the early morning and late afternoon, but avoids direct sun-
light. It is common both in and around houses. The yellow fever
mosquito may also bite after dark, as well as during the day. On
cloudy days in a darkened room they may spend much of the time
resting, preferring dark surfaces like dark clothing on which to rest.
The mouth parts of the female only are adapted for piercing the
skin. The insect, being very wary, is quite successful in avoiding
a swat.

This mosquito is distinctly a domestic mosquito breeding in and
around houses in bottles, cans, pots, cisterns, water barrels, buckets,
roof gutters, etc., which contain clean, fresh water. In the absence
of the usual breeding places, oviposition must, of course take place,
and under such circumstances the eggs may be laid in small pools
around a house which contain clean, fresh water, perhaps in street
266 INSECTS AND DISEASE OF MAN

gutters, collections of water in the axils of leaves or in knot holes in
logs and trees. If hard pressed it has been found even breeding in
slop jars and chambers containing dirty water. When found breed-
ing in unusual places it is likely that complete development rarely
takes place. While this mosquito may not mind some dirt in the
water it is not a cess pool breeder.

The eggs of Aedes aegypti are laid a little above the margin of
the water on the sides of the receptacle, at intervals commencing
from 1 to 7 days after feeding. They are laid singly in small groups
not in rafts like the Culex. They develop in from 2 to 8 days into
larvae which in about a week become pupae. These in turn develop
in about two days into the fully formed insects. The eggs are fusi-
form in shape and roughened in pattern, giving them a pearl neck-
lace-like appearance at the margins.

The distribution of the yellow fever mosquito is limited to the
area between 38° North latitude and 38° South Latitude. Above or
below these boundary lines the cold weather is inimical to the life
of the insect. In the tropics it is present all the year round. In
the sub-tropics where the colder weather brings frost, some of the
females hibernate through the winter as on the Gulf Coast of the
United States. Eggs have been found to retain their vitality for
five months or even longer out of water, and probably this is the
usual means of surviving through the winter. The yellow fever
mosquito does not fly far from her place of birth, rarely more than roo
yards or as far as the houses of adjoining neighbors. Their flight is,
therefore, extremely limited but they may be carried great distances
by ships and occasionally by train.

Recognition of the Disease.—Early diagnosis of yellow fever is
highly desirable. However, diagnosis is difficult in the early stages
and in mild cases, or in some instances one cannot make a positive
diagnosis. In a group of cases diagnosis should be easier. The
disease comes on suddenly. About one-half of the attacks commence
at night. The pains and malaise are much greater than one would
expect from the temperature which is rarely over 103.5°F. In light
cases the temperature is highest on the first day; in moderately severe
cases, on the first or second day when it commences to fall. The
temperature is a continuous one and reaches normal on the 4th, 5th
or.6th day. The headache is severe and invariably present. There
is troubled sleep or insomnia and restlessness. The facies are char-
acteristic early in the disease. There is intense active capillary con-
YELLOW FEVER 267

gestion of the skin and mucous membranes, producing injected and
watery conjunctivae. The upper lip is swollen and the whole face
puffed and red. The gums, tongue and fauces are red.

Too much dependence must not be placed on early yellowing of
the conjunctiva as an aid in the diagnosis as it will ordinarily be found
especially in the tropics, that many persons have some icteric tinge to
the conjunctiva due to other causes. Following the sthenic stage
on about the third day comes the stage of calm which is frequently
very short indeed. It may not be accompanied by any cessation of
the temperature but the distress, restlessness and pain disappear
and the patient is very tired, too tired to speak or even move a finger.
The mind is clear. Stasis or passive congestion now take the place
of the active congestion of the first stage. The face is a dusky yellow,
the conjunctiva are still red but dry and show the tortuous veins.
The conjunctive are now distinctly yellow and the gums are red,
spongy and bleed spontaneously or on very slight pressure. This
bleeding may be elicited by pressing the finger lightly over the upper
lip, not directly on the gums. If the nail be drawn across the skin
on the chest, a yellowish line will be left which finally turns red and
lasts for some time. The stomach is frequently painful, always
tender. This may be elicited by pressure over the epigastrium.

In the more severe cases nausea will now return after being
absent since the onset of the disease and gastric and intestinal
hemorrhages may occur. Jaundice, which was first noticed in the
sclerotics may now be general although frequently it does not make
its appearance until convalescence. While the mind is usually
clear and alert, violent delirium may be present.

Albuminuria is generally found on the evening of the third
day and if not present by the fourth day, it is rarely found later.
Albuminuria comes on even with very little fever, in an amount out
of all proportion to the rise of temperature and increasing in amount
with a falling temperature. Albumen making its appearance earlier
than the third day is a point indicating an unfavorable prognosis.
It is well to look for albumen at the very beginning of the disease as
it may be present from some other cause.

Yellow fever is not a disease of high temperatures, not usually
rising over 103.5°F., though fever of 104° or 105°F. may occur. The
pulse is rather characteristic. At the beginning of the disease, it is
higher than it should be for the amount of temperature, perhaps ten
or twenty beats; it then commences to drop, the distance between the
268 INSECTS AND DISEASE OF MAN

pulse and temperature curves, increasing as the disease progresses.
There is nothing characteristic about the blood picture. There
may be leucopenia, leucocytosis or the blood count may be normal.

Yellow fever must be differentiated from malarial fever, dengue,
influenza and measles. The principal points to be remembered in
the symptoms and signs of yellow fever are the early appearance of"
the albumen, facies, jaundice, tendency to hemorrhages, tenderness
in the epigastrium, lack of correlation between pulse and tempera-
ture, and a clear mind. The leucopenia of dengue, Koplik’s spots
of measles and the plasmodium of malaria should be kept in mind,
although it must be remembered that finding the plasmodium does
not exclude yellow fever, as both infections may co-exist, and that
leucopenia may be present in yellow fever. Where one is not able
to make an early diagnosis of yellow fever, it is better to wait until
the temperature becomes more typical, applying preventive measures
just the same. It is a serious thing to pronounce dengue fever yellow
fever and still more serious to miss a case of yellow fever by calling
it dengue.

Upon post-mortem examination cloudy swelling and fatty degen-
eration of liver cells will be noted. The liver is yellowish in color.
and oily on section. Icterus is marked. The endothelial cells of
capillary blood vessels undergo degeneration. The kidneys are
swollen and congested and show evidence of fatty degeneration.
Hemorrhages may be noted in the skin as well as mucous and serous
membranes. The stomach and intestines contain disintegrated
blood. The spleen does not show any change.

Methods of Prevention and Control.—There are two important
facts to be kept in mind; first, that without the yellow fever mos-
quito, yellow fever cannot spread even though a case is introduced
into a community; second, that the yellow fever mosquito cannot
become infected unless it has bitten a yellow fever patient some time
during the first three or four days of the illness. The essential
things to be done in the control of yellow fever are to protect the
patient against the bite of a mosquito from the very beginning of
the disease; to protect all persons from being bitten by mosquitoes, by
screening houses and sleeping under mosquito nets; to eradicate
yellow fever mosquitoes by oiling, Screening or eliminating their
breeding places.

Early Recognition.—Early recognition is essential. To be on
the safe side during an epidemic or threatened epidemic, every case
YELLOW FEVER 269

of fever should be placed under a mosquito net, even though the
disease may not prove to be yellow fever. Experts familiar with
the signs and symptoms of yellow fever should be available to assist
practicing physicians to make the diagnosis, clinically and at nec-
ropsy. It is advisable to inspect all dead bodies during a yellow
fever outbreak.

Reporting.—All cases of yellow fever should be reported immedi-
ately as well as all suspicious cases.

Placarding.—The house should be placarded.

Isolation.—Isolation under a mosquito net in a screened room
should be required. It is not necessary though better to remove
a patient to an isolation hospital where the proper precautions can
be taken.

Quarantine.—Quarantine may not be necessary, but contacts
should have their temperatures taken twice a day for six days, and
should be required to report to the health officer the minute they
feel ill. Contacts should be vaccinated.

Fumigation.— Disinfection is not required. Fumigation to
kill mosquitoes should be practised in a screened room to which the
patient should be transferred, after which the rest of the house,
including the room previously occupied by the patient should be
fumigated to kill mosquitoes.

Screening.—As a community measure screening on a large scale
is impracticable, as a protection to himself and family each house-
holder should screen his house against mosquitoes, using a wire
screening with a mesh not less than 18 to the inch.

General Measures.—The work of eradicating yellow fever
mosquitoes must be carried on energetically by an organized corps
consisting of laborers working under the supervision of inspectors.
The city should be divided into districts, and a sufficient number of
laborers and inspectors assigned to work therein so that the terri-
tories can be covered once a week. Their duties are to hunt out all
places in which yellow fever mosquitoes are breeding and do away
with them by spilling, filling, oiling, screening. Rubbish, like tin
cans and old bottles that may hold water, and therefore serve as
breeding places for mosquitoes, should be collected and disposed of
adequately. Bottles may be broken and tin cans smashed, so that
they cannot retain water. Cisterns and rain barrels give a great
deal of trouble. Those which cannot be done away with as is the
case in many instances, should be oiled once a week, or made mos-
270 INSECTS AND DISEASE OF MAN

quito proof by tight covers or some form of screening which will not
permit the ingress or egress of mosquitoes. Care must be taken to
screen the openings for ventilation.

The International Health Board has been very successful in the
use of fish for the extermination of larvae of the Aédes aegypti in
Nicaragua, Peru and Ecuador. The fish are placed in wells, cis-
terns, rain barrels, water bottles,—in fact in all but the smallest water
containers. In Perua fishknown locally as Chalaco has been found to
be the most useful. In Nicaragua the Poecilia sphenops has been
successfully used, which is probably the same fish as one used success-
fully in Peru known locally as the Chalquogque. Other fishes used in
Peru are known locally as Life, Majarra (Aequidens rivulatus)
Cachuelo, Tripon, and Bagre (a small cat fish).

When it is possible to empty containers, it should be done once a
week and the containers then exposed to the sun for three hours before
refilling. Straining out the larvae has been tried in an effort to save
the water. The successful use of fish in water containers makes
the entire problem a much easier one to solve. It must not be for-
gotten that even very small collections of water in and around the
house may breed Aedes, as for instance, in the base of flower pots, in
the water pan of a grind stone, baptismal fonts, tins containing water
in which the legs of tables have been placed, roof gutters, and a host of
other places that may easily escape notice. Roof gutters should be
repaired so that they drain completely.

A campaign of education should be carried on so that people srondit
understand what is being done for their good, and what they should
do to help out the situation.

Carter points out that in a small city where there is more or less
yellow fever, where there is no immigration, and where the only
increase of population is due to the births within its boundaries,
yellow fever tends to die out, because eventually an immune popu-
lation develops, and there is no susceptible material left, or at least
there is so little of it, that the probability of a chance infected mos-
quito coming in contact with the right person is very remote. Of
course, given a sufficient length of time during which there is a grad-
ual accumulation of susceptible material, a fresh introduction of the
disease might be the beginning of a limited outbreak depending upon
the amount of available material present and the prevalence of the
mosquito.
YELLOW FEVER 271

It cannot be expected nor is it necessary that all mosquitoes of
the species aegypti be exterminated. All that is necessary is to reduce
their numbers to a minimum. This minimum may be considered as
having been reached when it is shown that mosquito breeding is
taking place on not more than 19, of the premises comprising the
infected community. This percentage may be increased depending
upon the number of immune persons among the population. The
greater the number of immunes the higher the percentage of safety
based on the number of breeding places. On the other hand in a
community with a large susceptible population, where yellow fever is
introduced, the anti-mosquito work must be all the more intensive.

“Breeding” is not to be considered as synonymous, with ““pro-
duction.” In fact in mosquito work it is quite a different matter.
Where only small larvae are encountered no largelarvae and no pupae,
it may be assumed with certainty that the anti-mosquito work is
successful and that while breeding may be taking place, no larvae
will go on to the “production” of adults.

Immunization.—Noguchi has developed a serum which promises
very good results when used on or before the third day of the disease.
He also reports favorable results following the use of a protective vac-
cine made from killed culture of Leptospira icteroides.

A Guide for Formulating a Mosquito Ordinance

The following outline for a Mosquito Ordinance has been sug-
gested by the U. S. Public Health Service (Public Health Reports,
April 2, 1920). Like all model ordinances it may require some modi-
fication in order to adapt it to local conditions.

Model Ordinance

SectION 1. It shall be unlawful for any person to have, keep, maintain, cause,
or permit. within the corporate limits'of....... .. LL. Len any collec-
tion of standing or flowing water in which mosquitoes breed or are likely to
breed, unless such collection of water is treated so as effectually to prevent
such breeding.

Section 2. Collections of water in which mosquitoes breed or are likely to
breed are those contained in ditches, ponds, pools, excavations, holes, depressions,
open cesspools, privy vaults, fountains, cisterns, tanks, shallow wells, barrels,
troughs (except horse troughs in frequent use), urns, cans, boxes, bottles,
tubs, buckets, defective house roof gutters, tanks of flush closets, or other
similar water containers.

Section 3. The natural presence of mosquito larvae in standing or running
water shall be evidence that mosquitoes are breeding there.
272 INSECTS AND DISEASE OF MAN

SeEcTION 4. Collections of water in which mosquitoes breed or are likely to
breed shall be treated by such one or more of the following methods as shall be
approved by the health officer:

(a) Screening with wire netting of at least 16 meshes to the inch each way,
or any other material which will effectually prevent the ingress or
egress of mosquitoes.

(b) Complete emptying every seven days of unscreened containers, together
with their thorough drying or cleaning.

(¢) Using a larvicide approved and applied under the direction of the health
officer.

(d) Covering completely the surface of the water with kerosene, petroleum,
or paraffin oil once every seven days.

(e) Cleaning and keeping sufficiently free of vegetable growth and other
obstructions, and stocking with mosquito destroying fish.

(f) Filling or draining to the satisfaction of the health officer.

- (g) Proper disposal, by removal or destruction, of tin cans, tin boxes, broken
or empty bottles, and similar articles likely to hold water.

SEcTION 5. In case the person responsible for the condition of premiseson
which mosquitoes breed or are likely to breed fails or refuses to take necessary
measures to prevent their breeding within three days after notice in writing
has been given him by the health officer, or within such longer time after such
notice as may be specified in the notice, the said person responsible shall be
deemed guilty of a violation of this ordinance; and for each day after the expira-
tion of three days from the day on which such notice is given him, or for each
day after the expiration of the time specified in the notice, as the case may be,
that the person responsible fails or refuses to take such measures, the said person
responsible shall be deemed guilty of a separate violation of this ordinance, and
in case of such failure or refusal of the person responsible the health officer is
authorized to take necessary measures to prevent the breeding of mosquitoes, and
all necessary costs incurred by the health officer for that purpose shall be a
charge against the person responsible.

Section 6. For the purpose of this ordinance the person responsible for the
condition of any premises is the person using or occupying the same; or, in case
no person is using or occupying the premises, the person who by law is entitled
to the immediate possession of the same; or, in case the premises are used or
occupied by two or more tenants of a common landlord, or form grounds appurte-
nant to a house occupied by two or more tenants of a common landlord, then
the landlord; each tenant, however, is responsible for that part of the premises
which he occupies to the exclusion of the other tenants: Provided, That, in case
the premises are occupied by a tenant under a yearly or monthly tenancy, or
under a lease for not more than a year, or under any lease whereby the lessor is
expressly or impliedly obligated to keep the premises in repair, and the collection
of standing or flowing water in which mosquitoes breed or are likely to breed
is owing to the disrepair of the building or buildings, or to any natural quality
of the premises, or to any condition that existed at the time when the tenant
entered into possession, or to anything done on the premises by the landlord
during the existence of the tenancy or lease, then, and in such case, the landlord
is the person responsible: Provided further, That any person who has caused to
YELLOW FEVER 273

exist on any premises of which he is not the owner, landlord, occupant, or tenant
any collection of water in which mosquitoes breed or are likely to breed is
responsible, as well as the owner, landlord, tenant, or occupant, as the case
may be.

SECTION 7. For the purpose of enforcing the provisions of this ordinance,
the health officer, or his lawful subordinate, may at all reasonable times enter in
and upon any premises within his jurisdiction.

SEcTION 8. Any person found guilty of a violation of this ordinance, as
described in section 5 hereof, shall be punished by a fine of not less than one
dollar ($1) and not more than twenty-five dollars ($25).

SectION 9. This ordinance shall be in full force and effect on and after the
RAINE day from the day on which it is approved.

18
CHAPTER XXVII
DENGUE FEVER

Causative Agent.—Unknown. A filterable virus which is pres-
ent in the blood of patients from the second to the fifth day.

Source of Infection.— The virus circulating in the blood is trans-
mitted from the patient to a well person through the bite of a mos-
quito, Aedes aegypti (Stegomyia fasciata). The disease may also
be transmitted by the direct inoculation of blood from a patient.

Period of Communicability.—In order to withdraw the virus the
mosquito must bite the patient from the second to the fifth day of
the disease.

Period of Incubation.— Three to ten days.

Epidemiology.— Dengue fever is a disease of tropical and sub-
tropical countries and is common in India, China, and the Philippine
Islands. A number of epidemics have occurred in the Southern
United States. It appears in epidemic form spreading rapidly, and
attacking large numbers of people at or about the same time, like
epidemic influenza. It attacks both sexes. There is no racial
immunity. Death rarely occurs. One attack gives but uncertain
immunity. The extrinsic period of incubation is indefinite. There
may be two similar diseases included under the term Dengue fever.

The distribution of dengue fever corresponds rather closely to the
distribution of Aedes aegypti which in the United States is not found
further North than about 38°.

Habits of the Aedes aegypti (Stegomyia fasciata).—See Yellow
Fever.

Recognition of the Disease.— The disease sets in abruptly with
intense supra and post orbital headache, and chilly sensations.
There are pains in the back and very severe pains in the muscles and
around the joints. The temperature rises rapidly to 102° or 105° F.
The face is blotchy, the eyes are injected, the mucous membrane is
flushed. The pulse rate may be slow but usually varies directly with
the temperature. There is great depression, both mental and phys-
ical, malaise, loss of appetite, etc. The temperature remains high
for three or four days when it drops and is followed by a period of

274
DENGUE FEVER 275

remission during which the patient feels comparatively well. This
period of remission is sometimes extremely short and may pass
unnoticed, or it is usually somewhat indefinite lasting from 12 hours
to three days. After the remission the fever again rises abruptly and
the patient is even more severely ill than he was during the first stage.
The latter stage, however, does not last so long. The rash, which is
more or less typical of the disease, may appear with the intermission
or with the second rise of temperature. It first appears on the dorsal
surface of the hands and feet and the forearms and legs and after-
wards may be more widely spread. It is somewhat variable, some-
times absent or at least very evanescent. It has been described as a
rash more like measles, but it is as frequently a punctate decidedly
bright rosy blush, disappearing on pressure more like scarlet fever.
With the drop in temperature there may be epistaxis, profuse sweat
or diarrhoea. Leucopenia is marked and is found early in the disease,
about the second day. There is also a reduction of polymorphonu-
clear leucocytes. Albuminuria is absent. Dengue fever must be
differentiated from yellow fever and influenza, as well as from measles,
scarlet fever and even variola.

Methods of Control.—The patient should be kept covered by a
mosquito net at least five days from the beginning of the diseases
Destruction of the mosquito is called for. (See yellow fever.)
CHAPTER XXVIII
FILARIASIS

Causative Agent.—Filariasis is caused by a thread-like round
worm, Class Nematoda and Family Filariidae, the embryos of which
can usually be found circulating in the blood sometime during the
24 hours. There are at least five more or less important species
affecting man as follows:

Filaria bancrofti, the adult forms of which are located in the
lymphatics and lymphatic glands.

Loa loa

' Onchocerca volvulus the adult forms of which are
Acanthocheilonema perstans | located in the connective tissues.
Dracunculus medinensis |

Of these Filaria bancrofti is the most widespread and is the most
important.

FILARIA BANCROFTI

Source of Infection.— The adult worms are located in the lym-
phatic system. The embryos known as microfilariae are found circu-
lating in the blood at night, and not at all or in very small numbers
during the day. :

Mode of Transmission.— Transmission from person to person
is brought about through the bite of an infected mosquito, commonly
Culex quinquefasciatus, although other mosquitoes have been
implicated.

Period of Communicability.—As long as microfilariae are circu-
lating in the blood. :

Period of Incubation.— Indefinite.

Epidemiology.—Filariasis is a disease of tropical and subtropical
countries. In the United States cases have been traced to Charles-
ton, South Carolina, where the infection is present. It affects any
‘age and either sex.

Man is the definitive host. It is in man that the sexual cycle

occurs, and damage is done by the presence of the filariae only by
276
FILARIASIS 277

accident so to speak. The fully formed embryos (microfilariae) .
do no harm even though they may be present in large numbers.
They are small enough to pass through the capillaries. An accumu-
lation of adult worms, or perhaps embryos given off prematurely
when they may be coiled or looped, may offer an obstruction in the
lymphatic vessels or give rise to irritation. The mosquito is the
intermediate host. It suffers from the presence of the larval filariae.
Its life is shortened.

The habits of Culex quinquefasciatus indicate strongly that it
is the common transmitter of Filaria bancrofti. It is domestic in
its habits breeding in and around houses in receptacles containing
filthy water, in cesspools, open sewers, catch basins, accumulations of
water in city dumps etc. In the house it is especially voracious at
- night and therefore bites when the microfilariae are present in the
peripheral blood in largest numbers. Where the disease is present,
Culex quinquefasciatus is also found. However the mosquito is com-
mon in many places where the disease has never been known to occur.

Life History of Filaria Bancrofti—1It is convenient to start with
the embryos circulating in the peripheral blood. They do not
multiply in the blood. They are taken into the stomach of the
mosquito during the act of biting. Neither do they multiply in the
stomach of the mosquito. If only one is taken in only one can be
given out. Within the stomach of the mosquito, the embryo sheds
its sheath, makes its way through the walls of the stomach and into
the thoracic muscles where it undergoes a metamorphosis becoming
a larva. After a variable time, about two weeks, the larva migrates
through the connective tissue spaces to another part of the mosqui-
toes body, that is, it may pass towards the abdomen, into the legs,
into the head, into the antenna etc., or into the labium. In the
latter event, it is in a position to pass out and infect an individual.
When the infected mosquito bites, the stilette bundle penetrates the
skin, while the labium, which does not enter the skin, bends under
like a bow, its distal end touching the skin with the labellae spread
out steadying the piercing organs. The filaria coming down through
this labium pierces Dutton’s membrane, and is deposited on the skin
of the human host. It then wriggles its way through the skininto the
lymphatic system where it matures and becomes a sexually developed
adult. Here nothing further occurs unless a representative of both
sexes happens to find its way into the same gland. In this event one
female may produce as many as 1ooo embryos or more at one time.
278 INSECTS AND DISEASE OF MAN

The embryos then escape from the lymphatic system and circulate
in the blood as microfilariae. The cycle is then complete.

The adult male filaria is about 114 inches long, the female about
314 inches. The microfilariae are about 30 times longer than and
about as wide as the diameter of a red blood cell.

The periodicity displayed by the microfilariae of Filaria ban-
crofti seems to bear some relation to the hosts periods of sleeping,
for it has been observed that in persons like night watchmen who
sleep during the day, instead of during the night, microfilariae may
be observed in greatest number during the day.

Complications and Sequellae of the Disease.— Persons may have
filariasis without knowing it or the disease may manifest itsself by
attacks of fever and lymphangitis, filarial orchitis and hydrocele,
dilatation of the lymph vessels, varicose veins, chyluria, lymphuria,
elephantiasis etc.

Other Filariae

Loa Loa.—Mention should be made of Loa loa which is found
on the west coast of Africa and disseminated by the mangrove fly,
Chrysops dimidiata. The adult lives in the connective tissues and
may wander about so that its course may be marked by an oedema-
tous track. It is more frequently noted about the region of the eye.
The microfilariae circulate in the blood ‘as in the case of Filaria
bancrofti but are diurnal in their periodicity. For this reason the
parasite has been called Filaria diurna.

Dracunculus medinensis.—Related to the Filariae is Dracun-
culus medinensis or Guinea worm as it is sometimes called. Males
and females live in the connective tissue about the mesentery.
After fertilization has taken place the males probably die and the
females migrate downward towards the legs and feet. Arriving
under the skin the female bores her way through its deeper layers,
a little bulla on the surface marking her presence. (Contact with
water causes the bulla to burst and the embryos to be liberated.
When discharged into the water of a stream or pond the embryos
are taken in by a small crustacean, Cyclops, which when imbibed by
man with the drinking water dies in his stomach. The embryos
are released, bore through the stomach wall and find their way to
the connective tissue of the mesentery, where they develop into
adults thus completing the cycle.
CHAPTER XXIX

PAPPATACI FEVER
(Three Day Fever)

Causative Agent.—Unknown. A filterable virus, perhaps a Lep-
tospira. .

Source of Infection.—The blood of the patient during the first 24
hours of the illness.

Mode of Transmission.—The blood is withdrawn and infection
transmitted to another person through the bite of a moth midge,
Phlebotomus papatasii Scopoli of the Family Psychodidae. Other
species of the genus can also carry infection.

Period of Incubation.—The period of incubation is from 3 to 7
days. The extrinsic period of incubation is from 7 to ro days.

Epidemiology.— This fever is probably rather wide spread, in
coastal areas in tropical and sub-tropical regions of both hemispheres.
It has been studied in the Balkan States, also reported from Haiti,
India, Malta etc. It is a disease of the late spring and summer.
One attack produces an immunity, but relapses may occur. It is
rarely fatal. Tt is not unlikely that the fly may transmit infection
to her offspring.

Phlebotomus  papatasii—This dipteron is a hairy little insect
about 14s inch’in length. Its small size enables it to pass through
a very fine mesh. It is a vicious biter. Only the females bite, and
that after sundown and principally in the house. It avoids wind and
bright daylight. During the day the midges rest in cool, dark places,
in houses, hollows of trees, in latrines, etc. A full meal of blood is
taken after fertilization, and then the eggs are laid in damp places, in
cracks in bricks, rocks, stones, in caves, etc. The egg takes from 4
to 14 days to hatch, according to the temperature. The larvae are
attached to the surface on which they live. The larval stage lasts
from 8 to 28 days.

Recognition of the Disease.—The disease resembles very closely
dengue fever except that the fever only lasts about three days and
there is no secondary rise. The pulse is slow and there is no eruption.

279
280 INSECTS AND DISEASE OF MAN

Leucopenia is present. Other fevers have been described as seven
day fever, six day fever, and it is very likely that these are dengue
fevers where the fever is continuous.

Methods of Control.—The patient must be screened the first two
days of the disease. The mesh must be very small (45 meshes to
inch) as it is very difficult to keep the moth midge out.

Abolish the breeding places, by leveling, filling and tatiping;
removal of moist debris; permitting access of sunlight; painting
crevices; whitewashing, painting, tarring etc.; cutting weeds so that
holes may be filled and sheltered hiding places abolished.
CHAPTER XXX
TRYPANOSOMIASIS

Causative Agents.— There are a number of different species of
Trypanosomes affecting animals but so far only three have been
definitely identified with disease in man namely, Zrypanosoma
gambiense and Trypanosoma rhodesiense, causing African Sleeping
Sickness, and Schizotrypanum cruzi which is the cause of South
American Trypanosomiasis.

Trypanosomes affecting lower animals are as follows:

T. evansi causing ‘‘surra’’ in horses and mules in India, Philippine
Islands etc.

T. brucei causing ‘“‘nagana’ in horses, mules, dogs and cattle in
Central and South Africa.

T. equinum causing “mal de caderas” in dogs and horses in
South America.

T. equiperdum causing ‘‘Dourine” a disease of horses contracted
through coitus and seen in India, North Africa, and at times in
Europe and North America.

T. lewist of rats which apparently produces no lL effects on its
host.

These Trypanosomes are probably carried by non-biting flies
which may deposit Trypanosomes on sores, and by biting flies
such as Glossinae, Stomoxys, and Tabanidae. I". lewis: is trans-
mitted by the rat flea and perhaps the louse. Whether all of the
above Trypanosomes of lower animals are distinct species is doubtful.
A few cases of infection of man from some of these Trypanosomes
have been reported.

AFRICAN SLEEPING SICKNESS

Causative Agent.—7rypanosoma Senpiense and Trypanosoma
rhodesiense.

Method of Transmission.—The parasites are carried from the
sick to the well by certain biting Muscoidean flies, the Tsetse flies,

comprising the genus Glossina. Two species of Glossinae are
281
282 INSECTS AND DISEASE OF MAN

‘involved, Glossina palpalis carrying T'. gambiense, and Glossina morsi-

tans carrying 7. rhodesiense. Other members of the genus do not
carry the disease. The fly is the definitive host and man is the
intermediate host. The disease is transmitted by the fly mechanic-
ally or cyclically.

Source of Infection.— The causative agent is found in the blood,
in the enlarged lymphatic glands and, in later stages of the disease,
in the cerebro-spinal fluid. It is taken from the blood by the fly at
the time of biting. It must be kept in mind that certain of the
large wild animals of the locality and cattle may also act as reservoirs
of infection.

Period of Communicability.—As long as there are trypanosomes
in the peripheral blood and a sufficient number of insect hosts in the
locality.

Period of Incubation.—Ten to twenty-one days.

Epidemiology.—Sleeping sickness is found only in certain parts
of Africa never in districts where the tsetse fly is not found. On
the other hand there are districts in Africa where the fly is found
but the disease is absent. In such districts the introduction of a
case of the disease would probably result in its spread. A tsetse fly
has been found in Arabia but the disease has never been reported
from that country. Cases have been introduced into the West
Indies and rarely a case is imported into the United States but
secondary cases never occur because the insect host is not present.

On the West Coast of Africa where the disease has been present
for many years, though endemic it does not become epidemic. This
suggests that long exposure to the infection among a people
produces a certain degree of immunity. 1

All ages and both sexes are susceptible. gz

The tsetse fly does not fly far from its breeding places which are in
the jungles bordering streams. It has been estimated that the
flight distance is not more than 8o yards but they may be transported
much further by boats and other vehicles or on animals. They
subsist on the blood of warm blooded animals (perhaps the crocodile
as well) and bite in the day time principally around mid-day. The
larva is carried in the abdomen of the female until it is nearly ready
to pupate when it is extruded and in a short time finds its way into
the ground about the roots of trees to enter the pupal stage, which
lasts about one month. A second larva may be produced in about
two weeks.
TRYPANOSOMIASIS 283

The disease may be transmitted either direct (mechanically)
when at the time of biting the fly is harboring trypanosomes on or
in its proboscis, as would be the case when it had just bitten an
infected individual. It is very persistent in its efforts to secure a
full meal of blood, biting person after person if disturbed, until it is
replete. The disease may also be transmitted cyclically i.e. after a
change has occurred in the trypanosomes and they have invaded
the salivary glands. Briefly the changes that take place consist
of a multiplication by division in the stomach of the fly and the
development into long highly motile bodies which in 12 to 20 days
find their way into the salivary glands where in 2 to 5 days they
undergo fission forming what appears to be minute trypanosomes.
High atmospheric temperature hastens, low temperatures retard
development. The extrinsic period of incubation under favorable
conditions is from about 20 to 24 days.

Recognition of the Disease.— Three stages of the disease may be
recognized.

In the first stage the patient is apparently well or only slightly
sick with light intermittent fever, some muscular weakness and
increase in pulse and respiration rate after slight exertion. There
are no mental symptoms. Enlargement of the superficial cervical
lymph glands can be detected and trypanosomes can be demonstrated
in the blood drawn from these glands and usually from the peripheral
circulation.

In the second stage the symptoms mentioned above become more
pronounced and mental disturbances begin to manifest themselves.
Trypanosomes are present in larger numbers.

In the third stage mental symptoms are pronounced. There are
mental dullness, apathy, hesitancy of speech, lack of interest in
surroundings; tremors of hands and tongue and finally coma and
death. In this stage trypanosomes are also found in the cerebro-
spinal fluid.

Methods of Control.—The following have been attempted or
advised.

Location of camps away from streams or even the removal of
whole villages to locations unsuitable to the propogation of the
tsetse fly.

Personal protection against the bite of the fly especially during
the day.
284 INSECTS AND DISEASE OF MAN

Cleaning out underbrush and low-lying branches at the location
of fords, wharves, villages, washing places and sources of drinking
water etc.

Isolation of infected individuals, protecting them from the bite
of the fly and treating them with atoxyl-tartar emetic.

Prevention of the migration of infected persons to non-infected
regions where the tsetse fly is present. The enlarged cervical glands
and the detection of the parasites in blood aspirated from these
glands are practical points in the diagnosis when attempting to
restrict immigration.

SOUTH AMERICAN TRYPANOSOMIASIS

South American Trypanosomiasis is caused by the Schizotry-
panum cruzi which is transmitted by a bug, Conorkinus megistus, a
winged form of the Order Hemiptera. This insect lives in inhabited
houses and is a vicious biter, biting especially on the face. Children
are most frequently bitten and are therefore most liable to contract
the disease.

The disease may be acute or chronic. The acute disease develops
with fever, first continuous, with not more than the usual morning
fall and evening rise and is accompanied by oedema of the face.
It finally becomes remittent with periodic intervals. During the
fever trypanosomes can be found in the peripheral blood. There is
enlargement of the thyroid and cervical lymphatic glands, spleen
and liver. Transient oedemas may appear. Death may ensue or
the disease may assume the chronic form which in type may be myx-
oedematous, pseudomyxoedematous, cardiac or nervous. South
American Trypanosomiasis is associated with a high case fatality
rate.
CHAPTER XXXI

TULARAEMIA
(Deer Fly Fever)

Causative Agent.—Bacterium tularense, a small non-motile, gram
negative micro-organism, occurring in the rod and coccus forms,
stains readily with aniline gentian violet, difficult to stain in tissues.

Source of Infection. Material from the gland of the infected
person or the blood of the infected animal. The urine and nasal
secretions may also produce the disease. In Utah, the jack-rabbit
is probably the important reservoir of the infection in nature. The
infection is also present among the ground squirrels of California
(Citellus beechyi) and the lesions produced are quite similar to
plague. It is probable that the disease in rabbits has a wide distri-
bution in the United States.

Method of Transmission.—The disease is transmitted to man by
the bite of a horse fly, (Chrysops discalis, one of the so-called deer
flies) which has previously bitten an infected animal. Those
butchering or dissecting infected animals may also develop the
disease. In fact, the causative agent seems to be capable of passing
through the unabraded skin.

Period of Communicability.—As long as the causative micro-
organism exists in the peripheral blood of the animal reservoir. It is
rare to recover the causative agent from the peripheral blood of a
human case. It may remain in the arthropod host for long periods.

Period of Incubation.—Within forty-eight hours.

Epidemiology.—The micro-organism was first described in 1911
by McCoy and Chapin who recovered it from ground squirrels
(Citellus beecheyi) in California, which were affected with a plague-
like disease. Wherry in 1913, 1914, and 1916 described three cases
of infection in man in Cincinnati, Ohio. All had ulcerative conjunc-
tivitis, enlarged glands of the neck, and general symptoms. One
was a butcher, one was the wife of a farmer, who had handled wild
rabbit meat, and the Bacterium tularense was recovered from rabbits
found dead on a farm four miles distant from the farmer’s residence.

285
286 INSECTS AND DISEASE OF MAN

The third case was in a domestic who two days before had prepared
wild rabbits for the table. The disease has also been reported in
Washington D. C. among market men who handle wild rabbits.

The fly-borne disease, Tularaemia,* seems to be confined to a
section of the United States corresponding to the distribution of
the fly, especially Utah and Idaho. Like plague, it is primarily a
disease of rodents, man being infected by accident. Jack rabbits
are the reservoirs of infection in Utah although the disease may also
affect the ground squirrels (Citellus mollis) of the locality and
perhaps other rodents. It is not unlikely that the disease is spread
from rabbit to rabbit by means of the rabbit tick (Haemaphysalis
leporis-palusiris) and the rabbit louse (Haemodipsus venlricosus) as
laboratory experiments show that infection may readily occur in
this way. It is also present in nature in the Rocky Mountain
spotted fever tick of the Bitter Root Valley.

The longest time which elapsed between the time of biting an
infected animal by the horse fly and subsequent development of the
disease in healthy animals after being bitten by the same flies
was 4 days, although by inoculating the body of the infected flies
they were found to be infective up to 14 days. The longer they were
kept the less tendency they showed to be infective. The process
of transference of infection is probably mechanical.

The disease may affect all ages and both sexes, but particularly
attacks those working in the fields. The seasonal prevalence cor-
responds to the seasonal prevalence of the fly, June, July and until
late in August. The fly bites on the exposed surfaces of the body.

In the laboratory, successful transmission experiments have been
carried out with the horse fly (Chrysops discalis) the stable fly (Sto-
moxys calcitrans) the rabbit louse (Haemodipsus ventricosus) the
mouse louse (Polyplax serratus) the ground squirrel flea (Cerato-
phyllus acutus) the bed bug (Cimex lectularius) and the tick
(Dermacentor andersoni).

Recognition of the Disease.—The site of the bite can usually be
observed as an ulcer. The adjacent glands are practically always
swollen and tender and usually suppurate. :

The disease comes on suddenly and is very disabling, often caus-
ing two or three months of sickness. There are fever, pains, and

* This name was given to the disease by Surgeon Edward Francis, U. S. Public
Health Service. He was the first to recognize the condition as being a_manifesta-

tion of Bacterium tularense infection in man, and to study thoroughly its etiology
and epidemiology.
TULARAEMIA 287

great debility. The mortality is low. Diagnosis can be made
readily by inoculating infective material taken from the enlarged
glands of the patient into guinea pigs or rabbits subcutaneously in
the region of the abdomen and subsequent recovery of the micro-
organism from animals which usually die within a week showing
hemorrhagic oedema at the site of inoculation, enlarged lymph
glands of the groin undergoing granular caseation and great numbers
of small necrotic foci in the spleen and liver.

The best mediums for original isolation of the micro-organism
from animals are: serum-glucose-cystine-agar or coagulated egg
yolk, glucose-blood-agar, or serum-glucose-agar. To both of the
latter should be added a good sized piece of the spleen of the infected
animal, thus inoculating and enriching at the same time.

The blood of the patient will give a positive agglutination
reaction.
CHAPTER XXXII
PLAGUE

Forms of Plague.— Three clinical forms of plague have been
described, bubonic, septicaemic, and pneumonic plague. The first
is the common form and reveals itself by the formation of a charac-
teristic bubo in one of the glandular regions. It is primarily a
disease of rodents, from which it is transmitted to man by a biting
insect, a flea. Septicaemic plague is that form which develops as a

- septicaemia from the very beginning, a primary bubo being absent,

or the patient dying early before the characteristic bubo manifests
itself. This form of the disease is also due to the bite of an infected
flea. It is not unlikely that septicaemic plague is frequently a form
of bubonic plague in which the bubo has been overlooked, but may
be disclosed at autopsy. Practically every case of bubonic plague
is septicaemic some time during its course. However, a form of
plague, the so-called ambulant plague, has been noted, in which the
patient is only mildly ill and able to go about. Here the causative
agent is probably limited to the glands. Pneumonic plague is that
condition in which there is primarily a pneumonia caused by the
plague bacillus. It is spread direct from man to man as in the case
of other diseases of the respiratory type. A secondary plague pneu-
monia is at times found as a complication of one of the other forms
of plague, and it is likely that under suitable conditions this may be
the start of an epidemic of primary pneumonic plague. These condi-
tions seem to bear a close relation to low atmospheric temperature
and tightly closed overcrowded rooms in which a high degree of
relative humidity occurs.

Causative Agent.—Plague is caused by the Bacillus pestis, a
nonmotile, gram-negative bacillus characteristically staining at the
poles and sometimes taking on a coccoid form in the tissues. Even
the coccoid form retains the tendency to polar staining. © The micro-
organism is found in the plague pustule when that is present and
in the bubo in great numbers, in the blood, spleen and liver and in

foci of infection in the lungs.
288
PLAGUE 289

BUBONIC PLAGUE

Period of Communicability.—The disease is communicable as
long as septicaemia exists and the suitable insect host is present.

Method of Transmission.—Bubonic plague is primarily a disease
of rodents, commonly rats, and it is transmitted from rodent to rodent
and from rodent to man by a flea which has previously bitten a
septicaemic plague animal.

Period of Incubation.—The period of incubation is from two to
five days, usually two or three days.

Epidemiology.— Plague is a disease of great antiquity. Many of
the plagues written of in history were bubonic plague, notably the
one which spread throughout the Roman Empire in the sixth century,
and the great plagues of Europe in the fourteenth, fifteenth and
seventeenth centuries. In 1665 it was estimated that in London
‘alone 68,596 people died of plague. In more recent years the disease
has visited many parts of the world, including the United States,
Porto Rico, Philippine Islands, Hawaiian Islands, Australia, South
Africa, Peru, Ecuador etc. Epidemics of bubonic plague have
occurred annually in India and China during the past thirty years,
and the disease is common in Egypt, Senegal and Uganda in Africa.

Plague is introduced into a country through the migratory habits
of rats resulting in their being transported from place to place by
ships. This means that practically every port of entry is open to the
danger of the introduction of plague infection. Rats may also be
carried in freight trains. From ships they land by way of cargoes,
gangways and hawsers. :

Epidemics of bubonic plague are accompanied by epizootics among
rodents. Of all rodents, the rat is the one to be given greatest con-
sideration from the standpoint of prevention. The fact that an epi-
zootic in rats precedes and is coincident with epidemic plague in man
has been observed for many years, but it was not until a number of
years after Yersin discovered the plague bacillus in 1894, that the
true relation of the disease in rats to the disease in man was under-
stood. To account for the transmission of the disease from one ani-
mal to another the insect theory was advanced, and in recent years
the British Indian Plague Commission, as well as other investigators,
have proved conclusively that the flea is responsible. Their experi-
ments were numerous and extensive. They permitted direct con-
tact of a plague rat with a healthy rat in the absence of fleas and

found that the healthy rat remained well, whereas when fleas were
19
200 INSECTS AND DISEASE OF MAN

introduced the healthy rat contracted the disease. A single flea
may transmit the disease. The Commission found that only in rare
instances did a healthy rat contract plague by eating the carcass of
a plague rat. They were able to produce plague in guinea-pigs by
permitting them to live in houses from which plague cases had been
taken, but they were able to prevent infection by placing the animals
in cages hung above the jumping distance of fleas or by surrounding
the cage with sticky fly paper. The experiments were varied in
many ways. Plague bacilli were readily demonstrated in the
stomach and intestines of the flea after biting a septicaemic plague
rat, as well as in the fecal discharges. Inoculation of the material
into rats or guinea-pigs produced plague.

Ordinarily the introduction of a case of human bubonic plague
into a community would be, in itself, of little moment, although small,
self-limited epidemics of the disease may have occurred as a result of
direct transference of plague bacilli from man to man by the human
flea (Pulex irritans) or the bedbug (Cimex hemipterus or C.lectularius).
However, this is more or less a theory and at any rate must be of rare
occurrence. On the other hand, the introduction of a rat infected
with plague might be a serious matter. Its presence would be
unknown and the gravity of the situation would not be realized until
the infection among rodents had become widespread and human
cases began to appear. The finding of human bubonic plague indi-
cates the necessity for immediate investigation with reference to
rat infection. :

Other rodents which are known to be concerned with the spread
of plague are, the ground squirrel of California (Citellus beecheyi)
and the Siberian marmot (Arctomys bobac). The flea concerned is
the one having the plague animal as its normal host. For instance
in the case of rats it is either Xenopsylla cheopis, the common rat flea
of India and which is also found in the United States, or, Ceratophylius
fasciatus, the common rat flea of Europe, also more or less prevalent
in the United States. In the case of the California ground squirrel
the flea concerned is either Hoplopsyllus anomalus or Ceratophyllus
acutus. The flea of the Siberian marmot is Ceratophyllus silvantiers.

The incidence of bubonic plague shows a marked seasonal varia-
tion depending upon climatic conditions. A moist atmosphere at a
temperature of approximately 70 degrees F. is most favorable to the
production of an epidemic. Cold winters and hot dry summers are
unfavorable. This is because atmospheric temperature and
PLAGUE 201

humidity, especially the latter, have an important bearing on flea
breeding and flea Jongevity. Epidemic plague attains its greatest
proportions when rat fleas are most prevalent i.e. when breeding has
been most active and when fleas can survive longest after their
normal host (the rat) has succumbed to the disease.

When atmospheric conditions are favorable fleas can live for
considerable periods of time even unfed but Bacot and Martin have
shown that the survival of X. ckeopis apart from its host is in inverse
proportion to the saturation deficiency of the air or, in other words, it
is proportional to the rate at which the flea looses moisture. It has
also been shown that egg laying and the development from egg to
adult are most active when the weather is wet and the temperature
moderate and least active under dry and hot conditions.

Itis reported from India that in Belgaum plague can only assume
epidemic proportions in the latter half of the year, July to November,
and at this period rat fleas are most prevalent averaging in July,
August and September 18 fleas per rat, while in non-epidemic seasons
the average is only 4 or 5 per rat.

Bacot states that to induce ova of X. ckeopis to hatch, a tempera-
ture of over 6o degrees F. seems to be necessary while C. fasciatus
can hatch at an average temperature of 41 degrees F. The larvae of
X. cheopis cannot survive below go degrees F. while C. fasciatus finds
this temperature quite suited to its needs. In its reactions to tem-
perature eggs and larvae of P. #rritans resemble more closely X.
cheopis. Experiments with the pupal stage gave results similar to
the larvae. Bacot further states that at 45 to so degrees F. with
nearly saturated air fleas can live for many days unfed :—X. cheopis,
38 days; C. fasciatus, 95 days; P. irritans, 125 days; Ct. canis, 58
days. Kept in the ice-box and fed on the normal host X. cheopis
lived roo days; C. fasciatus, 106 days; P. irritans, 513 days and Ci.
canis, 234 days. Under natural conditions they would probably
live longer.

Bacot also states that X. cheopis has the habit of spending more
time on the rat than in the rat’s nest while the reverse is true of
C. fasciatus.

The seasonal prevalence of bubonic plague is naturally not the
same in all countries for, as has been said before, it is dependent upon
climatic conditions. For instance, in certain parts of India plague is
most prevalent in the first half of the year, the epidemic reaching
its height in the early Spring; in other parts of India the epidemic
292 INSECTS AND DISEASE OF MAN

reaches its peak in the Fall months, in Egypt the greatest number of
cases occurs during the Spring months; in those parts of the United
States and England which have been visited by bubonic plague,
cases in man begin in the late spring or early summer and attain
their greatest numbers in the late Summer or Fall months. There
are parts of the world where climatic conditions are favorable to the
spread of plague during any month of the year, and there are parts
of the world, as for instance the North Atlantic seacoast of the
United States, which, so far as known, have never been visited by
plague and where the disease might not be able to survive for any
length of time even though introduced. Robertson suggests that
atmospheric humidity and temperature are such that the flea popula-
tion is reduced to a safe minimum during a larger part of the year.

There are parts of India which have never experienced an epi-
demic of plague not-with-standing they are near to and have free
communication with regions where plague is prevalent. Rats are
present, rat fleas are present and climatic conditions are favorable
during some part of the year. Major Cragg has shown that the rat
flea which predominates in these areas is Xenopsvila astia or X.
brasiliensis and not X. cheopis although the latter is present in
smaller numbers. Differences in habits of X. astie may account
for the absence of plague. X. astia is the predominating rat flea in
Colombo which is remarkably free of plague. It is possible that X.
cheopis is the true plague flea and that while other rat fleas may
carry plague under experimental conditions they do not usually do
so in nature.

It is not always possible to trace with certainty the source of
infection in every human case. A case may develop in a house which
so far as known may be free from rats and which may have no known
relation to a plague focus. Epidemiological study must include not
only an investigation of conditions on the premises where the case
develops but also conditions at the place of work, or the place where
the patient eats, plays or visits. The guinea pig control may enable
one to trace the source of infection, even though a search on the
premises for infected rats has not been successtul.

Too much stress must not be laid upon the possibility of carrying
plague fleas in clothing as a factor to account for the development of
human plague, for it is probably an unusual way. When infected
fleas are carried they are usually transported on the body of the rat
during its wanderings from place to place. It is not necessary to
PLAGUE 203

assume that rats always travel on foot. Many times they are carried
in merchandise or in freight cars and escape with their fleas upon
reaching the point of destination. This explains why plague may
appear in a town far removed from the original focus of infection, the
intervening towns having escaped. In rural districts rats often
occupy nests of other animals such as the rabbit, squirrel, or
field rat. There is then a transfer of fleas between different rodents
and thus the possibility of transferring infection to the rodents
common to rural districts. This has been the case with regard
to the ground squirrel of California and accounted for the finding
of infected wild rabbits in England and field rodents in South Africa.

Plague attacks all ages and both sexes. It is more liable to
attack those whose habits of living and occupation bring them
in more or less direct contact with rats, such as crews of ships, steve-
dores, dock laborers, stablemen, warehouse men, etc. or those who
permit their houses to become rat infested. In ports the highest
incidence is likely to occur in the vicinity of the water front and
along or near water ways. It is not necessarily confined to such
areas however, because through their migratory habits, rats may
carry it to many parts of the city and into the country districts.

Where the black rat is present, it is the greatest menace. Itisa
climber and inhabits the upper parts of a dwelling thus coming into
closer contact with the occupants. The gray rat is a burrower and
prefers the lower floor, the cellar, or outside of the house.

Plague organisms taken into the stomach of the flea undergo
multiplication but do not penetrate the stomach walls and therefore
do not gain access to the body cavity, salivary glands or reproductive
organs. They are therefore not transmitted to the second genera-
tion nor are plague bacilli passed out in the salivary juices. The flea
gradually rids itself of plague bacilli through the peristalic move- .
ment of the stomach and intestines. Chick and Martin have shown
that at times the gizzard becomes so packed with plague bacilli
that the minute chitinous teeth are clogged and prevented from clos-
ing thus leaving an opening from the stomach to the oesophagus,
plague bacilli then develop in the oesophagus, regurgitation readily
takes place and the microorganisms pass into the wound made at
the time of biting. The fact that the gizzard is choked with bacilli
interferes with the passage of blood into the stomach and requires a
flea to bite oftener in its efforts to get nourishment. The process of
infection is purely mechanical and not biological as in the case of
204 INSECTS AND DISEASE OF MAN

infection with malarial parasites through the agency of a mosquito.
Fleas may remain infective for 15 days or even more, perhaps for
45 days without feeding on blood. An older theory to explain the
method of inoculation took into consideration the fact that the con-
tents of the rectum and therefore the expelled feces contained many
virulent plague bacilli and that like other parasitic insects the act
of biting was often accompanied by the act of defecation. It was
therefore assumed that infective fecal matter deposited near the
bite was afterwards rubbed in by scratching. No doubt infection
does occur in this way as well as by the other method.

For some time it was doubted that rat fleas would actually bite
man but it has since been proven by a number of observers that both
X. cheopis and C. fasciatus will readily feed on man’s blood. Lep-
topsylla musculi will occasionally bite. Both species of fleas of the
California ground squirrel as well as the flea of the Siberian marmot
have been shown to bite man. Clenophthalmus agyrtes, a flea of the
field mouse which was taken during a flea survey from rats trapped in
the country districts of England, was found not to bite man. It has
been known for years that not only the human flea but the cat, dog
and rabbit flea bite man.

Recognition of the Disease.—The disease develops suddenly with
a rapid rise of temperature, reaching 103 or ro4 degrees F. in two or
three days, after which it is more or less irregular. There is head-
ache; the eyes are injected and the facies are characteristic of extreme
illness. Prostration is profound and comes on early. Delirium also
appears early. The characteristic lesion of the disease, the bubo,
usually is sufficiently pronounced by the second day to be readily
detected. The most common site for the bubo is the femoral or
inguino-femoral region, then the axillary region, cervical, iliac
and popliteal. Over the enlarged glands oedema appears and
pressure elicits great tenderness. The individual lymph nodes can-
not be palpated. This swelling forms the primary bubo. Secondary
buboes may appear in other parts of the body. In these, the glands
are not matted together as in the primary bubo. Four forms of skin
eruption may be described—a petechial eruption, ecchymoses,
a subsuticular mottling, and the so-called plague pustule. The pete-
chial eruption is not often seen. The petechiae are usually scattered,
and with regard to location and numbers are not characteristic as in
the case of typhus fever. Ecchymotic areas may be present and just
before death there is a subcuticular mottling, somewhat resembling
PLAGUE 295

cadaveric lividity, but not confined to the dependent portions of the
body. It is due to the intense toxemia which produces changes
in the blood and in the walls of the smaller capillaries. An interest-
ing lesion is the so-called plague pustule, a bullous-like formation
containing thin, turbid material teeming with plague bacilli. It is
believed to indicate the original point of inoculation, the flea bite.
Extending from this to the nearest lymphatic glands, faint red lines
indicating lymphangitis, may be observed. A secondary pneumonia
due to the deposit of plague bacilli in the pulmonary tissues may
occur. In about a week, if the patient survives, the bubo breaks
down leaving an ulcer which heals slowly. The post mortem picture
is very striking. All glandular regions should be laid open to disclose
buboes. These have been described as primary and secondary.
The latter are divided into buboes of the first and second order. The
primary bubo is typical. It consists of a hemorrhagic, necrotic
mass of lymphatic glands matted together and surrounded by a
serosanguineous exudate. A serogelatinous exudate, which may be
found extending from the glands along the lines of the intermuscular
fascia is very characteristic. A secondary bubo of the first order
very closely resembles a primary bubo. It is located in the set of
glands adjoining the primary bubo and results from extension of
the inflammatory process by contiguity. A secondary bubo of the
second order is one located in a glandular region far removed from
the primafy bubo. In these the glands are distinct, firm, and hypere-
mic on section. Many glands of the body will show this reaction.
The spleen is enlarged and firm, although the pulp is congested and
friable. The other organs show the effects of a virulent toxemia;
petechial hemorrhages on the serous surfaces, cloudy swelling of the
kidneys and heart muscle and a congested liver. Necrotic foci may
be found in internal organs. The lungs are congested and may
show areas of plague pneumonia.

In suspected cases it must be borne in mind that the laboratory
furnishes a ready means of making an early diagnosis. It is an
easy matter to recover plague bacilli from material aspirated from
the bubo, and the causative organism is usually found in the blood.
Such material should be obtained from every case as soon as plague
is suspected. The material should be stained by a weak solution of
an aniline dye, such as carbol-fuchsin. Ordinarily, great numbers
of a bipolar staining organism are found, appearing typically as
bacilli but not infrequently as coccoid forms which are equally
206 INSECTS AND DISEASE OF MAN

characteristic. Some of the material should be spread on agar and
also planted in bouillon. Guinea-pigs should invariably be inoculated
by the cutaneous method. :

Prognosis.—The case fatality rate varies greatly, from 30 to 75%.

Treatment.—In the treatment of plague large doses of Yersins
serum should be used. The serum should be fresh, certainly not
more than 6 months old and should have been kept in the cold. Its
value should have been demonstrated before issue by experiments to
determine its protective power when used on guinea pigs and white
rats. A dose of serum as a curative agent in plague should be 150 to
200 cc. each day until decided improvement is observed. It may
be administered subcutaneously or intravernously. The use of
serum does some good. Perhaps reducing the case fatality rate 1o to
15%. Unfortunately itis a serum higher in bactericidal than in
antitoxic properties and therefore destroys the bacilli thus liberating
the endotoxin which, because of the weak antitoxin properties of the
serum, is not completely neutralized.

Persons exposed to infection are some times given a prophylactic
dose of Yersins serum. The passive immunity produced is fleeting
lasting probably not more than one week. 10 cc. is a prophylactic
dose given subcutaneously. The local reaction is sometimes annoy-
ing and a general reaction sometimes follows.

The use of Haffkine prophylactic, consisting of dead plague
bacilli, is not recommended as it is doubtful whether success obtained
following its use is commensurate with the time, trouble, and
expense entailed in its administration. Theoretically it should be
of great value for it should produce an active immunity of much
greater duration than the passive immunity following the use of
serum. 0.5 to 4 cc. are injected subcutaneously according to age
and size of the individual, followed in 10 days by a second inocula-
tion of a still larger amount.

Plague in Rats.—As has been said before bubonic plague is
primarily a disease of rodents. During the height of the epizootic,
pathological findings are usually very characteristic. There are
five signs to be observed. First, the bubo. This consists of a
mass of enlarged firm lymphatic glands, necrotic on section and sur-
rounded by a sero-sanguineous fluid; second, there is an injection
of the subcutaneous tissue often intense and of a crimson hue, third,
the spleen is enlarged, firm, dry and mahogany red; fourth, the
PLAGUE 297

liver may be studded with pin head areas giving it a speckled appear-
ance; or it may have smaller gray points of necrosis; fifth, pleural
effusion may be observed.

The location of the bubo depends upon the site of inoculation
(the flea bite). In India when single buboes only were present 75%
were found to be in the cervical region. In San Francisco, 75%
were found to be in the inguino-femoral region. While in New
Orleans only 439%, were observed in the groin, 289, being located in
the neck and 239% in the axilla.

When plague is in abeyance, as between out-breaks, post-
mortem signs of plague in rats are not so characteristic. One
may observe only the speckled appearance of the liver or there
may be larger necrotic areas (plague abscesses) in the liver, spleen, or
glands, indicative of sub-acute and chronic plague in rats. Accord-
ing to Williams there may be no macroscopic lesions whatever and
yet animal inoculation may disclose the presence of plague bacilli.
If while still trapping intensively a period passes without having
found a plague rat by the macroscopic method, the possibility that
some plague rats in which all macroscopic signs of plague are absent
may have been overlooked, must be kept in mind. In fact, it is
perhaps better, as plague rats become increasingly difficult to find
by the macroscopic method and plague seems to be disappearing
from the community, to inoculate material from the combined
spleens of a number of rats from the same location; otherwise a
focus of infection might be missed, and rat proofing operations
could therefore not be put into effect.

Plague produced artificially in rats differs somewhat from natural
plague in the pathological findings in-as-much as the glands while
sometimes enlarged and injected rarely show the typical, firm,
caseous bubo surrounded by an infiltrated area so commonly seen
in naturally infected rats. It is, however, common to find that the
enlarged glands have a number of yellowish points just under the
capsule: The liver has granular lesions similar to the liver of
natural plague infection, however if the rat lives for six days or
longer, larger necrotic foci replace the usual appearance. The
spleen is found to be mottled more frequently than in natural
plague and larger granules are more common. Subcutaneous injec-
tion is rarely so well marked. Pleural effusion is common. Local
reaction is usually quite marked, at the site of inoculation. :
208 INSECTS AND DISEASE OF MAN

Plague in Ground Squirrels.—The bubo is nearly always present
involving one or more glands. Most commonly in the inguinal
region, next the cervical and then the axillary. The area around
the bubo may be hemorrhagic and may show gelatinous infiltration
but in many instances there are no changes in the surrounding tissue.
On section the bubo is seen to be either blood stained, rather dry
and necrotic, or it may contain a purulent mass. (Probably a later
stage of the first.)

The spleen is usually enlarged and frequently contains caseous
or purulent foci.

The liver does not ordinarily show any changes but when it
does such changes are similar to those in the spleen.

The lungs are involved rather frequently and may show first
a more or less diffuse gray consolidation affecting a whole lobe or
a whole lung; second, disseminated purulent or caseous areas varying
in size ‘from a pin head to a pea.

Plague in squirrels is seen as acute cases, subacute cases and
residual abscesses.

Plague in ground squirrels must not be confused with the plague
like disease of rodents due to Bacterium tularense McCoy and
Chapin, which has very similar pathological characteristics. This
disease is readily transferred to guinea pigs, mice, rabbits, monkeys,
and gophers but rats are only moderately susceptible. Lesions in
guinea pigs, however, show a striking resemblance to plague. (See
Tularaemia.)

Plague in Guinea Pigs.—Plague in guinea pigs is ordinarily
seen only after inoculation in the laboratory. There is an area of
necrosis at the point of the inoculation. The subcutaneous tissue
is thickened and hemorrhagic and surrounded by gelatinous edema
and marked injection is present, especially noticeable around the
bubo. The glands are enlarged, caseous, hemorrhagic and sur-

‘rounded by injection and edema. The location of the bubo depends

upon the point of inoculation. The spleen is enlarged, dark, fri-
able, and studded with whitish areas about the size of a millet seed.
The liver is enlarged and congested.

Susceptibility toPlague of Certain Small Mammals of the United
States, Other than Rodents Which Have Been Found Naturally
Infected —Laboratory investigations made by McCoy have shown
that the following animals are susceptible to plague after inoculation.
PLAGUE 299

Arizona prairie dog (Cynomys ludovicianua arizonensis)
Rock squirrel (Citellus grammurus)

Antelope ground squirrel (Ammospermosphilus leucurus)
Chipmunk (Callospermophilus chrysodeirus)

Eastern desert wood rat (Neotoma albigula angusticeps)
Field mouse of California (Microtus californicus)
Family Mustelidae { Weasel (Putorius xanthogenys)

” : { Pocket gopher of California (7homomys botlae) very slight
Forally Geomyidas 1 susceptibility)

Family Felidae The Domesticated cat (Felis domestica)

Family Sciuridae

{
Family Muridae |

Cats naturally infected with plague are occasionally found
The disease is usually in a subacute form. Wild rabbits have been
found naturally infected with plague in England. Except for the
cat, domestic animals seem to be quite resistant to plague infection
and only experience local and temporary constitutional effect after
feeding on or inoculation with plague material, (pig, calf, goat, sheep,
dog, and pigeon).

Laboratory animals including guinea pigs, rabbits, white rats,
and monkeys are highly susceptible to plague infection. Guinea pigs
and white rats are especially valuable for use in demonstrating plague
infection, domestic rats may also be used. It must be remembered
that considerable natural immunity may be present in domestic rats.
This has been demonstrated by laboratory investigation. Indeed,
occasionally a guinea pig naturally immune may be encountered.

Morphology and Cultural Characteristics of Bacillus pestis.—A
short thick bacillus with rounded ends, non-motile, gram negative,
staining readily with weak aniline dyes more densely at the poles,
therefore called bipolar staining. In the tissues it not infrequently
appears in the coccoid form. This can be differentiated from a true
coccus because it will prove to be gram negative while a coccus is
gram positive. Too much importance must not be placed in the
morphology and tinctorial reactions of the plague bacillus. Animal
inoculation should always be made and usually cultural characteris-
tics should be determined. The appearance and character of the
culture should be as follows: (McCoy.)

Agar—Smooth, glistening, round whitish colonies which are found to be sticky
when touched with an inoculation needle.

Broth—A scanty surface growth which falls, often in globular masses, when the
tube is gently agitated; and a fine flocculent precipitate.
300 INSECTS AND DISEASE OF MAN

Litmus milk—Generally rendered slightly acid.

Glucose broth—Rendered slightly acid. Gas is not formed.

Lactose. broth—Unchanged in reaction. Gas is not formed.

Salt Agar—On 39% salt agar involution forms appear, the bacilli assuming large
balloon shape bodies like gigantic cocci, dumb bell and trypanosome-
shaped forms.

It is often possible to secure pure cultures from the heart’s blood,
‘bubo, spleen, or liver but it is always well to recover the organism by
animal inoculation using the cutaneous method. By this is meant
shaving the abdomen of the animal over an area of about one inch
square, abrading the epthelium very slightly. Suspected material or
culture is then rubbed in with dressing forceps. This method has
an advantage in that it acts as a filter preventing passage of most
microorganisms other than plague bacilli. Guinea pigs inoculated
by this method usually die in less than seven days. White rats die
a few days earlier. A control pig immunized with 1 cc. of Yersins
serum, given at the time of inoculation with the suspected material,
should be used.

Another useful method of inoculation is to make a small pocket
in the subcutaneous tissue of the abdomen inserting therein a piece
of the suspected material or a loop full of culture.

Examination of Rats for Plague.—Rats having been brought to
the laboratory properly dipped in kerosene and tagged are stretched
on a board, back down and fixed with a tack through each foot.
An incision is then made through the skin, in the median line, extend-
ing from the submaxillary to the pubic region. Two large skin
flaps are then dissected back on each side exposing the cervical,
axillary and inguinal regions.

The abdominal muscles are then grasped with a pair of forceps,
and with scissors, a large flap is cut from below upward exposing
the abdominal viscera. The ribs are then cut through on both sides,
thus making another flap which when raised exposes the contents of
the thorax. The glandular regions, subcutaneous tissue, spleen, liver,
and pleural cavity, should then be examined carefully for evidence of
plague.

Count should be made of the number of rats sent to the labora-
tory, their species and sex; the number pregnant, the number exam-
ined and the number found plague infected. For each plague infected
rat complete data should be kept as follows:
PLAGUE 301

Pracue Rar CArD

Plague rat No... oh
Date:
Species:
Sex:
No. of fetuses:
From:
Condition:
Subcutaneous injection:
Lymphatic glands, bubo or other lesions:
Liver:
Spleen:
Pleural effusion:
Purulent or caseous foci:
Diagnosis from gross lesions:
Diagnosis from smears:
Cultures:
Inoculation:
Vaccination:
Date suspicous:
Date positive:
Date negative:
Other pathological conditions:

The work should be done in a screened, rat proof room with
sewer connections. Examination tables should have a lead lined
top sloping towards the middle, with a drain leading into a bucket
‘of disinfectant solution.

Large stone jars of at least 20 gals. capacity may be used to
retain inoculated rabbits, guinea pigs and white rats, ascreen of
cheese cloth to be used as a cover. Inoculated wild rats should be
confined in cages placed within jars or garbage cans.

An incinerator should be provided for the disposal of plague
infected animals. Others may be placed in metal cans with tight

tops and taken to the municipal incinerating plant if there be one.

Methods of Control

In the prevention and control of bubonic plague the great
object to be attained is that of placing the environment in such
condition that man and rat or its fleas will not come into contact
and that conditions are such that the presence of rats will be
discouraged. The extermination of rats by the usual means is
practically impossible but it is quite possible to reduce the rat
population by trapping and poisoning, and to finally build them out
of existence, by proper rat proofing procedure, at the same time
abolishing all conditions that furnish a harboring, breeding and
302 INSECTS AND DISEASE OF MAN

feeding place for rats. Rats are killed in a campaign against plague,
not only to reduce the rat population, but also to discover plague
rats so that foci of infection may be known and stamped out by
proper rat proofing operations.

Organization.—To successfully carry on a campaign against
plague, ‘proper organization is necessary. This should include a
central office force, a laboratory and a field force. In the interests
of effective administration, the city should be divided into districts.
Each district should be in charge of a Medical Officer who should
have under his control the necessary personnel, consisting of inspec-
tors, foremen, trappers and laborers.

At headquarters policies should be adopted and educational
measures instituted, statistical information collected and compiled
and general supervision maintained over the entire work.

In the laboratory rats sent in are examined for plague to dis-
cover foci of infection, post mortems are performed and laboratory
diagnoses made of human cases. Identification of rats and flea
surveys are also made.

In the field, rats are trapped or poisoned and transmitted to
the laboratory. Inspections and reports are made of those places
in need of rat proofing, demolition, cleaning up, etc. It is well to
have all orders relative to rat proofing and similar requirements
emanate from headquarters but the follow up system to determine
if orders are being obeyed must be carried on by the district officer.
If there are no laws or ordinances under which to act, rat proof-
ing ordinances should be formulated, and promulgated promptly.
Enforcement of rat proofing ordinances is frequently difficult and
many obstacles may be expected. To rat proof requires money
which must come out of the pockets of those against whom an
order is issued. It is especially difficult to make them see the
necessity of rat proofing when rat plague only is present. Even
thinking business men, and city officials object until they realize
that without adequate measures their business is placed in jeopardy.
Preliminary to issuing rat proofing orders, clear evidence must be
procured of the conditions. Photographs are valuable evidence
and there should be at least two witnesses. Any case is liable to be
protested in court.

Foremen, Trappers, and Laborers.—Each foreman should have
under his supervision five laborers or trappers. Each trapper
should be provided with 25 cage traps and 50 snap traps.
PLAGUE 303

Trappers should receive a daily wage, plus a bonus for each
correctly labelled rat brought in, over a certain number, with an
extra bonus for each plague rat caught and sent to the laboratory.
The wages paid depend upon standard of wages in the locality.

In addition to trapping in the city, a certain amount of trap-
ping should be done on the outskirts, even extending into rural
districts, in an effort to get rats as well as other rodents common
to the locality. It is necessary to determine if plague infection
has spread to the country animals.

When a plague focus has been found, it is well to start intensive
rat eradication operations in at least twelve blocks using the house
from which a plague rat is taken as the center. A line of traps
and poison should be placed to encircle this area. Beginning at
the center, the work of demolishing rat harboring places by tearing
up wooden floors, tearing out double walls, cleaning up lumber and
rubbish piles and the like followed by adequate rat proofing, should
extend toward the periphery as intensive trapping and poisoning
is carried on in the surrounding zone extending towards the center.

Rat nests should be treated with insecticide and burned. It is
well to spray the ground area with insecticide. An emulsion of
equal parts of kerosene and a 3%, cresol solution is valuable or an
emulsion containing 85 parts of kerosene mixed with 15 parts of
hot soap solution, and used in the proportion of 2 parts of the emul-
sion to 98 parts of water.

Depopulation.—Depopulation is really a logical procedure where
it can be carried out. By this means persons are immediately taken
away from contact with rats and from fleas and not permitted to
return until the area has been put into a rat free condition. While
harboring places are being searched for, every effort should be made to
kill escaping rats by dogs, clubs and otherwise. It is a good plan to
surround the building, buildings, or even entire city blocks with a
galvanized iron fence to prevent the escape of rats to adjoining
buildings or blocks.

Traps.—Two kinds of traps may be used, snap traps and cage
traps. Ordinarily snap traps are more effective, i.e., in the long
run there will be more rats collected from snap traps than from cage
traps. The latter are large, unhandy to carry and require more
attention and are apt to be neglected by the trappers. It is quite
possible that equal attention paid to both on the part of the trapper
would increase the catch from the cage traps. A variety of bait may
304 INSECTS AND DISEASE OF MAN

be used, such as bacon, cheese, bread, green vegetables, meat, grain,
etc. As a general rule, the choice of bait depends on the character
of food supply in the place being trapped. First try baiting the
trap with the food most available, that is, in a butcher shop use meat,
in a granary use grain, if this is not successful, then use some other
kind of bait. Rotation of baits after a trial of each one for two or
three days should be practiced. If there is undoubted evidence of
rats and yet the first day or two none are caught, do not get dis-
couraged, leave the trap in its place until the rats become accustomed
to it. Rats are wary animals and not easily fooled. Cage traps
should be placed near rat holes or rat runs, and places where rats
are accustomed to feed. It is ordinarily desirable to cover them with
gunny sacks, straw or similar material. Snap traps preferably
should be placed in the rat run and sprinkled over with a little dust,
grain or any material available. Cage traps should be of the larger
type, 20 inches in length and the wire should be reinforced so that a
rat cannot push its way through by spreading the wires. When
after successful trapping operations several days pass without secur-
ing any more rats, traps should be moved to new places. One of the
most important things for successful trapping is that no food other
than bait in the trap should be available, therefore all food should
be protected against rats and garbage should be placed in tight cans
and properly disposed of. Traps and bait should be handled with
gloves.

The British have been successful in catching rats by using a sticky
substance consisting of linseed oil and rosin. This is spread over
trays with a piece of bait on cardboard placed in the center.

A certain number of live rats should be trapped forlaboratory
purposes, and in order to determine species and the number of fleas
per rat from season to season. There is thus obtained from time to
time the approximate degree of flea prevalence—a valuable index
bearing on the possibilities of spread of the disease. To secure live
rats, cage traps must be used as snap traps kill immediately.

Every opportunity should be taken to search for and transmit to
the laboratory all rats found dead. It is obvious that during epi-
demics of plague, large numbers of rats die from infection, thus the
chances of finding a plague infected rat among those found dead is
much greater than the finding of one among those trapped. It is
sometimes possible to recover by animal inoculation plague bacilli
PLAGUE 305

from a plague rat, even though decomposition is well advanced and
the characteristic signs of plague have disappeared. :

Guinea Pig “Controls” “Sentinel” or “Barometer.”— The use
of guinea pigs to detect plague infection in a house has been practiced
on a number of occasions. Several guinea pigs in cages are placed in a
suspected room or house. These animals will attract fleas and in the
presence of plague infection may develop plague. Creel has sug-
gested that more wide spread use be made of this procedure, in that.
the guinea pigs be released in one or more houses in each city block
in a hope that they may furnish an index to the distribution of the
disease. Houses known to harbor rats should be chosen and if,
after a week’s trial, no infection develops among the guinea pigs in
the block under observation they should be moved to other parts of
the city. In this way it might be possible to determine foci of rat
infection in advance of the slower method of trapping and examining.
Incidentally by attracting the fleas guinea pigs serve to protect human
beings. :

Poisoning.—Poisons are of doubtful value as aids to rat destruc-
tion. The number of rats found dead following intensive poisoning
operations is ordinarily not increased. It is possible that poisoned
rats may seek the sewers where they die and are washed out through
sewer outlets unnoticed. It is also possible that poisons may only
serve to drive the rats away to other parts. This is not desirable.

Poisons must be laid with great care, well out of reach of children
and domestic animals. Arsenic does not deteriorate and therefore,
remains poisonous for indefinite periods. Phosphorus deteriorates
with age. It is also inflammable, and must be placed away from
inflammable material.

A few formulas for rat poisons:

riBicesor corn menl.. lL Toh Sh sa ee a a as 5 lbs.
iCommereialiarsenie.. hw aS eS nei. Ee 1 lb.
Mix thoroughly and boil until cooked.

ZreSugaria non Ea al Ln rn SR Se LR 3 Ibs.
Oatmeal. olan LL lo CR 13 Ibs.
Commercial arsenic...) or ah ate Sate Baal iin So) 4 lbs.
Mix thoroughly.

2 Ground Tusty bacon. i... vv EEE I a 4 lbs.
Ground corn soaked over night in a solution of syrup and water 3 lbs.
CommeraialiarseniC. ta\ 00, in cos a SL a SU 14 1b.

Mix thoroughly.

Phosphorus may be used by mixing crude phosphorus in the

proportion of 59%, with cheese and sugar heated together to the
20
3006 INSECTS AND DISEASE OF MAN

consistency of syrup. The phosphorus is added after the syrup
has been taken from the fire and cooling has begun.

Strychnine has been found useful in the destruction of ground
squirrels. Wheat should be soaked over night in water. The
excess of water should then be poured off and the grain soaked in
a hot glucose solution containing 1{ oth. of 19, of strychnine sul-
phate. Stir well and then allow to dry in shallow pans over a slow
fire or by exposure to the sun. Cyanide of potassium or sodium
may be added in the proportion of 14 of 19.

Bacterial Virus.—The use of a bacterial virus such as Bacillus
typhi murium has not been successful in even reducing a rat popula-
tion. There is no disease with which rats can be infected that will
exterminate them. If there were, bubonic plague itself would
probably do it. The use of a bacterial virus is futile.

Rat Proofing

In view of the fact that total eradication of the rat by the usual
methods is impracticable, rat proofing becomes a logical and a
certain method for the control of bubonic plague. It has two chief
purposes. The first is to prevent contact between rat and man;
the second is to eliminate the breeding and feeding places of rats.
The methods used in rat proofing vary somewhat depending upon
the case. Perhaps the simplest form of rat proofing is by elevation
by which is meant the elevation of premises at least 2 feet above
the ground. The space underneath may be left uninclosed and
unobstructed so that free access to cats and dogs may be had.
There must be no accumulations of rubbish to furnish harbors for
rats. If the space is to be inclosed, walls should be of concrete, or of
brick set in cement either to extend at least two feet into the
ground. Openings provided for ventilation must be well screened
with heavy iron wire having a mesh not exceeding one-half inch.
Walls must be flush with the floor. Lumber and material about
the yard which cannot be destroyed, should be elevated at least
two feet from the ground.

Basements and cellars should be of concrete or of cement, rein-
forced by heavy wire screening. Concrete is by far the best rat
proofing material. It should be made of a standard cement, clean
sharp sand and stones in the proportion of 1:2:5. Walls should
be at least 6 inches thick and floors 3 inches thick with 14 inch of
cement laid on the surface.
PLAGUE 307

Double walls should be avoided, or the space between should
be filled above and below to prevent the entrance of rats, and a
wire mesh should extend upward back of the base-board. Base-
ment ceilings should remain unsealed.

Wooden floors, unless laid directly upon concrete, should be
made of two layers of tongue and groove boards, separated by a
layer of wire cloth with a mesh of about 14 inch. Doors, base-
ment windows, roof hatches, and the like should be well fitting.
Ventilation louvers, conduit openings, and openings for the entrance
of piping should be filled by cement or screened with 14 inch mesh
wire cloth, as the case may be.

Rats are frequently harbored under pavements. These should
receive attention. Wooden walks are especially objectionable.

Chicken Coops.—Chickens and pigs should not be kept within
the city limits. It is permissible to make an exception in the case
of chickens when chicken coops are properly constructed. They
should be surrounded by a concrete wall extending into the ground
at least two feet, and one foot above. The top and sides of the
coop should then be enclosed by wire netting of 14 inch mesh.

Stables.—Stables should have rat proof floors, i.e. concrete
floors preferably. Cribs should be built with a flareup from below
outward, and rendered rat-proof by a covering of zinc.

City Sewers.—Rats harbor in city sewers in large numbers.
They enter and leave mainly by way of the catch basin, but they
may go through house sewer systems, burrowing along side the house
sewer. Catch basins should be made rat-proof by having smooth
vertical sides, ‘with the opening from the street at least three feet
above the opening into the sewer. Traps in the sewer should be
done away with, as well as basins for the collection of silt. There
should be a smooth round bottom leading directly into the sewer
pipe. This is the modern idea of the catch basin. Incidentally
it does away with any collection of water at the bottom where
mosquitoes may, and in fact, frequently do breed. It will also
save money to the city, in that, cleaning of such a catch basin is
unnecessary.

Wharves.—Wharves should be of rat proof construction pref-
erably of concrete, with no harboring places for rats above or below.
They may be provided with rat proof compounds, into which cargo
may be unloaded.
308 INSECTS AND DISEASE OF MAN

Freight cars also require attention. They should be repaired
so that there are no openings for the entrance of rats, and when
left standing on track overnight, partly or wholly loaded, should be
closed.

Ships.—Ships should be fumigated regularly to kill rats and
while along side a wharf or dock should have rat funnels on all
lines. The gang-way should be hoisted at night and the vessel
should be fended off from the dock at least six feet. This may
be done by means of a raft floated between the ship and the wharf
piling.

Garbage.—Proper care of household garbage is important.
It should be kept in a galvanized iron can with tight fitting cover,
and should be collected at least once a week, and disposed of in an
approved manner.

Infected Buildings.— Occupants should be removed and the build-
ing fumigated; fumigation to be followed by a thorough renovating
to place the premises in a rat-free and rat proof condition. Double
walls should be torn out, planking must be torn up, and the ground
beneath broken to break up rat burrows, then soaked with kerosene
or a kerosene emulsion, and concreted.

The cessation of human plague is no criterion that plague has
disappeared. It is only when no plague rats have been found for
at least one year, during which period they have been trapped and
examined conscientiously, that one can believe that the infection
has been stamped out. Even then, it is unwise to discontinue rat
proofing, as rat plague may only be quiescent, or the same factors
which permitted the entrance of a plague rat may be still operative,
and reinfection may occur. Rat proofing measures should be carried
out at all times, with or without the presence of plague. This is a
preventative measure well worth the cost.

It is not unlikely that after intensive work to destroy rats, not
~ more than 509%, of the rat population is actually eliminated. It
would seem that as the activities progress, the rats that remain
have a much easier time in securing food, and it may be that with
their gradual extermination, breeding occurs more frequently in a
natural effort to resist extermination of the species.

After one has carried on an intensive campaign of trapping and
poisoning, it has been suggested that the repression of rats can be
accomplished quicker and with more permanent results, by sexual
selection—destruction of females only, permitting the males to go
PLAGUE 309

free. In this way there is brought about a natural but gradual
extermination of the species.

PNEUMONIC PLAGUE

Pneumonic plague is a form of pneumonia due to the plague
bacillus. It is a highly fatal disease resulting in a case fatality
rate of practically 1009. Epidemics of pneumonic plague are
not uncommon in North China during the winter months when
people are huddled within their houses without ventilation and with
a high degree of relative humidity. Such epidemics seem to have
had their beginning, in a case of bubonic plague contracted from
handling a plague infected marmot. It is curious that a small out-
break of pneumonic plague in Oakland, California, in 1919 had its
origin in a case of human bubonic plague contracted from a plague
infected ground squirrel. Pneumonic involvement in naturally
infected ground squirrels is a common pathological condition.

Cases of primary pneumonic plague are rare in warm weather.
Low temperatures, shut up houses and a high degree of relative
humidity seem to be necessary. In a warm dry atmosphere the
droplets expelled from the mouth and nose dry rapidly and plague
bacillus is very short lived. In a close humid atmosphere in closed
unheated houses the danger of spread is great.

_ Primary pneumonic plague is transmitted directly from person
to person as in other diseases of the respiratory type and does not
depend for its occurrence upon infection in rats or the presence of
fleas.

A Guide for Formulating a Rat Proofing Ordinance

The following outline for a Rat Proofing Ordinance has been
suggested by the U. S. Public Health Service (Public Health Reports,
November 3, 1920). Like all model ordinances it may require some
modification in order to adapt it to local conditions.

Ordinance No. ——

An ordinance requiring every building, house, outhouse, or other super-
structure hereinafter to be erected in the city of to be rat-proofed.

Be it ordained by the city council of

Section 1. That every building, house, outhouse, or other superstructure
of any and every character whatsoever hereafter erected in the city of
shall be rat-proofed in the manner hereinafter provided.

 

 

 
310 INSECTS AND DISEASE OF MAN

SEC. 2. It shall be unlawful for any person to construct any building, house,
outhouse, or other superstructure within the corporate limits of the city of
unless the same shall be rat-proofed as hereinafter provided.

Sec. 3. For the purpose of rat-proofing, all buildings, houses, outhouses, or
other superstructures, except stables, shall be divided into two classes, to wit:
Class A and Class B.

SEC. 4. That every restaurant and restaurant kitchen, hotel and hotel
kitchen, boarding-house kitchen, slaughterhouse, packing house, bakery, every
place where foodstuffs or refreshments of either solid or liquid form are manu-
factured, stored, kept, sold, prepared, or offered for sale, every warehouse,
freight shed; every place wherein live or dressed poultry, game, animals, or
birds are sold, stored, or kept for sale; every junk shop, chicken, or poultry
house, pen or inclosure, and every place where hides are kept, handled or stored,
shall be rat-proofed in the manner provided for hereinafter as Class A.

All other buildings, outhouses, and superstructures, except stables, not
hereinbefore specified as Class A, and all buildings used exclusively for resi-
dential purposes, shall be rat-proofed in the manner provided for hereinafter
as Class B; provided that the owner of any building, residence, outhouse, or
other superstructure in Class B, may, if he so selects, rat-proof the same in the
manner provided for in Class A.

“Foodstuffs,” as used in this ordinance, is hereby defined to mean flour,
flour products, animals and animal products, produce, groceries, cereals, grain
and the products of cereals and grain, poultry and its products, game, birds,
fish, vegetables, fruits, milk, cream, and the products from milk or cream, ice
cream, liquid refreshments of every character, or any combination of any one
or more of the foregoing.

Sec. 5. That the construction and material used in rat-proofing shall con-
form to the building ordinances of the city of , except, and only in so far,
as the same be modified herein.

Sec. 6. Class A. The ground floor of every building, outhouse or other
superstructure in Class A shall be of concrete, which concrete shall be not less
than three inches thick and overlaid with a top dressing of cement, mosaic,
tiling, or other material impermeable to rats, and such floor shall rest, without
any intervening space between, upon the ground; said floor shall extend, and
be hermetically sealed to, walls surrounding said floor, which “walls shall be of
concrete, or of stone or brick laid in cement mortar, and each wall to be not less
than six inches thick, and shall extend into and below the surface of the sur-
rounding ground not less than two (2) feet, and shall extend upwards not less
than twelve (12) inches above the surface of said floor.

Sec. 7. Class B. All buildings, outhouses, and other superstructures of
Class B, shall be set upon pillars or underpinnings of concrete, or of stone or
brick laid in cement mortar, such pillars or underpinnings to be not less than
eighteen (18) inches high, except where the building, outhouse, or superstruc-
ture is more than thirty (30) feet in width, the height to be measured from
the ground level to the top of said pillars or underpinnings, and the intervening
space between the building and the ground level to be open on at least three
sides and to be free from all rubbish and other rat-harboring material, or may

 

 
PLAGUE 372

be rat-proofed by constructing at the margin of the ground area of said building
a sustaining wall of concrete, or of brick or stone laid in cement mortar, such
wall to extend into and below the surface of the ground at least two (2) feet and
to meet the floor of the building above closely without any intervening space.
Such walls shall be at least six (6) inches thick and shall extend entirely around
the said building: Provided, That said walls may be built with openings therein
for ventilation only: And provided further, That such openings for ventilation
may be of such size as the owner may elect and shall be securely screened with
metallic gratings having openings between the bars of said gratings of not more
than one-half (14) inch, or with a wire mesh of not less than 12 gauge, having
openings between the wires of said mesh of not more than one-half (14) inch
and the whole so constructed and closed as to prevent the entrance of rats
beneath such buildings.

Provided, That when the owner of any building, outhouse, or other super-
structure, which is more than thirty (30) feet in width and which is herein
classified as Class B, shall elect to rat-proof same by elevating same, that he
shall elevate same to a height in excess of eighteen (18) inches to wit: that for
every additional ten (10) feet or fraction thereof in excess of thirty (30) feet in
width, the building outhouse, or other superstructure shall be elevated an
additional six (6) inches.

SEc. 8. That in any case where, under the provisions of this ordinance, any
building, outhouse, or superstructure is required to be rat-proofed as Class A,
and the said building or outhouse or superstructure is used in part for residential
purposes, and the part used as a residence is effectively separated from the part
falling within Class A by permanently and effectively closing all openings above
and below the ground floor or by constructing a new wall, and in either case
the whole, in such manner as to make such wall wholly and continuously in
its entirety without doorways, windows, or other openings between the part
used as a residence and that used for such purpose as makes it fall within Class
A, then in such case, and for rat-proofing purposes only, the said building will,
after such separation and closure of the openings, or by the construction of such
new wall, be deemed to be two buildings, and that the part used exclusively
for residential purposes may be rat-proofed in the manner provided for as a
Class B building, and the remaining part of said building shall be rat-proofed
in the manner provided for as Class A buildings.

SEC. 9. Stables—Every building hereafter constructed and used for stabling
any horse, cow, mule, or any other animal or animals shall be constructed as
in this section provided.

Walls.—The sustaining walls of such building shall be constructed of con-
crete, or of brick or stone laid in cement mortar, and shall be not less than six
(6) inches thick and shall extend into and below the surface of the surrounding
ground not less than two (2) feet, and shall extend above the ground a sufficient
height to be not less than one (1) foot above the floor level. All openings in
such foundation wall shall be covered with metal grating having openings not
greater than one-half (15) inch between the gratings.

Floors—The floors of stables and stalls shall be of concrete, not less than
three (3) inches thick, upon which shall be laid a dressing not less than one-half
312 INSECTS AND DISEASE OF MAN

(1g) inch thick, of cement, or of stone laid in cement mortar in such way as to
prevent ingress or egress of rats, and such floors to have a slope of one-eighth
(1g) inch per foot to the gutter drains hereinafter provided for.

It shall be unlawful to install or construct or permit to be installed or con-
structed any double wall, double floor, or double ceiling with open spaces
therein in any building or superstructure used or intended to be used as a stable.

Stalls. —Floors of stalls may be of planking, fitting together tightly to the
concrete floor, or elevated not more than one-half (14) inch from the concrete
floor and so constructed as to be easily removed. Such removable planking
shall be raised at least once a week and the said planking and the concrete floor
beneath thoroughly cleansed.

Gutters—Semicircular or V-shaped gutter drains shall be constructed in
such stables in such manner that the gutter shall be placed so as to receive all
liquid matter from each stall and to carry it from said stable.

Manure—All manure in and about all stables shall be removed therefrom
at least once a week, and the same shall be removed entirely from the premises,
- unless scattered as fertilizer or otherwise utilized, so as not to furnish food for
and attract rats.

Mangers.—Each manger shall be constructed so that the sides shall have an
inward slope from top to bottom of two (2) inches and, if made of wood, shall
be covered with tin or zinc and shall be at least eighteen (18) inches deep to
avoid the spilling of food.

Feed Bins.—All feed bins shall be constructed of cement, stone, metal, or
wood, and with close-fitting doors. If constructed of wood, the bin shall be
lined or covered with metal and the whole so constructed as to prevent the
ingress or egress of rats.

All grain, malt, and other animal food, except hay, stored or kept in any
stable must be kept in such feed bins. Said feed bins must be closed at all
times, except when momentarily opened to take feed therefrom, or when the
same are being filled. No feed shall be scattered about such bin or stable,
and all such feed found on the floor or in a stall of such stable shall be removed
daily with the manure. No foodstuffs intended for or susceptible of human con-
sumption shall be kept or stored in any stable or any other place where animals
are kept.

Sec. 10. That all accidental and unnecessary spaces and holes, ventilators,
and openings other than doors and windows, in every building, outhouse, and
other superstructure hereafter erected in the city of shall be closed with
cement mortar or other material impervious to rats or screened with wire,
having not more than one-half (15) inch mesh, as the case may require, or be
closed with galvanized iron; and all wall spaces shall be closed with cement
mortar or other material impervious to rats, which closure shall extend the full
thickness of the wall and shall extend upward at least twelve (12) inches above
the floor level, and the whole done in such manner as to prevent the ingress or
egress of rats: Provided, That in all buildings, outhouses, and other super-
structures of Class A, and in all stables where there are any spaces in walls
between the wall proper and the covering of same, or in ceilings between the
ceiling and the floor or other ceiling covering, both said spaces shall be elimi-

 
PLAGUE 113

nated by the removal of said covering or effectively blocked or closed so as to
prevent the ingress or egress of rats.

Sec. 11. That all premises, improved and unimproved, on all open lots,
areas, streets, sidewalks, alleys, in the city of shall be kept clean and free
from all rubbish, as well as loose material that might serve as harborage for
rats; and all lumber, boxes, barrels, and loose iron, as well as material that may
be permitted to remain thereon and that may be used as a harborage for rats
shall be placed on supports and elevated not less than two (2) feet from the
ground, with a clear intervening space beneath to prevent the harboring of rats.

Sec. 12. That all planking and plank walks on and in the yards, alleyways,
streets, sidewalks, or other open areas shall be removed and replaced with
concrete, or with brick or stone laid in cement or gravel, or the ground left
bare: Provided, That nothing herein shall apply to streets or other public places
paved with wooden blocks.

Sec. 13. It shall be lawful to install a cellar or basement in any building,
outhouse, or superstructure hereafter erected in the city of , but in
every such case the cellar or basement shall be inclosed within solid walls of
concrete, or of stone or brick laid in cement mortar, or tiles of not less than
nine (9) inches, with no openings below ground save for plumbing, and such
openings securely protected against the ingress or egress of rats, and with no
openings above ground, except doors and such windows or light or air vents
as will be susceptible of being screened with wire screens of not exceeding one-
half (14) inch mesh; and such cellars or basements shall have the floor con-
structed of concrete or stone at least three (3) inches thick, or of brick laid in
cement mortar, and such floor shall be hermetically sealed to the walls of such
cellar or basement. The doors or trapdoors for entry to such cellar or base-
ment shall be securely fitted in such manner as to prevent, when closed, the
ingress or egress of rats. :

SEC. 14. No permit shall be granted by the building inspector (or other
official whose duty it is to grant building permits) for the reconstruction, altera-
tion, or repair of any building, outhouse, or other superstructure in the city of
unless provisions shall be made in the plans therefor for the proper rat-
proofing of such building or superstructure in substantial compliance with the
provisions of this ordinance when, in the judgment of the building inspector (or
other official whose duty it is to grant building permits) it is practicable, desir-
able, or necessary that such rat-proofing be done; but in no event shall such
reconstruction, alteration, or repair be permitted without full compliance with
all the provisions of this ordinance, where the cost and expense of such recon-
struction, alteration, or repair shall, in the opinion of the building inspector
(or other official whose duty it is to issue building permits) equal or exceed
forty (40) per cent of the value of the structure sought to be reconstructed,
altered, or repaired.

Sec. 15. That the word person as used in this ordinance shall be taken to
mean and include firms, copartnerships, corporations, and persons of both sexes.

Sec. 16. That any ordinance or part of ordinance in conflict with the pro-
visions of this ordinance is hereby repealed to the extent of such conflict.

 

 

 
314 INSECTS AND DISEASE OF MAN

Sec. 17. Should any part of this ordinance be declared invalid, the remaining
portions shall not thereupon be invalidated, but shall remain in full force and
effect.

Sec. 18. Penalty.—Any person violating any of the provisions of this ordi-
nance shall be punished by fine not to exceed or by imprisonment not
to exceed or by such fine and imprisonment.

SEC. 19. Emergency.—(The clause declaring an emergency to be inserted if
necessary under local laws.)

With regard to the above model ordinance certain changes have been sug-
gested as follows:

That the ordinance be so worded that its provisions shall apply to the rat-
proofing of buildings already constructed when such a procedure shall be
deemed necessary, as well as to buildings to be erected in the future.

Sec. 2. “It shall be unlawful for any person to maintain or construct any
building etc.”

Sec. 6. Specify that the top dressing of cement be not less than one-half
inch in thickness.

Sec. 7. Permit the use of ordinary mortar in the construction of brick under-
pinning; also permit the use of wooden posts for underpinning.

Sec. 10. Specify that the wire screening of not more that one-half inch mesh
shall be not less than 14 inch gauge.

Sec. 13. Specify that the walls of basements whether of brick, stone, con-
crete or tile, shall be not less than nine inches thick. (Six inches is sufficient
for rat-proofing purposes but here strength of construction must be taken into
consideration.) Specify that the one-half inch wire screen shall be of not less
than 14 inch gauge.

In general,’ for rat-proofing purposes, walls should be not less than six inches
thick and floors not less than three and one-half inches thick. Brick should be
laid on one-half inch of cement and should have a top dressing of cement of not
less than one-half inch in thickness.

 

 
CHAPTER XXXIII
TYPHUS FEVER

Causative Agent.—Typhus fever is believed to be due to a micro-
organism known as Rickeltsia prowazeki. It is pathogenic for
monkeys and guinea pigs.

Source of Infection.—The blood of patients having typhus fever.

Period of Communicability.— During the febrile attack, especially
in the first ten days of the disease.

Mode of Transmission.—The disease can be contracted through
inoculation of infected blood. In nature transmission is brought
about through the agency of the body louse (Pediculus corporis) com-
monly, and the head louse (Pediculus humanus) occasionally. It
may be, that when transmitted by the latter, the disease runs a
milder course.

Period of Incubation.—5 to 20 days. Usually about 12 days.

Epidemiology.—Typhus fever has ravaged armies in the field
from time immemorial. Older descriptions of the disease un-
doubtedly combine descriptions of typhoid fever, for it was not until
the year 1837 that the differences between typhus fever and typhoid
were clearly recognized. There has probably not been a single war
in which typhus fever has failed to take its toll, from both the mili-
tary and the civil population. The disease was nearly always pres-
ent where there was overcrowding and filth, and it has been called
camp fever, jail fever and ship fever.

During the world war typhus fever was prevalent in Serbia,
Austria-Hungary, Germany, and Russia, Serbia suffered most
severely, and it has been estimated that there were 135,000 victims
to the disease. It was rare on the Western front.

Typhus fever is endemic in some of the larger European cities
and occasional cases are seen in the United States, where it passes
under the name of Brill’s disease. It occurs during the colder
months of the year, subsiding upon the advent of warm weather.
Except in high altitudes, it is practically unknown in the Tropics.
The body louse, which is the most important intermediary host, does
not seem to survive under tropical conditions. Furthermore in sum-

315
316 INSECTS AND DISEASE OF MAN

mer clothing is changed more frequently and is made mostly of
cotton goods. The disease is common in the higher altitudes of
Mexcio where it is known as tabardillo.

It attacks all ages and both sexes and is associated with cold
weather, overcrowding, filth and squalor,—conditions under which
body lice thrive.

Those infested with vermin are especially liable to attack although
a high percentage of doctors and nurses in attendance upon typhus
fever patients may become infected.

One attack confers lasting immunity. Second attacks are very
rare.

In children typhus fever has a low mortality. Passed middle
age the case fatality rate may be as high as 40 or 50%. The
average rate is about 12 to 20%.

The bite of one infected louse is sufficient to produce the dsirve.
The infective agent circulating in the blood is taken into the stomach
of the louse at the time of biting and is then transferred to the blood
of another individual. Theexact method of transmission isunknown,
and it may be purely mechanical. The feces of the louse have been
demonstrated to contain the causative agent. It would seem, how-
ever, that several days (8 to 9) must elapse before the louse can
transmit infection, and that it probably remains infective for the rest
of its life. It is therefore not improbable that there is a definite life
cycle, part of which is spent in the body of the louse. The micro-
organisms invade the cells of the lining of the gut of the louse. They
are intracellular. A similar microorganism is the cause of trench
fever which is also transmitted by lice. Here however the micro-
organisms are extracellar and there is little swelling of the cells.

When infected blood'is inoculated into a monkey intraperitoneally
or intravenously there follows, after an incubation of from 5 to 14
days, a rapid rise of temperature usually reaching a maximum of
about 41°C. in 36 to 48 hours. At the end of the febrile period the
temperature may decline gradually but more usually falls by crisis.
The rise of temperature is practically the only definite index that
infection has taken place. In guinea pigs there is a reaction in the
genitalia of male animals similar but milder in character to that seen
in pigs infected with Rocky Mountain spotted fever. The reaction is
characterized by swelling and petechial hemorrhages into the scro-
tum, testicles and epididymus and their envelopes, due to lesions of
the blood vessels. The lesions produced by typhus fever are micro-
TYPHUS FEVER 317

scopic. There is a proliferation and swelling of the endothelial cells
of the blood vessels, followed by a degeneration. Minute thrombi
and small areas of necrosis may result. The causative agent may be
demonstrated in the endothelial cells.

Recognition of the Disease.—Prodomal symptoms may be
present, but frequently the disease develops suddenly with chills,
vomiting, epistaxis, pain in the head, back, and limbs. The head-
ache is severe and persistent, the face is flushed and the conjunctivae
injected. Cough is present and prostration and delirium come on
early. The fever rises rapidly to 103°F. more or less, and by the
fifth day may reach ros degrees, remaining high with slight daily
remissions for about two weeks and ending characteristically by
crisis. Leucocytosisis present. The eruption appears on the third to
fourth or fifth day, first on the upper part of the chest and later on
the arms, abdomen, and legs. The face is ordinarily free. The
rash at first resembles the rose spots of typhoid fever, but is more
profuse and becomes petechial in character. As the disease advances
prostration becomes profound and the nervous symptoms more pro-
nounced. Coma vigil is present with subsultus tendinum. In
favorable cases there is a rapid termination. Broncho-pneumonia
may be a complication. Mild cases of typhus fever occur during
epidemics and a correct diagnosis may be difficult. Brill’s disease is
typhus fever in a mild form. Mild cases may be confused with
typhoid fever or in children especially paratyphoid. The sudden
onset, character of the rash, rapid termination, early prostration
and brain symptoms may be of value in differential diagnosis. How-
ever it must be kept in mind that in the milder forms of typhus the
rash may not be so profuse, prostration and brain symptoms may not
be pronounced and the disease may end by lysis rather than by crisis.
The presence of lice, especially in patients from the lower strata of
society, should make one suspicious. The results of the Widal
reaction and blood cultures are important. Confusion may also arise
in the differential diagnosis between typhus fever and influenza, small-
pox, cerebrospinal fever, measles and Rocky Mountain spotted fever.

The Weil-Felix reaction is an important laboratory aid in the
diagnosis. This is not a specific reaction as it depends upon the
presence of a proteus-like microorganism isolated from the urine or
blood of typhus fever patients in 1915 by Weil and Felix, which
organism does not seem to be etiologically connected with the
disease. They have designated the strain Xs, and Xs.
318 INSECTS AND DISEASE OF MAN

To perform the test use a fresh grown agar culture and suspend
in 1.5 cc. of salt solution. Test with the serum of the suspected
casein dilutions of 1:25and 1:50. In cases of typhus fever the agglu-
tination titre should rise from 1:25 on the sixth day to 1:200 or
1:500 or higher on the 12th day. If the agglutination titre does not
rise as indicated, typhus fever can usually be excluded. The reaction
appears during the first week and is at its height during the second
week and during convalescence.

Methods of Control.—The disease should be recognized as early
as possible by the clinical symptoms, the presence of lice, the social
status of the patient etc. ;

The patient should be isolated in a vermin free room and the
hair should be clipped from the head, body and pubic region. The
clippings should be destroyed by burning. The body should then
be washed with soap and water followed by kerosene or the kerosene
jelly may be used. The head should also be treated.

Attendants should wear vermin proof clothing.

Exposed susceptibles should be quarantined for 14 days from
date of last exposure.

Clothing should be treated to destroy vermin and rooms should
be kept vermin free.

When there is evidence of louse infestation persons coming from
infected areas should have the body and clothing subjected to a
delousing process.

There is no method for producing artificial immunity.

For delousing methods see Page 156.
CHAPTER XXXIV
TRENCH FEVER

Causative Agent.— Trench fever is due to a resistant filterable
virus which is present in the blood plasma of patients having the
disease. This virus is resistant to drying and is killed at a tempera-
ture of 70 degrees C., moist heat, for 30 minutes. A microorganism
— Rickettsia quintana—has been described as the cause.

Method of Transmission.—The disease is transmitted in nature
by the Pediculus corporis. :

Period of Communicability.— Throughout the course of the
disease. More communicable during the first and second day.

Period of Incubation.—14 to 30 days.

Epidemiology.— Trench fever is common among armies in the
trenches and is the cause of much disability among troops and a
great lessening of man power, although it is not important as a
cause of death.

The exact way in which the louse transmits the disease is not
known, except that it is through the bite. The insect need not
remain long on the body to infect. There is some evidence that a
definite life cycle takes place within the body of the louse. The
virus may also be present in the feces of the louse, and it is possible
that excrement may at times also act as the infecting agent by being
rubbed into the wound made at the time of biting. The virus is
also present in the sputum, feces and urine of the patient.

Recognition of the Disease.—Sudden onset with headache and
pains in the legs and back. Post orbital pain particularly when
eyes are moved; dizziness; nystagmus on turning eyes competely
sideways; injection of conjunctivae and sharp rise of temperature
to 103 degrees or, 104 degrees F. which in one half the cases subse-
quently assumes a relapsing character. Three types of the fever
exist; a short attack lasting about a week with sometimes a single
short rise after a few days; a more prolonged initial fever which may
last for 6 or 7 weeks with relapses not distinctly marked; more com-
monly a fever which relapses with more or less definite normal

319
320 INSECTS AND DISEASE OF MAN

intervals, lasting from 5 to 7 days. Variations from these types are
not uncommon.

The spleen is enlarged; small erythematous spots are present
in 70 to 809% of the cases on the chest, back and abdomen. They
are pink in color and disappear on pressure; often disappear in less
than 24 hours; in numbers they vary from several to one or two
hundred. The time of their appearance not constant. The rash
may be distinctly papular.

The urine may show a trace of albumen. The leucocyte count
is variable. Frequently there is a leucocytosis but at times the blood
is normal or there may be leucopenia.

The number of relapses varies, 3 to five periods are common.
Some attacks have 6 to seven relapses.

Recovery usually occurs in from 5 to 6 weeks.

Methods of Control.—Success in prevention lies in the destruc-
tion of lice. (See page 156.) A temperature which will kill lice is
not high enough to destroy the virus. This probably has little
significance as under natural conditions it is lice that transmit the
virus to man. However the sputum, urine and feces of the patient
should be sterilized.

 
CHAPTER XXXV
RELAPSING FEVER

Causative Agent.—Relapsing fever is due to a protozoon parasite
belonging to the Proflagellata and to the Genus Borrelia. The
Spirochaetes of relapsing fever vary somewhat in their specific
characteristics depending upon the geographical location of the
disease.

Method of Transmission.—Relapsing fevers may be divided
into two groups, depending upon whether they are louse borne or
tick borne. The louse borne relapsing fevers include the European,
North African, the Indian and the North American. The tick
borne relapsing fevers include the African, the Persian and the Central
and South American.

RELAPSING FEVER CAUSATIVE AGENT INTERMEDIATE HOST
North American B. novyi Lice
European B. recurrentis Lice and bed bugs
Indian B. carter: Pediculus corporis
Pediculus humanus
North African B. berbera Pediculus corporis
Pediculus humanus
East, West and South Africa B. duttonz Ornithodoros moubata
Persian B. persica Ornithodoros savignyi
South American. B. novyi Ornithodoros turicata
Panama B. novyi Ornithodoros talaje

Period of Incubation.—7 to 1o days.

Epidemiology.—In the case of lice, spirochaetes enter the body
cavity through the stomach wall. This takes place between the
second and eighth day. Infection results not from the bite, but
from crushing the louse and rubbing the contents of the body cavity
into the wound made at the time of biting. Lice may be said to be
capable of transmitting the infective agent during two periods;
first, just after inbibing infected blood, and again after two or more
days when the spirochaetes enter the body cavity. After the sixth
day their infectivity becomes less and less. It has been shown that

infection may be transmitted to the progeny.
21 : 321
322 INSECTS AND DISEASE OF MAN

In the case of ticks, the spirochetes are taken into the stomach
from the circulating blood, pass through the stomach walls and into
the body cavity, finding their way to the ovary, the eggs, the mal-
pighian tubules and coxal glands. The disease is not transmitted dur-
ing the act of biting, but results from scratching into the wound made
at the time of biting, the discharges from the malpighian tubules
or coxal glands. Infection is transmitted to the progeny, so that
the immature ticks may transmit the disease. Ornithodoros mou-
bata is the intermediate host of Borrelia duttoni. It infests
houses especially rest houses along the routes of travel, living by
day hidden within the cracks and crevices in walls and floors where
it also lays its eggs, coming out at night to bite. About 100 eggs
are laid and from these fully formed nymphs emerge, the larval
stage being spent within the egg. The nymphs may transmit the
disease as the spirochete is transmitted by the female to her progeny.
Both adult males and females transmit the infecting agent. The
act of biting occupies about one hour. Like the bedbug they do
not wander far of their own accord but may be carried in bundles of -
clothing. The other ticks transmitting the disease are somewhat
similar in their habits. Relapsing fever frequently attacks children
in severe form. One attack of relapsing fever conveys some im-
munity in that older persons who have had the disease in childhood
may suffer from mild attacks and thus serve as carriers by harboring
the spirochetes in the circulating blood. The relapse so character-
istic of the disease is caused by those spirochetes that have resisted
the action of antibodies.

Relapsing fever is more or less common in many parts of Africa
Asia, Europe, etc. and is occasionally present in North, Centraland
South America. Epidemics of relapsing fever are not infrequently
associated with epidemics of typhus fever, both being louse borne
diseases.

The case fatality rate is 5% to 20%.

Recognition of the Disease.—The disease is characterized by a
sequence of several febrile periods lasting about 4 days separated by
afebrile periods which last from 4 to 8 days, although these vary
depending upon the degree of immunity conferred by a previous
attack or by the particular species of spirochete.

The fever rises rapidly to about 104°F. continues high for 3 or 4
days and drops by crisis to be followed by the period of apyrexia
during which the patient feels much better. The crisis may be
RELAPSING FEVER 323

accompanied by symptoms of collapse, sweating, great prostration
and cardiac weakness. Other symptoms are severe headache with
pains in back and limbs, nausea and vomiting, absence of delirium,
accelerated pulse, precordial distress, cough, tenderness and moder-
ate enlargement of spleen, tenderness over the liver, jaundice and
polymorphonuclear leucocytosis.

The most important diagnostic feature is of course the presence
of spirochetes in the circulating blood during the febrile attack.
They are few in numbers or absent during the afebrile period.

The disease may be confused with malaria, dengue, smallpox.

Salvarsan and neosalvarsan are specific.

Methods of Control.—Destruction of the insect hosts would
seem to be logical. This is a difficult accomplishment. In many
places where relapsing fever is common, the natives are very indiffer-
ent and their cooperation hard to secure. In the tick borne relaps-
ing fevers of Africa, white travelers should avoid native rest houses
and should sleep in hammocks or beds isolated so that ticks can not
crawl up the legs. The louse borne infections require delousing
similar to methods of combatting typhus fever.
CHAPTER XXXVI
ROCKY MOUNTAIN SPOTTED FEVER

Causative Agent.— Unknown. Possibly a Rickettsia-like micro-
organism which Wolbach has named Dermacentroxenus rickeitsi.
A non-filterable virus, pathogenic for man, monkeys, guinea pigs and
white rats, and at least six varieties of the small wild rodents found
in the Rocky Mountain region. Larger domestic animals, like sheep
and cattle, seem to be immune.

The virus dies within a few days outside of the animal body or the
arthropod host. It is destroyed by grinding and loses its ability to
infect after 15 days on ice, after thirty minutes exposure to a tem-
perature of so degrees C., and within one and two days after complete
dessication. ;

Source of Infection.— The blood of infected animals; infection
occurs only by inoculation. In nature this is brought about through
the bite of a tick, usually Dermacentor andersoni, or the rabbit tick,
Haemaphysalis leporis-palustris, both of which are common in the
locality in which the disease occurs. Experimentally other ticks
have been shown to be capable of transmitting infection. The tick
remains infected throughout its life and the female can transmit the
virus to her progeny. Adult ticks, both male and female, larvae and
nymphs are capable of transmitting the infection after feeding on
infected blood, and the infection is passed on from one stage to the
other.

Incubation Period.—This is variable, it may be as long as 12 days,
usually four to seven days.

Epidemiology.—In nature the virus is probably carried by small
wild rodents and from this source ticks become infected. Under
experimental conditions the virus may be kept alive by passage
through guinea pigs. o.5 to 5.0 cc. of infected defibrinated blood,
blood serum or corpuscles may be inoculated subcutaneously or intra-
peritoneally. After a period of incubation of from two to five days,
a rise of temperature ensues reaching its height on the fifth to seventh
day when swelling and oedema of the scrotum and testicles devel-
op. Vulvar changes may occur in the female. The spleen is large

324
ROCKY MOUNTAIN SPOTTED FEVER 325

and congested. The soles of the feet, and ears are congested and
macules may be observed on the body. Emaciation is rapid and
death usually occurs after a week’s illness. If death does not ensue
recovery is slow, and may be accompanied by sloughing of the scro-
tum and loss of the ears. Microscopical lesions are found in the
bloodvessels, similar to those seen in typhus fever.

The disease has been transmitted to laboratory animals by allow-
ing them to be bitten by ticks which have fed on the blood of infected
animals.

Rocky Mountain Spotted Fever occurs in the Rocky Mountain
and Pacific States east of the Coast Range mountains. It has been
reported from California, Oregon, Washington, Montana, Idaho,
Nevada, Utah, Wyoming, Colorado, and Alaska. In the Bitter Root
Valley of Montana the disease is limited to the western side of the
Valley.

The disease attacks both sexes and all ages. One attack confers
lasting immunity.

The great majority of cases occur between the opening of spring
and midsummer, a few are contracted as late as August.

The Rocky Mountain fever tick is rural in its distribution and
man becomes infected only by accident. Those whose occupations
take them into the woods and fields, —lumbermen, engineers, sheep
herders, campers, etc.,—are more liable to contract infection,
although others may be infected from ticks brought to them on live
stock. The disease is therefore a rural rather than an urban disease.

Life History and Habits of Dermacentor andersoni.— (See
page 193.)

Recognition of the Disease.— The onset of the disease is similar
to other acute eruptive febrile diseases, the symptoms varying in
degree. There are chills or chilly sensations, severe headache and
pains in other parts of the body, flushed face and injected and
yellowish conjunctivae. Epistaxis is common. A macular roseolar
eruption may appear on the face, neck and upper part of the thorax
as early as the second day, but the characteristic petechial eruption
appears about the third or fourth day on the forehead, wrists and
ankles, spreading to the arms, legs and trunk. This petechial erup-
tion may become purpuric in character. Gangrene of the ears,
fingers, toes, scrotum or penis may occur. Leucocytosis is present.
Albumin and casts are found in the urine in about 509%, of the cases.
Delirium is commonly present although the mind may remain clear
326 INSECTS AND DISEASE OF MAN

throughout the disease. The temperature rises rapidly to a moder-
ate height where it remains for a week or ten days and then drops
by lysis. The eruption may at times be seen on the palms of the
hands and the soles of the feet. Jaundice is common. The case
fatality rates vary according to locality from 4 to 75%; in Idaho
4%.

Clinically the disease resembles typhus fever very closely but
cross immunization experiments have shown the two diseases to be
distinct.

Methods of Control.— Prevention lies in reducing the number of
ticks to a safe minimum. Burning over infested areas has been
suggested, thus destroying ticks and preventing the development of
the eggs.

Domestic animals should be dipped.

Sheep grazing should be practiced extensively over tick infested
areas. This is probably the most practical method. Ticks soon
die in the wool of sheep, for they find it difficult to move in the thick
wool, becoming entangled in the hairs they cannot feed and they
starve. Also the lanolin plugs their breathing spiracles. Copula-
tion does not take place.

It has also been suggested that wild animals, especially the small
rodents be destroyed. This is a difficult and expensive matter to
accomplish.

Dipping Solution for Caltle.

Sediumicarbonate, pounds... [ou Ted ans LE ae ad 24
Arsenious Oxide (A3:0:), pounds... ....0.i wulihcveniois csashane dy 18
Pinetar, callong. i en LE Ln sa, 2
Waterito make salons... 70. od wi onl hai BL neh La

A stock solution may be made by dissolving the soda in 25 gallons
of water, adding the arsenic and boiling until combined. When
cooled to 140°F. add the pine tar slowly while stirring. This con-
centrated solution may be diluted in the dipping vat when required
for use. To be efficacious the final solution must contain 0.29, of
arsenious acid. In the above formula it is therefore better to use
pure arsenious acid or a somewhat greater quantity of the com-
mercial form.

Tourists should be careful in camping where infected ticks are
known to be common.
CHAPTER XXXVII

TSUTSUGAMUSHI FEVER

(Japanese River Fever)

Causative Agent.— Unknown.

Methods of Transmission.—The disease follows the bite of an
infected mite (Trombicula akamushi) in its larval stage.

Source of Infection.—How the mite becomes infected is unknown.
The virus circulates in the blood of the patient and this blood when
inoculated into monkeys and small rodents produces the disease in
these animals. Rodents trapped in the locality and from which
infected mites may be taken do not seem to be affected with the
disease, although it is possible that they may act as reservoirs of
infection.

Period of Incubation.—From four to ten days.

Epidemiology.—The disease is limited to the immediate vicinity
of one of the rivers on the Island of Nippon, Japan, which overflows
its banks inundating the adjacent land during periods of flood.
This occurs about the month of June, the disease following in July
or August among those who have worked the ground after the floods
have subsided. The disease is said to occur also in Formosa.

The life history of the Kedani mite does not differ materially
from other mites. The larva is very small and bright red or
orange in color. The nymphal and adult forms do not bite but live
on vegetable juices. Blood is obtained by the larvae usually from
the small rodents of the locality especially the field mouse (Arvicola
hatanedzumsi) on which they congregate about the ears. The larva
develops into an octopod nymph which after one or perhaps more
moults becomes the fully formed acarine, which may be found under
fallen leaves or decayed vegetable matter in the inundated area.

The infection is carried over from the larval stage to the nymphs
and adults but as they do not bite they are not dangerous to man.

The disease does not develop after the bite of similar mites in
other localities nor are all mites infective in the infected locality.

Recognition of the Disease.—The prodromal symptoms are
headache, malaise and anorexia. The onset begins with a chill

327
328 INSECTS AND DISEASE OF MAN

followed by a rise in temperature which in 4 or 5 days may be very
high reaching 105 degrees F. The pulse is only moderately acceler-
ated. Cough is present. In about seven days after the fever begins
a rash appears first on the face and then extending to the trunk and
extremities, The rash, at first large red blotches, may become
papular—never petechial—and begins to disappear during the second
week when the temperature also begins to drop. Examination of
the body will disclose a more or less boil-like swelling which sloughs
at the centre leaving an ulcer. This represents the site of the bite.
The glands draining the bitten area are somewhat swollen and
tender. Leucopenia is present and the spleen is usually enlarged.

Methods of Control.—Avoid the infested locality during the
season of prevalence of the mite.
Abdomen of
acarines, 176
Anoplura, 143
Cimex, 162
Culicide, 13
Insects, 3
Muscoidean flies, 70
Siphonaptera, 116
Tabanidae, 55
ticks, 178
Acalyptratae, 5, 8, 61
Acanthia (see Cimex).
Acanthopsylla, 126
acanthopus (Hoplopleura), 151
Acariasis,
chorioptic, 210
psoroptic, 210
pulmonary, 203
sarcoptic, 208
Acarina, 175 (see also mites).
Anatomy of, abdomen, 176
alimentary tract, 177
legs, 176
mouth parts 175
tracheal openings, 177
classification of, 180
description of, 175
families, key to, 181
life history of, 177
superfamilies, key to, 180
ticks, 177, 182, 183
Acaropis, 207
Accessory plates, 91
Acroceridae, 7
Acropsylla, 128
Act of biting,
Anoplura, 143
biting Muscoidean flies, 70
mosquitoes, 10
Tabanidae, 53
Actenophthalmus, 123
Actenopsylla, 121
aculeata (Sarcophaga), 96
(Onesia), ror

INDEX

acutus (Ceratophyllus), 139
Adeomyia, 27
Aedes, 27, 28, 43
Aedoeagus, 15
Aegypti (Aedes), 24, 31, 32, 43
control of, 269
eggs of, 24
habits of, 43, 265
+ in Dengue fever, 274
in yellow fever, 265
larvae of, 24
pupae of, 25
affinis (Agria), 94
African sleeping sickness (see sleeping
sickness).
Agastopsylla, 128
agilis (Laelaps), 204
(Onesia), 101, 102
Agria, go
akamushi (Trombicula), 200, 327
alaskensis (Francilia), 103
(Steringomyia), 101, 102
albimanus (Anopheles), 29, 30
habits, 38, 243
Albumin in yellow fever, 267
alcedo (Sarcophaga), 95
Aldrich, J. M., go, 94, 227
aldrichia (Steringomyia), 101, 202
Alectorobius, 187
Alexandrian rat, 215
alexandrinus (Rattus), 215
Alimentary tract of,
‘Acarina, 177
Anoplura, 144
Cimex, 162
Culicidae, 15
insects, 2
Muscoidean flies, 73
Orthoptera, 168
Siphonaptera, 114
Tabanidae, 55
| ticks, 179
Allodermanyssus, 204
Allothrombidium, 201

329
330

alpina (Steringomyia), Too
Amblyomma, 183, 196
American, key to, 197
American cockroach, 168
americana (Periplaneta), 168
americanum (Amblyomma), 196, 198
americanus (Hoplopleura), 152
ampelophila (see melanogaster).
Amphipsylla, 125
Anal grooves, 178
Analgesidae, 181, 207
Anatomy of,
Acarina, 175
Anoplura, 143
Chironomidae, 50
Cimex, 160
Culicidae, 10
Diptera, 4
Insecta, 1
mosquito larvae, 18
Muscoidean flies, 62
Muscoidean fly larvae, 74
Orthoptera, 169
Psychodidae, 51
Simulidae, 50
Siphonaptera, 112
Tabanidae, 53
ticks, 177
andersoni (Dermacentor), 174, 193, 324
Angora goats, lice of, 151
annulatus (Boophilus), 190
anomalus (Hoplopsyllus) 137
Anomiopsyllus, 122
Anopheles, 27, 28, 34, 239
breeding places of, 240
carriers of malaria, 239, 242, 243
description of, 34
estivation, 245
hibernation, 243
species adults, key to, 28
species larvae, key to, 30
Anopheline mosquitoes
distinguished from culicines, 23
eggs of, 23
larvae of, 24
position at rest, 23
pupae of, 25
wings of, 23
Anoplura, 143
anatomy of,
abdomen, 144
alimentary tract, 144

INDEX

Anoplura, anatomy of head, 143
legs, 144
mouth parts, 143
thorax, 144
classification of, 149
description of, 143
diseases transmitted by, 149
eggs of, 145
eradication of, 156
key to, 153
nymphs of, 145
Antarctophthirus, 154
Antennae, 1, 4, 3, 12, 18, 22, 53, 64, 112,
160, 168
of mosquitoes to differentiate the
sex, 22
Antennal grooves, 64, 112
Antennal plate, 64
Antepygidial bristles, 116
Anthomyia, 108
Anthomyiidae, 8, 107, 109
anthropophaga (Bengalia), 106
Antimosquito measures,
in malaria, 249
in yellow fever, 268
antiqua (Hylemyia), 108
Anus, location of,
Acarina, 176
Cimex, 162
Siphonaptera, 117
ticks, 178
Apatolestes, 58
apimaculata (Anopheles), 29
Apiochaeta, 59
Apodeme, 67
Aponomma, 185, 196
Apophyses, 178
Arachnida, 174
Araeopsylla, 129
Archaeopsylla, 122
Archibald, R. G., 227
Argas, 184, 185, 186
Argasidae, 184, 185
differentiation from Ixodidae, 184
Argopsylla (see Echidnophaga).
argyritarsis (Anopheles), 29, 30
habits, 38, 243
Arilus, 164
Arista, 4
Arsenic, as cattle dip, 326
as rat poison, 305
Arsphenamine in relapsing fever, 323
INDEX

Arthropoda,
definition of, 1
divisions of, 1
how they cause disease, 231 to
236
Arvicola hatanedzumi, 200
Aschiza, s, 7, 60
Asilidae, 7, 59
asini (Haematopinus), 150
Aspiratory pharynx, 15, 66, 114
Ass, louse of, 150
Assassin bugs, 164
assidua (Sarcophaga), 93, 97
assimilis (Muscina), 85
astia (Xenopsylla), 134
Astigmatic mites, 180, 207, 208
atropos (Anopheles), 29
Atyphloceras, 126
Auchmeromyia, 99, 106
auris (Raillietia), 204
australasiae (Periplaneta), 168
Australian cockroach, 168
australis (Lucilia), 103, 104
(Boophilus), 190
autumnalis (Leptus), 201
(Musca), 8o
Auxiliary vein (see costal vein).

Babesia bigemina, 19o, 235
Bacillus pestis, 299
flea and, 293

Bacot, A. W., 291

bacoti (Liponyssus), 204

Bacterial virus to kill rats, 306

Bacterium tularense, 283, 298

Banks, Nathan, 109, 180, 188, 197, 201,
202,:208, 227

barbirostris (Anopheles), 243

Barn swallow bug, 159

Basicosta (see subepaulet).

Basis capituli, 177

Bats, bugs of, 158, 1509

Bdella, 199

Bdellidae, 183, 199

Beard, 65

Bedbugs, 159

diseases transmitted by, 159 (see also

Cimex).

beecheyi (Citellus), 218

bellator (Anopheles), 29

Bellolarynx, 8o

Bengalia, 99, 106

331

Bichloride of mercury, as an insecticide,
for bedbugs, 167
for pubic lice, 157
Biologic barriers in malaria, 262
Birds, lice of, 143
mites of, 199, 203, 204, 207, 210, 211
bisetosa (Sarcophaga), 94
Biting lice, 143
Biting Muscidae, 86
Black rat, 214
Black beetle, 168
Blatella, 168
Blatta, 168
Blattidae, 168
Blood smears, thick, in malaria, 246
Blood sucking Musidae, 80, 86
Blow flies, 93, 97
Blue bottle flies, 98
bobac (Marmota), 218
Body louse, 147
Bombyliidae, 7
Boophilus, 184, 190
Borax treatment of manure, 83
Borboridae, 9, 61
Borborus, 61
Boreélus, 100
Bot flies, 77
boueti (Cimex), 159
bovis (Hypoderma), 75
(Boophilus, see annulatus).
Brachycera, 3, 53, 59
homodactyla, s, 53
heterodactyla, 3, 59
Bradiopsylla, 125
brasiliensis (Xenopsylla), 135
brassicae (Hylemyia), 108
Break bone fever (see Dengue fever).
Breathing spiracles (see spiracles, breath-
ing).
Breathing tubes, 20, 21, 50, 51, 56, 60
Breeze flies, 53
Brill’s disease, 317
Bristles (see setae).
Brown rat, 213
Bryobia, 200
Bubonic plague, 289
bacillus of, 288, 299
control of, 301
epidemiology of, 289
examinaton of rats for, 300
fleas and, 289
in ground squirrels, 298
332

Bubonic plague, in guinea pigs, 298
in rats, 206
period of communicability, 289
period of incubation, 289
prognosis in, 296
recognition of, 294
rodents and, 289, 290
susceptibility of certain mammals

to, 298

transmission of, 289
treatment of, 296

Bucca, 65

Buccal cavity, 15,66, 114, 144, 171

Buffalo gnats, 50

Bugs, 158

bullata (Sarcophaga), 93, 96

Bursa copulatrix, 117

Byam, William, 227

Cabbage root maggot, 108
cadaverina (Cynomyia), 100, 102, 104
Cadicera, 57
caecata (Tunga), 130
caecigena (Tunga), 130
Caenopsylla, 123
caesar (Lucilia), 103, 103
caesarion (Cryptolucilia), 85
cajennense (Amblyomma), 197, 198
calcitrans (Stomoxys), 86

life history, 87
California ground squirrel, 218
Calliphora, 100, 101, 102, T04
Calliphoridae, 8, 97, 109

description of, 97

genera, key to, 99

habits of, 8

larva of, 98
Calliphorini, key to, 100
Callistopsyllus, 122
Callus, 54
Calypters (see squamae).
Calyptratae, 6, 8, 62
Camp fever, 313

* Camptops, go

Camptopyga, go
Canestriniidae, 181, 207
canicularis (Fannia), 107
Canine piroplasmosis, carrier of, 191
canis (Ctenocephalus), 135
Caparina, 209
capillatus (Solenoptes), 151
capitis (see humanus).

INDEX

Capitulum, 175, 177
cardinalis (Bdella), 199
Cardo, 170
Caris, 186
carnaria (Sarcophaga), 93
Carpoglyphus, 207
Carriers, human, in malaria, 239
detection of, 246
treatment of, 261
Carter, H. E., 227
Caruncle (see pulvillus).
casei (Piophila), 61
Castellani, Aldo, 227
Cat, flea of, 136
itch mite of, 210
louse of, 150
Catallagia, 123
Cattle, dip, 326
fever, Texas, 190, 233
lice of, 151
tick of, 190, 101
warbles in, 75
Cephalic glands, 179
Cephalo-thorax, 175
Ceratixoides, 189
Ceratonyssus, 204
Ceratophyllidae, 137
Ceratophyllus, 125, 137
Cerci, 13
Cervical grooves, 178
Cervophthirus, 155
Chaetopsylla (see Trichopsylla).
Chagas disease (see Brazilian
trypanosomiasis, 284 |
Chalmers, A. J., 227
Chaoborinae, 25, 28
Chaoborus, 28
Chapin, C. W., 285
Cheek, 65
Cheese fly, 61
Chelicerae (see mandibles).
cheopis (Xenopsylla), 133, 290, 291, 292,
204
Chiastopsylla, 123
Chickens, flea of, 131
mites of, 204, 210, 211
spirochaetosis of, carrier of, 185
tick of, 183
Chick; H., 203
Chigger, 201
Chigoe, 130
Chiliopsylla, 128
INDEX

Chimaeropsylla, 127
Chironomidae, 6, 50
Chiropteropsylla, 129
Chloroform, as a killing agent for insects,
220
in myiasis, 106
chordeilis (Haemaphysalis), 191
Chorioptes, 209, 210
Choristopsylla, 125
Chrysomyia (see Cochliomyia).
Chrysops, 57, 58
Chyletidae, 182, 199
Chyzeria, 201
ciliata (Psorophora), 31, 32, 46
cimbicis (Sarcophaga), 94
Cimex, 158, 159, 163
Anatomy of, abdomen, 162
alimentary tract, 162
head, 160
legs, 162
mouth parts, 160
thorax, 160
diseases transmitted by, 159
eggs of, 163
habits of, 159
immature forms, 163
Cimicidae, 158
classification of, 163
genera of, 158, 163
species of, 159, 164
Circulatory system of insects, 2
Citellus, 218
Clasp filament, 15
Claspette, 15
Clasping organs (see genitalia male).
Claws of,
Acarina, 176
Aedes, aegypti, 43
Anoplura, 145
Cimex, 162
Culicidae, 15
Diptera, 5
Pupipara, 111
Siphonaptera, 118
ticks, 178
Clearing agents, 227
Clearing in malaria control, 252
Cleopsylla, 127
climax (Trichodectes), 151
Clinocoris (see Cimex). :
Clover mite, 200
Club of antenna, 113

333

: Clypeus, 10, 54, 64, 169

Cnemidocoptes, 209

Coarctate pupa, 75

Cochliomyia, 99, 105

Cochroach, 168
as intermediate host, 172
eradication of, 172 (see also Orthop-

tera).

Coenomyiidae, 7

Collateral reading, 226

Collecting insects, 219, 247

Colleterial glands, 118

coloradensis (Sarcophaga), 95

(Calliphora), 101, 102

columbiae (Psorophora), 31, 32, 46

columbianus (see montanus).

communis (Psoroptes), 210
(Sarcophaga), 93, 97

Compsomyiops, 99

Comstock, J. H., 14, 227

Cone nose bugs, 165

Congo floor maggot, 106

Conorhinus, 165

Control of diseases (see disease in question).

Cooper, W. F., 227

Coptopsylla, 122

Corethra, 28

Corethrella, 28

Corethrinae (see Chaoborinae).

+ coriaceus (Ornithodoros), 188

corporis (Pediculus), 146, 147, 148
and disease, 149

Corypsylla, 129

Costal spine, 72

Costal vein or costa, 13

Coxa (see legs).

Coxal glands, 179

Crab louse, 149

Cragg, F. W., 133, 225, 226, 292

Craneopsylla, 126

Creel, R. H., 303

Creeping eruption, 76

Cricetinae, 213

Crista metopica, 200

cristatus (Arilus), 164

Crithidia, 232

Cross veins, 14, 71

Croton bug, 168

crucians (Anopheles), 29, 30, 31, 32
habits of, 36, 241

Crustacea, 1

Cryptolucilia, 79, 85
334

Cryptostigmatic mites, 180
Ctenidium, 118
Ctenocephalus, 122, 135
Ctenoparia, 127
Ctenophthalmus, 123
Ctenopsyllus (see Leptopsylla).
Culex, 27, 28, 29
eggs of, 24
larvae of, 24
pupae of, 23
Culicidae, 6, 10
anatomy of, abdomen, 15
alimentary tract, 15
antennae, 22
genitalia, 15
head, 10
larva, 18
legs, 15
mouth parts, 10
pupa, 20
thorax, 12
wings, 13
Anopheles, key to, adults, 28
larvae, 30
Anophelini, 34 (see anopheline mos-
quitoes).
classification of, 22, 25
collection of, 247
Culicini, 27 (see culicine mosquitoes).
diseases transmitted by, 230, 204,
274, 276
dissection of, 223
genera, key to, adults, 26
larvae, 28
identification of, 22, 235
larvae, key to, 28, 30, 32
life history of, 21
method of control, Anopheles, 250
Aedes aegypti, 269
sex, differentiation of, 135, 22
species, key to, adults, 30
larvae, 32
subfamilies, key to, 25
Culicinae, 23, 26, 34
Culicine mosquitoes, 27, 309
distinguished from anophelines, 23
position at rest, 23
wings of, 23
Culiseta, 27, 28
cuniculi (Cuterebra), 76
Cuterebra, 75, 76
cyaniventris (see hominis).

INDEX

Cyclops, 232, 278
Cyclorrhapha, s, 7, 60
Cynomyia, 100, 102, 104
Cytoleichidae, 181, 211
Cytoleichus, 211

Dasypsylla, 124
Deer fly, 58
Deer fly fever (see tularaemia).
Deinocerites, 27, 28
Delousing, 156
Demodex, 211
Demodicidae, 181, 211
Demodicoidea, 180, 181, 211
Dengue fever, 274
causative agent, 274
epidemiology, 274
insect host, habits of, 265
method of control, 275
mode of transmission, 274
period of communicability, 274
period of incubation, 274
recognition of, 274
source of infection, 274
Dermacentor, 185, 192
Dermacentroxenus rickettsi, 324
Dermal glands, 179
Dermanyssidae, 203
Dermanyssinae, 202
Dermanyssus, 204
Dermatobia, 73, 76
Dexiidae, 8
Diachlorus, 57
Dichoptic eyes, 53
Digestive system (see alimentary tract).
Digits, 178
dimidiata (Chrysops), 278
Dinopsylla, 126
Dinothrombidium, 201
Diplothrombidium, 201
Dipping solution for cattle, 326
Diptera, 4
Anatomy of
abdomen, 3
head, 4
legs, 5
mouth parts, 4
thorax, 4
wings, 5
classification of, 5
description of, 4
families, key to, 6
INDEX

Diptera, metamorphosis of, 3
Discal cell, s, 56, 71
Discal sclerite, 67
discalis (Chrysops), 58, 285
Diseases, how transmitted by Anthro-
pods, 231
Diseases of rats, 215
Disparipes, 207
Dissection of insects, 223
Ditching in malaria control, 250
Diversipes, 207
Dixa, 28
Dixinae, 26, 28
Dog, flea of, 133
louse of, 150
piroplasmosis, carrier of, 191, 196
ticks, of, 191, 192, 193, 195
Dolichopsylla, 124
Dolicopodidae, 7
domestica (Musca), 82
chigger of, 201
extermination of, 83
life history of, 82
domesticus (Glyciphagus), 207
Doratopsylla, 128
Dorso-submedian porose plates, 178
Dracunculus, 278
Drainage in malaria control, 250
Dried fruit, mite of, 207
Drips, oil, in malaria control, 253
Drone fly, 60
Drosophila, 61, 109
Drosophilidae, 9 =
dugesi (Pulex), 133
Dung fly, 61
Dutton’s membrane, 10
Dyar, BH. G., 25,28, 227
Dysentery, house fly and, 232

Ear tick, spinose, 187
echidninus (Laelaps), 204, 234
Echidnophaga, 121, 131
Echinophthiriidae, 154
Echinophthirus, 154
Economic considerations, in malaria, 245
rats, 216
Ectoparasites, definition, 231
of rats, 216
Ecto-skeleton, 2
Egg case of roaches, 168
Eggs of
Aedes aegypti, 24

333

Eggs of
Anophelines, 23
Anoplura, 145, 148, 149
Chironomidae, so
Cimex, 163
Culex, 24
Pediculus, 148, 149
Phthirus pubis, 149
Psychodidae, 51
Simulidae, 51
Siphonaptera, 118
eiseni (Anopheles), 29, 30
electus (see variabilis).
Elephantiasis, 278
elongata (Calliphora), 1o1, 102
(Lucilia), 103
Elytra, 162
emasculator (Cuterebra), 76
Emblemasoma, gt
Empidae, 7
Empodium, 3, 55
Endamoeba hystolytica and flies, 232
Enderleinellus, 153, 155
Endoparasites, definition of, 231
of rats, 216
Entomology, definition of, ©
Entonyssus, 203
Epaulet, 72
Epiandrum, 176
Epicephalon, 65
Epidemiological considerations, 231 to 238
Epigynum, 176
Epimerum, 116
Epipharynx, 114, 171
Episternum, 116
Epistoma, 64
Epistome, 175
equi (Gastrophilus), 77
equina (Hippobosca), 111
equinus (Borborus), 61
Eradication of
bedbugs, 165
fleas, 140
horse flies, 57
house flies, 83
lice, 156
mosquitoes, adult, 260
larvae, 250, 269
rats, 303 to 309
roaches, 172
Eriophydae, 181, 211
Eristalis, 60, 109
336

* erraticus (Culex), 31, 33, 34

erythrocephala (Calliphora), 101, 102,

104
Eucorethra, 28
Euhaematopininae, 154
Euhaematopinus, 154
Eulinognathus, 153, 155
Eupodidae, 183, 199
Eupodoidea, 181, 183, 199
eurysternus (Haematopinus), 151
Euthrombidium, 201
Ewing, H. E., 201, 203, 206
Examination of insects, 223

of rats for plague, 300
Expodite, 117
Extrinsic period of incubation, 234
exuberans (Sarcophaga), 96
Eyes, dichoptic, 53

glabrous, 53

holoptic, 53

of Anoplura, 143

of Cimex, 163

of Culicidae, 10

of Diptera, 4

of Insects, 1

of mites, 176

of Simulidae, 50

of Tabanidae, 53

pilose, 53

Face, 63
Facial bristles, 64

carina, 64

plate, 64
Facialia, 64
Facio-orbital bristles, 64
Fahrenholzia, 155
falciformis (Sarcophaga),fos
falculata (Sarcophaga), 96
Falx, 120
Fannia, 107, 109

larvae of, 107, 109
farinae (Tyroglyphus), 207
fasciata (see aegypti).
fasciatus (Ceratophyllus), 138
fatigans (see quinquefasciatus).
felis (Ctenocephalus), 136

as intermediate host, 136
femorata (Phora), 59
fenestralis (Scenopinus), 59
Ferris G. F,, 153, 227
ferruginea (Apiochaeta), 59

INDEX

Festoons, 178
Filaria bancrofti, infection from, 278
complications and sequellae, 278
epidemiology of, 276
insect host, habits, 277
life history of, 277
mode of transmission, 276
period of communicability, 276
period of incubation, 276
source of infection, 276
Filaria diurna, 278
Filariasis, 276
Filling, in malaria control, 251
in Pappataci fever, 280
Filth fly, 82
Fish, in malaria control, 256
in yellow fever, 270
Flagellates in insects, 232
Fleas, 112
and plague 29o to 293
biting of man by, 294
(see also Siphonaptera).
Flesh flies, 93, 104, 105
Flour mites, 207
Fly paper, 84
traps, 83, 84
Follicle mite, 174, 211
folliculorum (Demodex), 174, 211
Folsom, J. W., 227
Foot scab of sheep, 210
Forceps, 91
Forest fly, 111
Fork cells, 14
Forwarding insects, 223
Fovea, 178
Fowls, tick of, 185,
Fracticipita, 119, 120
Francilia, 103
Francis, Edward, 286
Frons, 10, 62, 112
Frontal bristles, 63
fissure, 64
lunule, 64
notch, 112
suture, 64
tubercle, 112
Frontalia, 63
Fronto-orbitals, 64
Fulcrum, 66
fuliginosus (Anopheles), 243
Fulturae, 144
fulvaster (Chrysops), 59
INDEX

fulvipes (Compsomyiops), 99

Fumigation to kill insects, 142, 156, 165,
173

funicola (Microneurium), 61

Furca, 67

Fusiform areas of fly larvae, 74

Gad flies, 53
Galea, 170
gallinacea (Echidnophaga), 132
gallinae (Cnemidocoptes), 210
© (Dermyanyssus), 204
Gamasus (see Parasitus).
Gambusia affinis, 256
Gamete, 244
Gametocyte, 244
Garbage, can for, 8s, 308
Gastrophilidae, 78
Gastrophilus, 73, 77
Gena, 64, 112
Genal process, 112
Genital aperture, mites, 176
Genitalia, male, of
Anoplura, 144
mosquitoes, 15
Muscoidean flies, 72
Psychodidae, 51
Sarcophagidae, 91
Siphonaptera, 117
Genovertical plate, 63
German cockroach, 168
germanica (Blatella), 168
Glires, 212
Gliricola porcelli, 157
Glossina, 70, 79, 87
life history, of, 88, 282
sleeping sickness and, 281
Glyciphagus, 207
Goat, louse of, 151
Angora, louse of, 151
Goeldia, 26
Gold fish, in mosquito control, 259
Goniops, 58
Goniopsylla (see Notiopsylla).
Gonopods, 144
grabhami (Anopheles), 29, 30
Grain itch, 203
Grasshopper, chigger of, 201
Gray rat, 213
Green bottle flies, 104
Green, C. T., 227
grisea (Symphoromyia), 59

22

337

Grocer’s itch, 207
Ground squirrel of California, 218
fleas of, 137, 139
louse of, 153
plague in, 298
Guinea pig, louse of, 151
plague in, 208
Guinea worm, 278
Guppy, 257
Gyropus ovalis, 151

habraeum (Amblyomma), 197
Haemagogus, 26, 27
Haemalastor, 189
Haemaphysalis, 185, 191
Haematobia, 80, 88
Haematobosca, 8o
Haematomyzidae, 154
Haematomyzus, 151
Haematophagous flies, 8o
Haematopinidae, 154
Haematopininae, 154
Haematopinoides, 154
Haematopinus, 150, 154
Haematopota, 57
Haematosiphon, 159
Haemodipsus, 151, 155
Haemogregarina canis, carrier of, 196
haemorrhoidalis (Gastrophilus), 78
(Sarcophaga), 93, 96
Haffkine prophylactic, 296
Hair clasping mites, 208
Hairs (see setae).
Halarachinae, 202
Halarachne, 203
Haller’s organ, 179
Halteres, 4, 14, 71
Harbeckia, go
Harpagones, 15
Harpagopyga, ot
Harpes, 15
Harvest mites, 200
Haustellum, 67, 143, 178
hawaiiensis (Laelaps), 204
Head of Anoplura, 168
Chironomidae, 50
Cimex, 160
Culicidae, 10
Muscoidean flies, 62
Orthoptera, 168
Psychodidae, 51
Simulidae, 50
Siphonaptera, 112
338

Head of Tabanidae, 53
Head louse, 149
~ Heart water fever in sheep,
carrier of, 196
Heated air to kill bedbugs, 167
Hectopsylla, 121
helicis (Sarcophaga), 96
. Hemelytra, 158
Hemiptera, 158
some familiar examples, 158
hemipterus (Cimex), 164
habits, 159
hermsi (Trichodectes), 151
Herpetomonas pediculi, 232
Heterodoxus longitarsus, 150
Hexactenopsylla, 129
Hind gut (see alimentary tract).
Hippelates, 61
Hippobosca, 111
Hippoboscidae, 111
Hippocentrum, 57
hirta (Symphoromyia), 59
hirundinis (Oeciacus), 159
Histiotoma, 207
Hog, louse of, 151
Homalomyia (see Fannia).
hominis (Dermatobia), 76
Hoplopleura, 152, 155
Hoplopsyllus, 122, 136
Hormopsylla, 129
Horn fly, 88
Horse bots, 77
Horse fly, 53
Horse, louse of, 150
Horse “tick,” 111
Host, definitive, 234
intermediate, 234
House fly, 82
and intestinal diseases, 231
House mouse, 215
Howard, L. O., 28, 227
humanus (Pediculus), 146, 149
hunteri (Sarcophaga), 04, 95
Hyalomma, 185, 196
Hydracarina, 180
Hydrotea, 107
Hylemyia, 107
Hypoderma, 75
Hypopelta, go
Hypopharynx, 10, 53, 114, 171, 175
Hypophthirus, 155
Hypopus, 177

INDEX

Hypopygium, 15
Hypostome, 175, 178

‘Hypsophthalmus, 127, 128

Hystrichopsylla, 127

Ichoronyssus, 204
Imparipes, 207
Impounded water, 252
Indian rat, 214
flea of, 133
inodorus (Haematosiphon), 159
Insecticides, for bedbugs, 165
fleas, 140, 142
lice, 156, 157
roaches, 172
Insects, and disease, 231
clearing specimens of, 221
collecting specimens of, 219
dissection of, 223
examination of, 223
forwarding of, 223
general description of, 1
killing agents for, 219
metamorphosis of, 3
orders of interest in preventive medi-
cine, 3
preserving specimens of, 222
sectioning of, 226
staining of, 223
insignis (Philaematomyia), 86
Integricipita, 119, 120
Intestinal diseases and flies, 231
Intestines (see alimentary tract).
irritans (Haematobia), 88
(Leptus), 201
(Pulex), 133, 290
(Trombicula), 201
Ischnopsyllus, 129 :
Itch, grocer’s, 207
human, 209
Itch mites, 208
Ixodes, 184, 188
Ixodidae, 182, 184, 188
differences between Argasidae and,
, 134
genera, key to, 184
Ixodoidea, 180, 182, 183
families, key to, 182
general description of, 133
Ixodorhynchus, 203

uz

Jail fever, 315
Janthinosoma, 46
INDEX

Japanese River fever, 327
Jigger, 130

Joblotia, 26

johnsoni (Sarcophaga), 96
Johnsonia, go
Johnstoniana, 202

Kala-azar, suspected carriers of, 136, 159
Kedani mite, 200, 327
- Kellog, V. 1.., 153, 227
kellyi (Sarcophaga), 97
Key to the
Acarina, families, 181
superfamilies, 180
Amblyomma, species, 197
Anopheles, adults, 28
larvae, 30
Anoplura, families, subfamilies and
genera, 153
Anthomyiidae, genera, 107
Argasidae, genera, 184
Calliphoridae, genera, 99
Calliphorini, species, 100
Culicidae, subfamilies, 23
genera, adults, 26
larvae, 28
species, adults, 30
larvae, 32
' Dermanyssidae, subfamilies and gen-
era, 203
Diptera, families, 6
Ixodidae, genera, 184
Larvae causing myiasis, 109
Luciliini, species, 103
Muscidae, genera, 79
Oestridae, genera, 75
Ornithodoros, species, 188
Parasitidae, subfamilies, 202
Sarcophaga, species, 94
Sarcophagidae, genera, go
Sarcoptidae, genera, 208
Siphonaptera, genera, 120
Tabanidae, genera, 57
Tarsonemoidea, families and genera,
206
Trombidiidae, genera, 201
Killing agents for insects, 219
King, H. H., 227
Klinophilos (see Cimex).
Knab, F., 28, 227
Koch-Weeks bacillus, carrier of, 61
Komp, W. H. W,, 30, 40

339

Labellae, 10, 53, 67
Labial gutter, 67
Labial salivary glands, 56, 74
Labium, 10, 53, 67, 160, 169, 171, 175
Labrum, 160, 169 :
Labrum-epipharynx, 4, 10, 53, 67, 114
Lacinia, 170
Laelaps, 204
Laminosioptes, 211
Largaropsylla, 130
Larva of
acarines, 177
Aedes aegypti, 24
anophelines, 24
causing myiasis, key to, 109
Chironomidae, 50
Culex, 25
insects, 3
mosquitoes, 18, 24, 25
keys to, 28, 30, 32
Muscoidean flies, 74
Psychoididae, 51
Sarcophagid flies, 93
Simulidae, 50
Siphonaptera, 118
Tabanidae, 56
Ticks, 180
Larvacides, in malaria control, 255
latifrons (Calliphora), 101, 102
latisetosa (Sarcophaga), 97
latisterna (Sarcophaga), 94
Latrine fly, 107
latus (Trichodectes), 150
Laws, model (see ordinances).
leachi (Haemaphysalis), 191
Lebistes reticulatus, 257
lectularius (Cimex), 159, 160, 164, 200
Legs of, acarines, 176
Anoplura, 144
Chironomidae, 50
Cimex, 162
insects, 2
mosquitoes, 13
Psychodidae, 51
Simulidae, 51
Siphonaptera, 118
Tabanidae, 55 57
ticks, 178
Leiognathus, 204
Lepidophthirus. 154
Lepidoselaga, 57
340
leporis-palustris (Haemaphysalis),
324

Leptidae, 7, 59
Leptopsylla, 127, 140
Leptospira icteroides, 264
Leptus, 201
Lice, 143

of the ass, 151

cat, 150

cow, I5I

dog, 150

ground squirrel, 153

guinea pig, 151

hog, 151

horse, 151

man, 145

monkey, 150

rabbit, 151

rat, 151

sheep, 151 (see also Anoplura).
Ligula, 171
Limatus, 26
lineata (Hypoderma), 76
Lingula, 171
Linognathinae, 154
Linognathoides, 153, 156
Linognathus, 150, 155
Liponyssus, 204
Listrophoridae, 208
Listropsylla, 124
Little house fly, 107
Lloyd, L1, 227
Loa loa, 278
Locust, chigger of, 201
Loemopsylla (see Xenopsylla).
Lone star tick, 196
Longitudinal veins, 13, 14, 71, 72
Lucilia, 100, 103, 104
Luciliini, key to, 103
ludlowi (Anopheles), 243
Lunula, 4, 64
luteola (Auchmeromyia), 106
Lutzia, 27
Lycopsylla, 122
Lyperosia (see Haematobia).
Lyperosiops, 80, 83

macellaria (Cochliomyia), 99, 105
Macgregor, M. E., 227
Macrogametocyte, 244
Macropsylla, 127

maculatum (Amblyomma), 197

INDEX

191,

maculipennis (Anopheles), 30, 38
maculipes (Anopheles), 29
Maggot trap, 83
Malacopsylla, 123
Malaria,
biologic barriers in, 262
blood index in, 246
carriers of, human, 2309, 246, 261
carriers of, insect, 239, 242, 243
causative agent, 239, 243
destruction of adult mosquitoes, 260
economic considerations in, 243
epidemiological study of, 245
epidemiology of, 239
history index in, 246
mode of transmission of, 239
mosquito survey in, 247
parasite of, life history, 243
period of communicability, 239
period of incubation, 239 '
prevention of mosquito breeding, 249
protection of healthy persons, 261
quinine prophylaxis in, 261
recognition of, 247
screening in, 262
seasonal prevalence of, 245
source of infection in, 239
splenic index in, 246
thick smears in, 246
treatment of carriers, 261
Malarial mosquitoes, 34 to 39, 239 to 243
area to be controlled, 259
breeding places, 240
control of, 249 to 260
habits of, 240 to 243
malefactor (Anopheles), 29, 30
Mallophaga, 143
and Anoplura differences between,
143 (see also lice).
Malpighian tubules, 2, 18, 56, 73, 116, 144,
163, 171, 177, 179, 322
Mammals, naturally infected with plague,
212
susceptible to plague infection, 298
Man, flea of, 133
itch mite of, 209
louse of, 147, 149
Mandibles, 10, 18, 53, 74, 114, 160, 169,
175, 177, 178
Mandibulo-basal articulation, 114
Mansonia, 21, 27, 28
Manubrium, 117
Manure, bins for, 83
disposal of, 83, 84
“Many comb’ bugs, 158
Margaropus, 191
marginata (Sarcophaga), 95
Marmota bobac, 218
Marmot, Siberian, 218
flea of, 218
Martin, C. J., 291, 293
Mass inoculations in rat plague, 297
Macxillae, 10, 53, 113, 160, 169
McCoy, G. W., 283, 298, 299
Medical entomology, definition of,
medinensis (Dracunculus), 278
mediopunctatus (Anopheles), 29
Megapsylla (see Malacopsylla).
Megarhinini, 26
Megarhinus, 26, 28
Megarthroglossus, 122
megistus (Conorhinus), 165, 284
megnini (Ornithodoros), 187
meigenii (Wohlfahrtia), 04
melampyga (Sarcophaga), 94
Melanodexia, 98, 99
melanogaster (Drosophila), 61
Melophagus, 111
Membrane, pleural, 3
pseudotracheal, 53, 67
Menolepsis, 26
Mentum, 20, 67, 171
Mesembrinella, 99
Mesopsylla, 123
Mesostigmatic mites, 180, 202
Metacephalon, 63
metallica (Protocalliphora), 99
Metamorphosis, 3
Metastigmatic mites, 180, 183
Metatarsus, 15, 178
meteorica (Hydrotea), 108
Mexican bedbug, 165
miacanthus (Polyplax), 151
Miamyia, 26
Miana bug, 185
Microgametocyte, 244
Microneurium, 61
Micropsylla, 122
Microthrombidium, 201
Midges, 50
Millions, 257
miniatus (Argas), 185
minimus (Anopheles), 243
minutus (Phlebotomus), 52, 279

INDEX 341

Mites, 175 (see also Acarina).
cattle, ear mite, 204
clover, 200
flour, 207
hair clasping, 208
harvest, 200
itch, 208
Kedani, 200, 327
of fowls, 185, 204, 210, 211
of man, 209
of mice, 199
of rats, 204, 207, 210
of sheep, 210
pulmonary, 203
red spiders, 199
snout, 199
spinning, 199
straw itch, 203
sugar, 207
troublesome to man, 174

Moeopsylla, 121

molestus (Tydeus), 199

Monkey, louse of, 150
mite of, 203

Monopsylla (see Ceratophyllus).

montanus (Linognathoides), 153

morsitans (Glossina), 87, 282

morticia (Calliphora), 102, 103

mortuorum (Cynomyia), 100, 102

Mosquito control, Anopheles, 250

Aedes aegypti, 269

Moth midges, 51

moubata (Ornithodoros), 186, 188, 322

Mounting insects, 220

Mouth parts of, Acarina, 175

Anoplura, 143
Cimex, 160
Culicidae, 10
Diptera, 4
Insects, 1
Mosquito larvae, 18
Musca, 65
Muscoidean flies, 65
Orthoptera, 169
Philaematomyia, 68
Siphonaptera, 113
Stomoxys, 68
Tabanidae, 53
Ticks, 177
Muridae, 213
Murinae, 213
342

Mus, 213, 215
Musca, 79, 80
muscarum (Trombidium), 201
Muscidae, 8, 79
genera, key to, 79
Muscina, 79, 85, 109
Muscinae, 109
Muscoidea, acalyptratae, 5, 8, 61
calyptratae, 6, 8, 62
Muscoidean flies, anatomy of, 62
abdomen, 72
alimentary tract, 73
head, 62
mouth parts, 65
thorax, 70
wings, 71
larva of, 74
pupa of, 74
musculi (Leptopsylla), 140
(Myobia), 199
musculus (Mus), 215
mutans (Cnemidocoptes), 210
Myiasis, 59, 60, 61, 75, 765 77, 93, 98,
104, 105, 1006, 107, 231
larvae causing, key to, 109
Myobia, 199
Myodopsylla, 129
Myriapoda, 1

Natural enemies of rats, 216
Nearctopsylla, 129
Needham, J. G., 14
neivai (Anopheles), 29, 30
Nematocera, 3, 6, 10, 49
Neohaematopinus, 156
Neopsylla, 128
Neotyphloceras, 128
Nervous system of insects, 2
Nesolagobius, 122
Noguchi, H., 264, 271
+Non-biting Muscidae, 8o
Non-biting stable fly, 85
Non-parasitic arthropods, how they cause
disease or injury, 231
norvegicus (Rattus), 213
Norway rat, 213
Notiopsylla, 125
Notochaeta, go
Notoedres, 208, 210
Nuttall, G. H. F., 133, 227
Nycteridopsylla, 129

INDEX

Nymphs of Acarina, 177
Anoplura, 145, 148
Cimex, 163
Ticks, 180

Obtect pupa, 21
occidentalis (Anopheles), 29, 30, 38
(Dermacentor), 193, 194
Occiput 10, 63, 112
ocellar, bristles, 62
triangle or plate, 62
Ocelli, 4, 58, 62, 112, 143, 176
ochracea (Sarcophaga), 93, 97
Ochromyia (see Bengalia).
Odontopsyllus, 123
Oeciacus, 158
Oesophagus (see alimentary tract).
Oestridae, 8, 75, 109
genera, key to, 75
QOestrus, 75, 77
Oiling in malaria control, 252
when to discontinue, 254
Oncopsylla (see Trichopsylla).
Onesia, 100
Onion maggot, 108
Operculum, 145, 148
opifera (Sarcophaga), 94, 95
Orbit, 63
Ordinances, guide for, antimosquito, 271
rat proofing, 309
Organ of Berlese, 162
Oribatoidea, 180, 2035
Oriental cockroach, 168
orientalis (Blatta), 168
Ornithodoros, 184, 186
species, American, key to, 188
Ornithopsylla, 121
Ortalidae, 8, 10g
Orthopodomyia, 27, 28
Orthoptera, 168
anatomy of
alimentary tract, 171
mouth parts, 169
salivary glands, 171
description of, 168
diseases spread by, 172
eggs of, 168
eradication of, 172
habits of, 169
species of, 168
Orthorrhapha, 5, 10, 53
osborni (Enderleinellus), 153
INDEX

Oscinidae, 9, 61

Otobius, 188

Otodectes, 209

ovinus (Melophagus), 111
Ovipositor, 72

ovis (Oestrus), 77

pachyprocta (Sarcophaga), 93, 96
Palaeopsylla, 128
pallescens (Lucilia), 103, 104
Palm rat, 215
palpalis (Glossina), 87, 282
Palpi, 1, 12, 23, 34, 39, 53, 66, 113, 114,
170, 171, 175, 177, 178
Pangonia, 57
Pangoninae, 57
papatasii (Phlebotomus), 52, 279
Paper, sticky for flies, 84
Pappataci fever, 279
causative agent, 279
control of, 280
epidemiology of, 279
period of incubation, 279
Phlebotomus fly and, 279
recognition of, 279
source of infection, 279
transmission of, 279
Paracephalon, 65
Parafacial area, 64
Parafrontals, 63
Parapsyllus, 124
Parasites, arthropod,
accidental, 231
definition of, 231
ectoparasites, 231
endoparasites, 231
how they cause disease, 232
permanent, 231
pseudoparasitism, 231
temporary, 231
Parasitidae, 182, 202
Parasitinae, 202, 204
Parasitoidea, 180, 182, 202
Parasitus, 203
Pariodontis, 121
passularum (Carpoglyphus), 207
Patton, W. S., 225, 226, 227
pedalis (Linognathus), 151
Pediciniae, 150, 154
Pedicinus, 154
Pediculidae, 145, 154
Pediculinae, 145, 150, 154

343

Pediculoides, 206
Pediculopsis, 206
Pediculus, 145, 150, 154
corporis and humanus, differences
between, 146
diseases transmitted by, 149
habits of, 146
penetrans (Tunga), 130
peniculata (Sarcophaga), 9s
Peripatus, 1
Periplaneta, 168
Peritreme, 202
Peritrophic membrane, 73
perniciosus (Phlebotomus), 52
persicus (Argas), 185
personatus (Reduvius), 164
Phalacropsylla, 128
Philaematomyia, 68, 79, 86
Phlebotomus, 52
fever, 279
Phora, 59
Phoridae, 7, 59
Phormia, 99, 103
Phorminae, gg
Phosphorus, as a rat poison, 305
Phrissopodia, go
Phthirpedicinus, 154
Phthirpediculus, 154
Phthirus, 149, 154
Phylum Arthropoda, 1
Pierce, W. D., 227
Pigeons, tick of, 186
Pigmeophorus, 206
pilatei (Lucilia), 103, 104
piliferus (Linognathus), 150
pilosellus (Cimex), 159
Piophila, 61, 109
pipiens (Culex), 31, 40
pipistrelli (Cimex), 159
Piroplasma canis, 196
Pipunculidae, 8
Piroplasmosis, canine, carriers of, 191, 196
Plague (see also bubonic plague).
bacillus of, 288, 299
bubonic, 289
forms of, 288
guide for formulating a rat proofing
ordinance, 309
pheumonic, 309
septicaemic, 288
Plasmodia of malaria, 239, 248
life history of, 243
344

Plates, accessory, ot

facial, 64

genovertical, 63

paracephalic, 65

pleural, 144

porose, 178

sternal, 144

ventral, 176, 188, 189
Pleura, 2
Pleural membrane, 3

plates, 144
plinthopyga (Sarcophaga), 97
Pneumonic plague, 309
Pneumonyssus, 203
Podapolipus, 207
Podothrombidium, 202
Poison, rat, 303

roach, 172
Pollenia, 98, 99, 106
Polleninae, 99
Polyctenidae, 158
Polyplax, 153, 156
Pomace flies, 61
popoffana (Steringomyia), 102
Porose areas, 178

plates, 178
portoricensis (Aedes), 45
Postscutellum, 13
praetiosa (Bryobia), 200
Prescutum, 70
Preservatives for insects, 222
Prestomal teeth, 67, 143
Pretarsal sclerite, 145
Prevention and control of malaria, 249

area to be controlled, 259
Proboscis (see mouth parts).
Proechinophthirus, 154
Proenderleinellus, 155
Prosopodectes, 208
Prosopolepis, 26
Prostigmatic mites, 180, 199
Protocalliphora, 99, 106
Protophormia, 100, 105
Protracheata, 1
Pseudoparasitism, 231
pseudopunctipennis (Anopheles), 29, 30,
3%, 37

habits, 38, 242
Pseudopyrellia (see Cryptolucilia).
Pseudotracheal membrane, 53, 67
Psorophora, 27, 28, 45, 76
Psoroptes, 209

INDEX

Psychodidae, 6, 51
Pterophthirus, 155
Ptilinal area, 64
suture, 4, 64
Ptilopsylla, 129
Pubic louse, 149
pubis (Phthirus), 149
Pulex, 121, 132
Pulicidae, 132
Pulvilliform empodium, 3
Pulvillus, 5, 176, 178
punctata (Haemaphysalis), 191
punctipennis (Anopheles), 29, 30, 31, 32,
37
habits, 37, 242
Pupa, coarctate, 75
obtect, 21
of Aedes aegypti, 25
anopheline mosquitoes, 25
Chironomidae, 50
Chrysops, 58
Culex, 25
Culicidae, 20
insects, 3
muscoidean flies, 74
Psychodidae, 51
Simulidae, 50
Siphonaptera, 119
Tabanidae, 57
Puparium, 75
Pupipara, 6, 111
Pycnosoma (see Cochliomyia).
Pygidium, 116
Pygiopsylla, 125
Pygmodispus, 207

quadrimaculatus (Anopheles), 30, 31, 32,
34
habits, 34, 241
quadrisetosa (Sarcophaga), 93, 97
Quinine prophylaxis, 261
quinquefasciatus (Culex), 31, 33, 40 °
habits, 41, 277

Rabbit, louse of, 151
tick of, 1g1
radicum (Anthomyia), 108
Raillietia, 204
Rat proofing, 306
by elevation, 306
concrete used in, 306
of basements, 306
INDEX

Rat proofing of chicken coops, 307
city sewers, 307
double walls, 307
freight cars, 308
ships, 308
stables, 307
walls, 306
wharves, 307
wooden floors, 307
ordinance for, 309
thickness of floors in, 306, 314
Rats, 213
diseases of, 215
economic considerations, 216
ectoparasites reported from, 217
fleas of, 133, 134, 138, 140
habits of, 213, 214, 215
louse of, 151
mites of, 204, 210
natural enemies of, 216
plague and, 289, 290, 293
plague in, 296
poisoning of, 305
trapping of, 303, 304
Rat tail larva, 6o
Rattus, 213, 214, 215
rattus (Rattus), 214
Receptaculum seminis, 117
ducts of, 117
recinus (Ixodes), 189
Rectal papillae or glands, 18, 56, 73, 116,
263, 171
Rectum (see alimentary tract).
Red spiders, 199
Reduviidae, 164
Reduvius, 164
Red water fever, carrier of, 190
cause of, 19o
reflexus (Argas), 186
regina (Phormia), 99, 105
Relapsing fever, 321
causative agent of, 321
control of, 323
epidemiology of, 321
intermediate hosts in, 321
louse and, 321
period of incubation in, 321
recognition of, 322
ticks and, 321, 322
transmission of, 321, 322
Respiratory system of insects, 2
restuans (Culex), 33

345

reversa (Sarcophaga), 95
Rhadinopsylla, 123
Rhinolophopsylla, 130
Rhipicentor, 185, 194
Rhipicephalus, 185, 195
Rhopalopsyllus, 124
Rhynchoprion (see Tunga).
Rhyncopsylla (see Hectopsylla).
Rhyphidae, 6
Rickettsia quintana, 319
prowazeki, 315
Robber flies, 59
Robertson, H. McG., 292
Robinson, L. E., 227
Rocky Mountain spotted fever, 324
causative agent of, 324
control of, 326
epidemiology of, 324
period of incubation in, 324
recognition of, 325
source of infection in, 324
ticks and, 193, 324
Rodents, 313
and plague, 289, 290
naturally infected with plague, 212
rodhaini (Bengalia), 106
Roof rat, 215
Rooseveltiella, 121
Root maggot flies, 108
Rostrum, 65, 114
Rothschild, N. C., 136
Rothschildiella (see Rhopalopsyllus).
rotundatus (see hemipterus).
rubrofasciatus (Conorhinus), 165
rudis (Pollenia), 106

Sabethes, 26

Sabethini, 26

Sabethoides, 26

salinarius (Culex), 31, 33, 41

Salivary canal, 10

Salivary glands,
labial, 56, 74

of Acarina, 177

Anoplura, 144
Cimex, 163
Culicidae, 18
insects, 2
Muscoidean flies, 73
Orthoptera, 171
Siphonaptera, 116
Tabanidae, 56
346

Salivary glands,

of ticks, 179

parasites of malaria in, 243

trypanosomes in, 283
Salt marsh mosquito, 44
salva (Sarcophaga), 96
Sand flies, 50
sanguineus (Rhipicephalus), 195
sanguisuga (Conorhinus), 165
sapphirinus (Uranotaenia), 32, 47
Sarcophaga, 91, 93, 04

species, key to, 94
Sarcophagidae, 8, go, 91, 109

description of, 91

genera, key to, go

habits of, 93

larvae of, 93
Sarcophagula, go
Sarcopsylla (see Tunga).
Sarcoptes, 209
Sarcoptidae, 181, 208
Sarcoptoidea, 181, 205
Sarothromyia, go
sarracenioides (Sarcophaga), 93, 96
savignyi (Ornithodoros), 174, 187, 188
sayi (Psorophora), 31, 32, 47
scabiei (Sarcoptes), 209
Scabies, 209
Scab mite of sheep, 210
scalaris (Fannia), 107

(Trichodectes), 151
Scales of mosquitoes (see setae).
Scatophagidae, 8
Scenopinidae, 7
Scenopinus, 59
Schizophora, 3, 8, 60
Schizotrypanum cruzi, 284
Scipio, 155
Sciuridae, 218
Scorpions, 174
Screening,

against house flies, 84

in malaria, 262

pappataci fever, 280
yellow fever, 269

Screw worm fly, 105
scrofa (Hypopelta), 93
Scutellum, 12, 71
Seutum, 71, 175, 177, 178
Sectioning insects, 226
securifera (Sarcophaga), 96
Sensory plate, 116

INDEX

Sepsidae, 8
Sepsis, 61
sericata (Lucilia), 103, 104
Serpenticola, 204
serratus (Polyplax), 151 :
Setae, 3 (hairs, bristles or scales).
of Aedes, 43
Anopheles, 34
Cimex, 162
Culex, 39
mites, 176
mosquito larvae, 18
mosquitoes, 10
muscoidean flies, 62, 70, 71
Psychodidae, 51
Siphonaptera, 118
Tabanidae, 55
setigera (Sarcophaga), 95
Sewer rat, 213
Shannon R. C., 23, 99, 100, 103
Sheep “louse,” 111
tick,’ 11%
Sheep, louse of, 151
scab mite of, 210
Shields, ventral," 176
Ship fever, 315
rat, 214
silacea (Chrysops), 57
Simulidae, 6, 50
Simulium reptans, 50
sinensis (Anopheles), 243
sinuata (Sarcophaga), 94
Siphonaptera, 112 (see also fleas).
Anatomy of
abdomen, 116 ,
alimentary tract, 116
genital organs, female, 117
genital organs, male, 117
head, 112
legs, 118
mouth parts, 114
thorax, 116
classification of, 119
eggs of, 118
eradication of, 140
genera, key to, 120
larvae of, 118
plague and, 289 to 293
pupae of, 119
Sleeping sickness, African, 281
causative agent in, 281
control of, 282
INDEX

Sleeping sickness, epidemiology of, 282
flies and, 281, 282
period of communicability, 282
period of incubation, 282
recognition of, 282
source of infection, 282
transmission of, 281
Solenoptes, 151, 155
sollicitans (Aedes), 31, 32, 44
Spalacopsylla (see Ctenophthalmus).
Spermatheca, 117, 179
Spiders, 174
Spilopsyllus, 122
Spines, of fleas, 118
Spinning mites, 200
Spinose ear tick, 187
Spinturnicinae, 202
spinulosa (Polyplax), 151
Spiracles, breathing, 20, 74, 116, 144,
162, 177
Spirochaetosis of fowls, carrier of, 183
Spurs, 3, 57
Squamae, 3, 72
Squirrel, California ground, 218
fleas of, 137, 139
louse of, 153
plague in, 2908
Stable fly, 86
stabulans (Muscina), 85
stabularius (Laelaps), 204
Staining, 225
Stegomyia fasciata (see aegypti (Aedes)).
Stem vein, 72
Stenistomera, 127
Stenonotus (see Ceratophyllus).
stenopis (Linognathus), 151
Stenoponia, 127
Stenopsylla (see Doratopsylia).
Stephanocircus, 126
Stephanopsylla, 126
Steringomyia, Too
Sternites, 2, 3
Sternopsylla, 129
Sthenopyga, 91
Sticky substance to catch, flies, 84
rats, 304
Stigmal plates,
of fly larvae, 74
ticks, 179
Stigmatic openings (see spiracles, breath-
ing).
Stiles, C. W., 179

347

Stimson, A. M., 264
stimulans (Lyperosiops), 89
Stink glands, 162
Stipes, 170
Stitt, E. R., 237,248
Stivalius, 125
Stoma, 67
Stomach (see alimentary tract).
Stomoxys, 68, 8o, 86
Stratiomyiidae, 7
Straw itch, 205
strigimaculata (Anopheles), 29, 30
Stygeromyia, 8o
Style, 4, 117
Subcostal vein, 14, 71
sclerite, 72
Subepaulet, 72
Submentum, 171
subrostrata (Trichodectes), 150
Sucking louse of, ass, 150
COW, I5I
dog, 150
goat, 151
hog, 151
horse, 150
man, 145
monkey, 150
rabbit, 151
rat, 151
sheep, 151
squirrel, ground, 153
Sugar mites, 207
suis (Haematopinus), 151
Sulphur, as insecticide, 142, 165, 173
in acariasis, 210
suturalis (Enderleinellus), 153
sylvarum (Lucilia), 103
sylvestris (see vexans).
Symphoromyia, 59
Syrphidae, 8, 60

Tabanidae, 7, 53
alimentary tract of, 55
anatomy of, external, 53
classification of, 57
eggs of, 56
genera, key to, 57
larvae of, 56
pupae of, 57
salivary glands of, 56
wings of, 55

Tabaninae, 57
348

Tabanus, 57
Tachinidae, 8
Tadpoles, 259
taeniorhynchus (Aedes), 31, 32, 45
talaje (Ornithodoros), 187, 188
Tanaupodus, 201
tarsalis (Histiotoma), 207
tarsimaculata (Anopheles), 29, 30
habits, 38, 242
Tarsonemoidea, 206
Tarsonemus, 207
Tarsonomidae, 181, 205
Technique, 219
Tegula (see epaulet).
Telson, 144
tenax (Eristalis), 60
Tergites, 2, 3
terraenovae (Protophormia), ros
territans (Culex), 31, 41
testaceus (Culex), 31, 33, 42
- Tetragonyssus, 203
Tetranychidae, 182, 199
Texas bedbug, 165
Thaumapsylla, 129
Thelodiscus, or
Thervidae, 7
Thorax,
Cimex, 160
Culicidae, 12
divisions of the, 2
insects, 2
Muscoidean flies, 70
of Anoplura, 142
Siphonaptera, 116
Tabanidae, 55
Three day fever, 279
Ticks, 177, 183
anatomy of, 177
argasid, 185
collecting, 219
dissection of, 224
examination of, 223
ixodid, 188
preservation of, 222
Tipulidae, 4, 6
tlalzahuatl (Trombicula), 201
Top minnows in mosquito control, 256
Tracheal openings (see spiracles, breath-
ing).
Transverse impression, 64
suture, 4, 70

INDEX

Trapping, fly larvae, 83
house flies, 83
rats, 303, 304
roaches, 172
Trench fever, 319
causative agent in, 319
control of, 155, 319
delousing in, 155
epidemiology of, 319
louse and, 319
period of communicability, 319
period of incubation, 319
recognition of, 319
transmission of, 319
Triatoma (see Conorhinus).
Trichodectes, 150, 151
Trichopsylla, 124
trigonum (Euthrombidium), 201
Trombella, 201
Trombicula, 201
Trombidiidae, 182, 200
Trombidioidea, 181, 182, 199
Trombidium, 202
Trypanosomes, 281
carriers of, 87, 281
Trypanosomiasis, African, 281
South American, 284
Trypetidae, 9, 109
Tsetse flies, 87, 282
Tsutsugamushi fever, 327
causative agent in, 327
control of, 328
epidemiology of, 327
Kedani mite and, 327
period of communicability, 327
period of incubation, 327
recognition of, 327
source of infection, 327
transmission of, 327
tuberculatum (Amblyomma), 197
tuberosa (Sarcophaga), 93, 96
Tularaemia, 285
arthropods and, 283, 286
causative agent in, 283
epidemiology of, 285
period of communicability, 285
period of incubation, 285
recognition of, 286
source of infection, 285
transmission of, 285
Tunga, 121, 130
Tungidae, 130
turicata (Ornithodoros), 188
Tydeus, 174, 199
Typhloceras, 126
Typhlothrombidium, 201
Typhoid fever and flies, 232
Typhoid fly, 82
Typhus fever, 315
causative agent in, 315
control of, 318 :
delousing in, 156, 318
epidemiology of, 315
lice and, 315, 316
period of communicability, 315
period of incubation, 315
recognition of, 317
source of infection, 315
transmission of, 315
Weil-Felix reaction in, 317
Tyroglyphidae, 181, 207
Tyroglyphus, 207

Unci, 135

unicolor (Lucilia), 103, 104
Uranotaenia, 27, 28, 47
Uranotaenini, 27, 47
Uropodinae, 202, 203
Uropsylla, 125

utilis (Sarcophaga), 97

variabilis (Dermacentor), 192

Variatipes, 207

Vascular system of insects, 2

Veins, of wing (see wings).

Ventral plates or shields, 176

ventricosus (Haemodipsus), 151
(Pediculoides), 205

venustus (Dermacentor), 194

Ver du Cayor, 106

Vermipsylla, 124

Vertex, 10, 62

Vertical bristles, 62

vestimenti (see corporis).

vestitipennis (Anopheles), 29

vexans (Aedes), 31, 32, 44

Vibrissae, 64

vicarius (Oeciacus), 159

vigil (Wohlfahrtia), 94

violacea (Sepsis), 61

viridescens (Calliphora), 101, 102

vituli (Linognathus), 151

vomitoria (Calliphora), 102, 103, 104

Vulva, 117, 162, 176

INDEX ; 349

walkeri (Anopheles), 30
Warble flies, 75

Warburton, Cecil, 227
Watson, Malcolm, 227
Weil-Felix reaction, 317
Wharf rat, 213

Wheel bug, 164

wheeleri (Compsomyiops), 99
Wherry, W. B., 285

White rat, 215

' Williston, S. W., 227

Window fly, 50
Wing veins and cells, terminology of, 13,
14, 15

Wings of
Chironomidae, 50
Culicidae, 13, 23
Diptera, 4
Hemiptera, 158
insects, 2
Muscoidean flies, 71
Orthoptera, 168
Psychodidae, 51
Simulidae, 50
Tabanidae, 55

winthemi (Margaropus), 191

Wohlfahrtia, go, 93

Wood tick, 192

Wyeomyia, 26, 28

Xenopsylla, 121, 134
Xestopsylla (see Echidnophaga).
Xiphiopsyllus, 124

Xylol and carbolic acid, 221
Xylol, clearing agent, 221
Xylomyiidae, 7

Xylophagidae, 7

Yellow fever, 264 .
Aedes aegypti, habits of, 265
causative agent in, 264
control of, 268
epidemiology of, 264
mosquito and, 264, 265
ordinance, antimosquito, guide for,

271
period of communicability, 264
period of incubation, 264
recognition of, 266
source of infection, 264
transmission of, 264
Yersin’s serum, 296
 
Nii

C02924ke2?