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57-426-12M

TEXAS AGRICULTURAL EXPERIMENT STATION

B. YOUNGBLOOD, DIRECTOR
COLLEGE STATION, BRAZOS COUNTY, TEXAS

BULLETIN NO. 339 _ APRIL, 1926

DIVISION OF EN TOMOLOGY

THE COTTON FLEA HOPPER

 

AGRICULTURAL AND MECHANICAL COLLEGE 0F TEXAS
T. O. WALTON, President

i

S TATION STAFF?

ADMINISTRATION:
B. YOUNGBLOOD, M. S., Ph. D., Director
A. B. CONNER, S., Vice-Director

. E. KARPER, B. S., Assistant Director
. S. WARE, Secretary

. P. HOLLEMAN, JR., Chief Clerl:
. K .FRANCKLOW, Assistant Chief Clerk
M. SCHAEDEL, Executive Assistant

C. B. NEBLETTE, Technical Assistant

VETERINARY SCIENCE:
*M. FRANCIS, D. V. M., Chief
H. SCHMIDT, D. V. M., Veterinarian
W. L. BLACK, D. V. M., Veterinarian

CHEMISTRY:

G. S. FRAPS, Ph. D., Chief; State Chemist
S. E. ASBURY, M. S., Assistant Chemist
WALDO H. \VALKER, Assistant Chemist
J. K. BLUM, B. S., Assistant Chemist

J. E. TEAGUE, B. S., Assistant Chemist
VELMA GRAHAM, Assistant Chemist

ADAH E. PRocToR, B. S., Assistant Chemist
N. J. VOLR, M. S., Assistant Chemist

E. C. CARLYLE, B. S., Assistant Chemist
R. O. BROOKE, M. S., Assistant Chemist

HORTICULTURE:
W. B. LANIIAM, M. A., Chief
H. NEss, M. S., Berry Breeder

Swg>w

RANGE ANIMAL HUSBANDRY:
J. JONES, _A. M., Chief; Sheep and Goat
Investigations

J. L. LUSII, Ph. D_., Animal Husbandman;
Breeding Investigations
FRANK GRAYsON, Wool Grader

ENTOMOLOGY: _

F. L. THOMAS, Ph. D., Chief; State
Entomologis‘ _

H. J. REINIIARDJB. S., Entomologist

W. L. OwEN, M. S., Entomologist

S. E. lVICGREGOR, JR., Acting Chief Foulbrood
Inspector

GILLIS GRAIIAM, Apiary Inspector

OTTO MAcRENsEN, Foulbrood Inspector

AGRONOMY: _
E. B. REYNOLDS, M. S., Chief
A. B. CONNER, S., Agronomist, Grain
Sorghum Research _
R. E. KARPER, B. S., Agronomist, Small
Grain Research
D.’T. KILLOUGH, M. S., Agronomist, Cotton
Breeding _ _
R. H. STANSEL, B. S., Assistant in Crops

PLANT PATHOLOGY AND PHYSIOLOGY
J. J TAUBENIIAUS, Ph. D., Chief

FARM AND RANCH ECONOMICS:
L. P. GABBARD, M. S., Chi
B. YOUNGBLOOD, M. S., Ph. D., Farm an
Ranch Economist
G. L. CRAWFORD, B. S., Research Marketin
Specialist
**GLADYS D. LINDSEY, M. S., Assistant i
Farm and Ranch Economics
V. L. CORY, M. S., Grazing Research Botani:
**T. L. GASTON, JR., B. S., Assistant, Farr
' Records and Accounts
**J. N. TATE, B. S., Assistant, Ranch Record
and Accounts

SOIL SURVEY:

**W. T. CARTER, B. S., Chief

H. W. HAWKER, Soil Surveyor

E. H. TEMPLIN, B. S., Soil Surveyor
T. C. REITCH, B. S., Soil Surveyor

BOTANY:
H. NEss, M. S., Chief

PUBLICATIONS:
A. D. JAcKsoN, Chief

SWINE HUSBANDRY:
FRED HALE, M. S., Chief

DAIRY HUSBANDRY:
Chief

POULTRY HUSBANDRY:
R. SHERWOOD, M. S., Chief

***AGRICULTURAL ENGINEERING:
MAIN STATION FARM:
G. T. McNESS, Superintendent

APICULTURAL RESEARCH LABORATORY:
(San Antonio)
H. B. PARKS, B. S., Apiculturist in Charge
A. H. ALEX, B. S., Queen Breeder

FEED CONTROL SERVICE:
F. D. FULLER, M. S., Chief

S. D. PEARcE, Secretary

J. H. ROGERS, Feed Inspector

W. H. WOOD, Feed Inspector

K. L. KIRKLAND, B. S., Feed Inspector

W. D. NORTHCUTT, JR.. B. S., Feed Inspector
V. C. GLASS, B. S., Feed Inspector

E. H. GARRETT, Feed Inspector

SUBSTATIONS

No. l, Beeville, Bee County:
R A. HALL, B. S., Superintendent

No. 2, Troup, Smith County:
W. S. HOTQIIKISS, Superintendent

No. 3, Angleton, Brezoria County:
V. E. HAENER, B. S., Superintendent

No. 4, Beaumont, Jetferson County:
R. H. WYCHE, B. S., Superintendent

No. 5, Temple, Bell County:
H. E. REA, B. S., Superintendent

No. 6, Denton, Denton County:
P. B. DUNKLE, B. S., Superintendent

No. 7, Spur, Dickens County:
R. E. DICKSON, B. S., Superintendent

No. 8, Lubbock, Lubbock County:
D. L. JONES, Superintendent
FRANK GAINES, Irrigationist and Forest
Nurseryman

No. 9, Balmorhea, Reeves County:
J. J. BAYLES, B. S., Superintendent

No. 10, Feeding and Breeding Station, near
College Station, Brazos County:
R. M. SHERWOOD, M. S., Animal Husband-
man in Charge of Farm
L. J. McCALL, Farm Superintendent

No. l1, Nacogdoches, Nacogdoches County:
H. F. MORRIS, 1W. S., Superintendent

**No. 12, Chillicothe, Hardernan County:
J. R. QUINBY, B. S., Superintendent _
**JOSEPH C. STEPHENS, Junior Agronomist

No. 14, Sonora, Sutton-Edwards Counties:
W. THOMAS, B. S., Superintendent

D. H. BENNETT, D. V. M., Veterinarian

V. L. CORY, 1W. S., Grazing Research Botanisl
**O. G. BABCOCK, B. S., Collaborating

Entomologist
O. L. CARPENTER, Shepherd

No. 15, Weslaco, Hidalgo County:
W. FRIEND, B. S., Superintendent
E. HOBBS, B. S., Entomologist

No. l6, Iowa Park, Wichita County:
E. J. WILSON, B. S., Superintendent

Teachers in the School of Agriculture Carrying Cooperative Projects on the Station:

. BILSING, Ph. D., Professor of Entomol

W.
. ogy
.  BUECHEL, Ph.

. P
. g) POLLOCK, A.

EUU1<QWMQ

TASOf May 1, 1926. _ _
*Dean, School of Veterinary Medicine.

ADRIANcE, M. S., Associate Professor of Agriculture

D., Professor of Agricultural Economics
GROUT, M. S., Professor of Dairy Husbandry

. LEE, Ph. D., Professor of Agricultural Economics

. M., Assistant Professor of Agronomy

COATES, A. E., Professor of Agricultural Engineering

. P. SMITH, B. S., Associate Professor of Agricultural Engineering

**'In cooperation With U. S. Department of Agriculture.
***In cooperation with the School of Agixculture.

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SYNOPSIS

This Bulletin contains a report 0n the life history and habits
of the cotton flea hopper in the vicinity of College Station.
This insect is widely distributed over Texas and occurs in
many other states. By means of cage experiments the cotton
flea hopper is shown to be definitely associated with a new type
of injury to cotton. This injury is characterized by the ex-
cessive blasting of small squares, the suppression of fruiting
branches, and the tendency of plants to abnormally tall growth.
All stages of the insect are described, and a list of thirty-eight
food plants is given. The insect hibernates in the egg stage.
The winter host plants vary in different regions of the State;
however, sageweed or goatweed is the most important." The
results of preliminary experiments on control of this insect
indicate that cultural measures are most important and effec-
tive in preventing infestation. These consist of good farming
practices, includingidestruction of cotton stalks and especially
weed eradication. Sulphur applied as a dust is an efficient
insecticide in controlling this pest.

CONTENTS

 

PAGE
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Scientific Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  . 7

Common Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. '7

Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Egg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Nymphal Stages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

First Instar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9

Second Instar . . . . . . . . . . . . . . . . . . . . . . . . . . ., . . . . . . . . . . . 10

Third Instar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .; 10

Fourth Instar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Fifth Instar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Adult . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 11

Geographical Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Food Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Methods of Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 15

Character and Extent of Injury . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Life History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 21

Table 1, Life Cycle in Spring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Mating and Fertility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 23'

Oviposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 23

Host Plants . . . ; . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Table 2, Duration of Oviposition Period . . . . . . . . . . . . . . . . . . . . . 25

Table 3p, Total and Daily Rate of Oviposition . . . . . . . . . . . . . . . . . 26

Hatching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I . . . . . . . . . . . 2'7

Table 4, Duration of Egg Stage . . . . . . . . . . . . . . . . . . . . .  . . . . 2'?

Table 5, Nympha] Development in Summer . . . . . . . . . . . . . . .. 29

Table 6, Summary of Development . . . . . . . . . . . . . . . . . . . . . . . . 30

Adult . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Table '7, Length‘ of Life of Adults . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Feeding Habits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Protective Habits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 31

Hibernation . . . . . . . . . . . . Q . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Natural Enemies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Methods of Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  . . . . . . . .. 33

Cultural Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Use of Insecticides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 35

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 37-

Acknowledgmentts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  . 38

Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 439

mwyfgfyfivwwma . . .

THE COTTON FLEA HOPPER
H. J. REINHARD

In the localities where the cotton flea hopper has demonstrated its
ability to produce injury to the cotton crop, the unanimous opinion

I of growers has been that this insect is more destructive than the boll

weevil. .

The insect has been present in Texas for many years but attracted
no attention as an economic pest until 1920. At that time there was
a question as to the responsibility of the cotton flea hopper for the
appearance of a new type of damage to cotton which was manifested
by the excessive shedding of minute squares. Investigations in this
connection proved the insect to be definitely associated with the dam-
age to cotton. The facts established by these investigations are given
in this Bulletin‘. Inasmuch as the cotton flea hopper may become sud-
denly a very destructive pest in practically any section of the cotton-
growing regions, this information is considered timely and pertinent
especially to the cotton growers of Texas.

SCIENTIFIC NAME

The cotton flea hopper was first named and described in 1876 by
Renter as Atomoscelis seriatus (6), from specimens collected in Texas
by Belfarge. The species was referred to by this name in all sub-
sequent literature until 1916, when Van Duzee placed it in the genus
Psallus (10). This arrangement obtains at the present time and is
accepted by authorities as best expressing the taxonomic position of
the species.

COMMON NAMES

The common name “cotton flea” was first applied to this insect by
growers in the coastal region of Texas, where the injury to cotton first
became noticeable. Undoubtedly, the size and appearance of the insect
in connection with its, habit of jumping influenced the layman in
choosing this name. Among cotton growers in Texas the name has
become definitely associated with this insect. The late Dr. W. D.
Hunter, in an effort to secure a more appropriate common name from
an entomological viewpoint, was the first to suggest and use the term
“cotton hopper”. This was a distinct improvement over the original
name, because it described better the taxonomic position of the species.
To incorporate this desirable feature and at the same time retain. the
original tcrm, a combination of the two names, “cotton flea hopper”,
is used in this Bulletin as the common name of the insect.

8 BULLETIN NO. 339, TEXAS AGRICULTURAL EXPERIMENT STATION

DESCRIPTION

Egg

The egg is elongate, considerably enlarged and broadly rounded at
the caudal end; with a constricted curved neck and truncate cap. The
truncate end is somewhat compressed in plane of curvature, cap con-
cave, the projecting edge or rim ellipsoidal in outline when viewed
dorsally. When first laid the egg is glistening white, but it assumes
a yellowish tinge before hatching. The chorion is lustrous, apparently

Figure 1. _Stem of sageweed or goatweed
plant with bark removed showing eggs
of cotton flea hopperiin natural position.
Enlarged about three times.

smooth, but under magnification it shows distinct irregular hexagonal
reticulations. In size the egg is slightly variable, averaging 0.87 mm.
and 0.20 mm. in greatest dimensions. ‘

N ymphal Stages

There are five nymphal stages in the development of the cotton flea
hopper. The first instar is characterized by the narrow elongated body
andslender legs. It bears less resemblance to the adult insect in out-
line and general appearance than any of the succeeding stages, From

‘l2.
i}.

 

THE COTTON FLEA HOPPER 9

the second to the last instar the thorax and abdomen increase rapidly
in width, and the body becomes more compact and robust. After the

fourth molt the nymph closely resembles the adult in appearance, ex-

cepting the Wings, which are not yet fully developed.

Figure 2. Nymphs of the cotton flea hopper. instar.

(c) Third instar. (d) Fourth instar. (e) Fifth instar.

(a) First instar. 5b) Second

Great y enlarged.

First Instar: Length 1 mm.
prothorax and broadly rounded in front. Body color translucent White
after hatching, becoming pale green soon after feeding begins. Eyes
prominent, bright scarlet in color. Rostrum apparently three-jointed,
rather thick and long, extending slightly beyond the hind coxae, tip
faintly dusky. Antennae densely pubescent, four-jointed, first joint

Head Width 0.25 mm., as Wide as a

1O BULLETIN NO. 339, TEXAS AGRICULTURAL EXPERIMENT STATION

slightly thickened, length 0.6 mm., second 0.12 mm., third 0.12 mm.,
fourth 0.20 mm., total length 0.50 mm.. Thoracic and abdominal
segments distinct. Abdomen narrow, elongate, tapering to caudal ex-
tremity and strongly constricted before tip. Body sparsely clothed
with short hairs and each abdominal segment bearing a more or less
regular median transverse row of short bristles. Legs long, basal
joints somewhat enlarged, tibia and tarsus slender, claws minute, dusky.

Second Instar: Length 1.15 mm. Head Width 0.43 mm., wider
than prothorax, and obtusely rounded in front. Body color pale green,
punctate above With minute dark spots. Eyes bright scarlet. Ros-
trum as in preceding stage, greenish-white, darker at tip. Antennae
pale greenish, densely pubescent, four-jointed, first joint 0.07 mm. in
length, second 0.17 mm., third 0.17 mm., fourth 0.25 mm.; total length
0.66 mm. As compared With first instar, body more compact and
robust. Constrictions between thoracic segments pronounced, posterior
border of mesothorax slightly emarginate at middle showing first in-
dication of hemelytra. Abdominal segments with a median transverse

v row of short black bristles, widest at second segment. Legs pale green,

femur and tibia bearing short black bristles, tarsus faintly darkened
at tip, claws small.

Third Instar: Length 1.55 mm. Head width 0.4.6 mm., as wide
as prothorax. Color as in preceding stage, but more densely mottled
with black spots on dorsum. Eyes bright scarlet. Rostrum greenish,
tip brown, basal joint thick. Antennae greenish-white, darker at joints,
entirely densely pubescent, basal joint somewhat swollen, 0.10 mm. in
length, second 0.26 mm., third 0.20 mm., fourth 0.26 mm. ; total length
0.82 mm. Posterior border of meso and metathorax widely emarginate at
middle. Wing pads distinctly defined. Abdominal segments with a
transverse row of bristles as in preceding stage, fourth segment Widest,
thence tapering sharply to each extremity. Legs pale green, femur,
tibia and tarsus bearing short black bristles, claws small, dusky.

Fourth Instar: Length 1.85 mm. Head Width 0.5’? mm., wider
than prothorax. Color green, mottled above. with black spots on head,
thorax, wing pads and abdomen. Eyes scarlet. Rostrum pale greenish,
reaching to the hind coxae. Antennae densely pubescent, basal seg-
ments with one to three black spots on inner and dorsal side, first seg-
ment 0.11 mm. in length, second 0.39 mm., third 0.34 mm., fourth 0.30
mm.; total length 1.14 mm. Wing pads extending to or slightly beyond
base of second abdominal segment. Entire dorsum densely covered with
bristles, the larger ones surrounded at base by black spots. Legs pale
green, the larger bristles on exterior and anterior margins of femur
and tibia surrounded by black spots at base, tarsus densely covered with
short hairs, claws darker, small.

Fifth Instar: Length 2.20 mm. ‘Head width 0.69 mm., hardly
as wide as prothorax. Color green, head, thorax, wing pads" and ab-

THE COTTON FLEA HOPPER 11

domen densely mottled with black spots, and covered with suberect
black bristles. Eyes scarlet. Rostrum greenish, extending t0 hind
coxae, tip brown. Antennae green, paler towards apical segment, mark-
ings as in preceding stage, first segment 0.15 mm. in length, second
0.58 mm., third 0.46 mm., fourth 0.35 mm.; total length 1.54 mm.
Wing pads extending to about middle of abdomen, metathoracic pair
slightly longer. Legs greenish-white, with rows of spines and black
spots on femur and tibia, tarsus thickly covered with short stiff hairs,
claws dusky. '
Adult

Body outline obovate or more or less elongate, subshining, pale green,
color pattern variable, usually densely punctate on entire dorsum with
small fuscous spots; moderately clothed with black appressedbristly
hairs, intermixed with whitish pilosity on margins and shorter tufts
of silvery semiscale-like hairs on the clavus, corium and embolar margin.

Figure 3. Adult cotton flea hopper. Greatly enlarged.

Male: Lenth 3.4 mm.; width 1.01 mm.

Head: Width 0.65 mm., vertex 0.33 mm.; pale to yellowish or
darker green, sparsely covered with rather long bristly hairs arising
from dark spots on vertex and to lesser degree on frons. Eyes reddish
to brown. Rostrum reaching to or a little beyond hind coxae, pale
green, apical joint brownish, apex almost black. Antennae four-jointed,
densely covered with a pale sericeous pubescence; first segment length
0.17 mm., with two black spots near apex on dorsal and inner side;
second 0.76 mm., usually with three black irregular spots on dorsal

12 BULLETIN NO. 339, TEXAS AGRICULTURAL EXPERIMENT STATION

surface, first spot located near base and distal one at or slightly beyond
middle, three or more similar spots on ventral or inner side; third
0.54 mm., pale greenish, with narrow dark rings on base; fourth 0.38
mm., entirely pale or faintly darkened on narrow base; total length
1.85 mm.

Thorax: Pleura pale green, subshining, bearing a few scattered
white hairs. Pronotum, mesoscutum and scutellum concolorous, pale
to darker green, clothed with black bristly hairs intermixed with shorter
white flattened or scale-like hairs, margins of pronotum rather densely
pilose. Hemelytra green, paler or almost colorless along the embolar
margins, densely punctate with small fuscous spots and clothed with
black appressed bristly hairs, with a conspicuous strigose tuft of longer
bristles located on margin anterior to the large areole, membrane with
a dark triangular spot shortly posterior to cuneus extending linearly
inward from outer margin, tips faintly cloudy, veins white.

   

           
  
   
  
   

   
       
 

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 / "

      

       
  

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s
\\\\

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Figure 4. Distribution of the cotton flea hopper in the United States is indicated
by the shaded areas.

_ Abdomen: Venter green, usually without any markings, but some-
times sparsely punctate with small dark spots on caudal half, sparsely
covered with pale hairs.

Legs: Whitishior pale green, hind femur considerably thickened,
with a row of fuscous spots on dorsal margin extending almost to base,
outer side with spots irregularly arranged and usually becoming in-
distinct on basal half, front and middle pair with similar spots on
outer side but generally less distinct; tibia bearing three rows of prom-
inent black spines surrounded at base with black spots usually becom-

THE COTTON FLEA HOPPER 13

ing obsolete on apical portion of segment, tarsus pale, darker on apical
portion, claws small, dusky. ‘

Female: Length 3.5 mm., width 1.07 mm. Very similar to male
in structure and coloration.

GEOGRAPHICAL DISTRIBUTION

According to the available references, the cotton flea hopper is widely
distributed within the United States. The geographical distribution
is shown by the shaded areas in Figure 4, which include twenty states,
besides the District of. Columbia. It is interesting to note that this
distribution covers a wide range in latitude and extends from the At-
lantic to the Pacific borders of this country. Undoubtedly the species
is also present in many other states from which it is not here recorded.

FOOD PLANTS

The following list includes the food plants of the cotton flea hopper
recorded from different sections of the State during the course of
these studies:

 

Scientific name. _ Common name.
Amaranthus blitoides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Pigweed

Aumranthus viridis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Pigweed

Ambrosia psilostachya . . . . . . . . . . . . . . . . . . . . . . . . . . Ragweed, hogweed

Amphiachyris dracunculoides . . . . . . . . . . . . . . . . . . . . . . . . . .Broomweed

Asclepias viridula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Milkweed

Atriplex sp . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Orach

Boerhaavia uiscosa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Cerastium uulgatum . . . . . . . . . . . . . . . . . . . . . . . . . .Mouse-ear chickweed

Chaerophyllum Floridanum . . . . . . . . . . . . . . . . . . . . . . . . . .Wild caraway

Chenopoduum album . . . . . . . . . . . . . . . . . . . . . .Lamb’s Quarters, pigweed

Citrullus citrullus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Watermelon

Oroton capitatus . . . . . . . . . . . . . . . . . . . . . . . . . . . .Sageweed or goatweed

Oroton Engelmanuii . . . . . . . . . . . . . . . . . . . . . . . . . .Sageweed or goatweed

Croton Liuidheimerianus . . . . . . . . . . . . . . . . . . . . . .Sageweed or goatweed

Oroton monanthogynus . . . . . . . . . . . . . . . . . . . . ..Sageweed or goatweed

(lrotou Texensis . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Sageweed or goatweed

Geranium Carolinianum . . . . . . . . . . . . . . . . . . . . . . . . . . . .Wild geranium

Gossypium herbaceum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Cotton

H elemlum teuuifolium . . . . . . . . . . . . . . . . . . . . . . .Sneezeweed, bitterweed

H elianthus M aximilian-ii . . . . . . . . . . . . . . - . . . . . . . . . . . .Wild sunflower

Hibiscus esculentus . . . .' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Okra

I pomoea trifida . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Morning-glory, tie-vine

Kallstroemia hirsutissima . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Caltrop

. Lamium amplexicaule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Henbit

Lepidium Virginicum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Peppergrass

Ltppia nodiflora . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fog-fruit

14 BULLETIN NO. 339, TEXAS AGRICULTURAL EXPERIMENT STATION

Scientific name. Common mama
Malvaviscus Drummondii . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..May apple A

M elilotus oflicinalis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Sweet clover

M onarda fistulosa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Horsemint

M onarda punctata. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Horsemint

Panicum Texanum . . . . . . . . . . . . . . . . . . . . .Texas millet, Colorado-grass

Portulaca oleracea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Purslane, pursley

Solarium elaeagnifolium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Horsenettle

Solarium rosiratum . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Yellow horsenettle

Stachys cordata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .IIedgenettle

Trianthema portulacastrum . . . . . . . . . . . . . . . . . . . . . . ._ . . . . . . . . '

Tribulus terrestris . . . . . . . . . . . . . . . . . . . . . . . . . . . .Ground-bur, bur-nut

Vigna sinensis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Cowpea

Apparently the cotton flea hopper is able to subsist on a large variety
of succulent weeds, and further studies in this connection undoubtedly
will result in the addition of many other food plants to the present list.
In the laboratory newly hatched nymphs were placed on thirty-two
Widely related plants represented in the ‘above list, and reared to ma-

turity. When the insects‘ were migrating from Croton during October _

1925, adults were repeatedly taken on bitterweed, broomweed, cowpea,
milkweed, okra, and watermelon, apparently feeding either on the foliage
or on the blooms. No nymphs were observed or reared on these plants.
The principal food plants are the various species of Oroton, which are
commonly known to the farmer as goatweed or sageweed. These are
distributed generally throughout the State; however, some species are
more or less restricted to certain kinds of soil. Sixteen species of
Croton from Texas are listed by Small’; of this number capitatus, Engel-
mannii, Lindheimerianus, monanthogynus and Texensis have been col-
lected from a number of eastern and southern counties of this State,
and all were found to be infested with eggs, nymphs, and adults. It
may be safely assumed that other members of this group of plants found
in Texas are also attacked by the insect- In the vicinity of College
Station, capitatus is the most abundant species of Cretan, and one of
the commonest weeds. Every year under favorable conditions it pro-
duces a copious crop of seed, and the possibility of its eradication over
any considerable area is very remote. y
In the black-land sections of Texas, horsemint is one of the important
food plants in addition to the Crotons which occur throughout this
region. It is interesting to note that, while horsemint is not restricted
to the black-lands in distribution, it is largely within these limits that
it appears to be especially attractive to the insect. During June 1925,
two species of horsemint, Monarda fistulosa in Navarro County, and
M onarda punctata in Nueces County, were found heavily infested with
adult cotton flea hoppers and nymphs in all stages of development.

‘Flora of the Southeatern United States, pp. 694-8.

THE COTTON FLEA HOPPER I _ 15

In Hunt County, wild sunflower H elianthus Maximilianii was found
infested with cotton flea hopper eggs on November 18, 1925. The rela-
tive importance of wild sunflower as a food plant of this insect is not
known at present. It may prove to be of some importance, however,
in connection with the hibernation of the insect in localities where the
plant is abundant. Besides Oroton and cotton, sunflower is the only
plant in the black-land section in which overwintering eggs of the
cotton flea hopper have been found.

From the name cotton flea hopper it might be inferred that the
insect feeds generally on cotton. The contrary, however, appears to
be true. In the laboratory, cotton is readily accepted. as food, but
when growing in the field it is attacked sporadically in more or less
localized areas, the extent of infestation apparently depending upon
a combination of factors which are at present only partially understood.
At no time during-the period of these observations has cotton ever
been found as severely attacked as sageweed, horsemint, or Atriplex.
Normally cotton appears to be most attractive as a food plant in the
spring and fall. _

Atriplex is another important food plant of the cotton flea hopper.
However, in Texas this weed is restricted largely to the Rio Grande
Valley in distribution. In Hidalgo County, Atriplex occurs abundantly
in cultivated fields. as well as on waste lands. During the late sum-
mer and fall of 1925, the plant in this locality was found to be heavily
infested with cotton flea hopper eggs and all stages of developing in-
sects. Aside from its importance as a food plant, Atriplea: also serves
as a winter host in which the insect eggs deposited late in the fall are
carried throughto the next spring.

METHODS OF STUDY

All laboratory records on the cotton flea hopper were made under
conditions approximating, as nearly as possible, those obtaining in the
field. Croton capitatus was used as the host plant for the purpose of
observing the details of the-life history. -

Individual pairs of hoppers were confined in' glass cylinder cages
(150 mm.x 25 mm.), the ends of which were covered with cheese-cloth
to permit a free circulation of air. An uninfested seedling plant, with
roots inserted into a small vial of water to keep it fresh, was ‘supplied
the insects for food and oviposition. Additional food was supplied

‘ by means of a small piece of sponge moistened in a sugar solution. At

the end of each 24-hour period throughout the life of the insects,
a fresh plant and a new supply of food were placed in the" cage.
As the plants were-removed from the cages they were isolated and kept

in good condition, during the incubation period of the eggs, by sub-

merging the roots in water which was renewed once or twice daily.
One or two days before the nymphs were expected to hatch, the plants
were placed singly in 4-ounce tin salve boxes which contained a

16 BULLETIN NO. 339, TEXAS AGRICULTURAL EXPERIMENT STATION

small piece of moistened blotting paper. These boxes Were examined
twice each day for hatched nymphs, Which Were removed and isolated

on Croton heads in glass shell vials (100 mm. x 25 mm.), for complete

records on each individual. During hot Weather the Croton heads
dried up quickly and it was necessary to replace them each morning
and afternoon, in order to secure a uniform development of the nymphs.

Figure 5. Type of cage used for making observations on the injury caused by the
cotton flea hopper.

For the purpose of studying the relation of the insect to injury to
cotton, field plants were grown under cages designed to protect them
from attack, and at the same time approximate conditions which would
permit normal growth. The type of cage used measures 4x4x4 feet.
The entire cage was covered with fine mesh sheeting, except a 12-inch

THE COTTON FLEA HOPPER

 

\

Figufe 6. A scfries‘ of blasted sqg

ares from cotton plants
opper. Natural S126.‘

attacked by the cotton fléa

17

18 BULLETIN NO. 339, TEXAS AGRICULTURAL EXPERIMENT STATION

strip around the top of the sides, which was covered with Oel-O-Glass
to permit the entrance of sufficient light for normal growth. Three
plants were grown in each cage. The insects used in the experiments
were collected from sageweed, horsemint, and cotton. Each experi-
ment consisted of two cages containing cotton plants of the same age
and variety, and grown under identical conditions. At the beginning
of each experiment the plant heights, number of squares, blooms and
bolls were carefully noted. Adult cotton fiea hoppers or nymphs col-
lected from one species of host plant were then introduced into one
cage, and excluded from the other, which served as a check in deter-
mining the extent of injury. Subsequent introductions of insects were
made as often as was necessary to maintain an infestation. The period
over which the insects were introduced was varied, and the number
of-insects released in the experimental cages ranged from few nymphs
to nearly 7000 adult cotton fiea hoppers. Records of plant heights,
number of blasted squares, shed squares, blooms, set fruits and other

details were made at regular intervals during the course of each ex-

periment. j .

To obtain data on hibernation, infested host plants were pulled up
in the fall at 14-day intervals beginning September 1. These plants
were allowed to remain in the field under natural conditions until
the following February or March. -They were then placed in small
emergence cages which were covered with one thickness of black
percale. Several glass vials were inserted near the top of each cage to
attract the nymphs as they hatched from the eggs in the plants. As
the nymphs collected in the vials they could be counted readily and
removed as often as necessary without disturbing the plants.

CHARACTER AND EXTENT OF INJURY

The first complaints of noticeable injury to cotton by the cotton fiea
hopper were received in 1919 from growers in the coastal regions of
Texas. For a number of years-the trouble remained localized, then
increased and spread rapidly to other sections of the State. In 1923
it became a serious problem to the growers. At that time the evidence
that this insect caused the trouble was entirely circumstantial and
studies were begun to determine whether a positive relation between
insect and injury existed. _ A series of cages were placed over seedling
cotton plants in the field, and the performance of these plants when
later subjected to cotton fiea hopper attack showed that the insect is
definitely associated with the damage.

The percentage of small squares shed by the plants subjected to
cotton flea hopper attack in the experimental cages ranged from 15
to 53 per cent. The maximum injury occurred in the cage in which
1725 nymphs were introduced over a period of 69 days. The mini-
mum injury occurred in the cage in which 135 nymphs were in-
troduced over a period of 18 days. The plants in the two check

THE COTTON FLEA HOPPER l 19

cages of these experiments shed 3 and 4 per cent of the small squares.
In one experiment 6291 adults were liberated in the cage over a period.
of 51 days. with the result that only 31d per cent of the small
squares were shed. However, the temperatures were abnormally high
during this period and the rate of mortality of the insects in the cage

Figure 7. (a)_ Uninjured cotton plant withznormal fruiting branches. (b) Cotton
plants IHJIJPGd by the cotton flea hopper. showing the suppression of
ifruitlng branches and whipfhke growth.

was so great that it was impossible to maintain an infestation. With-
out exception there was a much larger percentage of small squares shed
by plants in the cages in which insects were liberated, as compared with
the percentage shed by the plants in cages from which the insects were
excluded. While some shedding of small squares occurred in the check

2O BULLETIN NO. 339, TEXAS AGRICULTURAL EXPERIMENT STATION

cages there seems to be no doubt that the cotton flea hopper is the
main factor in causing the injury.

The injury to cotton resulting from cotton flea hopper attack is
manifested bycharacteristic symptoms, the most striking of which are:
the excessive shedding of very small squares, the suppression of fruit-
ing branches, and the tendency to abnormally tall (growth. Infested
fields often exhibit a variety of interesting features in connection with
the damage Wrought by the cotton flea hopper. For instance, plants

TEXAS AGRICULTURAL EXPERIMENT STATION

AGRICULTURAL AND MECHANICAL COLLEGE
6F TEXAS

Figure 8. Counties from which injury by the cotton flea hopper has been reported.

may shed small squares excessively in some fields in the early part of
the season where there appear to be few insects; and conversely, very
few blasted squares may be found in other fields in the latter part of
the season where the infestation is fairly abundant. On the other
hand, apparently normal well fruited stalks are often found surrounded
by barren plants showing every characteristic of the injury, while in

THE COTTON FLEA HOPPER 21

another locality exactly the opposite may be true. Excessive shedding
of squares may continue in the absence of insects after the initial
attack; however, under certain conditions plants occasionally recover
from the efiects and retain squares to maturity. The result is that
such plants may have a normal number of bolls and squares on the
lower and uppermost branches and the intermediate ones Without a
single fruit. Apparently every variety of upland cotton is subject to
attack, regardless of the type of soil on which it is growing. However,
the damage appears to be more severe in the black-land section of the
State. Reports of injury have been noted in fifty counties of Texas,
which are shown in Figure 8.

As has already been pointed out, the principal food plants of the
cotton flea hopper consist of a number of our most common roadside
weeds, and usually it persists on these throughout the season. Migra-

tion to cotton is not a definite procedure; quite the contrary appears

true, but unfortunately even when the insect attacks cotton in appar-
ently small numbers, the result may be a heavy loss in yield. Invariably
the injury appears to be greatly out of proportion to the number of
insects present. These observations, in addition to the fact that plants
often continue to shed minute squares excessively long after the insects
have ceased to attack them, have resulted in the theory that the insect
transmits a toxic virus. This theory is further supported by the fact
that the cotton flea hopper has been present in Texas for many years,
and only recently has it attracted attention as an economic pest. Fur-
thermore, it seems incredible that the condition of excessive shedding
of squares could be the result of only mechanical injury inflicted by
the insect punctures. Additional research is necessary before the com-
plete solution of this problem can be determined. '

LIFE HISTORY

Prior to the year 1920 no mention of the cotton flea hopper was
made in economic literature. Since that time it has become a pest
of paramount importance to the cotton growers of Texas. Life history
and biological studies of the insect were made at this Station to obtain
information on which to base satisfactory remedial or control measures.

These studies were begun in the summer of 1924. and continued
throughout the ifollowing year. The mossi-gtant features of the
results obtained up to the present time a-jwi    ' following
pages. Much additional information is ' 
injury to cotton is effected and why this 
in the State for many years (6) without’

i

age, has now become an important enem“

   
  

 
    
   
  

 

-“wb_;,’; .7.‘

22 BULLETIN NO. 339, TEXAS AGRICULTURAL EXPERIMENT STATION

Table 1. Life Cycle in Spring

          
    
    
   
 
     
 

     

 
     
    
 

   
      
 
 
 
 
 
 
 
 
  
 
 

Date of Date of Date of Date of Da_te of Average

N0. Date Date FlfSl. Second Third Fourth Flfth Total Mean
Laid Hatched Molt Molt Molt Molt Molt Days Temp.

22 May 6 May 14 May 16 May 18 May 2O May 22 May 27 21 78.7
31 . May 10 May 18 May 21 May 24 May 28 May 31 June 3 24 80.0
34 May 13 May 20 May 23 May 27 May 31 June 6 June 9 27 81.3
36 May 13 May 2O lVIay 23 May 26 May 29 June 3 June 7 25 81 O
39 May 13 May 21 May 23 May 27 May 31 June 4 June 7 25 81 O
41 May 13 May 21 May 25 May 29 June 1 June 4 June 7 25 81 0
45 May 13 May 22 May 27 May 3O June 2 June 6 June 9 27 81 3
47 May 13 May 22 May 26 May 29 June 1 June 4 June 8 26 81 3
48 May 13 May 22 May 26 May 30 June 2 June 5 June 9 27 81 3
52 May 13 May 23 May 29 May 31 June 4 June 8 June 11 29 81 3

' 53 May 14 May 23 May 28 May 31 June 3 June 7 June 10 27 81 2
54 May 14 May 23 May 28 May 30 June 3 June 6 June 9 26 81 2
55 May 14 May 23 May 28 May 31 June 4 June 8 June 11 28 81 2
56 May 14 May . May 28 May 31 June 3 June 6 June 9 26 81 2
57 May 14 May 28 May 31 June 3 June 7 June 1O 27 81 2
58 May 14 May May 26 May 29 June 2 _Ju'ne 5 June 8 25 81 2
64 May 14 May 24 May 29 May 30 June 3 June 7 June 9 26 81 2
66 May-16 May 24 May 28 May 31 June 3 June 7 June 10 25 81 2
67 May 16 May 24 May 28 June 1 June 3 June 7 June 10 25 81 2
70 May 18 May 27 May 31 June 3 June 6 June 9 June 12 25 81 5
71 May 18 May 27 May 31 June 3 June 5 June 8 June 11 24 81 5
74 May 18 June 1 June 4 June 7 June 10 June 13 26 81.7
75 May 18 May 31 June 2 June 6 June 9_ June 12 25 81.5
77 May 18 M May 31 June 5 June 8 June 0 June 13 26 81.7
78 May 18 May 31 June 2- June 5 June ‘8 June 11 24 81.5
8O May 18 May 31 June 2 June 5 June -8 June 11 24 81.5
82 May 18 May 31 June 3 June 5 June 9 June 12 25 81.5
83 May 18 May 31 3 June 7 June 9 June 12 25 81.5
87 May 18 June 1 4 June 8 June 11 June 14 27 82.0
93 May 18 June 1 4 June 7 June 9 June 12 25 81.5
94 May 18 June 1 4 June 7 June 9 June 12 ' 25 81.5
111 May 22 June 3 6 June 9 June 11 June 14 23 82.6
112 May 22 June 4 7 June 9 June 12 June 14 23 82.6
113 May 22 June 3 '7 June 9 June 11 June 13 22 82.4
114 May 22 June 3 6 June 9 June 12 June 14 23 82.6
116 May 22 I June 3 6 June 9 June 12 June 14 23 82.6
117 May 23 June 6 9 June 12 June 14 June 16 24 83.0
124- May 23 June 6 9 June 11 June 13 June 15 23 82.8
126 May 23 June 6 8 June 1O June 12 June 14 22 82.6
129 May 23 June 6 9 June 1O June 12 June 15 23 82.8
130 May 23 June 6 8 June 11 June 13 June 15 23 82.8
134 May 25 June 6 9 June 11 June 13 June 15 21 82.6
135 May 26 June 6 8 June 11 June 13 June 15 2O 83.4
137 May 29 June 11 13 June 14 June 16 June 19 21 85.0
138 May 31 June 11 12 June 14 June 15 June 17 17 85.3
140 May 31 June 12 13 June 14 June 16 June 18 18 85.4
141 June 1 June 12 13 June 14 June 16 June 18 17 85.6
142 June 1 June 11 12 June 14 June 16 June 18 17 85.6
143 June 1 June 11 13 June 14 June 15 June 17 16 85.6
144 June -1 June 12 14 June 15 June 16 June 18 17 85.6
145 May 30 June 14 June 15 June 17 June 18 19 85.1
147 May June 14 June 15 June 17 June 19 19 85.6
150 June 9 June - 14 June 15 June 16 June 18 16 , 85.6
154 June 14 June 15 June 17 June 19 17 85.8
158 June 14 June 16 June 17 June 19 17 85.8
162 June 14 June 15 June 16 June 18 16 85.6
167 June 15 June 16 June 18 June 20 17 85.9
169 June 15 June 16 June 17 June 19 16 85.8
170 June 15 June 16 June 17 June 19 16 85.8
172 June 15 June 16 June 18 June 20 17 85.9

 

  

The detaile    udies Were started in May 1925 soon
after the nymphs began to hatch from the overwintering eggs and
continued until July 1. The studies were resumed during September
for the purpose of obtaining comparative data. Records on the life
cycle of 6O individuals are given in Table 1. The time required for

THE COTTON FLEA HOPPER 23 .

complete development varied from 16 to 29 days depending upon
prevailing temperatures. From May 6 to June 3, the average period
of development was 22.5 days.

Mating and Fertility

Mating does not commonly occur during the daytime, either in the
laboratory or in the field. a Observations in this connection are limited
to “one confined pair of insects, which were noted in the act of mating
on the morning of May 15, at 11:15 o’clock. The insects were still
united at 12 o’clock,ibut had separated when next observed, one hour
later. The maximum time consumed in the process was not deter-
mined. During the act of copulation the insects are united at the
tips of their abdomens facing in opposite directions.

After transformation to adult, a certain feeding period is necessary
to attain sexual maturity. When newly emerged insects of the opposite
sex are placed together they remain indifferent to each other and begin
feeding immediately, and not until an average period of 3 days" has
elapsed does oviposition begin, indicating that fertilization has been
effected. One successful mating is sufficient to fertilize the average
number of eggs laid by the female. A

Oviposition

During the spring and summer a feeding period of 3 or 4 days after
emergence is required before oviposition begins. It generally occurs
between 6 o’clock in the evening and '7 o’clock in the morning.

The eggs are laid singly within the plant tissue by means of a strong
sword-like ovipositor. There is very little uniformity‘ of position in
which the eggs are placed; most frequently, however, they are situated
obliquely to the main axis of the stem with the cap end directed up-
ward and flush with, or slightly protruding from the surface of the
stem. Occasionally, the depth to which they are inserted does not
exceed the cambium layer, but more often the woody portion of the
stem is penetrated by the ovipositor so that the base of the egg is
firmly imbedded and when the bark is removed it remains attached to
the stem. The female oviposits promiscuously in practically all por-
tions of the plant. As the host plant matures, egg deposition is con-
fined more or less to the growing tips and stems immediately beneath
them. -

Oviposition begins in April or May soon after the nymphs hatching
from the overwintering eggs have reached maturity, and continues
throughout the warm season. At College Station the seasonal peak
of oviposition in 1925 was reached in August and September. Sage-
weed or goatweed is preferred for oviposition, although horsemint and
Atriplea: apparently are also very attractive host plants.

24 BULLETIN NO. 339, TEXAS AGRICULTURAL EXPERIMENT STATION

Ifigure 9. (a) Ovipositor of cotton flea hoglper. (b) Section of cotton stalk showing
position in which the e g is Placed beneath the ark. (c) Sketch of insect in lateral aspect
showing relatlve proport on o ovipositor when extended. Greatly enlarged.

THE COTTON FLEA HOPPER 25

Host Plants

All species of plants in which cotton fiea hopper eggs have been
found are listed below.

Scientific name. Common name.
Atriplea: sp.  . . . . 
Uroton capitatué ...........................Sageweed or goatweed
Oroton Engelmannii . . . . . . . . . . . . . . . . . . . . . . . .Sageweed or goatweed

Oroton Lindheimerianus . . . . . . . . . . . . . . . . . . . .Sagewood or goatweed

Croton monanthogynus . . . . . . . . . . . . . . . . . . . . . Sagewood or goatweed

Groton Texensis . . . . . . . . . . . . . . . . . . . . . . . . . . . .Sageweed or goatweed

Gossypmm herbaceum  . . . . .  . . . . . . . . . . ...........Cotton

H elianthus M aximilianii . . . . . . . . . . . . . . . . . . . . . . . . . .Wild sunflower
Malvaviscus Drummondii  apple
Monarda fistulosa  . . . . . . . ...Horsemint
M onarda punctata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Horsemin¢t
Solanum elaeagnifolium . . . . . .  . . . . . . . . . . . . . . . . . . . . . .Horsenettle

Table 2. Duration of Oviposition Period

Period of
Pair First Egg Laid Last Egg Laid Ovi osition, Temperature,
ays Mean
1 . . . . . . . . . . . . . . . . . . . . . . . J111?1%5 2 Jzlxgisll 10 84.2

2 . . . . . . . . . . . . . . . . . . . . . .. June 2 June 10 9 84.6

3 . . . . . . . . V . . . . . . . . . . . . .. June 13 June 23 11 87.3

4 . . . . . . . . . . . . . . . . . . . . . . . June 12 June 29 18 87.0

5 . . . . . . . . . . . . . . . . . . . . . .. _ June 14 June 25 123 81.5

6* . . . . . . . . . . . . . . . . . . . . .. June 12 June 17 _ 6 89.6

7 . . . . . . . i . . . . . . . ..‘ . . . . .. June 12 June 27 16 86.8

8 . . . . . . . . . . . . . . . . . . . . . . . June 17 June 28 12 86.3

9 . . . . . . . . . . . . . . . . . . . . . . . June 22 June 28 7 86.4

10* . . . . . . . . . . . . . . . . . . . . . . June 22 June 29 8 86.3

‘incomplete record

In the laboratory the period of oviposition during June 1925 varied
from 7 to 18 days. The average duration of the period was approxi-
mately 11.5 days. Undoubtedly, oviposition continues over a much
longer period under natural conditions since the insects may live for
29 days in close confinement during the warm season. The data given
in Table 2 were taken over a period of high temperatures and maximum
insect activity, and do not approximate spring or fall conditions when
the period of oviposition is increased by lower temperatures.

26 BULLETIN NO. 339, TEXAS AGRICULTURAL EXPERIMENT STATION

Table 3. Total and Daily Rate of Oviposition

Average Pair Number
Date, ean
1925. Temp 1 2 3 4 5 6 7 8 9 10
May 28 77.5 EM EM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

May 29 78.5 0 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

May 30 79.5 0 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

May 31 81.5 0 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

June 1 86.5 0 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

June 2 87.0 4 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

June 3 87.0 6' 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

June 4 82.5 4 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

June 5 84.0 2 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

June 6 83.5 1 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

June 7 85.5 2 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

June 8 87.5 1 3 EM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

June 9 83.5 3 3 0 EM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

June 1O 81.0 1 3 0 0 EM EM EM . . . . . . . . . . . . . . . . ..

June 11 80.5 1 0 0 O O 0 0 EM . . . . . . . . . . ..

June 12 88.0 0 0 0 4 0 3 1 0 . . . . . . . . . . ..

June 13 89.0 . . . . .. 0 3 3 0 5 3 0 . . . . . . . . . . ..

June 14 88.0 . . . . .. 0 2 3 2 0 5 0 . . . . . . . . . . ..

June 15 88.0 . . . . .. 0 0 1 2 0 6 0 . . . . . . . . . . ..

June 16 88.5 . . . . .. 0 1 1 1 1 0 0 . . . . . . . . . . ..

June 17 85.5 . . . . .. 0 1 1 O 4 2 1 . . . . . . . . . . ..

June 18 87.0 . . . . . . . . . . .. 1 1 2 0 1 0 EM EM

June 19 89.5 . . . . . . . . . . .. 0 0 0 0 1 0 0 0

June 20 89.0 . . . . . . . . . . .. 2 3 0 * 0 0 0 0

June 21 86.0 . . . . . . . . . . .. 0 1 _ 1 . . . . .. 0 0 0 0

June 22 87.0 . . . . . . . . . . .. 2 3 0 . . . . .. 1 2 7 6

June 23 86.5 . . . . . . . . . . .. 1 2 0 . . . . .. 2 2 2 8

June 24 88.5 . . . . . . . . . . . .- 0 . 6 0 . . . . . . 4 2 0 2

June 25 86.5 . . . . . . . . . . .. 0 3 3 . . . . .. 5 0 5 1

June 26 83.0 . . . . . . . . . . .. 0 ' 0 0 . . . . .. 2 0 1 0

June 27 86.5 . . . . . . . . . . . . . . . . .. 0 0 . . . . .. 1 0 1 1

June 28 87.0 . . . . . . . . . . . . . . . . .. 0 0 . . . . .. 0 1 3 0

June 29 86.0 . . . . . . . . . . . . . . . . .. 2 O . . . . .. 0 0 0 5

June 30 87.5 . . . . . . . . . . . . . . . . .. 0 0 . . . . . . 0 0 0 0

July 1 85.0 . . . . . . . . . . . . . . . . .. 0 . . . . . . . . . . .. 0 . . . . .. 0 *

July 2 86.0 . . . . . . . . . . . . . . . . .. 0 . . . . . . . . . . .. 0 . . . . .. 0 .....

July 3 85.5 _ . . . . . . . . . . . . . . . . .. 0 . . . . . . . . . . . . . . . . . . . . . . .. 0 . . . . ..

July 4 87.5 . . . . . . . . . . . . . . . . .. 0 . . . . . . . . . . . . . . . . . . . . . . .. 0 ..

July 5 83.5 . . . . . . . . . . . . . . . . .. 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

July 6 87.5 . . . . . . . . . . . . . . . . .. 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

July 7 89.0 . . . . . . . . . . . . . . . . .. 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

EM—-Emerged, mated
flncomplete record

The total and rate of oviposition in the laboratory for ten pairs of
cotton flea hoppers are given in Table 3. These data are based upon
the number of nymphs hatching from the eggs deposited in plants sup-
plied each pair of adults for oviposition. Infertile eggs or those fail-
ing to hatch for other reasons are not included, and it should be noted,
therefore, that these figures do not represent maximum numbers. After
oviposition is begun it usually continues quite regularly until each
female’s average quota of eggs has been laid. In confinement, from
1 to 3 eggs for a 24-hour period appears to be the average rate of
deposition, although as many as 8 were obtained in one day. The
maximum number of eggs recorded for a single female is 34.

Dissections of a number of females collected in the field were made
to obtain additional information concerning the egg-laying capacity of
the insect. It was found that the uterus contained an average of 8

eggs per individual ranging from a minimum of 2 to a maximum of‘

23 eggs.

THE COTTON FLEA HOPPER 27

Hatching

Some time before hatching, the egg changes from the original glisten-
ing white color t0 a dull yellowish-white. The outline and position of
the nymph within the egg are plainly visible under a microscope. The
scarlet eyes are conspicuous near the cap or truncate end of the egg
through which the nymph emerges as soon as embryonic development
is completed. The egg shell is broken by the nymph, which gradually
pushes out head first through the opening. During the process of
hatching the body is moved backward and forward, which releases the
appendages from their original closely appressed position on the ventral
surface of the body. The freed appendages are then used by the
nymph to complete emergence from the egg. The entire process of
hatching requires from 45 minutes to 1 hour.

Table 4. Duration of Egg Stage

Laid Hatched
Lot Egg Lot_ Tem erature
Number Days Incubation . ean
Date Lot Date Nymphs Period. Days '
Number Emergecl
May 13..... 1 May 19-23.... 12 103 8.58 80.8
May 14..... 2 May 22-24.... 13 115 8.84 - 81.0
May 15..... 3 May 21-23  5 38 7.60 80.6
May 16..... 4 May 24 . . . . . .. 2 16 8.00 80.8
May 17..... 5 May 26 . . . . . .. 18 9.00 78.8
May 18..... 6 May 27-29.... 33 318 9.63 78.3
May 19..... 7 May 28-30.... 15 147 9.80 78.3
May 20..... 8 May 29 . . . . . .. 4 ‘ 36 9.00 78.2
May 21..... 9 May 3O . . . . . .. 3 27 9.00 78.5
May 22. . . .. 1O May 30-June 1 25 226 9.04 79.7
ay 23..... 11 June 1- 2.... 20 195 9.75 80.0
May 24..... 12 June 2- 3 19 9.50 80.0
May 25.... . 13 June 2- 3 15 130 8.66 79.7
ay 26..... 14 June 2- 4.... 8 65 8.12 81.4
May 27..... 15 June 3- 6.... 18 158 8.77 82.4
May 28..... 16 June 3- 6.... 12 93 7.75 82.7
ay 29..... 17 June 4- 8. 23 190 8.21 83.9
May 30..... 18 June 6- 9.... 11 89 8.09 84.3
May 31..... 19 June 7-11.... 5 44 8.80 84.4
June  20 June 9-10.... 5 41 8.20 84.8
June  21 June 9-12.... 3O 248 8.20 84.5
June  22 June 11-14.... 30 263 8.76 85.0
June  23 June 11-14.... 25 211 8.44 84.8
June  24 June 13-14.... 7 60 8.57 85.0
June 6... .. 25 June 13-15.... 10 84 8.40 85.0
June  26 June 14-16.... 7O 7.77 85.9
June  27 June 15-16.... 11 81 7.36 86.0
June  28 June 16-17.... 4 30 7.50 86.2
June 10..... 29 ' June 17-18.... 5 36 7.20 86.1
June 11..... 30 June 17 . . . . . .. 2 12 6.00 86.0
June 12..... 31’ June 19-20.... 5 36 7.20 88.0
June 13..... 32 June 19-20.... 15 97 6.46 88.0 _
June 14..... 33 June 20-23.... 13 86 6.61 87.5
June 15..... 34 June 21-23.... 20 134 6.70 87.4
June 16..... 35 June 22-24.... 9 62 6.88 87.5
June 17. . . .. 36 June 23-25. . . . 18 124 6.88 87.2
June 18. . . .. 37 June 24-26. . .. 13 93 7.15 87.0'
..lune19..... 38 June 26-27.... 54 7.71 86.9
June 20. . . .. 39 June 27-28. . .. 10 72 7.20 86.6
June 21... . . 40 June 27-30. . .. 19 138 7.26 86.4
June 22.... . 41 June 28-July 1 38 273 7.18 86.3
June 23. . . .. 42 June 29-July 2 ’ 24 176 7.33 86.2-
June 24. . . . . 43 June 30-July 3 32 232 7.25 86. 1
June 25.. . . . 44 July 1- 5 39 290 7.43 85.8
June 26.. .. . 45 July 2- 5 14 100 7.14 86.1
June 27. . . .. 46 July 4- 6 7 53 7.57 86.2
June 28..... 47 July 5- 6 11 82 7.45 86.1
June 29.... . 48 July 6- 8 68 7.55 86.7
June 30..... 49 July . . . . . .. 1 8 8.00 86.8
uly  5O lulv10..... 1 8 8.00 86.5

28 BULLETIN NO. 339, ‘TEXAS AGRICULTURAL EXPERIMENT STATION

Records on the incubation period of 50 egg-lots, including a total
of 671 eggs, are given in Table 4. Temperature has a positive effect
on the duration of the egg stage. The time required for incubation
varied according to the prevailing temperatures, from a minimum of 6

‘days to a maximum of 12 days. The mean temperature for May

and June, 1925 was 7'7 and 86 degrees F, respectively. The effect
of this difference in temperature is quite apparent, for it will be noted
that the incubation periods as recorded in Table 4 were consistently
longer in May. The Weighted average duration of the egg stage, for
the entire period during which these data were recorded, was approxi-
mately 8 days. .

Eggs which are laid in the late fall do not hatch until March or
April of the following spring. The average mean monthly temper-
atures from November to March inclusive, at College Station, range
from 50 to 60 degrees F. Since the eggs remain dormant during most
of this period it may be assumed that an average mean temperature of
50 to 60 degrees F. is effective.

--~~.--. 1 _ 1)

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89.3 0.3 015 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . “nasal mud

91.5 0.1 9.7 . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . Hlmsul qunod

8L1 0.1 0.12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hnnsul pllql

09.1 0.1 0.8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11815111 puooas

30.2 g1 0.? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hlmsul 15nd

96.!‘ 0.9 0.8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N833
sfieq sfleq 989g
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2/11

30 BULLETIN NO. 339, TEXAS AGRICULTURAL EXPERIMENT STATION

There is a considerable variation in the duration of the instars as
will be noted by reference t0 Table 5. These variations are due to
difference in food supply and temperature. When nymphs were fed
on Croton foliage, 13 t0 20 days were required for complete develop-
ment, While on Croton heads, the period of development was much
shorter, ranging from 9 to 14 days. During the warm season the aver-
age period of nymphal development is approximately 11 days. The
effect of temperature on the rate of development is shown in Table 1.
There is no discernible difference in the time required for development,
between male and female individuals.

Table 6. Summary of Development

Maximum Minimum Avera e
Period Period Perio
Days Days Days
Egg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 12.0 6.0 7.96

First Instar . . . . . . . . . . . . . .; . . . . . . . . . . . . . . . . . . .. 4.0 2.5 3.02

Second Instar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3.0 1.0 1.60

Third Instar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0 1 .0 . 1.78

Fourth Instar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4.5 1.0 2.16

Fifth Instar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.0 2.0 2.58

In Table 6 is given a summary of the development of the cotton flea
hopper. All stages are subject to considerable variation. The dura-
tion of the egg stage is affected by the prevailing temperatures and
varies from 6 to 12 days. The first instar comprises the most time,
ranging from about one-half to one and one-half days more than
any of the succeeding instars- The average time required for com-
plete development during the warmest months is 16 or 1'7 days.

Adult

In 1925 the first adult cotton flea hopper in the field was observed
on April 21, about three weeks after hatching of the overwintering eggs
was first observed. From this date the number of adults increased‘
rapidly reaching maximum abundance during August and September.

There is no indication of definite broods in the multiplication of the
insects, but rather a general overlapping of generations, which results
in a more or less uniform increase of numbers until late summer and
early fall. With the approach of cold Weather the irisects die of’
rapidly, andfew, if any, are apparent in the field after the first frosi
has occurred. _ '

Theoretically, seven or eight complete generations of the cotton flea
hopper are possible in one season.

. —~ ./— .-
L! "2 i ' A; i
v k~~

THE COTTON FLEA HOPPER 31

Table 7. Length of Life of Adults

Male l Female

Number
Emerged 1 Died l No. Days Emerged i Died No. Days
1 l
1 . . . . . . . . . . . . .. May 27 June 12 16 May 27 June 12 16

2 . . . . . . . . . . . . .. May 27 June 16 2O lWay 27 June 17 21

3 . . . . . . . . . . . . .. June 9 July 8 29 June 8 June 26 18

4 . . . . . . . . . . . . .. June 9 July 3 24 June 9 July 7 28

5 . . . . . . . . . . . . .. June 1O July 3 23 June 9 June 3O 21

"i . . . . . . . . . . . . .. June ll July 1 . 2O June 1O July 2 22

‘ . . . . . . . . . . . . .. June 12 June 29 17 June 12 June 3O 18

i . . . . . . . . . . . . .. June 17 July 6 19 June 15 July 6 21

9 . . . . . . . . . . . . .. June 18 July 2 14 June 18 July 5 17

LO . . . . . . . . . . . . .. June 18 July 4 16 June 19 July 5 16

 

The cotton flea hopper does not withstand confinement very satis-
factorily, and it may be safely assumed that the normal life-period is
greatest underfield conditions. In the laboratory the duration of life
of twenty adult insects varied from 14 to 29 days during May and
June .1925, as is shown in Table '7. The average life-period of both
sexes in confinement is about 20 days.

FEEDING HABITS

The adults feed usually upon the most tender portions of the plants,
showing a preference for the growing terminal bud cluster. They
feed by inserting their beaks into the epidermis of the plant and suck-
ing the juice from the tissue. Usually an individual continues feeding
for only a short time in one location, then moves to another, where it
again punctures the tissue and resumes feeding. This operation may
be repeated many times within a few minutes. The scars resulting
from the feeding punctures are very minute. In confinement adults
will feed readily on a dilute solution of sugar or honey, sucking it
from a sponge. During the course of the life history studies of this
insect, several cases were observed where an active individual had thrust
its beak into the body of a dead cotton flea hopper in the cage, ap-
parently feeding on the body juices. _

The feeding habit of the nymph is very similar to that of the adult
insect. Soon after hatching, it begins to feed and moves to the tender
growing tip, where it remains usually until after the second or third
molt. In cases of severe infestation, ~20 to 30 nymphs may be
found feeding on a single Cretan head. When disturbed, the nymphs
seek protection by secreting themselves on the under sides of the leaves
or by hopping to the ground.

PROTECTIVE HABITS

The cotton flea hopper cannot be classed as a strong flier. However,
when disturbed, the insect invariably resorts to flight as a means of
protection. It usually flies to a nearby plant and seeks concealment

32 BULLETIN NO. 339, TEXAS AGRICULTURAL EXPERIMENT STATION

beneath a leaf or on the opposite side of a stem from the approaching
object. There appears to be no difference in the protective habits of
male and female cotton flea hoppers; both are active and will resort
to flight in eluding enemies.

The nymphs have long legs and are able to run rapidly. On plants
they cling closely to the stem or foliage and invariably move to the
side opposite from an approaching object. Ordinarily, running is the
common protective instinct. However, nymphs are also able to jump
or hop and when unduly disturbed they will resort to this means of
protection. The greatest distance covered by a single jump or hop
rarely, if ever, exceeds 3 or 4 inches horizontally. Individuals of
the later instars when disturbed have frequently been observed hop-
ping from plants to the ground and seeking the nearest available shelter.

Aside from the protective habits mentioned above, further protection
is afforded by a natural coloration which blends effectively with the
plants upon which the insect feeds.

HIBERNATION

In the vicinity of College Station the cotton fiea hopper is found
in greatest abundance during August and September and rapidly di-
minishes in number with the approach of lower temperatures. Most
of the nymphs and adults are killed by cold weather prior to November
15. The insect passes the winter in the egg stage. Hibernation may
begin as early as September 1, although the eggs were observed to
hatch during a period of several weeks after this date in the fall of
1925. The latest date of hatching was recorded on November 12.
The data obtained on emergence from plants confined in cages show
that hibernation is well under way by October 1. The first emergence
of nymphs from the overwintering eggs in 1925 was recorded on April
2, and in 1926 first emergence occurred on March 7. During the
former year the nymphs continued to emerge irregularly for a period
of about six weeks. -

At College Station, Oroton capitatus was found to be the most com-
mon host plant in which the eggs are carried through the winter.
However, nymphs were also reared from cotton stalks collected from
local fields and in Williamson, Hunt, Rusk, and Smith counties. In
the black-land sections of the State the indigenous species of Orotons
very likely will be found serving generally as winter host plants. Aside
from Croton and cotton, a species of wild sunflower collected in Hunt
County, November 1925, was found infested with ‘cotton flea hopper
eggs. In the localities where wild sunflower is abundant it may prove
to be of some importance in connection with the hibernation of the
insect. Further observations on the winter host plants are being made,
especially in the black-land regions, where the injury to cotton appears
to be most severe. In the Rio Grande Valley, Atriplex is an important
host plant. Many specimens of this plant collected in Hidalgo County

 
 
     

THE COTTON FLEA HOPPER 33

_ I  the winter season of 1925 were found infested with cotton flea
-  eggs. yNo other winter host plants have been recorded from
 gion, but it is likely that cotton also is important in this con-

    
 
 
   
     

.' L?‘ 

NATURAL ENEMIES

,2 h pent knowledge indicates that the cotton flea hopper is not held
 ' i. k effectively by natural enemies. Probably the most important
’- ir natural enemies are the field spiders. A number of different
it» of these have been observed frequently capturing both the adult
 and partially developed nymphs. While a considerable number
qvilcts may be destroyed by spiders they cannot be considered sig-
“W143i from the standpoint of natural control.

A e nymphs of the cotton_flea hopper are also frequently attacked
by thQ larva of a small red predacious mite, Bochartia sp., of the
family Erythraeidael. The mite attaches itself to the host and feeds
on the body juices. Nymphs thus attacked remain active for a con-
siderable period of time, and it may be safely assumed that the number
destroyed in this manner results in no appreciable reduction of infes-
tation in the field.

During the late summer of 1925 while the occurrence of the cotton
flea hopper on Crozfion or goatweed was at its peak, unusually large
numbers of ladybird beetles, Hippodamia convergens Guer, migrated
to the infested plants in several fields. There is some possibility that
this species may prove to be a natural enemy of the cotton flea hopper.
However, the ladybird beetles in the fields under observation did not
multiply sufficiently on the Oroton plants to produce any apparent re-
duction of the number of nymphs present.

METHODS OF CONTROL
Cultural Measures

  

As a result of the study of the life history of the cotton flea hopper
it will be noted that there are five important facts which can be utilized
mats control:

First, the insect hibernates or passes the winter in the egg stage
within the host plants.

Second, at College Station hibernation begins as early as Septem-
ber 1. »

Third, the principal Winter host plants comprise a number of our
common weeds. Wherever Oroton or sageweed occurs it is the pre-
i, m»); host plant._ In the Rio Grande Valley, Atriplez is the most im+
 known winter host plant. In the black-land sections of the

   
 

   

ined by Dr. H. E. Ewing, Bureau of Entomology, U. S. Department
. lture . "

    
 
   
    

34 BULLETIN NO. 339, TEXAS AGRICULTURAL EXPERIMENT STATIO

State, eggs of the insect have been found during the winter se
wild sunflower.

Fourth, cotton stalks remaining in the field are a source ,0
tation to young cotton the following spring.

Fifth, insects, emerging in the spring before cotton is availabl
and subsist upon practically any succulent weeds, and later m
grate to young cotton. -

Since the cotton flea hopper hibernates in the egg stage with
host plants, obviously control measures should begin with the d
tion of these in the late summer and early fall. At College
sageweed is the common host plant. If these Weeds are cut or
up by September 1, practically all the insect eggs which they c
hatch before cold weather begins, and very few remain dormant and
hatch in the following spring. A series of experiments in this con-
nection show that cutting or pulling up the plants at later dates is
not effective, and if they are allowed to remain in the field they will
prove to be a source of infestation to the succeeding crop. In fact,
sageweed plants pulled up in November and December of 1925, com-
pared with those which were allowed to remain standing in the field
until just before emergence began in March of the following year,
yielded as many insects as the latter, in the emergence cages. It is
therefore necessary that the destruction of the host plants be complete
if they are cut or pulled up after September 1. Plowing under the
weeds in the winter, if thoroughly done, will prevent emergence of the
insects. However, there is always the possibility of bringing undecayed
remnants of infested weeds to the surface while preparing the seed bed.
Burning is the most effective means of destroying the infested host
plants. _ '

Cotton stalks must be considered as a source of _ infestation, since the
insect has been obtained in the emergence cages ‘from plants collected
in various sections of the State. Plowing under cotton stalks during
the fall and winter is recommended. This measure is not only effective
in combating the cotton flea hopper, but also is a desirable practice in
cotton boll weevil control. "

The fact that the cotton fiea hopper will feed and mature on prac-d

tically any succulent weeds found in or near cotton fields makes clean
culture an important practice in controlling the insect. Furthermore,
emergence of the nymphs from the overwintering eggs usually begins
before cotton plants are available; hence the practice of clean culture
will result in starving out an incipient infestation.

Aside from the fact that the cultural measures recommended here are
effective in combating the cotton fiea hopper, they are considered to be
good farming practices and will increase crop production whet
insect is present or not. l

   

THE COTTON FLEA HOPPER 35

Use of Insecticides

In addition to the cultural measures recommended above, insecticides
may be used to a good advantage in controlling the cotton flea hopper.
In preliminary experiments a number of different insecticidal materials
were used, among which were monohydrated copper sulphate dust, cal-
cium ‘ifluosilicate, sodium fiuosilicate, calcium cyanide, tobacco dust,
hydrated lime, nicotine sulphate dust, sulphur-lime, sulphur, sulphur-
nicotine, and sulphur-naphthalene. Early results indicated that sul-
phur and the materials containing sulphur gave the best promise of
control. Consequently the experiments Were continued with sulphur
and mixtures containing sulphur. i

During the progress of these experiments in July and August 1925
at College Station, the insects were not present on cotton in sufficient
numbers to obtain reliable data on control. Therefore the efforts were
confined to sageweed which was heavily infested. Heavy applications
of all insecticides were made with hand and traction dusting machines
at 7- and 10-day intervals. A summary of the results obtained is
given in Tables 8 and 9.

Table 8. Per Cent of Daily Control After One Application

First Second Third Fourth Fifth Sixth Sev’th Eighth Ninth Tenth
Day Day Day Day Day Day Day Day Day Day

Sulphur . . . . . . . . . .. 71.7 86.9 89.6 90.2 9191.1 . . . . .. 79.7 79.5 66.7 89.5 p
Sulphur-
naphthalene..... 88.7 91.7 87.5 92.4 92.6 . . . . .. 93.9 81.2 83.5 83.9

Number Tests . . . . . 6 6 5 6 5 . . . . . . 4 3 A 3 2

Table 9‘. Per Cent 0f Daily Control After Two Applications

l

i First Second i Third i Fourth Fifth Sixth Seventh

i Day Day Day ‘ Day Day Day Day

i V l
Sulphur . . . . . . . . . . . . . . .  93.8 i 94.7 89.6 92.7 94.3 . . . . . . .. 67.1
Sulphunnaphthalene. .   97.3 i 95.4 99.0 98.2 100.0 . . . . . . . . 91.8
Number Tests . . . . . . . . .  2 i 2 2 - 2 2 . . . . . . . . 2

It will be noted that both sulphur and sulphur-naphthalene gave
excellent control. However, ‘since the sulphur-naphthalene mixture is
Einuggagxpensive and not readily obtainable On the market, sulphur is
  ended for use in cotton flea hopper control. Aside from its
i __ss sulphur is readily available to all local growers. Commercial
l is sold in various grades of fineness under a. variety of trade

  
       

36

BULLETIN NO. 339, TEXAS AGRICULTURAL EXPERIMENT STATION

. . ‘ i? .' i;  ‘LuJ-rx
Figure 10. Three good types of dustmg machmes.  , 
. TN
. 1.1”.» \
' ' $.31’; A

THE COTTON FLEA HOPPER _ 37

names. It has not been possible, up to the present, to test the effective-
ness of all these grades in the control of the cotton flea hopper. In the
control experiments at College Station the brand of sulphur ‘known
commercially as fine sublimed flowers of sulphur was used and found
to be satisfactory for dusting purposes. In Nueces County commercial
flour of sulphur was used on cotton in control experiments. This
grade of sulphur is also effective in controlling the insect, but is not
distributed as uniformly by the dusting machines as are the finer and
lighter grades. l

The following recommendations for controlling the cotton flea hopper
by the use of sulphur are based upon the results of control experiments
conducted on sageweed at College Station and field observations on

infested cotton in Nueces, WilliamsomHunt, Rusk, and Smith counties:

1. Sulphur applied as a dust is an effective insecticide for con-
trolling the cotton flea hopper.

2. The finer grades of sulphur are best adapted for dusting purposes.

3. iThe cheapest and most efficient method of applying sulphur to
plants is by means of good types of dusting machines.

4. From 12 to 15 pounds of sulphur per acre for each application
gives effective control. i

5. Early applications of sulphur are the most effective since the
young insects or nymphs are more susceptible to the effects of sulphur
and adults are not killed generally by the dust.

6. The proper time to begin dusting depends upon local conditions.
Every effort should be made to control the infestation from the be-
ginning.

'7. Three or four applications at 10- or 12-day intervals in the
early part of the season should give protection to the crop in its early

stages. If later applications are necessary the interval between dust-p

ings should be reduced to 8 days.
8. Applications may be made any time during the day.

SUMMARY

The cotton flea hopper has long been an inhabitant of Texas and is
widely distributed. within the State. Within the last three or four
years the insect has become a major cotton pest, causing severe losses
in many localities. The injury to cotton resulting from attack by this
insect is manifested by excessive shedding of very small squares and
the suppression of fruiting branches.

Groton or sageweed is the preferred food plant of the insect. How-
ever, it has been reared on a large number of different species of plants,
principally common weeds. Sageweed is also the preferred host plant,
but the insect will ovipost in cotton, Atriplesv, horsemint, wild sun-
flower, horsenettle, and May apple.

_The_ cotton flea hopper hibernates in the ‘egg stage. The over-
wintering eggs begin to hatch 1n March or April of the following spring.

38 BULLETIN NO. 339, TEXAS AGRICULTURAL EXPERIMENT STATION

There are no distinct broods or generations of this insect. Reproduc—
tion is continuous throughout the Warm season. Cold Weather in the
fall kills all stages of the insect except the egg.

The time required for completedevelopment during the Warm season
varies from 16 to 29 days, averaging 22.5 days in May and June. Ovi-
position begins shortly after the insects become mature. During the act
of oviposition the plant tissue is punctured by the ovipositor and the eggs
are laid singly Within the plant. The duration of the egg stage varies
from 6 to 12 days, depending upon prevailing temperatures. There
are five nyrmphal stages in the development of the insect. The nymphs
are active and feed on the tender portions of the plants by inserting the
beak and sticking the plant sap. There is some indication that the
insect may transmit a toxic virus.

No natural enemies of importance have been observed. Cultural
measures of control are recommended. These consist of the early
destruction of host plants and the practice of clean culture. Sulphur
and sulphur-naphthalene are effective insecticides in controlling the
cotton flea hopper.

ACKNOWLEDGMENTS

Dr. F. L. Thomas, Chief, Division of Entomology, and Mr. E. Hobbs,
formerly Assistant Entomologist of this Division, conducted a large
part of the Work on insecticidal control reported in this Bulletin.
Especial thanks are also due Doctor Thomas for helpful suggestions in
the preparation of the manuscript; Mr. C. S. Rude, formerly a member
of the Sta-tion staff, for drawings of the insect; Mr. H. Ness, Chief,
Division of Botany, for determinations of plants; and Dr. H. H.
Knight for permission to include several unpublished records on the
distribution of the insect. '

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THE COTTON FLEA HOPPER 39

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