A8-428~9,000-L18O

TEXAS AGRICULTURAL EXPERIMENT STATION

A. B. CONNER, DIRECTOR
COLLEGE STATION. BRAZOS cons“. ‘runs

BULLETIN NO. 380 MAY, 1928

DIVISION OF EN TOMOLOGY

INVESTIGATIONS ON CONTROL
OF COTTON FLEA HOPPER
IN I927

 

AGRICULTURAL AND MECHANICAL COLLEGE OFT TEXAS
T. O. WALTON, President

STATION STAFFT

     
 

ADMINISTRATION: VETERINARY SCIENCE:
A. B. CONNER, M. S., Director ,_*M. FRANCIS, D. V. M., Chief
R. E. KAIRPER, B. S., Acting Vice-Director H. SCHMIDT, D. V. M., Veurinarian
.11“ SIfIIHAEDEL, Sficretigliit f Cl k J . D. JoNEs, D. V. M., Veterinarian e
. . OLLEMAN, R., ie er _
J. K. FRANCKLOW, Assistant Chief Clerk pljA§TTgégalighgGgh AgDcIhi-PIYSIOLOGY‘
CnEsTEn HIGGS, Executive Assistant L’  PESSIN Ph ‘D ‘ Plant P "I i -t dl
CIJEBLEHE, Technical Assistant ' Laboratoiiy TéChhi-ci-an a 00g" an '
TRY: - ~
G. s. FRAPS, Ph. D., Chief; State Chemist ypflufififfisygsiqtp'i,'if,,fjai,'j§ifgf‘isi
%  ‘ESBURY’ MB SS’ Aézictant Chemist I B F DANA M  Plant Pathologisat
. . ARLYLE, . ., emist ' ' ’ ' "
WALno H. WALKER, Assistant Chemist FARM AND RANCH ECONOMICS: .
VELMA GRAHAM, Assistant Chemist , L- P- GABBARD- M- -- C c .
R_ Q_ BROOKE, M_ S“ Assistant Chemist G. L. CnAvqi-"onn, M. S., Marketing Research;
T. L. OGIER, Assistant Chemist Spcclallct
J. G. EVANS, Assistant Chemist 6' A- B°NNEN- M: s.“ 1'71"" Manaccmcm
ATiiAN J. STERGES, B. S., Assistant Chemist Research Spcclallst . . ‘
G_ $_ CRENSHAW, A_ B" Assistant Chemist “V. L. Comr, M. S., Grazing Research Botanist
JEANNE M_ FUEGAS’ Assistant Chemist T. L. GASTON, Jn., B. S., Assistant; Farm

HQRTICULTURE: Records and Accou_nts _
HAMILTON p_ TRAUB; ph_ D" Chief **J. N. TATE, B. S., Assistant; Ranch Recordr
H. NEss, M. S., Berry Breeder and Accounts

 

RANGELANIMAL HUSBANDRY: RURAL HOME RESEARCH:
J. M. JoN_Es,_A. M., Chief; Sheep and Goat JEssiE WurrAcnE, Ph. D., Chief ’
Investigations _ MAMIE GRIMES, 1\I. S., Textile and Clothing.
J. L. LUSLi, Ph. D.,_An_imal Husbandman; Specialist .~
Breeding Investigations EMMA E. SUMNER, M. S., Nuirition Specialist‘
STANLEY P. DAvis, Wool Grader SOIL SURVEY:
ENTOMOLOGY: _ **W. T. CARTER, B. S., Chie
F. L. THOMAS, Ph. D., Chief; State E. H. TEMPLIN, B. S., Soi Surveyor
Entomologist _ T. C. REITCH, B. S., Soil Surveyor
H. J. REINHARD, B. S., Entomologist HARVEY OAKES, Soil Surveyor e
B. K. FLETciiEa, M. A., Entomologist BOTANY: i
W. L. OWEN, JR., M. S., Entomologist H. NEss. M. S., Chief T
FRANK M. HULL, M. S., Entomologist PUBLICATIONS: i,
J. C. GAINES, JR., M. S., Entomologist A. D. JAcKsoN, Chief ,
C. J. Tom), B. S., Entomologist SWINE HUSBANDRY:
F. F. BIBBY, B. S., Entomologist _ FRED HALE, M. S., Chief
S. E. McGREGOR, Ja., Acting Chief Foulbrood DAIRY HUSBANDRY: “
Inspector , Chief
A. B. KENNERLY, Foulbrood Inspector POULTRY HUSBANDRY:
GiLLis GRAHAM, Foulbrood Inspector R. M. SiiEnwoon, M. S., hief
AGRONOMY: _ ***AGRICULTURAL ENGINEERING:
E. B. REYNoLns, M. S., Chief _ _ MAIN STATlONgFARMz
A. B. CONNER, M. S., Agronomist; Grain G. T. cNEss, Superintendent
Sorghum Research _ _ APICULTURE, San Antonio):
R. E. KARPER, B. S., Agronomist; Small Grain H. B. PARKS, . S., Chief
Research v _ A. H. ALEx, B. S., Queen Breeder
P. C. IVIANGELSDORF, Sc. D., Agronomist; FEED CONTROL SERVICE:
in charge of Corn and Small Grain Investi- F. D. FULLER, M. S., Chief i?
ations _ S. D. PEARCE, Secretary
D. . KiLLouGii, M. S., Agronomist; Cotton J. H. ROGERS, Feed Inspector
Breedinfi _ W. H. W000, Feed Inspector
H. E. REA, ._S., Agronomist; Cotton Root Rot K. L. KIRKLAND, B. S., Feed Inspector s
Investigations _ _ W. D. Noivriicurr, Jn. B. S., Feed Inspector ~
E. C. CUSHING, M. S., Assistant _in Crops SIDNEY D. REYNoLos, Jim, Feed Inspector
P. R. JOHNSON, B. S., Assistant in Soils P. A. MOORE, Feed Inspector
SUBSTATIONS
No. I, Beeville, Bee County: No. l0, Feeding and Breeding Station, near
R. A. HALL, B. S., Superintendent Colle e Station, Brazos County:
R. M. HERWOOD, M. S., Animal Husband-

No 2, Troup, Smith County:

‘.z>.....i|m..i.~_~_ ,...;--........az_.. 4.2“... m. Y

 

' - man in Charge of Farm ~
w' 3' HOTCHKISS’ Supimntendent L. J. McCALL, Farm Superintendent
N“ 3- Anilcccn- Bumm‘ Cmlnt?‘ No. ll, Nacogdoches Nacogdoches County:
R- H- STANSEL» M- S» S"Pc"l"tc"dc."l H. F. Moimis M.  Superintendent
FRANK M- HULL» M- S" Enlomolog"! "No. l2, Chillicothe, [Iardeman County:
No. 4, Beaumont, Jetferson County: J. R. gumnv, B. S., Superintendent _
R. H. WYCHE, B. S., Superintendent "J. C. TEPHENS. M. A., Junior Agronomist
No. 5, Temple, Bell County: _ No. 14, Sonora, Sutton-Edwards Counties: g
HENRY DUNLAVY, M. S., Suliicriritendent W. H. DAnEaoN, B. S.. Superintendent
B. F. DANA M. S., Plant Pat ologist E. A. TUNNICLIFF, D. V. M., M. S.,
H. E. REA, B._S., Agronomist; Cotton Root Rot Veterinarian _ -
Investigationsi V. L. Coiw, M. S., Grazing Research Botanist i
No. 6 Denton, Denton County: **0. G. BABCOCK, B. S., Collaborating “r
P.  DUNKLE, B. S., Superintendent Entomologist

No. ‘t, SBur, Dickens County; 0. L. CARPENTER, Shepherd
R. E. ICKSON‘, B. S., Superintendent No. I5, Weslaco, Hidalgo County: 5
No. 8, Lubbock, Lubbock County: W. H. FRIEND, B. S., Superintendent _ ,
D. L. JoNEs, Superintendent SHERMAN W. CLARK, B. S., Entomologist ,

FRANK GAINES, Irrigationist and Forest W. J. BAcn, M. S., Plant Pathologist
Nurseryman No. l6, Iowa Park, Wichita County:
No. 9, Balmorhea, Reeves County: E. J. WILSON, B. S., Superintendent _
J. J. BAYLES, B. S., Superintendent J. PAUL Lusx, S. M., Plant Pathologist

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

. W. AnniANcE. M. S., Associate Professor of Horticulture

. W. BILSING, Ph. D., Professor of Entomology _

. P. LEE, Ph. D., Professor of Martceting and Finance

A. E., Professor of Agricultural Engineering

P. Surrii, M. S.. Associate Professor of Agricultural Engineering

. H. WILLIAMS, Ph. D., Professor of Animal Husbandry

. K. MAcKEv, M. S., Associate Professor of Animal Husbandry

. S. Mocronn, M. S., Associate Professor of Agronomy

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9
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IAs of May 1, 1928. *Dean, School of Veterinary Medicine.
* In cooperation with U. S. Department of Agriculture.
‘"10 cooperation with the School of Agriculture

SYNOPSIS

During the early part of the growing season of 1927 infesta-
tions of the flea hopper on cotton were not suflicient to produce
any appreciable damage to the crop and no comprehensive

‘ data on insecticidal control of the pest were secured. Late

in the season heavy infestations of the cotton flea hopper
occurred on cotton near Granger and Hutto, in Williamson

» County. These outbreaks were controlled satisfactorily on

half-acre plats by applications of sublimed flowers of sulphur
made at weekly intervals. The data presented show a reduc-
tion of the number of insects on the treated plats; a reduction
of the percentage of small squares injured or blasted; and an
increase in the number of blooms and of the number of fruits
set.

The results secured in fifteen triplicate tests on the in-
secticidal control of the insect on goatweed indicate that
Superfine dusting sulphur, Electric sulphur, Sublimed flowers
of sulphur, and Superfine ventilated sulphur are all etfective
insecticides when applied at the rate of 15 to 20 pounds per
acre at weekly intervals. The average daily control secured
with these grades of sulphur over a 14-day period ranged from
79.8 to 86.7 per cent. Applications of insecticides made at
5-day intervals proved most elfective in reducing infestations

of the cotton flea hopper; however, applications made under
' similar conditions at 7-day intervals also resulted ina satis-

factory control of the pest. Sulphur applied early in the
morning when there was little or no air movement was gen-
erally slightly more effective in controlling the insect than
applications made later in the day. '
Young insects or nymphs are killed by sulphur on goatweed

i plants when it is applied under favorable climatic conditions.

The mature insects or adults were not affected unfavorably
by the sulphur applied to the plants under observation.

Five new food plants of the cotton flea hopper have been
found. These comprise common species of weeds collected ‘at
Robstown, Wharton, Taylor, and College Station during May,
1927. -

CONTENTS

PAGE
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Object of the Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Method of Procedure . . . . . . . . . . . . . . .1 . . . . . . . . . . . . . . . . . . . . . . . . . 6

Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ., . . . . . . . . . . . . . . 6

Data Recorded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  7

Factors Affecting the Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7

Experiments on Control of the Cotton Flea Hopper on Cotton . . . . . . 8
Discussion of Control Experiments on Light Infestations of
Insects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Control Experiments at Granger . . . . . . . . . . . . . . . . . . . . . . . . .. 11

Control Experiments at Hutto . . . . . . . . . . . . . . . . . . . . . . . . . . .. 13

Efl"ect of Sulphur on Infestation . . . . . . . . . . . . . . . . . . . . . . . 14

Effect of Sulphur on Squares Blasted . . . . . . . . . . . . . . . . . . 16

Efiect of Sulphur on Blooming . . . . . . . . . . . . . . . . . . . . . . . . 16

Effect of Sulphur on Forms . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Effect of Sulphur on Fruiting . . . . . . . . . . . . . . . . . . . . . . .. 20
Experiments on Control of the Cotton Flea Hopper on Goatweed. . . 20
Tests on Time and Frequency of Application . . . . . . . . . . . . . . . 21
Tests on Comparative Eifectiveness of Insecticides . . . . . . . . . . . 22
Action of Sulphur on the Cotton Flea Hopper . . . . . . . . . . . . . . . . . . . 25
Observations on Food Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

BULLETIN NO. 380 MAY, 1928

INVESTIGATIONS ON CONTROL OF THE COTTON FLEA
HOPPER IN 1927

H. J. REINHARD AND W. L. OWEN, JR.

Practically all the cotton grown in Texas may at times be injured
extensively by the cotton flea hopper Psallus 86mm The injury pro-
duced appears to be most severe when climatic conditions in the spring
delay the hatching of the overwintering eggs of the insect to the time
when young cotton is up generally in the field. Since there is no cer-
tainty regarding the natural control factors which may prevail during
any season the insect assumes the status of a potential enemy of cotton

roduction in this State. a

From the time that the cotton flea hopper first attracted attention
during the seasons of 1919 and 1920 by its attacks on cotton the injury
accomplished by the insect has spread from localized areas in the coastal
regions of Texas to practically the Whole of the State. In 1926 wide-

spread infestations of the cotton flea hopper were accompanied by a

heavy shedding or blasting of small squares generally over the important
cotton-producing regions in the State. This resulted in extensive areas
of practically barren cotton plants up to the middle of the growing
season. Much concern was manifested by growers regarding this situa-
tion and a general demand arose for definite information with respect
to methods of controlling the insect or reducing the damage done to the
crop.

Prior to 1926 the Division of Entomology, Texas Agricultural Experi-
ment Station, had concluded the life history studies on the insect and
had also conducted a series of control experiments which indicated that
sulphur applied as a dust was an eflicient insecticide for reducing infesta-
tions. The results of these investigations were published in Texas
Station Bulletins 339 and 356. However, many local growers reported
unsatisfactory results in combating the cotton flea hopper with sulphur
dust. This was primarily due to the fact that essential information,
such as the time, rate, and frequency of application of the insecticide
was not available. Realizing the seriousness of the problem confront-
ing the farmers of this State the Texas Agricultural Experiment Station
outlined and conducted a comprehensive series of experiments on the
control of this insect during the season of 1927. This Bulletin contains

a description of the experimental work conducted and presents the data "
which were secured during 1927.

OBJECT OF THE EXPERIMENT

These studies were made to secure definite information concerning
the most effective insecticides for controlling the cotton flea hopper; to
determine at what rate, frequency, and time applications of insecticides

6 BULLETIN NO. 380, TEXAS AGRICULTURAL EXPERIMENT STATION

should be made to secure satisfactory control of the insect; and tot;
obtain data on the performance of cotton plants in the field under flea

hopper conditions.
METHOD OF PROCEDURE

Location

In selecting the location for these investigations an attempt was made

to conduct the experimental work in various sections of the State where 
the flea hopper in previous years had done the most severe damage to the 
crop. This was also a desirable procedure from the standpoint of se- '
curing information on variations in the results due to differences in a

climatic conditions. The original locations selected were College Sta-

tion, Hillsboro, Paris, Robstown, and Taylor. These locations represent I

the south, central, north-central, and north-eastern cotton-producing

regions in Texas. As the season progressed it developed that the flea I
hopper infestation on cotton at Robstown remained practically negligible I
and for this reason the work was transferred to McKinney on June 

19, 1927.
Plan

The experiments at each location were conducted on half-acre plats.
The plats were carefully selected with respect to uniformity in stand of

cotton, age and growth of plants, soil conditions, fertilizers used, and

variety of cotton. One plat in each series of tests was left untreated
for a check or control on the treatment applied.

The work outlined for each location included the following series of l

experiments: -
Two 4-plat series on time and frequency of application using sublimed

velvet flowers of sulphur and “L” grade tobacco dust. Day or dry

applications of each insecticide were made on cotton at 5- and 7-day
intervals and dew applications at 7-day intervals.

One 4-plat series to determine the effect of deferred applications using
superfine dusting sulphur. The dust was applied during the daytime

‘at 7-day intervals, beginning the treatment on one plat at the ordinary

time, that is, as soon as cotton began to fruit, and deferring the applica-
tions on the other two plats 3 and 6 weeks, respectively, after the first
application of insecticide had been made.

Three 3-plat series on comparison of materials in dry or daytime
applications at 7-day intervals using superfine dusting sulphur, “L”
grade tobacco dust, and 50:50 mixtures of sulphur-tobacco dust “L”
grade and sulphur-lime.

One 4-plat series on combination dew applications for control of the
boll weevil and the cotton flea hopper by the use of calcium arsenate
and 50:50 mixtures of calcium arsenate-sulphur and calcium arsenate-
tobacco dust “L” grade. All mixtures of insecticides were applied at

the rate of 12 pounds per acre and the undiluted calcium arsenate at 8

pounds per acre.

INVESTIGATIONS ON CONTROL OF TEE COTTEN FLEA HOPPER 7

Four 2-plat series without any applications of insecticides to determine '

the effect of “strip planting” on the progress of flea hopper infestations
on cotton planted in this manner. “Strip planting” is a local term
applied to interspersing cotton rows with some other crop. Usually 50
to 90 rows of cotton are alternated with 1O to 25 rows of corn or sorghum.
Some growers reported that this practice was effective in protecting the
cotton from severe injury by the cotton flea hopper.

Data Recorded

To determine the insecticidal value of the materials applied and the
progress made by the plants on all plats, regular and uniform observa-
tions were made at each location where the work was conducted. The
infestation records were made twice each week: first, by noting the
average number of insects on 50 plants at 3 different points in each plat
using the same plants for each observation; second, by determining the
per cent of small squares blasted out of 100 squares counted including
all less than i inch in size on consecutive plants in the row at 3 points in
each plat. Bloom counts were made twice each week on 100 or more
consecutive plants in the row on all plats. This record was made to
indicate the reaction of the insects to the particular control measure
that was being applied. Plant height records were made at bi-weekly
intervals during the growing season on all plats by measuring 100 con-
secutive plants in the row at 3 different points on all plats. The
measurements were made on the same plants each time. Since cotton
attacked by the flea hopper usually makes a tall vegetative growth, this
record was taken as an index to any injury accomplished by the insect.
Form counts including squares, blooms, and bolls were made once each
week on 50 plants continuous in the row at 2 or 3 points on all plats.
This record was taken as an index to the development of the crop and
the influence of climatic conditions as well as a measure of the extent of
damage done by the insect. Boll counts were made during the latter
part of the growing season in the same manner as described above for the
form counts. This record was made to determine the actual extent of
fruiting on all the different plats as an indication of the extent of injury
done by the insect, and other possible factors affecting the results. Yields
of seed cotton were secured in all tests that were carried to completion as
a final test of the value of the treatment applied, for data on the extent
of losses due to the insect, and variations in yields due to factors other
than the damage done by the cotton flea hopper.

FACTORS AFFECTING THE EXPERIMENT

The principal limiting factor affecting the experimental work on the
control of the cotton flea hopper during the season 192'?’ was the general
scarcity of infestations of the flea hopper on cotton. With only two
exceptions the number of insects present on cotton was neither sufficient
to do any extensive damage to the crop, nor to secure comprehensive

8 BULLETIN NO. 380, TEXAS AGRICULTURAL EXPERIMENT STATION

data on the value of any insecticides applied for controlling the insect. i
However, the work was continued wherever there was a remote possibility 
of securing any results. In those locations where infestations of the .
cotton flea hopper did not develop, Work on other cotton insect pests, f

particularly on the boll weevil and on the boll worm, was conducted.

The results secured in these experiments will be published in another i;

bulletin from this Station.

EXPERIMENTS ON CONTROL OF THE FLEA HOPPER ON COTTON

The general scarcity of infestations of the flea hopper on cotton during
the early part of the growing season in 1927 precluded the possibility
of securing definite or conclusive data in the experiments conducted
during that time on the control of the pest. However, in the latter part
of July and during August, 1927, rather heavy infestations of the cotton
flea hopper developed in a field of cotton located 4 miles south of Granger
and in another field 1 mile east of Hutto, Texas. These infestations
were the heaviest noted during the entire season, and although existing
for only two or three weeks, they afforded an opportunity for repeating
the experiment conducted earlier in the season to determine the effective-
ness of sulphur and “L” grade tobacco dust in controlling the insect on
cotton. The data secured in this connection are presented on the follow-

ing pages and indicate that sulphur is a very effective insecticide for A

controlling infestations of the flea hopper on cotton.

Discussion of Control Experiments "on Light Infestations of Insects

Observations on the time and frequency of applications of insecticides
for the most effective control of the cotton flea hopper were made at all
locations indicated above, over varying periods between May 21 and
August 21. Applications of superfine sulphur and “L” grade tobacco
dust were begun at about the time the plants were beginning to form
squares freely. The insecticides were applied at the rate of approxi-
mately 15 pounds per acre, at 5- and 7-day intervals under dry condi-
tions, and at 7-day intervals when the plants were Wet with dew.

At the time the applications were begun the per cent of plants in-
fested with cotton flea hoppers was very low at all points Where the
work was conducted. The number of plants infested ranged from O per
cent at all locations to a maximum of 1 per cent at Hillsboro, 8 per cent
at Taylor, 12 per cent at Paris, 17 per cent at College Station, and 18
per cent at McKinney. Very few of the heaviest infestations indicated
were sustained for more than four or five days at any location. As the
season advanced the number of insects did not increase materially on
cotton; in fact, the reverse was true, especially at College Station, Hills-
boro, and Paris. These conditions were unfavorable for securing any
definite results; however, the experiments were completed at all locations
except at College Station. -

A summary of the observations made in these experiments with data

INVESTIGATIONS ON CONTROL OF THE COTTON FLEA HOPPER

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l0 BULLETIN NO. 380, TEXAS AGRICULTURAL EXPERIMENT STATION

on the infestations and yields is given in Table 1. Since the infesta-
tions of cotton flea hoppers did not increase 0n the untreated 0r check
plats t0 the extent of producing any appreciable injury, no definite data
were secured on the effectiveness of the control measures applied; in
other words, the differences in yields on the treated and untreated plats
were not significant. The points of interest in connection with these
experiments may be summarized briefly as follows: (1) When the
number of flea hoppers on cotton was small the per cent of minute
squares injured was not significant. (2) An increase in the number

, of this insect was accompanied by a corresponding increase in the per

cent of squares blasted and shed by the plants. (3) Superfine dusting
sulphur proved more effective than “L” grade tobacco dust in checking
infestations of the cotton flea hopper. (4) No appreciable damage re-
sulted when approximately 7 per cent of the cotton plants were infested
by 1 to 3 nymphs or immature insects per plant during the optimum
fruiting period.

The conditions which prevailed during the season of 1927 were also
very unfavorable for securing definite data on the effect of any treatment
applied in the experiments conducted for the purpose of determining the
best time to begin dusting cotton with sulphur for the most effective
control of the flea hopper. Observations in this connection were begun
at all locations during May and June and continued to the middle of
July. Throughout this period less than 3 per cent of the cotton plants
on the treated and untreated plats in the experiment at all locations were
infested with cotton flea. hoppers. The extent of injury to minute
squares on the plants under observation was also very limited ranging
from 0.3 per cent to 10.6 per cent and averaging approximately 5 per
cent over the period of observation. These continued light infestations
0f insects were not sufficient to produce any appreciable damage to the
crop and the data secured as the result of sulphur applications were not
significant.

Superfine sulphur, “L” grade tobacco dust, 50 :50 mixtures of sulphur-
tobacco dust “L” grade, and lime-tobacco dust “L” grade were used in a
series of control tests at all locations to determine the comparative
effectiveness of these insecticides for controlling the cotton flea hopper.
These observations extended from May 26 to August 18. As has already
been pointed out above, the number of flea hoppers on the cotton during
this period was too small to produce any apparent damage. These con-
ditions were unfavorable for obtaining any definite information in these
tests with respect to the comparative efiectiveness of the materials ap-
plied for controlling the insect on cotton.

Observations on the effect of “strip planting” as a measure for pro-
tecting the crop from injury by the cotton flea hopper were made on a
series of plats located at Taylor, Hillsboro, and McKinney, from May
28 to July 11. The number of insects during this period remained
practically insignificant on the plats at all locations and no definite data
were secured.

INVESTIGATIONS ON CONTROL OF THE COTTON FLEA HOPPER 11

Control Experiments at Granger, Williamson County

These experiments on the control of the cotton flea hopper were located
on the farm of Mr. G. C. Pope and begun on July 23, 1927. At that
time there were practically no small squares on the plants; however, the
lower fruiting branches were bearing bolls and large squares indicating
that the cotton had not been heavily infested by the insect early in the
season. The initial observations on infestation showed that approxi-
mately 50 per cent of the plants on the experimental plats selected were
infested by cotton flea hoppers. Superfine dusting sulphur and “L” grade
tobacco dust were applied under similar conditions on separate plats to
determine the effectiveness of these materials in controlling the insect.
No appreciable reduction in the number of cotton flea hoppers occurred
on any of the plats treated with “L” grade tobacco dust as a result of the
applications made.

Three plats of cotton were dusted with superfine sulphur at 5- and '7-
day intervals under dry and dew conditions as indicated in Table 2.

Table 2. Record of sulphur applications made on cotton at Granger

Plat 1 Plat 2 Plat 3 Plat 4

July 23, 1927* July 23, 1927* July 23, 1927'

25, 1927 July 25, 1927 July 25, 1927
Date of application... . . . .. Check, no Aug. 1, 1927 July 30, 1927 Aug. 1, 1927
treatment Aug. 8, 1927 Aug. 4, 1927 Aug. 8, 1927

Interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-day 5-day 7-day

Dry or dew applications. . . . . . . . . . . . . . . . . . Dry_ Dry_ Dew_
applications applications applications

Average rate of application '
per acre . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.3 pounds 17.8 pounds 21 .9 pounds

*Washed ofl‘ by rain, redusted July 25.

Since the plants on all plats in this experiment had practically ceased
growth at the time the first application of sulphur was made the reduc-
tion of the infestation on the treated plats is the best index of the
effectiveness of this insecticide in controlling the insect. The data se-
cured in this connection are presented in Table 3. The first application
of sulphur was washed off by rains within 24. hours after it had been
applied and the plats were redusted on the following day. Climatic
conditions during the remainder of this experiment were favorable for
securing the maximum effectiveness of the insecticides applied.

It will be noted that the number of insects decreased rapidly from
July 23 to July 30, on all the plats dusted with sulphur. During the
same period the number of insects increased approximately 20 per cent
on the untreated or check plat. After the second and third applications
of sulphur were made the infestation on all the treated plats was prac-
tically negligible and the subsequent applications were effective in pre-

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Eomcmpme an 82g wficoiioaxe ee eemwmwmewe~ .m view.

INVESTIGATIONS ON CONTROL OF THE COTTON FLEA HOPPER 13

venting any increase in the number of insects. In this connection it
should be pointed out that natural factors also reduced the infestation
on the check plat after August 3. However, the reduction in the num-
ber of insects on the untreated plat occurred much more slowly than on
the treated plats and did not reach the minimum which obtained on
the latter.

The plants on all the plats in this experiment had practically ceased
fruiting at the time these observations were begun and no significant
data were secured on the effect of sulphur applications in reducing the
percentage of minute squares injured by the insect. On August 29, all
plats averaged approximately 2.25 bolls per plant. Most of these, how-
ever, had been set prior to the time when the experiment was started.
The yields of seed cotton per acre secured were as follows: plat 1, (check)
480 pounds; plat 2, 522 pounds; plat 3, 522 pounds; and plat 4, 498
pounds. While all plats treated with sulphur produced a larger yield
than the check or untreated plat the differences were not sufficient to be
significant.

The results of this control experiment may be summarized briefly as
follows: (1) Sublimed velvet flowers of sulphur when applied at the
rate of 20 pounds per acre is an effective insecticide for controlling an
infestation of the flea hopper on cotton. (2) Applications made at
7-day intervals were practically as effective in controlling the insect as
those made at 5-day intervals. (3) Applying the sulphur when the
plants were wet with dew did not result in any increased effectiveness
of the insecticide.

Control Experiments at Hutto, Williamson County

The heaviest infestation of the cotton flea hopper noted during the
season of 1927 occurred on Mr. Carl Allgreen’s farm located 1 mile east
of Hutto, Texas. The infestation developed late in the season in a por-
tion of a large field where a poor stand of volunteer cotton had been
plowed up and replanted to cotton on June 6. On August 19, when these
observations were started, the older cotton in the field showed practically
no injury by the flea hopper while the infestation on the young or re-
planted cotton was practically complete; that is, the number of insects
present was sufficient to prevent the development of any squares. There
were very few bolls present at the time the first observations were made,
indicating that the infestation had existed from the time that the plants
were beginning to fruit. Many of the plants had made the usual tall
whip-like growth as a result of the sustained cotton flea hopper infesta-
tion. Another type of injury accompanied the heavy infestation of this
insect. In this case the plants were deformed having a topped appear-
ance with many abnormal short lateral branches bearing excessive foliage.
The principal growing tips of these plants showed evidence of having
been injured or destroyed some time prior to the date on which these
observations were started. In this connection it should be pointed out
that in 1926 a similar type of injury was noted in local cotton fields in

14 BULLETIN NO. 380, TEXAS AGRICULTURAL EXPERIMENT STATION

which there were very light infestations of the insect. However, the 1
injury was more pronounced in the heavily infested cotton at Hutto ; in f‘
fact, only a small proportion of the plants appeared normal, most of ‘;

them exhibiting either one or the other types of injury described above.

‘These experiments on the control of the cotton flea hopper were begun 1
on August 19. On that date the initial observations on the extent of 

infestation showed that 34 to 52 per cent of the plants on the experi-

mental plats selected were infested with the insect. Sublimed velvet .1

flowers of sulphur and “L” grade tobacco dust were applied at 5- and
7-day intervals under dry and dew conditions as indicated in Table 4.

Table 4. Record of sulphur applications made on cotton at Hutto

Plat 1 Plat 2 Plat 3 Plat 4

Aug. 26, 1927 Aug. 23, 1927 Aug. 26, 1927

Date of application... . . . .. Check, no Sept. 2, 1927 Aug. 29, 1927 Sept. 2, 1927
treatment Sept. 9, 1927 Sept. 3, 1927 Sept. 9, 1927
Sept. 8, 1927
Interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-day 5-day 7-day

Dew

Dry or dew applications. . . . . . . . . . . . . . . . . . Dry _  . _
applications applications applications

Average rate of application
per acre . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.0 pounds 17. 5 pounds 17.0 pounds

Climatic conditions during the extent of these experiments were favor-
able for securing the maximum effect of the insecticides applied. Prac-
tically no control of the cotton flea hopper was secured on any of the
plats treated with “L” grade tobacco dust, although essentially the same

Aug. 19, 1927 Aug. 1e, 1927 Aug. 1e, 1927 A i‘

procedure was followed in applying and noting the effect of this in- i

secticide as in the experiments with sulphur described below.

Effect 0f Sulphur 011 IIIfBStHtiOIII The data secured on the reduction
of the number of insects as a result of dusting the plats with sulphur are
presented in Table 5. From August 19 to September 5, the number
of insects on all treated plats decreased steadily, while the infestation
on the check increased materially during the same period. After Sep-
tember 5, natural factors reduced the infestations on all plats, although
the number of insects on the untreated cotton remained greater to the
end of the experiment, indicating that the last applications of sulphur
were producing most of the excellent control which obtained on all the
treated plats on the final days of the test. _

In Figure 1 is illustrated graphically the per cent control secured on
each treated plat for the duration of the test. There was no marked
difference in the effectiveness of dry applications made at 5- and 7-day
intervals, or dry and dew applications made at 7-day intervals. The
variations in the control secured as indicated by the curves, especially
after September 8, are probably due to the reductions in the infestation
eflected by natural factors.

15

INVESTIGATIONS ON CONTROL OF THE COTTON FLEA HOPPER

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l6 BULLETIN NO. 380, TEXAS AGRICULTURAL EXPERIMENT STATION»

Elfect of Sulphur on Squares Blasted: The reductionain the Hum
of cotton fiea hoppers on all plats treated with sulphur was followed b
a decrease in the number of small squares which were injured 0
blasted. The data secured in this connection are given in Table 6. 
August 20, more than half of the young squares on all plats were blaste
as a result of the attack by this insect. The effect of the sulphur appli
cations became apparent on September 5, at which time the plants on a p
treated plats were beginning to retain the minute squares which were
being formed rapidly. The number of squares injured by the insects on.
the check or untreated plat remained high up to the final observations
made on September 16, when there were approximately 50 per cent more‘
squares blasted or injured than on any of the plats dusted with sulphur.’

PERCENT

9O
80
70
60
50

40

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Fig. 1.——Showing the control of the flea h0pper_o_n cotton secured with sublimed flowers of
sulphur at Hutto, Williamson County.

Effect 0f 5111911111‘ 0H Blflflmillgi The number of blooms is an excellent
index to the effectiveness of the sulphur applications which were made
in this experiment to control the cotton fiea hopper. The data secured
in this connection are presented in Table 7. Plats 1, 2, and 4 contained
approximately the same number of plants, while the number on plat 3
was considerably larger. Calculated on the acre basis the stand of
plants for each plat was as follows: plat 1, 15,532 ; plat 2, 15,233; plat
3, 16,390; and plat 4;, 15,235. It will be noted that very few blooms
occurred on any of the plats from August 23 to September 9, during the
time when the infestation of cotton fiea hoppers was at its maximum.
About three weeks after the first application of sulphur was made, the
number of blooms on all treated plats increased materially while the
check plat showed no corresponding increase; in fact, the number of
blooms on the check plat decreased at that time. From September 16
to October 14, the plants on all the plats dusted with sulphur were bloom-
ing profusely. The check or untreated plat did not show any material

lA.._.~i.._....-.¢~.— ~ '

INVESTIGATIONS ON CONTROL OF THE COTTON FLEA HOPPER.

.17

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18 BULLETIN NO. 380, TEXAS AGRICULTURAL EXPERIMENT STATION

  
  
  
   
 
  
 
   
  
  
   
    
   
   
  
  
   
    
   

Table 7. The relative number of blooms on the treated and untreated plats, computed - 1

acre basis
‘Date Plat 1 Plat 2 Plat 3 Plat 4
(Check) _
August 23, 1927. . . =. . . . . . . . . , . . . . . . . . . . . . . . 103 152 152

August 26, 1927 . . . ~. . . . . . . . . . . . . . . . . . . . . . . . 413 203 109

August 30, 1927 . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 101 109

September 2, 1927 . . . . . . . . . . . . . . . . . . . . . . . . 207 52 O

September 6, 1927 . . . . . . . . . . , . . . . . . . . . . . . . 52 101 109

September 9, 1927.- . . . . . . . . . . . . . . . . . . . . . . . 258 304 164

September 12, 1927. . . . . . . . . . . . . . . . . . . . . . . . 207 354 380 ‘

September 16, 1927 . . . . . . . . . . . . . . . . . . . . . . . . 568 1 .116 984 1 ,7 -

September 19, 1927 . . . . . . . . . . . . . . . . . . . . . . . . 155 1,012 1 .203 1,0

September 23, 1927 . . . . . . . . . . . . . . . . . . . . . . . . 310 1 ,552 1 ,148 2, I

September 26, 1927 . . . . . . . . . . . . . . . . . . . . . . . . 861 2,888 3,499 4,6 '_

September 30, 1927 . . . . . . . . . . . . . . . . . . . . . . . . 568 2,280 2,952 3, c‘ ;

October 3, 1927. . .~, . . . . . . . . . . . . . . . . . . . . . . . 1 , 188 10,236 12,460 11 ,09

October 5, 1927 . . . . . . . . . . . ... . . . . . . . . . . . . . 2,015 13,528 11,644 9,47

October 7, 1927. . .-. . . . . . . . . . . . . . . . . . . . . . .. 2,377 12,160 9,039 7,4 _

October 10, 1927 . . . . . . . . . . . . . . . . . . . . . . . . . . 4,030 17,075 19,680 16,8 _

October 14, 1927. . .; . . . . . . . . . . . . . . . . . . . . . . . 4,288 16,315 15,908 14,4

increase in thenumber of blooms until the first week in October. Un
doubtedly the greater number, of blooms which occurred thereafter r
the check plat was due to the fact that natural factors reduced the in
festation of cotton flea hoppers after September 5 and the untreated
plants also began to retain and develop squares. However, each of the
treated plats had three or four times as many blooms as the check plat
on the date when the final counts were made. A

Effed 0f 31111111111‘ 011 F Ormsi Observations on the development of:
squares, blooms, and bolls were made on all plats at weekly intervals
from August 20 to October 14. The data secured are presented in Table
8. These data .further evidence the insecticidal value of sulphur in con-
trolling the cotton flea hopper. At the time the first applications of sul-‘
phur were made, the plants on all plats were retaining very few squares.
as a result of the injury produced by the cotton flea hopper. It will
be noted that there were practically no blooms present and that the num-,
ber of bolls which the plants had set was very small. This condition.
remained unchanged until the first week in September when the effect.
of the sulphur applications in reducing the infestation of insects became .
apparent by a rapid increase in the number of squares formed on all the I
cotton dusted with sulphur. The natural decrease of the number of j;
insects on the check plat during September was manifested also by an 5‘
increased number of squares produced on the untreated plants. How- 
ever, the number and the rate of increase in the squares formed was 1
much less pronounced and occurred two or three weeks later than on the.
cotton treated with sulphur. As the squares developed, the number of 
blooms on all the treated plats were increasing rapidly during the first
two weeks in October. ‘The final observations showed that the plants j
on these plats averaged more than one bloom per plant while on the '
check or untreated plat the average was slightly less than one bloom to s;
every three plants. 

19

INVESTIGATIONS ON CCTNTROL OF THE COTTON FLEA HOPPER

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20 BULLETIN NO. 380, TEXAS AGRICULTURAL EXPERIMENT STATION

   
   
 
  
  
 
 

Elfect of Sulphur 0n Fruiting= In Table 8 it will be noted that mo 
of the bolls were set after October 1. Obviously this was too late in the
season for these bolls t0 mature and hence yields are not available to de-
termine the effectiveness of sulphur in controlling the insect. In th
connection, however, the number of bolls set by the plants on all the
plats is a good basis for comparison. An increase in the number, of,
bolls set by the plants on all treated plats became apparent on September
23, approximately four weeks after the first application of sulphur was
made. Each record made thereafter showed a heavy increase in the
number of bolls on the treated cotton. On October 14, when the last,
observations were made, the untreated cotton averaged 1.4 bolls per=
plant while the cotton dusted with sulphur averaged 4.2 bolls per plant.“-
In other words, there were three times as many bolls set on the cotton
which was dusted with sulphur to control the cotton flea hopper. a

The significance of these results may be emphasized by pointing out‘
that the experiment was conducted late in the growing season when the Q:
boll weevil destroyed many forms on the plants under observation, and
that a practically complete infestation of cotton flea hoppers had pre- _
vailed and destroyed a large proportion of the squares formed on the »
cotton for some time prior to August 19, when the first applications of l,
sulphur were made. f

The results secured in this control experiment on the cotton flea ‘
hopper may be summarized briefly as follows: (1) A complete in- i,
festation of this insect on cotton was efiectively controlled by applying VT
sulphur dust at the rate of 1'7 pounds per acre. (2) Applications of f
this insecticide made at 5- and 7-day intervals during the daytime and it
at 7-day intervals early in the morning when the plants were wet with ‘
dew, all proved efficient in reducing the number of insects. (3) The 1i
reduction in the number of insects on all treated plats was followed by a '
decrease in the per cent of minute squares injured or blasted. (4) ;
The increased number of small squares retained by the sulphured plants .
became apparent about three weeks after the first application was made. _
(5) Four or five applications of sulphur materially increased the num- »
her of blooms on all treated plats. (6) q The number of bolls set on the
cotton dusted with sulphur was approximately three times greater than
the number set by the plants which were not treated.

. sum,‘

EXPERIMENTS ON THE CONTROL OF THE COTTON FLEA HOPPER
ON GOATWEEDS

To further note the insecticidal value of the various materials used in
controlling the cotton flea hopper and to secure further information
regarding the most effective time and frequency of application of in-
secticides, fifteen triplicate control tests on this insect were conducted
on Uroton, or goatweed, during August and September, 1927.

Each series of these control tests extended over a period of two weeks
and was conducted on four one-eighth-acre plats. One plat of goatweeds

INVESTIGATIONS ON CONTROL OF THE COTTON FLEA HOPPER 21

in each series was left untreated to serve as a check on the effectiveness .

of the insecticides applied on the other three plats. Daytime or dry
applications of insecticides were made at 5- and 7-day intervals, and
early morning 0r dew applications at 7-day intervals. All of the in-
secticides were applied uniformly over the area of each plat at the rate
of 15 to 20 pounds per acre with hand-operated Niagra dusting machines.
Prior to the first application and each day thereafter during the extent
of the tests fifty terminal bud-clusters were removed from plants situ-
ated on all portions of both treated and untreated plats. These samples
were placed in tight containers and taken to the laboratory where the
insects present on the bud-clusters were counted carefully to determine»
the extent of infestation. The number of insects present on the bud-
clusters taken from the untreated plats was considered to be a 100 per
cent infestation and the daily control secured on all plats was computed
on that basis.

Climatic conditions during these control tests were favorable for main-
taining the maximum effect of all insecticides applied. The tempera-
tures were high throughout August, 1927, and the rainfall for the month
totaled 0.01 inch. These conditions were unfavorable for plant growth
and the weeds on some plats deteriorated before the tests were com-
pleted. In effect, this naturally reduced the number of cotton flea
hoppers on the plats affected most by the drought, and the calculations
on the per cent of daily control obtained on these plats were based upon
comparatively small numbers of insects, which in some instances averaged.’
less than one insect per plant. Undoubtedly the unusually high control
of insects secured on these plats is attributable in part to the reduction
in infestation produced by natural factors.

Tests on Time and Frequency of Application

Nine triplicate control tests on the cotton flea hopper were conducted.

to determine any difference in efiectiveness of dry and dew applications
of insecticides and also to secure data on the comparative effectiveness
of applications made at 5- and 7-day intervals.

During these control tests dews were very light and often hardly
noticeable. However, conditions for applying the insecticides in the»

early morning were more favorable since there was practically no» aiir;

movement at that time. Strong winds often interfered with securing:

uniform applications during the mid-day or afternoon. A summary of].

the data secured in these tests is presented in Table 9. These data indi-
cate that applications of insecticides made early in the morning at 7-day
intervals are more effective in reducing the infestation of insects than

the applications made later in the day at the same intervals when winds. _

interfered. As has already been pointed out, the dews were very light:
or practically insignificant at the time these tests were conducted and‘.
the increased effectiveness of the early morning applications apparently-
was due to the more favorable conditions for applying the dust. These-

_mixtures than on those treated with the straight sulphurs.

‘Z2 BULLETIN NO. 380, TEXAS AGRICULTURAL EXPERIMENT STATION

data also indicate that applications of insecticides made at 5-day inter- ,
vals when the plants are dry produce a higher control of the cotton flea;
hopper than those made at weekly intervals. The increase in per cent .
of control was more apparent on the plats dusted with sulphur-tobacco 

However, a

this was due, in part at least, to the more rapid deterioration of the 1

plants on all plats dusted with the sulphurs, which effected a natural l
reduction of the number of insects present. i :

The effect of time and frequency of application of insecticides on goatweed for the l

 
 
  

Table 9.
control of the cotton flea hopper
_ _ Per Cent
Insecticide Schedule of Average
Application Daily
Control
Sulphur-Tobacco Dust “L” grade, 60:40 mixture . . . . . . . . . . . . . 7-day, dry 46.9

Sulphur-Tobacco Dust,“L” grade, 70:30 mixture . . . . . . . . . . . . . 7-day, dry 74.7

Sulphur-Tobacco Dust,.“L” grade, 80 :20 mixture . . . . . . . . . . . . . 7-day, dry 73.3

Sulphur-Tobacco Dust_ “L” grade, 60:40 mixture . . . . . . . . . . . . . 5-day, dry 72.4

Sulphur-Tobacco Dust,“L” grade, 70:30 mixture . . . . . . . . . . . . . 5-day, dry 71.9
_5iilphur-Tobacco Dust,“L” grade, 80:20 mixture. . .. . . . . . . . . . 5-day, dry 84.4
Sulphur-Tobacco Dust;.“L” grade, 60:40 mixture . . . . . . . . . . . . . 7-day, dew 72.0

Sulphur-Tobacco Dust"‘L” grade, 70:30 mixture . . . . . . . . . . . . . 7-day, dew 87.6

Sulphur-Tobacco Dust “L” grade, 80:20 mixture . . . . . . . . . . . . . 7-day, dew 77.2

Sulphur-Tobacco Dust 3% Nicotine, 60:40 mixture . . . . . . . . . . . . . 7-day, dry » 58.3

ulphur-Tobacco Dust 3% Nicotine, 70:30 mixture . . . . . . . . . . . . . 7-day, dry 60.0

Sulphur-Tobacco Dust 3% Nicotine, 80:20 mixture . . . . . . . . . . . . . 7-day, dry 56.2
Sulphur-Tobacco Dust 3% Nicotine, 60:40 mixture. . . . . . . . . . . . . 5-day, dry 70.2
Sulphur-Tobacco Dust 3% Nicotine, 70:30 mixture . . . . . . . . . . . . . 5-day, dry 77.0
Sulphur-Tobacco Dust 3% Nicotine, 80:20 mixture . . . . . . . . . . . . . 5-day, dry 72.2
Sulphur-Tobacco Dust 3% Nicotine, 60:40 mixture. . . . . . . . . .  . 7-day, dew 64.1
Sulphur-Tobacco Dust 3% Nicotine, 70:30 mixture . . . . . . . . . . . . . 7-day, dew 73.6

Sulphur-Tobacco Dust 3% Nicotine, 80:20 mixture . . . . . . . . . . . . . 7-day, dew 79.2

ulphur, Superfine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7-day, dry 81.9

Sulphur, Swan No. 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-day, dry 91.4

Sulphur, Electric . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-day, dry 88.8

Sulphur, Su erfine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-day, dry 96.0

Sulphur, Ve vet flowers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-day, dry 97.4

Sulphur, Electric . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-day, dry 97.3

Sulphur, Su erfine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-day, dew 94.5

Sulphur, Ve vet flowers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-day, dew 90.0

Sulphur, Electric . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-day, dew 88.7

Tests on Comparative Elfectiveness of Insecticides '

From August 20 to September 3, six series of triplicate tests were

conducted for the purpose of comparing the effectiveness of several in-

secticides in controlling the cotton flea hopper. Each series of these

‘tests extended over a period of fourteen days and included two dry or
daytime applications of insecticides at 7-day intervals. A summary of

the data on the per cent of daily control secured in these tests is
presented in Table 10.

It will be noted that the effectiveness of these insecticides varied
greatly in controlling infestations of the cotton flea hopper. Seven out
of the nineteen difierent materials used resulted in an excellent control
of the insect. These include the four brands of sulphur which were used;
two sulphur-tobacco dust “L” grade mixtures; and the mixture of

23

INVESTIGATHTNS ON’ CfiNTROL OF THE COTTON FLEA HOPPER

 

  

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24 BULLETIN NO. 380, TEXAS AGRICULTURAL EXPERIMENT STATION

sulphur-tobacco dust-lime. The performance of the sulphurs in reduc-
ing the number of insects is especially noteworthy. Each brand of
sulphur used resulted in a very rapid reduction in the infestation and ”
remained effective in checking the multiplication of the insects through- p’;
out the duration of the tests. On the basis of the average per cent of I

daily control produced the sulphurs rank closely together ranging from

79.8 to 86.7 per cent. These differences are not considered significant F
and the cost of the material is the determining factor regarding the kind 1
or grade of sulphur to use in combating outbreaks of the cotton flea ;

hopper.

Many requests have been received for information regarding the pos- 
sibility of controlling the cotton flea hopper and the boll weevil simul- 5
taneously with a mixture of sulphur and calcium arsenate. To deter- 
mine the effectiveness of a combination insecticide for controlling the
cotton flea hopper a mixture containing 5O parts sulphur and 50 parts 5
calcium arsenate was applied on a plat of goatweeds infested with the 
insect. The results secured are presented in Table 10, and indicate 
that this combination insecticide is decidedly less effective than un- 
diluted sulphur in controlling infestations of the cotton flea hopper. An f
average daily control of 59.3 per cent was secured by the use of this 3
mixture while the undiluted sulphurs applied under comparable condi- j
tions produced an average daily control ranging from 79.8 to 86.7 per 

cent. In the light of these results and the control secured in experi-
ments on the boll weevil it is not considered that applications of this
combination insecticide would be warranted even though both insects
may be present.

The results of several preliminary tests reported in Texas Station
Bulletin 356 indicate that mixtures of sulphur and tobacco dust were
slightly more effective than straight sulphur in controlling the cotton
flea hopper. To secure additional information on this point seven differ-
ent mixtures of sulphur-tobacco dust and two grades of undiluted to-
bacco dust were applied on twelve separate plats of infested goatweeds.
The results secured in these tests are given in Table 10. Under the
conditions of these tests none of the materials produced the high con-
trol of the insect that was secured on the plats dusted with the sulphurs.
In fact, only the 70 :30 and 80 :20 mixtures of the sulphur-tobacco dust
“L” grade resulted in a uniform reduction of the number of insects
present on the treated plats throughout the duration of the tests.

The results of these tests on the control of cotton flea hopper may be
summarized briefly as follows: (1) Early morning or dew applications
of insecticides are slightly more effective in controlling the cotton flea
hopper than daytime or dry applications. (2) Insecticides applied at
5-day intervals were most efiective in reducing the number of insects
present, but a satisfactory control was also secured by applications made
at 7-day intervals. (3) Electric sulphur, Superfine ventilated sulphur
or Swan brand No. 1, Superfine dusting sulphur, and Sublimed velvet

INVESTIGATIONS ON CONTROL OF THE COTTON FLEA HOPPER 25

flowers of sulphur proved to be the most effective of all the insecticides
used in the control tests on the cotton flea hopper.

ACTION OF SULPHUR ON THE COTTON FLEA HOPPER

Several tests were conducted to determine the action of sulphur on the
cotton flea hopper. Individual goatweed plants were selected in the
field and dusted liberally with sulphur while exposed to the direct sun-
light during the hottest portion of the day. Superfine sulphur was
applied in the first test at 2 :05 o’clock p. m. on August 25, 1927. The
day was hot and sultry, the sky partly cloudy, and the sun frequently
obscured for brief periods. There was practically no air movement
during the time the observations were made. The temperatures taken
20 inches above the surface about on a level with the plant ranged from
98 to 104 degrees F.; averaging 101.8 degrees F. during a 2-hour period,
from readings taken at 10-minute intervals. The effect of the sulphur
on the insects first became apparent 42 minutes after it was applied, at
which time the youngest nymphs began dropping to the ground and died
shortly thereafter. The older nymphs were also beginning to exhibit
discomfort at this time and moved about as if seeking relief. The first
fatality among the insects which were one-half or more developed was
noted at 2:57 o’clock or 52 minutes after the sulphur was applied.
Thereafter most of the youngest nymphs on the plant died rapidly,
although there were several fifth instar individuals alive on the plant
two hours after it had been dusted with sulphur. Twenty-four hours
later the plant was again carefully examined and only one live fourth
instar nymph was found. These observations indicate that sulphur
applied under favorable conditions becomes effective quickly and is a
very eflicient insecticide for killing the immature stages of the cotton
flea hopper.

Throughout the duration of these tests the adult cotton flea hoppers
on the plant were not noticeably affected by the application of sulphur.
Many were observed to fly away as the insecticide was being blown over
the plant with a hand-operated dusting machine. However, a number
of the adult insects remained on the sulphured plant for at least two
hours without showing any indication of being affected unfavorably

either by coming in contact with or by the fumes given off by the

sulphur.

Sublimed velvet flowers of sulphur was used in a test similar to that
described above. The results secured were essentially the same; that
is, in about one hour after the sulphur was applied to the plant a large
proportion of the young cotton flea hoppers were killed by the effects
of the insecticide. Twenty-four hours after the application of sulphur
had been made, an examination of the plant disclosed no live nymphs
although adult cotton flea hoppers were hardly less abundant than on
the adjacent untreated plants.

26 BULLETIN NO. 380, TEXAS AGRICULTURAL EXPERIMENT STATION

  
    

OBSERVATIONS ON FOOD PLANTS

During the course of these investigations several food plants of the;
cotton flea hopper, not heretofore recorded, were encountered in the
field during May, 1927. These include the following five species of
weeds collected at Robstown, Wharton, Taylor, and College Station: 3

Scientific Name Common Name
Abutvllon myalacwn . . . . . . . . . . . . . . . . . . . . .Indian Mallow

pGaillamdia pulchella . . . . . . . . . . . . . . . . . . . .-—-—i—-

Gaum brachycarpa, . . . . . . . . . . . . . . . . . . . . _Primrose

Gaura, Pwltcheri . . . . . . . . . . . . . a . . . . . . . . . . .Primrose

Marrubiuvn vulgare . . . . . . . . . . . . . . . . . .. Hoarhound

Additional food plants of the cotton flea hopper are reported in Texas 
Station Bulletins 339 and 356. Among the food plants listed above, 
Gaura brachycairpa is also known to be an important factor in the hiber- a ‘
nation of the insect (Texas Station Bulletin 377) in the vicinity of '11"
Wharton, Texas. Although the present known food plants of this insect 1
include 59 different species, principally common weeds, there are un- f
doubtedly many other plants, not yet discovered, which are also im- i
portant in this connection.

Since the insect feeds upon a large variety of early spring weeds com- f
monly found in cotton fields, the complete destruction of all weed growth
several days prior to planting cotton is a desirable procedure in com- .
bating early infestations of the insect.

SUMMARY

During the early part of the season in 1927 infestations of the cotton
flea hopper were generally light on cotton and very little injury by this
insect was noted. During July and August rather severe infestations
of the flea hopper were found in cotton fields located near Granger
and Hutto, Texas. ~

Control experiments were conducted on half-acre plats in these in-
fested fields using “L” grade tobacco dust and sublimed velvet flowers 
of sulphur. The applications were made at 5- and 7-day intervals un- 1'
der dew and dry conditions at the rate of 15 to 20 pounds per acre.

No satisfactory control of the cotton flea hopper was secured by the
use of “L” grade tobacco dust.

Sublimed flowers of sulphur applied either in the early morning or
during the daytime proved very effective in reducing infestations of the
insect. The reduction in the number of insects on all treated plats was
followed by a material decrease in the number of minute squares in-
jured or blasted. The increased number of small squares retained by
the sulphured plants became apparent about three weeks after the first
application was made. Four or five applications of sulphur greatly
increased the number of blooms on all treated plats. On the final date

INVESTIGATIONS ON CONTROL OF'THE COTTON FLEA HOPPER 27

of observation the untreated cotton averaged 1.4 bolls per plant; the
sulphured cotton 4.2 bolls per plant. The bolls were set too late in the
season to mature and the comparison of yields of the treated and check
plats could not be secured.

Nineteen different insecticides were used in a series of tests to deter-
mine the effectiveness of these materials for controlling infestations of
the cotton flea hopper on goatweed. All insecticides were applied at 7-
day intervals during the daytime at the rate of 15 to 20 pounds per acre
and each test extended over a period of 14 days. Climatic conditions
were favorable for securing the maximum effect of the insecticides used
in all tests. ~

Electric sulphur, Superfine ventilated sulphur, Superfine dusting
sulphur, and Sublimed flowers of sulphur proved the most effective in-
secticides among the materials used for controlling the cotton flea hop-
per. The average daily control secured with these grades of sulphur
in all tests over 14-day periods ranged from 79.6 to 86.7 per cent. Two
mixtures of sulphur-tobacco dust “L” grade, viz., 70:30 and 80:20, re-
sulted in an average daily control of 71.1 and 74.2 per cent, respectively.

In nine series of tests insecticides applied at 7-day intervals early in
the morning under conditions of very light dews produced a slightly
higher control of the insect than daytime applications of the same ma-
terials made at 7-day intervals. Applications of insecticides made at 5-
day intervals were most effective although an average daily control of
8O per cent was secured with materials applied at 7-day intervals under
favorable climatic conditions.

Sulphur applied under conditions of little or no air movement during
hot clear days affects the young cotton flea hoppers very quickly. Ob-
servations in this connection show that many nymphs are killed within
an hour from the time of applying the insecticide. The adult or
matured insect apparently is not aifected unfavorably by the insecticide
applied under field conditions.

Five new food plants of the cotton flea hopper are listed. These
comprise common species of spring weeds collected at Robstown, Whar-
ton, Taylor, and College Station, Texas.