FIFTY YEARS OF RESEARCH

ON THE PINK BOLLWORM

IN THE UNITED STATES

Agriculture Handbook No* 357

ART

r/ifñV1 ^9 1QA IQAO

BELTSViUE BRANCH

"I ' {!•

Agricultural Research Service

UNITED STATES DEPARTMENT OF AGRICULTURE
Trade names are used in this publication solely to provide specific

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name does not constitute a warranty or an endorsement of the

product by the U.S. Department

of Agriculture to the exclusion of

other products not mentioned.

Mention of chemical compounds

in this publication is not intended

as a recommendation. No product

should be used in insect control

unless it is registered for the

specific use intended, as clearly

shown on the product label.

rOLCOW THK I.ABBL

Washington, D.C. Issued March 1969

For sale by the Superintendent of Documents, U.S. Government Printing Office

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Contents

Page

Background 2

Initial infestations and spread . 2

Research laboratories 5

Research achievements 7

Biology and behavior . 8

Developmental stages 8

Diapause 12

Host plants 13

Means of spread 16

Transportation of larvae 16

Moth movement 16

Cotton crop damage 18

Square injury 18

Boll injury 18

Loss in yield and quality 19

Biological control 19

Native parasites 19

Introduced parasites 20

Predators 21

Pathogens 22

Chemical control 22

Foliar applications 23

Resistance to insecticides -^-. 23

Soil treatment 25

Control by plant resistance 25

Kill at gin and oil mill and in planting-seed treatment 26

Kill in ginning operation 27

Survey of gins in quarantined area 27

Fan treatment of gin trash and oil-mill byproducts 28

Treatment of planting seed 28

Changes in quarantine requirements 29

Cultural control 29

Planting date and early crop maturity 30

Shredding and field cleanup 33

Survival under different practices and climatic conditions 35

Recommendations for cultural control 40

Other methods of control*" 41

Light traps 41

Release of sterile males 42

Chemical attractants 43

Sex lure _ - . . _ 44

Rearing 45

Preparation of rearing medium 45

Equipment and rearing procedure 46

Surveys 47

Need for surveys 47

Survey methods _ - 47

Present status 50

References 50

n
FIFTY YEARS OF RESEARCH

ON THE PINK BOLLWORM

IN THE UNITED STATES

By LLOYD W. NOBLE, Entomology Research Division, Agricultural

Research Service

The pink bollworm (Pectinophora gossypiella (Saunders)) was

described in 1843 from specimens collected in India in 1842 and

is probably indigenous to that country. It was reported as a serious pest of cotton in 1904, when it caused damage in what was

then known as German East Africa. It has since become the most

injurious insect pest of cotton in many cotton-growing regions of

the world. Potentially it is a serious pest of cotton in the United

States. Quarantine regulations and cultural and chemical controls

have reduced economic damage in most years in the infested areas

of this country and have retarded spread of this insect to new

areas.

The U.S. Department of Agriculture recognized the pink bollworm as a potential pest of cotton in this country before its

discovery in Mexico, and sent August Busk to Hawaii to observe

the pest there in 1915. It has conducted research on control of

the pink bollworm in Mexico and the United States since 1918.

Through cooperative arrangements with the Mexican Government, work has been done in Mexico as though no border separates the two countries. The research has been conducted by the

Entomology Research Division of the U.S. Agricultural Research

Service or its predecessor agencies. Much of the work has been

performed in cooperation with the Texas Agricultural Experiment Station and also more recently with States that participated

in a regional project planned for research on the insect.

In addition to the cooperative work with Mexico and Texas,

the agricultural experiment stations of Alabama, Arizona,

Arkansas, Georgia, Louisiana, Mississippi, New Mexico, Oklahoma, Puerto Rico, and, since 1965, California have participated

in pink bollworm research. Cooperating agencies in the Agricultural Research Service are the Agricultural Engineering Research, Crops Research, and Plant Pest Control Divisions. Industry has cooperated in the work and the Oscar Johnston Cotton

Foundation has contributed funds to support the research. The

outstanding research findings reported by authors of these Federal and State agencies ^ are summarized here, including some

unpublished observations.

^ See references at end of this publication.
2 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

BACKGROUND

This report on pink bollworm research would be incomplete

without an account of the establishment and spread of the pest

in this country, with current delineation of the infested areas^

and a brief description of the research laboratories since 1918.

Initial Infestations and Spread

Surveys to detect the pink bollworm, eradication of isolated

infestations, and suppressive measures to slow or prevent

spread have been carried out by the Plant Pest Control Division

or its predecessor agencies in cooperation with industry and

with regulatory agencies of the States and counties involved.

Cooperative suppressive measures adopted in Mexico are the same

as in the United States.

The pink bollworm entered Mexico in seed imported from

Egypt in 1911, but it was not discovered until the fall of 1916,

when an infestation was found near Torreón, Coahuila. This

finding in 1916 presented immediate, especially grave problems

for the U.S. Department of Agriculture, because recent importations of seed from Mexico had been received at widely distributed

oil mills in Texas, some as far east as Houston and Beaumont.

Infestations West of the Mississippi River

The pink bollworm was first found in Texas by Ivan Shiller

at Hearne, Robertson County, in the fall of 1917. This infestation

was near an oil mill that had received seed from Mexico. From

1917 through 1921, infestations were found in several other counties in eastern Texas and southwestern Louisiana. By using noncotton zones and regulatory and cleanup measures, these early

infestations were eradicated. However, the insect has persisted

in an area along the Mexican border in western Texas since

1918 and probably longer. In that year infestations were found

along the Rio Grande in Presidio and Brewster Counties and in

the Pecos River Valley in Ward and Reeves Counties. In the next

decade infestations were discovered in the El Paso area of Texas

and New Mexico and in the Pecos Valley of New Mexico in 1920,

eastern counties of Arizona in 1926, Plains area of western Texas

in 1927, and Salt River Valley of Arizona in 1929.

Infestation was not seen in the lower Rio Grande Valley of

Texas and adjacent Mexico until 1936. Gradual spread from this

area and western Texas left some sections of Texas free of known

infestation until the early 1950's. A relatively rapid spread in the

late 1940's and early 1950's expanded the infested area to include all cotton-growing areas of Texas, New Mexico, and Oklahoma and sections of Arizona, Arkansas, and Louisiana. At that

time the insect had been long established in all cotton-growing

areas along the border in Mexico except in the western States

of Sinaloa, Sonora, and Baja California. Infestations were found

near Culiacán, Sinaloa, in 1954 and in 1957; both were eradicated. From the mid-1950's to 1967 the eastern boundaries for
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 3

this insect in the United States have remained nearly unchanged, whereas western spread has included parts of California

and Nevada with an increased intensity of infestation in

Arizona.

The initial infestation in the Salt River Valley was eradicated

and the quarantine was removed in 1934. Infestation reappeared

in 1938. After a buildup in only a limited area by 1946, this

infestation was eradicated, and after negative inspections in

1947-49, the area was released from quarantine for a second

time in 1950. Infestation was found again in central Arizona in

1958. An eradication program was vigorously conducted in the

area from mid-1958 through 1963 and was successful in greatly

reducing the infestation.

During this program, however, pink bollworm populations increased considerably in immediate outlying eastern areas and

thus presented new problems involving suppression of the insect

in eastern Arizona and western New Mexico to prevent its movement into central Arizona. This and other problems, chiefly withdrawal of cooperator support, resulted in termination of eradication activities following the 1963 harvest. Since 1958 all cottongrowing counties of Arizona have been under quarantine regulation except Yuma, Mohave, and Yavapai. Yuma County was

placed under regulation in 1965 and the other two counties are

being recommended for inclusion in the regulated area.

The pink bollworm was discovered in 1965 in limited areas of

California and in 1966 in Nevada and additional areas in California, where many fields in Imperial, Riverside, San Bernardino,

and San Diego Counties were severely damaged during the 1966

season. The pink bollworm was also found for the first time in

1965 in limited areas of Sonora and Baja California, Mexico.

Infestations in Florida and Georgia

The pink bollworm has existed in wild cotton in southern

Florida since its discovery there in 1932. How long it had been

there or where it came from is unknown. First indication that the

insect had become established in Florida was on June 1, 1932,

when larvae in bolls collected from experimental cotton on March

7 at Chapman Field, about 13 miles south of Miami, were identified as pink bollworm. Upon this discovery and the immediate

finding that wild cotton was infested, a program was undertaken

to determine the distribution of the insect and this host in the

State and to eradicate both.

On June 3 pink bollworms were found on an isolated cotton

plant about 5 miles north of Chapman Field. Other immediate

findings showed that heavy infestations already existed in wild

cotton at other places in the southern extremity of the State. Infestation in cultivated cotton was found and eradicated in seven

counties of northern Florida and two counties of southern

Georgia during 1932-36 and has not recurred since then. At

present the pink bollworm population in southern Florida, existing in wild cotton only, has been brought to a very low level.
4 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

Wild and dooryard cotton.—The wild cotton in Florida is a

form of Gossypium hirsvtum. It grows on higher ground than

does mangrove, but it is seldom found more than 5 miles from

the shoreline. The initial surveys showed that wild cotton was

distributed in many of the Florida Key^ beginning at Key West^

at numerous locations along the west coast as far north as Hudson in Pasco County, and in a small area on the east coast at

Grant in Brevard County. Dooryard cotton plants, or cultivated

varieties used as ornamentals, were common in the southern half

of the State.

The initial survey for pink bollworm in wild cotton showed

that infestations were generally distributed in the Keys of

Florida Bay and along the west coast in all counties as far north

as Manatee County. On the east coast, infestations north of

Miami were found only in dooryard cotton at Lake Worth, Palm

Beach County.

Work to eradicate wild and dooryard cotton in southern Florida

has been carried out since 1932 except from July 1, 1947, through

June 30, 1949, when Federal funds were not available for the

project. Unavoidably a few plants are missed. The seed may

remain viable in nature for many years. The various areas are

surveyed at least once yearly to destroy existing plants from late

September to May, when weather conditions permit work in the

junglelike areas where the plants grow. The procedure has been

effective in suppressing the pink bollworm.

Although the aim to eradicate wild cotton from southern

Florida has not been attained, the program has been successful

in reducing the pink bollworm population so that spread to cultivated hosts has been prevented. Since the initial cleanup, the

insect has not been found in wild cotton north of Lee County.

Commercial cotton and other cultivated hosts.—Initial findings

of pink bollworms where cultivated cotton became infested in

northern Florida were in Alachua and Columbia Counties in

1932, Madison County in 1933, and Hamilton, Jackson, Levy, and

Suwannee Counties in 1934. In southern Georgia, infestations

were found at Enigma in Berrien County and at Brookfield

in Tift County, both in 1933. Eradication was commenced

immediately after the insect was discovered in these areas. Infestation was not found in Georgia after 1933 and the quarantine

of that State was lifted on December 5, 1935. After negative inspections in northern Florida during 1935-36, the quarantine

was lifted on October 14, 1936.

In southern Florida where the former Bureau of Plant Industry had experimental cotton plantings infested by the pink bollworm in the Plant Introduction Garden at Chapman Field (first

finding of pink bollworm in the State), the infestation was eradicated without destroying all the plants, some of which were rare

breeding stocks. At that time cotton was cultivated south of

Alachua County only on small acreages in Sumter, Pasco, and

Hillsborough Counties. Florida law currently prohibits the

growing of cotton from Tampa south, including Pinellas, Hillsborough, Hardee, Highlands, Okeechobee, and St. Lucie Counties.
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 5

Okra is currently grown on 800 to 1,000 acres in Dade County,

more than 20 miles from the nearest known wild cotton. Okra

may volunteer from seeds, or new plants may grow from old

roots and thus give rise to wild okra for several years after a

planting has been grown under cultivation. Wild okra is fairly

common in southern Florida, particularly around old home sites.

Such okra was found heavily infested by the pink bollworm on

Plantation Key, where it was growing near infested wild cotton

earlv in 1954.

Kenaf, another attractive host for the pink bollworm, is also

grown in Dade County for local use as bean poles on several

thousand acres of runner beans. The pink bollworm has never

been found in these plantings. For bean poles, kenaf is planted

broadcast in a thick stand to prevent branching. Seed pods fall

to the ground when the plants are cut by hand and tied in

bundles. Planting seed is not grown locally.

Research Laboratories

In February 1918, the U.S. Department of Agriculture established a laboratory for pink bollworm research at Lerdo, Durango,

Mexico, where the insect populations were sufficient for such

studies. The work in Mexico was interrupted from late in 1919

until early 1921 and then resumed at Tlahualilo, Durango, where

it was continued until April 1925. The Tlahualilo laboratory was

closed at that time, because infestations in southwestern Texas

had built up to the extent that work on the pest could be conducted there.

In July 1927, headquarters for research on the pink bollworm

by the U.S. Department of Agriculture were established at El

Paso, Tex., and since that time all subsequent Federal laboratories

have been in Texas and have conducted research in cooperation

with the Texas Agricultural Experiment Station, Texas A&M

University.

The first experiment conducted with the insect in this country

was begun in the fall of 1927 at Castalon, now in the Big Bend

National Park. A laboratory staffed by both Texas and Federal

personnel was estabUshed at Presidio in April 1928 and it became

headquarters for this work in 1933. In August 1928, a sublaboratory of the Presidio laboratory resumed work at Tlahualilo, where

it was operated until 1936. A sublaboratory established at

Brownsville in 1939 became the headquarters laboratory in 1941.

Then the Presidio station became a sublaboratory and was operated as such until it was closed in 1947. A sublaboratory was operated at Ysleta, El Paso Valley, from the fall of 1944 until the

spring of 1952 and another at San Benito from 1944 to 1951. Later

sublaboratories were operated at Lubbock and Port Lavaca, both

during 1953-56. Some phases of the work, coordinated by the

Brownsville laboratory, were carried out by personnel of the

cotton insect laboratories at College Station and Waco during

1954-57 and 1954-62, respectively. A new laboratory at Phoenix,

Ariz., will conduct research on the pink bollworm.
6 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

Pink bollworm research programs were expanded in the early

1950*s as a result of increased intensity of infestations in southern Texas, associated with northerly and easterly spread that

caused an alarming threat to the States bordering Texas on the

east. The increase resulted from laxity on the part of growers to

carry out control recommendations and from adverse weather

conditions, which prevented proper execution of the compulsory

cultural control program requiring early stalk destruction in

southern Texas. Infestation in the area showed an upward trend

during the years immediately preceding 1952.

Because of very heavy rain in the fall of 1951, the harvest and

stalk-destruction activities w^re greatly delayed. Much of the

rain-damaged seed cotton infested with potential overwintering

pink bollworms was left in the field, and the larval population

was increased by reproduction in green bolls, which were abundant in many fields as late as November. This high fall population

with a dry period in the winter and spring favorable for a high

winter survival resulted in a population explosion in 1952.

After this outbreak the Pink Bollworm Advisory Committee

was formed to coordinate research and control efforts. It was

composed of representatives of the Agricultural Research Service, the Texas and Mississippi Agricultural Experiment Stations,

cotton growers, and the National Cotton Council.

The Entomology Research Division and the Texas Agricultural

Experiment Station expanded their research programs on control

of the pink bollworm in 1952. The Brownsville laboratory was

enlarged to serve as a center for this research. The Pink Bollworm Advisory Committee arranged for funds and personnel to

be furnished to the Brownsville laboratory by Alabama, Arkansas,

Georgia, Mississippi, and the Oscar Johnston Cotton Foundation

to assist the expanded research program. The Louisiana Agricultural Experiment Station located a staff member at the Texas

Agricultural Experiment Station at College Station as its contribution to the pink bollworm research.

The Pink Bollworm Technical Research Committee was organized in 1955. It consisted of a representative from each cooperating cotton-growing State, the Entomology Research and Plant

Pest Control Divisions, and the National Cotton Council. The

primary function of the committee was to formulate plans for a

cooperative regional research project. This committee was the

forerunner of the Technical Committee for Regional Project S-Sl.

In January 1956, Regional Research Project S-37, entitled

'Tink Bollworm Control,'' was planned. The project was revised

in 1959 and the title changed to **Basic Factors Involved in Pink

Bollworm Control," and again in 1964 with the title changed to

^'Factors Involved in the Control and Eradication of the Pink

Bollworm.'' State and Federal agencies that obtained approval

of projects contributing to Regional Project S-37 were the

Arizona, Arkansas, Puerto Rico, and Texas Agricultural Experiment Stations and the Entomology Research, Agricultural Engineering Research, and Crops Research Divisions. In addition, the

Plant Pest Control Division, the Cooperative State Research Serv-
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 7

ice, and the Louisiana and California (since 1965) Agricultural

Experiment Stations actively participated in the work of the S-37

Technical Committee. Research under this regional project continues; however, Arkansas discontinued its contributing project

in 1963 and Puerto Rico withdrew in 1966.

Research Achievements

Pink bollworm populations in Texas were at their highest peak

in 1952, and the insect caused very heavy losses in southern Texas

that year. Control methods developed by research and control

agencies were effective in reducing the infestation to a low level

by the late 1950's. Since that time the populations in Texas have

remained low and crop losses have been confined to a relatively

small acreage in the southern and southwestern parts of the

State.

Factors responsible for reducing the infestation in Texas after

1952 were (1) research that provided effective control methods;

(2) regulatory requirements by the Plant Pest Control Division

and the Texas State Department of Agriculture, and the educational campaign of the Texas Agricultural Extension Service to

convince cotton growers of the necessity for following the recommended control programs; and (3) the wide-scale application

of recommended control practices by growers, particularly in

compliance with cultural control requirements, on a communitywide basis. Also, favorable weather was conducive for the effectiveness of the program in reducing the peak infestation. Because

of the effectiveness of the cultural control practices employed, the

growers had to apply relatively small amounts of insecticides

solely to control the pink bollworm.

In the lower Rio Grande Valley, where the highest infestation

occurred during the 1952 outbreak, a serious problem with the

bollworm (Heliothis zea (Boddie)) and the tobacco budworm

(H, virescens (F.)) has developed, resulting in increased use of

insecticides for their control. This intensive insecticide program

in addition to cultural practices is currently holding pink bollworm damage in the area below the economic level.

The recommended pink bollworm control program is also an

excellent cotton-production program. Almost all practices in cotton production from seedbed preparation to harvest can be carried out to the disadvantage of the pink bollworm in Texas

without adversely affecting yields or profits.

The outstanding achievements brought about by the concerted

efforts of research and regulatory agencies have been as follows :

(1) Development of highly effective cultural and insecticide

control methods.

(2) Development of the '*community-action'' concept in insect

control programs.

(3) Evaluation of stalk-shredding machines for killing the

potential overwintering insects; incorporating the use of

shredders in a pink bollworm control program.

(4) Development of specifications for fans that will kill pink
8 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

boHworm larvae in gin trash; finding that nearly all larvae in

infested seed v^ill be killed during the ginning in modern saw gins

and the processing in oil-mill plants. As a result of these findings the States with regulations requiring heat treatment of cottonseed as a continuous process of ginning have rescinded this

requirement and thus effected savings to the ginning and oil-mill

industry that have more than paid for the entire research

program.

(5) Development of synthetic diets and techniques for rearing

pink bollworms and other insects in the laboratory for experimental purposes so that scientists can study the physiology,

biology, nutrition, and other basic aspects of insect research heretofore impossible.

(6) Basic research findings that have shown promise for controlling or eradicating the pink bollworm through male annihilation or sterile-insect release methods, including discovery and

synthesis of a chemical in the female that is attractive to the

male; development of methods for sterilizing the insect with a

radioactive material or chemosterilant.

(7) Development of survey and detection tools such as the gin

trash machine, argon light and blacklight traps, sex-lure traps,

and lint cleaner inspection and field inspection techniques.

BIOLOGY AND BEHAVIOR

The pink bollworm is best adapted to areas with low rainfall

and a long growing season. Development from egg to adult requires about 25 to 30 days in midsummer. There may be as many

as four to six generations a year where long growing seasons

occur. Diapause larvae pass the winter in seeds, old bolls, and

trash in the fields or at gins and seed-storage facilities.

Developmental Stages

Adult

The pink bollworm adult (pi. 1, E) is a grayish-brown moth

with a wingspread of 15 to 20 mm. The moths emerge early in

the spring and summer from overwintered larvae. They live 10

days to 2 weeks during midsummer and longer during cooler

weather. The female may lay about 100 to 200 eggs, depending

on the food on which the immature stages develop and the age

of the larva from which the adult emerges. Moths emerging from

overwintered larvae and larvae developing in squares have a lower

fecundity than do those of the summer generations developing

in bolls. The moths may feed on nectar or honeydew in the field.

In the laboratory, moths supplied with simulated nectar and other

sugar solutions laid significantly more eggs than did those given

water only. The moths hide under objects on the soil or in soil

cracks during the day and become active for mating and laying

eggs at night.

The greatest mating activity takes place after midnight, probably because of a biological clock that determines the time when
Aííriculture Handhook 357, U.S. Dept. of Airi'iculturt; Pl.ATK 1

^W PINK

BOLLWORM

/

Cottèifcbloom rosétted by feeding of the pink bollworm.

Green cotton with the boH sectioned; a, Eggs laid inside

ic calyx of cotton boll; b, entrance hole made by newly

hatched larva (invisible to naked eye); c, larvae in cotton

seed; i/. hole in partition made by a larva traveling trom one

lock to another; e, exit holes of larvae. C. Mature larva. D

Pupa. E. Adult. F, Damaged open boil. (A, B, F, twice

natural size; D and E, three and one-half times natural size;

C, five times natural size.)
10 AGRICULTURE HANDBOOK S57, U.S. DEPT. OF AGRICULTURE

the female releases a sex attractant. Males in the laboratory

respond to the sex attractant at any time of day when exposed to

an extract from the females. Mating may occur the first night

after emergence and one or more times thereafter. Males mated

an average of 4.2 times and females 2.3 times when the respective

sexes were caged with a greater number of the opposite sex in

the laboratory. Actual frequency of mating in the field, however,

is probably much less than that observed in the laboratory. Examination of females collected from the field in light traps showed

they had mated from one to six times, with an average of 1.1

times.

Oviposition begins on the second night and the daily number

of eggs laid is at a peak on the third night after emergence.

More than 80 percent of the eggs are laid before midnight. Below 70° F. moth activity and egg deposition are sharply reduced. Oviposition practically ceases at 60°.

Egg

The pink bollworm egg is pearly white when laid. It changes

to a light reddish orange late in the incubation period. Incubation

lasts 4 to 5 days in midsummer. Hatching occurs during approximately 3 hours from 8 to 11 a.m. Eggs may be distributed over

all parts of the cotton plant, but most are laid on the fruiting

forms of cultivated varieties. Early in the cotton season before

bolls^ are present, eggs are laid singly on squares, stems, and

terminal buds. Bolls become the preferred place for oviposition

when they are 15 days old or older. Eggs laid on bolls are deposited singly and in clusters, rarely exceeding four or five per

cluster. Usually the single eggs on bolls are laid oji the apex or

above the calyx and the clu&ters at the base. Most are laid at

the base between the glovelikc calyx and carpel, where they are

considerably protected from predators. (PL 1, S.)

Larva

The pink bollworm has four larval instars. The first instar,

except its brown head, has very little color when hatched and

becomes glossy white after entering the square or boll. Late instars acquire a cream color, with the dorsal side having transverse

bands of mottled pink that darken with age until the fully grown

fourth instar has the deep pink appearance for which the insect

]s named. The cylindricalfully grown larva is about 2.5 mm. in

diameter and 11 to 13 mm. long. (PL 1, C.)

Larvae that hatch on squares or bolls usually enter that form

withm about one-half hour after hatching and therefore are exposed to predators for a very short time. Those hatching under

the calyx may enter at that place, thus escaping exposure to

predators and insecticide residues. Those that hatch on parts of

the plant other than squares and bolls are subject to some mortahty resulting from failure to find a fruiting form as well as

greater exposure to their natural enemies and insecticides. Once

the larvae enter fruiting forms, where they feed for 10 to 15
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 11

days, they are fully protected from predators and insecticides.

They complete their development in a single square or boll and

never move to a second one for feeding. The fully developed fourthinstar larvae drop to the ground to pupate. Most of the overwintering ones remain in the seeds in which they developed.

Infestation in squares.—A larva developing in a square spins

a web, which usually keeps the bloom from opening fully, and

thus forms a rosette (pi. 1, A). Rosette blooms are easily detected on the plant, and they afford a convenient means of counting infestations for measuring the early spring larval population.

Larvae enter and develop in squares that are over 10 days old.

Squares infested before that age shed from the plant and the

larvae do not survive. Larval development in squares is faster

than in bolls. The rate of development increases with age of the

square, and thus larvae are more likely to complete feeding by

the flowering stage. Most larvae complete feeding by the time

the bloom forms and then drop to the ground, either from the

live bloom or with the dead bloom. A few feed on the young boll

that is just beginning to form when the bloom unfolds, and thereby they destroy the boll.

Infestation in bolls.—Pink bollworm larvae usually infest bolls

20 days old or older. They may enter and develop in bolls about

10 days old, usually when older bolls are absent or scarce or the

moth population is high relative to the number of older bolls

present. Bolls over 4 weeks old give a better criterion of the degree

of infestation. Larval development is faster in the older bolls.

The larval entrance hole, which may occur at any place on the

surface, is barely discernible with the naked eye. The mines (fig.

1) visible on the inner carpel wall are easily discernible, and a

count of these is the most convenient means of determining the

degree of infestation. In watery, young bolls the larva may tunBN-31!t02

FIGURE 1.—Interior carpel wall of green boll with locks removed, showing

mines (darker areas) made by tunneling of small larvae when entering

the boll.
12 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

nel directly through the carpel, leaving only a small discolored

spot inside similar to that resulting from punctures of certain

other insects. In older bolls when the lining has hardened, the

larvae tunnel along the outer surface of the lining before cutting

through it and thus leave lengthy mines that cannot be confused

with the sign of other cotton insects. (PL 1, 5 and F.)

After completing feeding, the nondiapause larva cuts a round

exit hole in the carpel, through which it crawls and drops to the

ground. Some diapause larvae exit in this manner and form cocoons to pass the winter. These exit holes too are easily differentiated from the sign of other cotton insects, but they represent

a small part of the larvae present of different ages and therefore

should not be used as a criterion for determining when to apply

insecticides. Nearly all larvae that stay in bolls after they finish

feeding have entered diapause and do not cut an exit hole. They

usually remain in a single seed, but sometimes they spin a cocoon

tying two seeds or hulls together, which resembles a double seed.

Cocoon and Pupa

The nondiapause larva spins an elongate, loose-fitting cocoon

in which It pupates. The diapause larva may spin a slightly

elongate cocoon, but usually it spins a closely wov^n, tight-fitting

spherical cocoon, which it abandons before pupating, and then

may either spin a loose elongate one or pupate naked. The pupa

is about 6 to 8 mm. long by 2.5 mm. at the widest part and is a

shiny brown. (PI. Xy D.)

Diapause

The pink bollworm has inhabited a wide geographical range,

undoubtedly because it enters diapause before the seasonal onset

of unfavorable environmental conditions. Moisture helps to break

the diapause or to stimulate pupation. Diapause larvae have been

reported to live as long as 2i/i years under dry seed-storage conditions, but there are no data on fecundity or even a record that

the insect can reproduce after such a lang period. Larvae in seed

stored from fall until late the next summer showed some mortality

and the survivors produced moths of very low fecundity. The

insect has never been found to survive a second winter in the

field. Larvae in bolls buried in November in an arid climate

showed stragglers that emerged as adults in September of the

next year. This emergence was stimulated by rain after limited

summer irrigation.

A few pink bollworm larvae may enter diapause in the first

bolls formed in the crop season. At Waco and Brownsville, Tex.,

the seasonal initiation of pink bollworm diapause occurs in the

generation hatching the last part of June. However, only a small

percentage of the population enters diapause before September.

Beginning with the generation hatching about the first of September, the incidence of diapause increases rapidly until the

middle of October, when about 95 percent of the larvae developing

in bolls are in diapause. Diapause in larvae developing in squares
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 13

is not initiated until cool fall temperatures prevail At Waco a

f^w diapause larvae occur in the first bolls formed, whereas at

Brownsville, because of warmer climate and earlier planting, the

cotton crop is well advanced when the first diapause larvae appear, although the date of initiation of diapause in the two areas

is about the same.

In the early research on the pink bollworm a greater proportion of diapause larvae found in old bolls than in young bolls

was attributed to nutritional diiferences between boll ages. The

rapid increase in proportion of larvae entering diapause as the

season advanced in late summer and fall was attributed to seasonal change in temperature. Data from different regions of the

world, however, indicated that diapause involved some factor in

addition to diet and temperature, and when considered in relation

to latitudes of the different regions, the data suggested a response of the insect to photoperiod.

Experiments carried out under controlled photoperiods and

temperatures showed that diapause in pink bollworm is controlled by photoperiod, with diet and temperature exerting a secondary efTect. The proportion of the population entering diapause

may be increased by a diet such as that furnished by a nearly

mature cotton boll and by low developmental temperature, both

operative only under photoperiods that induce diapause.

In latitudes from 26° to 32^ the seasonal diapause in pink

bollworm is initiated shortly after the summer solstice (June

22), when daylengths have begun to decrease, as demonstrated

at Waco and BrowUvSville. The proportion of larvae entering diapause increases as the days become shorter, and the increase is

accelerated by seasonal drop in temperature and maturity of the

crop. Reports from tropical latitudes between 10"^ and 22° indicate that diapause is initiated there in September, and the proportion of larvae in diapause increases until December. A concerted

search reported by six authors failed to disclose the presence of

pink bollworm diapause in the equatorial region between north

and south 10'' latitudes, where daylength continues unchanged

throughout the year.

HOST PLANTS

Gossypvimi is the preferred host of the pink bollworm. Plants

of worldwide distribution representing seven families, 24 e:enera,

and 70 species have been recorded as alternative hosts. Most of

the hosi-s belong to the family Malvaceae. Of these mallows, the

genus Hibiscus ranks high in the insect's preference. Six cultivated plants are attacked. The ornamental and wild host plants

(43 species) found in the Southwestern United States and northern Mexico exert a negligible efl'ect on the pink boUworm population in the generally infested area because of their sparsity or

lack of attractiveness to the insect. However, wSome may perpetuate the insect in small numbers and become important in an

eradication progi^am. A problem with eradication of an isolated

infestation exists in southern Florida, where the insect main-
14 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

tains itself in wild cotton. The insect has also been found on

Gossypium thurberi in Arizona.

The cultivated plants attacked are okra, kenaf, jute, roselle,

muskmallow, and castorbean. Okra is the only one currently

produced extensively in the United States, but some of the others

have been considered as potential crops for this country. A fev^

larvae developed when moths were caged on flax, but this cultivated plant was not found infested under natural conditions.

Okra is probably preferred next to cotton and must be considered in the same category with regard to cultural control

measures and quarantine regulations. High populations develop

on plants grown for a seed crop or abandoned during the growing season after an edible-crop harvest, and the residues of such

crops carry a high potential overwintering population. A new infestation may be established from a shipment of infested edible

okra if all is not consumed and the remaining pods are discarded

where the larvae can complete development in them. First-in^tar

larvae have completed development when placed on pods as young

as 1 day. When infested edible pods were removed from the plants

and caged, the larvae readily completed development and emerged

as adults in the cage.

Kenaf was found heavily infested in experimental plantings in

th^ lower Rio Grande Valley. When grown extensively, this plant,

like okra, may cause control problems. Similar problems may be

caused by jute, roselle, and muskmallow. The castorbean, although

found infested, does not appear sufficiently attractive to be of

any appreciable consequence as a host.

Plant species in the genus Gossypium are excluded from the

list given here because they are considered as preferred hosts of

the pink bollworm. A few other recorded hosts may have been

missed in the review of literature. The known alternative hosts

are listed here with their common name, if available. The location, when given, indicates that the species was found infested

under natural conditions in the United States, Mexico, or both.

Species on which diapause larvae were found to survive the

winter in seed pods are marked with an asterisk.

Malvaceae (mallow family)

Abutilón amplum Benth.

A, hirtum G. Don; Texas

A. hypoleucum Gray (A. jacquinii Don) ; Mexico

'•^4. incanum (Link) Sweet (A. texense T. & G.)—Indian-maUow; Texas

A. indicum (L.) Sweet (A, americanum (L.) Sweet)

"^A. lignosum (Cav.) Don {A. berlandieri Gray) ; Texas

A. otocarpum F, Muell.

A. trisulcatum (Jacq.) Urban (A. triquetrum (L.) Sweet) ; Texas, Mexico

"^Althaea rosea (L.) Cav.—hollyhock; Texas, Mexico

Callirhoe involúcrala var. lineariloha (T. & G.) Gray—poppy-mallow; Texas

Fugosia australis (F. Muell.) Benth.

Hibiscadelphus hualalaiensis Rock

'"^'Hibiscus abelmoschus L. {Abelmoschus moschatus Medic)—muskmallow;

Texas

*i?. acuieatus Walt.; Texas, Mexico

H. bifurcatus Cav.
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 15

*H. hrasiliensis L.; Texas, Mexico

*J?, canrvabinus L.—kenaf; Texas

*H. cardiophyllus Gray; Texas, Mexico

*if. coccineus Walt. (H, speciosus Ait.)—Texas-star, scarlet-rosemallow;

Texas, Mexico

H. coulteri Harv.—desert-rosemallow ; Mexico

'^H. dasycalyx Blake & Shiller; Texas

H. denudatus Benth.—paleface-rosemallow; Mexico

H. divaricatus Grah.

H. drummondii Turcz

*H, esculentus L.—okra, gumbo; Texas, Mexico

H. furcellatus Lam. var. youngianus (Gaud.) Hochr.

H, heterophyllus Vent.—yellow-flowered variety

*J3". incanus Wendl.; Texas

*H. lambertianus HBK. (H. cubensis Rich.) ; Texas

*H. lasiocarpus Cav.—wooUy-rosemallow ; Texas

*H, leucophyllus Shiller; Texas

H. ludwigii Eckl. & Zeyh. {H. macranthus Höchst, ex Rich.)

*H. militaris Cav.—rosemallow; Texas, Mexico

*H. mutahilis L.—cotton-rose, confederate-rose; Texas, Mexico

H. panduraeformis Burm. f.

H, rosa-sinensis L.—rose-of-china; Texas

H, sabdariffa L.—roselle

í¡r. syriacus L.—rose-of-Sharon, shrubby althea; Texas, Mexico

H. tiliaceus L.

H. trilobus Aubl.

H, tubiflorus DC. (H, pilosus (Sw.) Fawc & Rendle) ; Texas, Mexico

H, vitifolius L.

Kosteletzkya altkaeifolia (Chapm.) Gray; Texas

K, virginica (L.) Gray—saltmarsh mallow; Mexico

"^Malachra capitata L. (M. palmata Moench) ; Texas

Malva parviflora L. ; Texas

M, sylvestris L.—high-mallow; Texas

Malvastrum coromandelianum (L.) Garcke (M. americanum (L.) Torr.)

(M. tricuspidatum (Ait. f.) Gray)—false-mallow; Texas, Mexico

Malvaviscus arboreus Cav.—Turks-cap, South American waxmallow; Texas

*M. drummondii T. & G.—waxmallow, Texas-mallow; Texas, Mexico

^Pseudabutilonlozani (Rose) Fries (Wissadula lozani Rose)—false-ahutilon;

Texas, Mexico

^Sida cordifolia L. ; Texas

S. corrúgala Lindl.

*iS. spinosa L.—prickly-sida ; Texas

S, virgata Hook

Thespesia danis Oliv.

JT. grandiflora DC. (Montezuma speciossima Sesse & Moc. in DC.)

r. lampas (Cav.) Dalz. & Gibs.

^T. populnea (L.) Soland. ex Correa—tulip tree, portia tree; Texas

Euphorbiaceae (spurge family)

'^Crotón capitatus Michx.—crotón, goatweed; Texas

'^C. texensis (Klotzsch) Muell. Arg.—crotón, goatweed; Texas

^Ricinus communis L.—castorbean; Texas

Leguminosae (pea family)

Acacia wrightii Benth.—tree cat*s-claw; Texas

'^Daubentonia punicea (Cav.) DC. (Sesbania punicea (Cav.) Benth.)—

coffeebean, purple-sesban; Texas

^Gleditsia triacanthos L.—honeylocust; Texas

Prosopis juliflora (Sw.) DC. var. glandulosa (Torr.) Cockerell (P. glandulosa Torr.) (P. chilensis (Molina) Stuntz)—mesquite; Texas
16 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

Convolvulaceae (morning-glory family)

Ipomoea crassicaulis (Benth.) Robinson (7. fistulosa Mart.; 7. texana Coulter)—Texas bush morning-glory; Texas

Tiliaceae (linden family)

Corchorus olitorius L.—jute

Bombacaceae (bombax family)

Bombax munguha Mart. & Zuce.

Cochlospermaceae (cochlospermum family)

Cochlaspermum regium (Mart.) Pilger (C. insigne St. Hil.)

MEANS OF SPREAD

Transportation of Larvae

After the pink boHworm became a pest of commercial cotton,

it was carried long distances when infested cottonseed was transported in commerce. It rapidly invaded most major cottonproducing countries throughout the world. The insect lends itself

to dispersal by man, because the diapause larva has the habit of

remaining in the seed in which it developed. Besides the transport

of bulk cottonseed, there is a hazard in moving the baled lint,

mechanical cotton pickers, and vehicles that have been used to

transport seed or seed cotton, oil-mill products, and other items

subject to contamination by infested seeds. Larvae may be transported in okra and therefore are a hazard in marketing this

crop (see Host Plants).

Moth Movement

Light traps generally show greater catches of pink bollworm

moths in the spring before the cottonfields have produced squares

than after fruiting forms become abundant, indicating moth

flight in search of fruiting plants. Late in the season there is another much higher peak in number of moths trapped, indicating

greater flight activity after seasonal population buildup and after

crop maturity when green bolls are scarce.

Local Flight

Occurrence of early- and late-season local night from field to

field is reflected in the heavier infestations prevailing in early

and late plantings compared with plantings of intermediate date.

The spring generation developing in squares is higher in early

than late plantings, even though some of the early cotton is in

fields not planted to cotton the previous year and therefore is

infested only by migrant moths. A heavy late-season local moth
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 17

movement is shown in the sudden, sharp increased intensity of

infestation in late plantings after the earlier planting's have

matured.

Long-Distance Dispersal by Flight or Wind

Much evidence has been obtained that indicates pink bollworm flight activity is not restricted to local fields, because the

moths may fly considerable distances or may be carried by the

wind. They have been caught in light traps at least 25 miles from

infested fields.

Moths collected by airplane,—Possibility of long-distance dispersal of adults was recognized when moths were collected as

high as 3,000 feet on airplane flights over the heavily infested

Torreón area of Mexico in 1928. Moths were taken at altitudes of

100 to 1,000 feet on similar flights over the lower Rio Grande

Valley and King Ranch areas of Texas in 1954. Late in the cotton

season of 1956, flights were made over central Texas and the

northeastern (Arkansas-Louisiana) fringe of the quarantined

area. The insect-collecting screens were exposed for a total of 99

hours in central Texas and 40 hours in the fringe area. Sixteen

moths were taken in the flights over central Texas : 3 at 200 feet,

7 at 500 feet, 4 at 1,000 feet, and 2 at 2,000 feet; none were

trapped at 3,000 feet. Two pink bollworm moths were collected

in the lightly infested Arkansas-Louisiana fringe area, one at

500 feet and the other at 2,000 feet above ground.

During the flights in central Texas the near-surface wind was

mostly from a southerly direction. Small hydrogen-filled balloons

released at Waco and College Station drifted to the north and

northeast for distances up to 195 miles, as indicated by a small

number recovered. In previous studies, separate from pink bollworm investigations, other workers found that during May and

June balloons drifted as far as 375 miles from south-central Texas,

with prevailing winds to the north and northeast. It is thus

evident that pink bollworm moths, aided by the wind, may drift

from the more heavily infested areas of central Texas to outlying

areas on the north and northeast, and similar spread may occur

in other areas.

Isolated infested plantmgs.—Early experiments in Mexico

showed that isolated plantings of cotton as far as 40 miles from

the nearest source of infestation readily became infested where

chances of man's carrying the insect were meager. Small plots

of cotton became infested from 35 to 65 miles from the nearest

cotton in an arid section of western Texas where other host

plants were not a factor in the spread. These plots were planted

over a 6-year period with a total of 90 plantings. Of the 90 plantings, 18 became infested; none were found infested before the

last part of September. A planting 35 miles from cottonfields

became infested in 4 of the 6 years.

Surveys shoiving spread.—During the surveys to determine

spread of the pink bollworm in this country, many new infestations found at long distances from the nearest previously known
18 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

infestations could be accounted for only by moth movement. In

1947, for example, new infestations were found in 30 counties in

northern Texas and in Oklahoma, covering an area extending

northward for about 170 miles from the nearest previously known

infested^ county. Allowing for any doubt as to some undetected

spread into this area before 1947, despite surveys made in the

area, still the findings that year certainly demonstrate widespread dispersal of the moth.

COTTON CROP DAMAGE

Square Injury

Most infested squares develop to flowering stage with normal

pollination and boll formation. A few shed because of infestation

at an unusually early age or injury to the young boll after flowering. This loss in number of squares produced is minor. Any

measures used to control the spring population developing in

squares are necessary only to reduce the potential population that

would attack bolls later in the season.

Boll Injury

Larval feeding in bolls results in lowered quality of lint and

seed as well as reduced yield in weight. Reduction in quantity of

seed cotton produced is the more important loss in high infestations, but reduction in quality may be of considerable importance

at a degree of infestation too low to appreciably reduce the

yield.

Loss in yield of seed cotton consists of the bolls and locks that

are nonpickable either because of destruction of the seeds and

lint resulting from heavy larval feeding or development of bollrot organisms introduced into the boll through larval exit holes. A

lightly infested boll may develop a fungal growth resulting in

hard locks, as opposed to fluffy locks, which are nonpickable

and may range from one lock to the entire content of the boll.

The quality of lint is lowered because of discoloration and reduced fiber length and strength. Loss in lint value resulting from

injury is greatest when climatic and agronomic factors are favorable for production of a high quality fiber. Many of the seeds in

pickable cotton have been consumed and the quality of those ginned

is lowered because of reduced protein and oil content and increased free fatty acids.

Effect of Boll Age

Greatest damage occurs in the younger bolls where more seeds

are consumed and lint injury is greater than in older bolls.

A larva mfestmg an old boll may complete development in a single seed. The proportion of bolls becoming infested at a young

age mcreases with buildup of the insect population in a field.

Upon maturity of the early plantings, the fields with late cotton

may receive a sudden influx of moths when many of the old bolls
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 19

are still free of infestation. Under these conditions in a dry

climate as many as 29 larvae have been found to develop in an

old boll that opened when fully mature v^ith fluffy pickable locks.

However, the younger bolls fail to open under such conditions, or

they open prematurely with the locks so badly damaged that

they are nonpickable.

Effect of Rain and Humidity

A given degree of infestation causes greater damage in an area

with heavy rainfall and high humidity, resulting in greater boll

rot, than in a dry area. The entrance of rot organisms into green

bolls through larval exit holes is aided by rain, and the moisture

is favorable for development of the organisms. As a result, many

infested bolls do not open and the number of hard locks in those

that open is increased in a wet area.

Loss in Yield and Quality

Reductions in yield and quality of cotton due to pink bollworm damage were determined at Brownsville, a high humidity

area, with infestations introduced into cages at levels designated

as light, medium, and heavy. The highest level resulted in a seasonal average of 60 percent of the bolls infested. At this intensity of infestation, crop value was reduced by 34 percent, and

the losses were about equally distributed between reduced yield

and reduced quality of lint and seed. The lower infestations resulted in losses due chiefly to reduced quality of lint and seed.

Estimates of losses to be expected due to nonpickable bolls and

locks, without insecticide control of heavy infestations in a high

humidity area, can be obtained from results of insecticide experiments conducted in the lower Rio Grande Valley in 1952, the

year of peak infestation. The experiments were conducted in

flelds with infestations ranging from intermediate to high for

the area that year. They showed reductions in yield ranging from

about 50 percent, representative of many fields in the area, to as

high as 80 percent in some fields. Losses in quality of the seed

and lint harvested were not determined. The total loss from pink

bollworm damage was in addition to that caused by the boll

weevil {Anthonomtis grandis Boheman). The cotton rendered

nonpickable due to pink bollworm injury was determined by

comparing the yield from plots treated for control of both insects with that from plots treated only for the boll weevil.

BIOLOGICAL CONTROL

Native Parasites

At least 18 parasitic insects native to the United States and

Mexico have been found to attack the pink bollworm. The prevailing low parasitization observed was of minor importance in

controlling the pest. All the parasites were hymenopterous species

except one tachinid fly {Erynnia sp.) reared from larvae collected
20 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

in cotton blooms. AH attacked the larva except four egg parasites—Chelonus texanus, two new Chelonus spp., and Trichogramma minutum. The species giving the highest parasitization

were Bracon gelechiae, B. mellitor, and B. platynotae. A list of the

species found to parasitize the pink bollworm is given here. Several other species emerged from caged bolls infested with both

this host and the boll weevil and possibly were parasitic on the

pink bollworm.

Bethylidae

Epyris californicus (Ashmead)—western Texas

Parasierola emigrata (Rohwer)—Durango, Mexico

Parasierola punctaticeps Kieifer—Mexico and Texas

Braconidae

Apanteles pholisorae Riley—southern Texas

Bracon gelechiae Ashmead—Durango, Mexico

Bracon mellitor Say—Mexico and Texas

Bracon platynotae (Cushman)—Mexico and Texas

Chelonus texanus Cresson—Texas

Chelonus n. spp.—southern Texas

Opius dimidiatus (Ashmead)—southern Texas

Orgilus gelechiaevorus Cushman—southern Texas

Chalcididae

Spilochalcis flavopicta (Cresson)—western Texas

Eîasmidae

Elasmus setosiscutellatus Crawford—western Texas

Pteromalidae

Heterolaccus kunteri (Crawford)—Durango, Mexico

Zatropis incertus (Ashmead)—western Texas

Tachinidae

Erynnia sp.—Durango, Mexico

Trichogrammatidae

Trichogramma, 'minutum Riley—western Texas

Introduced Parasites

Eleven species of foreign parasites were reared in the laboratory and released in large numbers in Texas and Mexico. The

work was beg'un at the Presidio laboratory in 1932 and discontinued there in 1944 before the rapid spread of the pink

bollworm to the northeast beginning about 1950. Work was resumed at the Brownsville laboratory in 1952 and continued

through 1955. Besides the 11 species released, four others were

received, but the stocks died in the laboratory: Bracon greeni

Ashmead from India, B. vidgaris Ashmead and Calliephialtes

dimorphus Cushman from Brazil, and Elasmus platyedrae Fernere from Egypt.
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 21

Investigations at Presidio

Most of the parasites reared at Presidio were released in local

areas with limited releases in Mexico near Las Delicias, Chihuahua, and Torreón, Coahuila. Texas releases were restricted

to the Presidio Valley because of the prevailing low pink bollworm infestation in other parts of the State at that time. The

species released and origins of the breeding stocks were as follows: Bracon brevicornis Wesmael—southern Europe, B. kirkpatricki (Wilkinson)—east-central Africa, ß. mellitor Say—

Hawaii, B. nigrorufum (Cushman)—Japan, Chelonus blackbumi

Cameron—Hawaii, C, pectinophorae Cushman—Japan, and Exeristes roborator (F.)—southern Europe.

All species were recovered in field collections made in the current summers of the releases and, with the exception of Bracon

brevicornis and B. kirkpatricki, all overwintered in hibernation

cages. None of the species became established in this country or

Mexico. Their failure to become established in the arid sections

where all were released was apparently due to early spring

emergence with a lack of other hosts for their propagation before

pink bollworms became available in cotton squares.

Investigations at Brownsville

When work was resumed at the Brownsville laboratory, the

recent spread of the pink bollworm and a buildup in southern

Texas were believed to afford more favorable conditions for parasites to maintain themselves than at the time of the previous

releases. Five species imported from India were reared and released in southern Texas and northeastern Mexico. They were

Apanteles angaleti Muesebeck, Bracon brevicornis, B, gelechiae,

Chelonus heliopae Gupta, and C. narayani Rao. None of these

parasites were recovered in collections made at 170 liberation

sites. Apparently contributing to failure of the parasites to maintain themselves were the intensive use of insecticides and the

cultural control program directed against the pink bollworm,

which reduced the parasites as well as their host.

Predators

Little work has been done to determine the predators that attack the pink bollworm and to evaluate their effectiveness in controlling the pest. Undoubtedly many of the arthropods that prey

on other lepidopterous cotton insects also feed on eggs and larvae

of the pink bollworm but to a less degree because of protective

m^echanisms. Eggs laid under the calyx are protected from predators. Newly hatched larvae are exposed for a very short time

before they enter the square or boll where they are protected

during their feeding period.

A predacious mite, Meh'c/iares (Blattisocius) tarsalis (Berlese),

was observed feeding on pink bollworm eggs from moths caged
22 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

in the laboratory. This mite was also found on cotton growing

on the laboratory grounds, indicating that it may contribute to

natural control of the pink bollworm. Other mites—Glycyphagus

destructor (Schrank), Parasitus sp., and Tyrophagus putrescentiae (Schrank)—are known to feed on larvae in stored cottonseed.

The lacewing Chrysopa rufilabris Burmeister is reported to feed

on newly hatched larvae and the larger larvae in flowers. The

checkered beetle Enoclerits quadrisignatus (Say) was frequently

found feeding on larvae in blooms. Several unidentified spiders

and ants were observed attacking larvae in blooms and larvae

that had left the fruiting forms for pupation. Also, unidentified

spiders were seen attacking moths on the cotton plant at night.

Further evidence of moth attack was obtained in a pink bollworm

dispersal study, in which moths tagged with P "^^ were released,

and spiders found near the release point by means of a Geiger

counter had been secondarily tagged by feeding on the radioactive

insects.

Pathogens

Bacillus thuringiensis Berliner was investigated in the laboratory and in field-cage and small-plot tests, in which the organism

was applied against overwintering and summer populations of

the pink bollworm. This pathogen was effective in reducing the

populations but at application rates too high for use as a practical

control measure. A nematode with an associated pathogen (nematode DD-136) was similarly tested, and it too was effective but

not sufficiently to warrant its use for pink bollworm control.

Several bacteria, fungi, and a cytoplasmic virus have been

found in diseased pink bollworm larvae from laboratory cultures

and field collections. Their effect on field populations has not been

studied. A disease observed among fourth-instar larvae being used

to rear parasites was named "pink bollworm septicemia," and the

bacterial species causing the disease was named Bacillus pectinophorae White. Of the different pathogens found in pink bollworms,

the cyioplasmic virus has attracted greatest attention. It has a

wide range of insect hosts and has caused concern through contamination of cultures reared for experimental purposes. Although

it is not highly pathogenic, it appears to warrant investigation

as a possible agent for controlling the pink bollworm and other

insects.

CHEMICAL CONTROL

Recommendations on the chemical control of the pink bollworm

are subject to frequent change and are not given in this publication. For such recommendations, see U.S. Department of Agriculture Farmers' Bulletin 2207, ^'Controlling the Pink Bollworm

on Cotton."
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 23

Foliar Applications

Only those contact insecticides causing mortality of the adult

pink bollworm as well as newly hatched larvae have given satisfactory control of the insect. DDT was the first one found to be

highly effective. When DDT became available for field testing in

1945, all the insecticides then commonly known had proved inadequate for practical control of the insect. New insecticides, including systemics, were tested as they became available. Of the

many compounds screened in the laboratory, relatively few gave

results warranting further testing in the field. Of those showing

promise in laboratory tests, many failed to give satisfactory control when tested in the field. None of the systemic insecticides

have been effective against the pink bollworm.

Methods were developed to control the pink bollworm with

azinphosmethyl, carbaryl, or DDT, applied at 5-day intervals.

Methoxychlor, EPN (0-ethyl 0-p-nitrophenyl phenylphosphonothioate), and Dilan (a mixture of one part l,l-bis(29-chlorophenyl)-2-nitropropane and two parts of l,l-bis(29-chlorophenyl)-

2-nitrobutane) were also shown to be effective, but for several

reasons they were not developed for control of this insect.

Experiments showed that early-season application of insecticides, begun before the occurrence of squares susceptible to attack, was effective in reducing the spring piiik bollworm population found in blooms compared with that in untreated fields.

However, such early application is not required for economic control of the insect. Good control of the pink bollworm can be

obtained with insecticides applied when needed, based on infestation counts (fig. 2).

Although the spring generation developing in squares does not

cause economic damage, a high population found in early blooms

may require immediate insecticide application to prevent serious

damage to the first bolls formed. Therefore, infestation counts

made to determine when insecticides should be applied involve

the early square generation as well as the later generations developing in bolls. (See Surveys for description of bloom and boll

inspection methods.)

Treatment with an insecticide should begin immediately in a

field where a spring count shows 350 or more larvae per acre

in blooms. When less than 350 larvae per acre are found, further

inspection may be delayed until the first bolls are 4 weeks old.

After that time treatment should be started when 10 to 15 percent of the bolls are infested. Once treatment is begun, the scheduled applications should be continued until most bolls are open.

Resistance to Insecticides

The pink bollworm has acquired a high resistance to DDT in

the Torreón area of Mexico, and laboratory data have shown
24 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

BN-31899

FIGURE 2.—Results from controlling pink boUworm with insecticides : Treated

plot on right produced 2,702 pounds of seed cotton per acre compared with

668 pounds for untreated plot on left.

less resistance in varying degrees at several localities in Texas.

Many cotton growers of the Torreón area reported poor control

of the pink bollworm vi^ith DDT in 1958-60 after its extensive

use in the area since 1947. In 1960, laboratory tests at Brownsville showed that the dosage of DDT for 50-percent mortality

(LDr.o) of moths originating near Torreón was 13.6 times greater

than that for the LD.,o of moths originating at El Paso. Susceptibility of moths from the Brownsville area was not significantly different from that of the El Paso moths. Appreciable pink

bollworm resistance to DDT in Texas was first indicated in laboratory tests with moths from the 1962 crop at Coyanosa (near

Pecos) and Presidio. The greatest resistance (6.6-fold) was in

moths from Presidio.

Field experiments conducted near Torreón in 1961 showed

that DDT alone was no longer effective against the pink bollworm

in that area. Azinphosmethyl, carbaryl, and a mixture of azinphosmethyl and DDT gave excellent control and were slightly

more effective than a mixture of benzene hexachloride-DDT. Laboratory tests indicated that the toxic effects of the last mixture

were more than additive and may be classified as synergistic,

because benzene hexachloride alone is only slightly effective.

In a study of increased resistance to DDT in pink bollworm

adults, a laboratory culture was propagated with moths that survived topical application of DDT. Such selection, continued
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 25

throue*!! 21 generations with a DDT dosage estimated to kill about

one-third of the moths, resulted in an eighteenfold increase in

resistance. The increase was very rapid during the last five generations.

Soil Treatment

Results of experiments at the Brownsville laboratory indicate

that the overwintering pink bollworm population can be greatly

reduced by soil treatment with fumigants and organic insecticides

but at dosages too expensive for use as a practical control measure.

In these experiments, bolls infested with diapausing larvae were

buried in cages, and evaluation of the treatments was based on

records of moth emergence from the treated bolls compared with

nontreated bolls. Examples of the dosage and larval mortality obtained are as follows:

Pounds Larval mortality

Chemical fer acre ^ (percent)

Endrin 8 94

Parathion _ _ 10 92

DDT 20 53

Nemagon^ 250 96

D-D « r 25 43

^ Dosage in gallons per acre for D-D.

^ l,2-Dibromo-3-chloropropane.

^ Dichloropropane-dichloropropene mixture.

CONTROL BY PLANT RESISTANCE

Use of plant varieties resistant to insect attack is a highly

desirable way to control the pests. In India, where the pink bollworm is believed to have originated, imported commercial cottons

were more susceptible to attack by the insect than were the indigenous cottons. None of the commercial cottons grovra in this

country have shown resistance to pink bollworm attack. Earlyfruiting, quick-maturing varieties escape some damage from the

late-season buildup in population, and an open-type variety has

less boll rot from pink bollworm infestation than does a densefoliage type.

A long-range breeding program directed toward developing a

commercially accepted variety resistant to pink bollworms was

undertaken in the early 1950's. Approximately 150 cottons have

been screened for resistance to the insect and further studies made

of certain plant characteristics. A cotton possessing both resistance and desirable agronomic characters has not as yet been

developed.

Some of the cottons tested apparently were more preferred

than others by the pink bollworm moth. Of all the cottons observed, Gossypium thurberi was the least attractive for oviposition.

Two species and a cross with a third species exhibited proper-
26 AGRICULTUEE HANDBOOK 857, U.S. DEPT. OF AGRICULTURE

ties detrimental to pink bollworm larvae. This was evidenced by

a reduction in numt^r of surviving larvae on Gossypium thurberi

and a G, tomentosum x G. hirsntum (Stoneville 2B) cross and

by a lengthening of the larval developmental period on G. arboreum. The mechanism of resistance in the cross appeared to be a

physiological response of the seed to insect injury. When the seeds

were attacked, large masses of cells were proliferated and they engulfed and killed many larvae.

Morphological characters of certain cottons were found to affect the oviposition sites selected by the pink bollworm, with a

greater percentage of the eggs being laid away from the bolls as

compared with other cottons. As a result, there was greater exposure of the eggs and of newly hatched larvae to insecticides,

parasites, and predators. Greater larval mortality was due to failure of the wandering larvae to find bolls. The studies showed

that oviposition on bolls decreased when the boll had a very

tight-fitting calyx without well-defined lobes, flared bracts, or

both. The moths were attracted to vegetative parts having heavy,

coarse pubescence and leaves with heavy veins for oviposition.

In a field-plot experiment, however, the number of larval mines

in bolls of hirsute and glabrous strains was not significantly

different.

The studies suggest that it may be possible to increase the resistance of cotton to the pink bollworm and other insects by

breeding for a higher gossypol content of the plant. The presence

of gossypol in the seed, however, renders the cottonseed meal

poisonous as feed to nonruminant animals, and in cottonseed oil

it hinders the oil-refining process for oleomargarine and salad

dressing.

In cage experiments a cotton without extrafloral nectaries reduced pink bollworm reproduction, presumably because of lack

of nectar as food for the moths. However, field experiments were

unsuccessful in demonstrating the effect of nectarless cotton on

pink bollworm infestation.

KILL AT GIN AND OIL MILL

AND IN PLANTING-SEED TREATMENT

Kill of pink bollworms in cottonseed and seed cotton is necesvsary for local insect control in a generally infested area. This is

in addition to the quarantine requirement that infested materials

be treated to render them free of live larvae before they are

moved out af an infested area. Soon after the insect became

established in this country. Federal and State governments

adopted regulations requiring that gins and oil mills in quarantined areas be provided with special equipment for killing the

larvae.

Such equipment consists of heat sterilizers for treating cottonseed as a continuous process of ginning, fumigation equipment

and steel rollers for treating lint and linters, and incinerators or

other special equipment for burning or treating gin trash. Install-
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 27

mg and operating this equipment in infested territory have cost

farmers and processors many millions of dollars.

As more and more gin machinery came into use with improved

harvest and ginning practices, it became evident that increasing

percentages of pink bollworms brought to gins in seed cotton

were killed by the operation of the gins themselves. Beginning

in 1953, investigations were conducted to determine the pink bollworm mortality resulting from modern gin and oil-mill processing and^ if possible, to find ways of increasing it. Also, investigations were made on larval kill by delinting and hot-water treatments of cottonseed intended for planting.

Kill in Ginning Operation

In the ginning laboratory at Mesilla Park, N. Mex., results of

tests on infested snapped cotton indicated that ginning with the

simplest saw-gin setup possible for handling this kind of cotton

had killed 84 percent of the pink bollworms in seed taken at the

gin stand. With gradual addition of machinery to make an elaborate gin setup, the kill increased to more than 99 percent. Results with infested handpicked cotton showed a similar trend.

Further kill was caused by the seed-blow system. In tests at

commercial gins similar results were obtained regarding pink

bollworm mortahty in the ginning operation. The large number

of live pink bollworms found in gin trash, despite the high kill

in seed, confirmed the need for treating this material to kill the

larvae.

Pink bollworm kill in seed cotton ginned with a roller gin

is lower than that resulting from a saw gin. When infested cotton

passed through the gin stand alone, bypassing all other equipment, the larval mortality was 6 percent for a roller gin compared

with 32 percent for a saw gin operated at 570 r.p.m. and 77

percent at 865 r.p.m.

Survey of Gins in Quarantined Area

A survey was made of the cleaning and ginning equipment of

all the saw gins in the pink bollworm quarantined area of Texas,

New Mexico, Oklahoma, and regulated areas of Arizona, Arkansas, and Louisiana, and a record was kept of the number of bales

ginned by each in 1955. The machinery in the respective gins

was coded as in the ginning experiments. The effectiveness of

each gin in killing pink bollworms was then estimated, based on

results of the ginning experiments.

Of the 2,340 saw gins in the quarantined area in 1955, equipment estimated to kill less than 90 percent of pink bollworms

was found in only 47, and less than 1 percent of the cotton produced in the area was ginned at these 47 plants. Some of these gins

showing low kill have been taken out of service since the 1955

survey. Gins classified as equipped to kill at least 95 percent of

pink bollworms numbered 2,019, and their output of cotton made
28 AGmCULTURE HANDBOOK 357, U.S. IXEPT. OF AGRICULTURE

up 94 percent of the year's total for the area. Roller gins used

for American-Egyptian varieties numbered only 16 in the quarantined area in 1955.

Fan Treatment of Gin Trash and Oil-Mill Byproducts

Fractions of samples of seed cotton used in the ginning experiments showed that waste material per bale averaged 70 pounds

in handpicked cotton and 689 pounds in snapped cotton, both

containing many live pink bo^worms. There is a demand for this

material, which is used profitably for soil improvement and as

stock feed when it is free of live pink bollworms. The alternative

for disposing of the material is burning it. Besides the cost of

using incinerators to dispose of gin trash, serious problenis have

been created in some localities because of the smoke and disagreeable odors.

Preliminary work to determine the effectiveness of oil-mill

processes in killing pink boHworms showed that 26 percent of

the larvae in seed survived the first delinting and 1.8 percent

survived the second. Large numbers of live larvae were found in

the shaker waste.

Tests were made with fans of the kinds commonly used for

moving trash to an incinerator as it occurs in the ginning operation and for moving motes and linters to the press at oil

mills. Gin trash used in the tests originated with the ginning

of heavily infested cotton and contained many live pink bollworms in seed in waste locks as well as free larvae. Infested seed

was added to the oil-mill byproducts used in the tests. Fans tested,

whether their housings were unlined or had rubber linings, were

found to kill all pink bollworms in gin trash and in linters, motes,

and hulls if designed and operated according to specifications

developed as a result of the experiments conducted. The fans at

both the gin and oil mill are installed in the duct system.^

Treatment of Planting Seed

Investigations of treatments commonly used for cottonseed intended for planting showed that 100 percent of the larvae in

infested seed were killed by the standard acid or mechanicalflame delinting process. Also, the hot-water treatment sometimes

used to hasten germination of the American-Egyptian variety

was effective in killing the larvae in infested seed. Immersion

of the seed for 45 seconds at 150° F. or higher resulted in 100-

percent kill. At 140°, 80 to 120 seconds was required for 100-

percent kill.

^For information on specifications and installation of the fans, consult the

Plant Pest Control Division, Agricultural Research Service, Fetderal Center

Building, Hyattsville, Md., 20782, its field offices, or the State regulatory

agencies in the States where the fans are used.
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 29

Changes in Quarantine Requirements

The research conducted at the gin and oil mill has brought

about several changes in the pink bollworm quarantine requirements. These changes are now saving cotton growers and processors more than $3 million a year.

The high pink bollworm kill in the normal ginning operation

and the further kill in oil-mill processing or planting-seed treatment have led to the conclusion that under present practices

the survival in cottonseed is of little, if any, importance when

the seed is used within the generally infested area. As a result

of this conclusion, based on research conducted in the mid1950's, Texas, New Mexico, Arizona, Arkansas, and Louisiana

promptly abolished their regulations requiring heat treatment of

cottonseed as a continuous process of ginning. Oklahoma has

never required it nor do the recently infested States of California

and Nevada. Because of the danger of pink bollworm spread from

the fringe of the infested areas, however, seed returned to the

farm from gins with low pink bollworm-killing capacity in these

areas is required to be treated. Although fumigation usually is

the preferred treatment, a few gins in Arkansas and Louisiana

still operate heat sterilizers for the benefit of farmers who want

to take their seed home*

Planting seed that is delinted at approved acid or mechanicalflame delinting plants or that receives approved heat treatment

may now be certified for movement out of the pink bollworm

quarantine area without further treatment.

Fans meeting approved specifications may now be used instead

of more expensive treatments formerly required for killing pink

bollworms in linters, motes, and hulls at the oil mill. They also

may be used to kill the larvae in gin trash and thus free this

material for local use rather than burning it. There are occasions

when gin trash is still burned to get rid of it, although it has

been passed through an approved fan at places where it is not

in sufficient demand and where local regulations do not prohibit

burning.

CULTURAL CONTROL

During the many years before efliective insecticides were

available for controlling the pink bollworm, research was directed

primarily toward developing cultural control methods. Even with

the present-day insecticides, practical control of the insect still

is dependent mainly on cultural practices. Mandatory cultural

control zones are in effect in the southern, central, and eastern

sections of Texas, in regulated areas of Arkansas, and certain

regulated areas in Louisiana, Arizona, and California.

The pink bollworm is the only major cotton insect that passes

the winter in crop residue in the field in which it developed.

Because of this habit it is especially susceptible to destruction
30 AGRICULTURE HANDBOOK 357, U.S. DEPT. OP AGRICULTURE

by mechanical and cultural means. Although the most effective

cultural controi measures are aimed at destroying the overwintering larvae, certain practices during the crop-production season

help to reduce crop damage and buildup of the potential overv^^intering population.

Planting Date and Early Crop Maturity

The main objective to be accomplished by cultural practices

during the cotton-production season is to shorten the season in

order to minimize pink bollworm damage and still permit maximum yield and profit This objective involves planting date and

practices to hasten crop maturity.

Planting Date

Many pink bollv^orm moths from overw^intered larvae emerge

early in the spring and die before cotton squares become available

for their reproduction (suicidal emergence). At Waco, Tex., for

example, about 65 percent of the emergence from overwintered

larvae is suicidal if cotton is planted the first of April. Suicidal

emergence increases v^ith delay in planting; hov^ever, a delay

past the optimurti planting date may increase the larval population in diapause at harvesttime.

Planting-date experiments v^ere conducted for 4 years at Presidio, Tex. The plantings were started at different dates on caged

plots to prevent moth movement from plot to plot. The 4-year

average data indicate that delay in planting caused a decrease in

pink bollworm population during the early blooming and early

boll period; however, at harvesttime the diapause larval population was much greater in the late than ia the early plantings.

A wide range in planting dates in an area extends the cotton

production season and reprx)duction period of the pink bollworm.

Extremely early, scattered plantings attract early emerging moths

from surrounding fields and thus the spring population developing

in squares is increased. Because of this concentration of spring

emergence, heavy damage may occur in the early plantings. When

early plantings mature, the moths emerging in them move to

later fruiting, more attractive cotton. Extremely late plantings

may be severely damaged because moths move into them in large

numbers after the early and intermediate plantings have matured,

Thus a long planting period results in greater damage by the

pink bollworm, and because of the longer growing season with

abundant late bolls, a greater buildup occurs in the insect population compared with a short planting period. Therefore planting

in a community should be completed in the shortest period possible.

Reports by agronomists show that cotton should not be planted

until the daily minimum soil temperature at an 8-inch depth

averages 60° F. or above for 10 days preceding planting. At lower

temperatures/germination and seedling growth are retarded, the

incidence of seedling disease is increased, and the young plants
FIFTY YEAES OF RESEARCH ON THE PINK BOLLWORM 31

are exposed to early-season insects such as thrips for a longer

period.

Under good conditions for plant growth, first squares are

formed on upland cotton within 40 to 50 days of planting and

first blooms within 60 to 70 days. The crop will mature sufficiently

under these conditions for chemical defoliation within 125 to 150

days of planting and may be harvested within 160 days. Thus

there is ample time for maturing and harvesting a crop in advance

of stalk-destruction deadlines, and there is little reason for planting to begin extremely early or to continue for a long period.

The reports show that the best stands, highest yields, and

lowest production costs occur when cotton is planted at the

optimum date based on soil temperature (recommended average

of 60"" F.). Where American-Egyptiaoi (long staple) varieties are

grown, they should be the first plantings in a community because

they are later and slower fruiting than upland varieties.

Early Crop Maturity

Production of an early crop in the shortest period possible,

with early harvest, prompt stalk destruction, and deep plowing,

is most important in reducing the overwintering population of

the pink bollworm. (See Survival Under Different Practices and

Climatic Conditions.) Bolls formed in the first part of the season

escape severe damage because they mature before the pink bollworm infestation builds up to its seasonal maximum intensity.

Crop production in a short period decreases the seasonal buildup

of the insect and may result in fewer larvae entering diapause

to live through the winter.

Late irrigation in order to produce a late top crop of bolls

after the plants have matured an early crop tends to foster a tremendous population of pink bollworms and boll weevils, if they

are present. The possibility of a high winter carryover of the

pest, plus the cost of additional insecticide applications, usually

makes the production of a late top crop unprofitable to the cotton

grower. Tests conducted at Presidio showed that withholding

late irrigation speeded up maturity of the cotton and reduced the

overwintering pink bollworm population.

A serious problem has been created by an outbreak of the pink

bollworm in the Far West, where the climate is favorable for a

high winter survival of the insect and cotton growers are accustomed to very high yields resulting from a long growing season

with favorable weather for a late harvest. The growers think they

cannot afford to eliminate the late top crop of bolls produced

there. It appears that this late crop will soon become very expensive, even in the absence of the boll weevil. Certainly the intensive use of insecticides will be required or the pink bollworm

will take the late crop, and growers may find it is to their advantage to shorten the production and harvest period, unless research improves or develops other ways of handling the insect

in the immediate future.

Prefrost stalk destruction.—Early destruction of stalks before
32 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

frost may decrease pink bollworm reproduction by two or three

generations in areas with a long growing season. Prefrost stalk

destruction may stop reproduction before many larvae have entered diapause, and winter mortality of those in diapause is increased when they are plowed under early.

Experiments in the lower Rio Grande Valley, simulating stalk

destruction on August 15, September 15, and October 15 with

the infested bolls buried V/¿ inches on these dates, showed that

winter survival of the diapause larvae increased greatly with

delay m stalk destruction. Based on moth emergence after March

15, with squares available for reproduction by moths emerging

at that time, the survival was 55 times greater for September

and 400 times greater for October than for August stalk destruction. This increase in winter survival with delay in stalk destruction is m addition to seasonal buildup of the larval population and the increase in the proportion entering diapause as the

season advances.

Use of preharvest ehemicals.—ln the lower Rio Grande Valley

a mandatory stalk destruction deadline of August 31, when less

than ^0 percent of the pink bollworm larvae are in diapause, has

Deen very effective m controlling the insect. Occasionally weather

conditions require extending the deadline. Farther north where

later stalk destruction usually is necessary, a greater percentage

oí the larval population enters diapause.

The time of harvest and stalk destruction may be hastened

and the diapause larval population reduced by using chemical détonants or desiccants. Preharvest chemicals do not prevent larvae

that^develop m bolls from entering diapause. However, they stop

plant fruiting and make the plant unattractive to pink bollworm

moths for oviposition, besides hastening maturity of the bolls

present.

Certain hazards are involved in using desiccants or defoliants.

Ihe principal danger is if the chemical is applied too early,

serious yield losses may occur with additional losses in quality

0Î the hnt and seed. Defoliation is not recommended until 60

percent of the bolls are open.

Stub Cotton

Where the winters are not cold enough to kill cotton roots, the

iand may be left unplowed after the stalks are shredded, and

tue old plant stubs will grow new sprouts for producing the next

crop (stub cotton). In a program to control the pink bollworm,

the production of stub cotton should be prohibited.

btub cotton results in a higher winter survival of larvae because the infested crop residue left in the field after harvest of

tfte previous crop is not plowed under. It decreases the spring

suicidal moth emergence, because it produces squares before any

are formed on the earliest possible spring planting, and thus the

moth population at the beginning of the cotton fruiting season

IS iurther increased. It increases the length of the plant fruiting

and insect reproduction season, adding at least an extra genera-
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 33

tion to those possible on cotton planted at the optimum time,

and thereby increases the seasonal population buildup, crop damage, and potential overwintering population to attack the next

crop.

Shredding and Field Cleanup

Pink bollworms in bolls and locks remaining in the field after

harvest are the main source of carryover to the next crop. Diapause larvae in cocoons in the soil are very common in the West,

but this free-cocoon population is less important. Data obtained

during a period of several years at Presidio showed that the cocoon population accounted for only 16 percent of the total diapause larvae present in the fields after harvest, though the percentage was much higher in some fields. Also, the winter survival of larvae in cocoons is lower than in bolls. (See Survival

Under Different Practices and Climatic Conditions.)

Pink bollworms in the harvested crop carried to the gin are

killed during the ginning and oil-mill processing and by the

planting-seed treatment. Clean harvesting of the crop by hand or

mechanical picker and using a cotton gleaner if appreciable cotton is left on the ground help to reduce the crop residue. Snapping the bolls by hand or with a machine stripper, where practical,

is very effective in removing infested bolls from the field.

Stalk Cutting and Shredding Equipment

Great progress has been made in the development of stalk cutting and shredding equipment since the days when horsedrawn

equipment was commonly used. The early stalk cutting equipment

used with tractors, generally an adaptation of the horsedrawn

rolling cutter, was of little value in killing pink bollworms except

to cut the stalks in pieces that could be plowed under. The appearance of power-driven shredders was hailed as a promising

means of killing larvae in crop residue. Tests showed that they

were effective. A shredder also cuts the stalks in finer pieces and

spreads them over the ground so that they can be plowed under

more thoroughly than when the stalks are cut with a rolling

cutter.

Different makes of shredders and new models were tested as

they became available to evaluate their effectiveness in killing

pink bollworms in crop residue. From information gained in these

tests, adaptations or improvements of the commercial machines

were made and evaluated. Some of the adaptations found to

improve the killing efficiency have been incorporated in presentday commercial shredders.

Stalk shredders are of two types—one with a vertical shaft

and a horizontal rotating blade (horizontal rotary type) and the

other with a horizontal shaft and many free-swinging, vertical

rotating knives (flail type). Experiments have shown that the

flail shredder is more effective in killing pink bollworms than the

horizontal rotary shredder.
34 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

The flail shredder will kill about 85 percent of the pink bollworms in crop residue compared with 55 percent for the horizontal rotary type. Experiments have revealed no significant difference in kill between different makes of the same type. Although

killing efficiency of the flail shredder is higher with a correspondingly higher degree of stalk shredability, the power requirement

is greater than for the horizontal rotary shredder.

A part of the crop residue containing pink bollworms may

be found on the ground before shredding or may be shattered

from the plants during the shredding operation. An improvement

iîi'the horizontal rotary shredder was to shape the blades so as

tí) create a suction to lift the shattered bolls and expose them to

shredding action. The flail shredder creates a tremendous suction

and the bolls are exposed to greater shredding action (fig. 3)

than with the horizontal rotary type. In one experiment prefrost

shred'ding with a flail shredder resulted in 98-percent larval mortaytj^ where 4 percent of the population was on the ground before

shredding.

Burning and Grazing Stalks

During the early existence of the pink bollworm in this country,

Federal and State regulatory agencies and growers had no choice

but .to cut and burn cotton stalks or graze the fields to reduce

the pink bollworm population in crop residue before plowing. Although both methods are effective, they have serious disadvantages and have never been used to any appreciable extent for

practical pink bollworm control.

In a"field cleanup program conducted by the Plant Pest Control

Division for 9 years in the Presidio area, the effectiveness of

burning,stalks for pink bollworm control was evaluated. Approximately 90 percent of the larvae in bolls and locks were destroyed

when the stalks were cut by hand, piled with a pitchfork, and the

shattered bolls picked up or raked by hand and burned with the

stalk piles. The remaining 10 percent of the larvae were accounted for in bolls and locks that were missed in the cleanup

process! The amount of bolls shattered from the stalks was greater

and eflficiency of the cleanup process decreased when stalks were

cut with a tractor mower and piled with a push rake or dump

rake. Besides the high cost of cutting and burning stalks with

the crop residue, it is desirable to retain this material in the field

for soil improvement.

Investigations on pasturage of infested fields for pink bollworm

control were made during a period of several years at Presidio.

Where fields were heavily pastured with cattle or goats, over 90

percent of the overwintering pink bollworms were destroyed. To

be highly effective, large numbers of livestock must be kept in

the fields. Food value of the cotton plant for animals is poor, and

also grazing fields that have been treated with insecticides is

hazardous.
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 35

BN-31901

FIGURE 3.—Stalk shredding with flail shredder (top) and machine lifting

bolls from ground and shredding them (bottom).

Survival Under Different Practices

and Climatic Conditions

Experiments conducted with the pink bollworm in bioclimatic

cabinets simulating temperatures and rainfall at representative
36 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

localities outside the infested area indicate that the insect can

survive an average M^inter throughout the Cotton Belt. Work

performed in arid sections of southwestern Texas and northern

Mexico has shown that a heavy larval mortality occurs when infested bolls are buried in the fall, especially if the soil remains

thoroughly moistened for a considerable time.

Data from experiments in central Texas show that plowing

the land to a 6-inch depth in November with a moldboard plow,

followed by listing in February, will give better pink bollworm

control than any other winter cultural methods that have been

practiced in the area. These experiments indicate that when a

winter grazing or cover crop follows cotton, the land should be

plowed before planting, especially if the crop is to be left for

harvest, instead of plowing it under in the spring.

Investigations of winter survival of the pink bollworm in field

cages (fig. 4) at several localities in Texas and Oklahoma have

furnished data to help determine the effects of fall and winter

cultural practices, rainfall, and winter temperature on survival

of the insect, although other factors such as soil type probably

had considerable efl'ect in the experiments. Climatic conditions

at the localities in which the experiments were conducted ranged

from subtropical and humid at Brownsville to cold and arid in

western Texas to cold and wet at Heavener, Okla.

Results of these widely separated experiments, simulating four

winter cultural practices under natural rainfall conditions, showed

FIGURE 4.—Cages used to study survival of overwintering larvae of pink

bollworm.
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 37

that the cultural practices affected pink bollworm survival and

that this effect varied in different localities and was largely due

to climatic conditions. Variation in survival due to climatic conditions can be seen by comparing the average survival (percent

ifor the four treatments) at eight localities in Texas and tv^o in

Oklahoma as follows: Brownsville 1.1, El Paso 12.8, Greenville

3.9, Lubbock 3.2, Mt. Pleasant 10.2, Port Lavaca 2.9, Vernon 2.1,

Waco 11.9, Chickasha 3.8, and Heavener 1.1.

Fall burial of infested bolls greatly decreased survival over

that for bolls that remained on the soil surface until buried

in the spring except at localities in a dry climate. The highest

survival occurred in bolls that remained on the soil surface

throughout the experiments at all localities except Brownsville,

where the highest survival occurred in bolls exposed above ground,

simulating standing stalks. Where the temperature dropped to

15° F. or lower, the lowest survival occurred in bolls exposed above

ground until buried in the spring. Under farm practice, however,

where much of the cotton has shattered to the ground, it is not

advisable to leave the land unplowed to take advantage of this

mortality on standing stalks resulting from low air temperature.

Time and Depth of Burial and Winter Irrigation

Experiments to furnish data on this subject were conducted

on a clay soil in arid climate at Presidio. An irrigation on March

15 was included in all treatments, simulating the preplanting

irrigation practiced in the area.

Winter burial of infested bolls followed by winter^ irrigation

greatly decreased pink bollworm survival and two irrigations

were more effective than one. Survival where the soil was not

irrigated during the winter was three to seven times greater

than that in soil receiving two winter irrigations. The earlier

in the winter the bolls were buried and irrigated, the lower the

survival was. However, when bolls were not irrigated, there was

no marked difference in survival between burial dates.

As the depth of burial increased, the survival decreased from

15.1 at 2 inches to 3.1 percent at 6 inches. Of the total number of

moths that emerged from the experiments, 61, 26, and 13 percent

came from the 2-, 4-, and 6-inch depths, respectively. It is therefore apparent that early deep plowing with high soil moisture

is a major factor in pink bollworm control. In extremely cloddy

soil it may be necessary to use a disk harrow before irrigation to

adequately cover the infested bolls.

Winter and Spring Rainfall

Dry weather during the fall and winter is favorable for a high

survival of pink bollworms, as shown in the experiments at Presidio previously discussed. Also, the higher survival in the cold

climate of El Paso, as compared with warmer localities having

higher rainfall, is attributed to the aridity of the climate there.

In the El Paso experiment, however, spring and summer irriga-
38 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

tions were favorable for pupation and may partly account for

the higher survival there than at Lubbock. The effect of spring

moisture to stimulate pupation and moth emergence v^as shov^n

in a 2-year experiment at Presidio, in which spring irrigation

compared vnth nonirrigation increased survival from 2,8 to 7.1

percent in one year and from 6.8 to 12.3 percent in the other year.

Effects of rainfall were evident in the yearly fluctuations of

survival at several localities in Texas where yearly rainfall varied

considerably during the 5-year experiments. Increases in survival

for 2 years at Lubbock, a low rainfall area, were attributed to

higher spring rainfall that was more favorable for spring pupation than in the other years. At Waco, a higher rainfall area,

survival was decreased in 2 drought years, in which low spring

rainfall was unfavorable for pupation. However, the fall moisture

in these years was sufficient to cause a high mortality in bolls

buried on November 15. A similar instance occurred at Greenville

in one winter. Unusually high rainfall in one winter at Waco

reduced survival in buried bolls to less than that in any other

year; however, it was rather favorable f<)r survival in bolls on

the soil surface.

Undoubtedly winter rainfall was the major cause for the low

survival at Greenville compared with Waco. In one year at Greenville, a rainfall of 57 inches from November through June accounted for an extremely low survival in both buried and surface

bolls. Not only did the winter rain produce adverse conditions

for the larvae but 19 inches of rain in April and 14 inches in May

certainly exceeded the amounts favorable for moth emergence.

Fall and Winter Temperature

Survival of the pink bollworm under winter temperatures with

a minimum below 0° F. was demonstrated in the arid El Paso

area. Winter temperatures there are characterized by wide

fluctuations, with daily highs above 50° except during extremely

cold periods, which always last for only a few days. Laboratory

studies and an experiment conducted in a bioclimatic cabinet

simulating the climate at Maiden, Mo., indicate the survival is

not only affected by the extreme minima but greatly reduced by

long periods in which the maxima are about 40"". Diapause larvae

stored for experimental use may be held for a long period under

dry conditions at about 55°. At a refrigerator temperature of

approximately 38° a high mortality will occur within a month.

The wide fluctuation in winter survival during 8 years of experiments at El Paso, averaging from 4 to 21 percent, was attributed to low temperatures. Unusually cold weather occurred in

three consecutive winters. In January 1947 the temperature remained below freezing for 136 hours, with a low of 4° F. A low

of -6° occurred in January 1948, an alltime low for the area.

The temperature dropped to -2° in January 1949. During each

of these winters survival decreased compared with that in the

milder winters. This low survival was reflected in greatly decreased field infestations in the area during the 3 years.
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 39

The effect of temperature and level of soil moisture on survival of diapause pink bollw^orms in buried bolls was studied in

biodimatic cabinets that v^ere programed to simulate the December 1960-March 1961 temperatures at Waco and Heavener, areas

of generally high and low winter survival of the insect, respectively. At the moderate Waco soil temperatures (mean 51.7° F.), moderate soil moisture (16 percent) reduced larval survival compared

with that obtained at a low level of moisture (8 percent). At

Heavener soil temperatures (mean 44.1° ), survival was very low

at both 8- and 16-percent soil moisture, with no significant difference between these levels.

Sudden fall freeze.—In the fall, pink bollworm mortality in

green bolls is negligible if light frosts persist for several days

before subfreezing temperature, whereas a sudden drop in temperature sufficient to freeze succulent bolls results in almost 100-

percent mortality. Such sudden freezes occur in the colder climates

of the infested area where many bolls are green at frost date.

When these bolls are frozen, the pink bollworm population is

greatly reduced.

High soil temperature.—A high larval mortality resulting from

high temperatures may occur in bolls on the soil surface after

prefrost shredding of the stalks. From August 19 to September

15, when maximum soil-surface temperatures ranged from 123°

to 155°F. at Brownsville, mortality was 100 percent in open bolls

held in direct contact with the soil surface for 14 days and nearly

100 percent for 7-day exposures. In the field where some of the

bolls were protected by debris after shredding, the mortality

was slightly lower. In later exposures the mortality progressively

decreased with seasonal decrease in temperature after heavy rainfall on September 11. In the lower Rio Grande Valley there is

danger in delaying plowing to take advantage of the larval kill

from soil temperature because of the fall rainy season, which

may result in plant regrowth and a very late plowing if not done

before the rains begin.

Winter Survival in Clay and Sandy Soils

Winter survival of the pink bollworm was two to three times

greater in a heavy clay soil than in sandy soil in experiments

conducted during the winters of 1928-30 and 1938 at Presidio.

In the 1928-30 experiments, survival in nonirrigated bolls buried

4 inches was 3.1 percent in clay soil and 1.4 percent in sandy

soil. In the 1938 experiments, survival in bolls buried 2 to 6

inches and irrigated on March 15 was 7.9 and 2.5 percent for the

respective soils.

Winter Survival in Bolts and Free Cocoons

Pink bollworms in free cocoons and in blooms at Brownsville

pupated and emerged in the fall and winter; consequently, none

were left to infest the next crop in the subtropical lower Rio

Grande Valley. There was no winter carryover during 1 of 2 years
40 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

in which experiments with cocoons were conducted at Port Lavaca,

where mild weather induced fall and winter pupation.

Larval survival in bolls was greater than in free cocoons under

identical treatments in experiments at Presidio, El Paso, and

Waco. In nonirrigated treatments survival in bolls was approximately 15 times greater than that in cocoons at Presidio, eight

times greater at El Paso where the weather was colder, and 12

times greater at Waco where the weather was milder but rainfall

greater than at the other two localities. Winter burial and irrigation at Presidio were more effective in reducing survival of

larvae in free cocoons than in bolls. Because of the high larval

mortality in cocoons and the smaller number present, compared

with the population in bolls, the overwintering cocoon population

is considered to be of minor importance, especially in areas of

high rainfall or where the land is irrigated during the winter.

Recommendations for Cultural Control

Recommended practices for controlling the pink bollworm as

given here are based on the foregoing discussions. Every cotton

grower in pink bollworm-infested areas should follow recommended control practices for the benefit of himself and other

growers of his community.

For the most effective cultural control of the pink bollworm,

the cotton crop should be produced and harvested in the shortest

period possible, with stalk shredding and deep plowing performed

immediately after harvest. There is sufficient time for producing

and harvesting a crop before stalk-destruction deadlines if planting is done at the optimum time and recommended practices to

hasten crop maturity are carried out. Recommended control practices are as follows:

(1) Shorten the planting period and plant at the optimum

time for a given locality. Use seeds of an early-maturing variety

that have been culled, treated with a fungicide, and tested for

germination.

(2) Leave as thick a stand as has been recommended for the

section and type of soil.

(3) Use practices during the cotton-production period that promote early maturity. Early-season control of certain insects has

proved advantageous in some States but not in others. Practice

early-season control where recommended by controlling the cotton aphid {Aphis gossypii Glover), the boll weevil, the cotton

fleahopper {Pseudatomoscelis seriatus (Reuter)), cutworms,

thrips, and any other insects that may retard the growth and

fruiting of young plants. Protection of early fruit may make

possible an early harvest.

(4) Withhold late irrigation. Use defoliants or desiccants to

hasten opening of the bolls remaining after 60 percent have

opened.

(5) Harvest cleanly. Use strippers where practicable. In areas

where spindle pickers are used, final scrapping with a stripper
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 41

is desirable. Use a cotton gleaner if appreciable cotton is left on

the ground after harvest.

(6) Shred and plow under the stalks and debris as soon as

possible after harvest. The flail-type shredder is recommended

over the horizontal rotary type for pink bollworm control. Okra

stalks and debris should be shredded and plowed under at the

same time because this plant is a preferred secondary host. In arid

areas where the crop debris is plowed under in the late fall or

early winter, the fields should be irrigated in the winter to increase

pink bollworm mortality. Fields left fallow or unplowed in the

fall or winter should be plowed early in the spring.

(7) The production of stub cotton, possible only in the warmer

areas, should not be practiced. Early prefrost shredding and plowing decrease reproduction of the insect and increase mortality of

the overwintering larvae. All sprouting and seedling cotton and

okra developing after plowing should be destroyed before fruiting

to create a host-free period between crops.

OTHER METHODS OF CONTROL

Light Traps

The pink bollworm moth is attracted to light radiated in the

near ultraviolet range of the spectrum. The blacklight fluorescent

(mercury vapor) and argon glow (mixture of gases) are examples

of lamps that radiate strongly in the near ultraviolet region. A

15-watt blackUght lamp was highly attractive to the pink bollworm and a 2-watt argon glow was almost as attractive to this

insect but was much less attractive to orders other than Lrepidoptera. Traps equipped with blacklight and argon bulbs attract

and catch pink bollworm moths. Males and females are equally

attracted.

Finding that the argon lamp is selective led to the design

of a special argon light trap. It is commonly used for pink bollworm surveys, because the time required to examine the trap

collections is shorter than that for the larger volume of other

insects in blacklight traps. A comparison of collections from

blacklight and argon light traps during May and June at Brownsville showed that the ratios of pink bollworm moths caught by

the blacklight trap to those by the argon light trap varied from

1.7:1 in May to 3.2:1 in June.

Light traps of the electric-grid type with two 15-watt blacklight fluorescent bulbs were used by growers for insect control on

cotton, corn, and vegetable crops at Batesville, Tex., in 1955. There

were 142 traps operated on ñve adjacent farms comprising approximately 3,000 acres. Infestation counts in representative

fields of cotton in the trap area and check fields outside the area

indicated that these traps were of no benefit in controlling the

pink bollworm. Counts at 100, 450, and 800 feet from traps

showed that the infestation did not vary appreciably with distance from the traps.

At Brownsville, cotton infested with the pink bollworm was
42 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

grown in a screened cage partitioned into two sections, 40 by 60

feet each, and an insect-collecting type of trap with four 15-watt

blacklight bulbs was operated in one section while the other was

used as a check. Although the trap caught a large number of pink

bollworm moths during 8 weeks, there was no appreciable difference in buildup of infestation between the light trap and

check sections. The bolls infested reached 100 percent in both

sections within the same week. This lack of reduced infestation

in the trap section, despite the high moth catch, indicates that

the moths deposit eggs before being trapped.

Release of Sterile Males

Experiments indicate that the pink bollworm may be controlled

or eradicated by releasing sterile males to prevent fertilization

of the female population in nature. Before this method of control

can be undertaken, problems are still to be solved, such as the

development of practicable techniques for mass rearing and sterilizing the moths for release. Utilization of this method should

take advantage of winter mortality, cultural control, and possibly

insecticide applications to reduce the natural population to a low

level before the sterile-male releases are begun.

Sterilization by Gamma Radiation

Experiments were conducted to determine the optimum sterilizing dosage for pink bollworms treated as pupae with gamma

radiation from cobalt-60. Pupal sensitivity to gamma radiation

was dependent on age at time of treatment—the older the pupae,

the less susceptible they were. When 1- and 3-day-old pupae were

irradiated, dosages inducing complete sterility also caused some

pupal mortality and appreciable moth damage. However, irradiation of 5- to 7-day-old pupae induced almost complete sterility

without pupal mortality or adult malformation.

When males from irradiated 7-day-old pupae were mated with

untreated females, complete sterility was achieved at 55 kr. At

dosages of 30 to 60 kr no more than 3 percent of the oviposited

eggs hatched for any one exposure dosage. Exposure at 40 kr

was sufficient to sterilize females. Longevity of males from 7-

day-old pupae treated with 35 through 90 kr was significantly

shorter than that of untreated moths. Also, the males sterilized

by gamma radiation did not fully compete with nonsterile males

for the females.

Work on sterilization of the adult pink bollworm by irradiation

is in progress.

Sterilization With Metepa

Metepa was found to sterilize pink bollworm males, without

impairing their competitiveness for females, when applied topically at 15 ixg. per moth or when the moths are exposed to residues

on glass at 26 /^g. per square centimeter for 15 minutes. Further
FIFTY YEAKS OF RESEARCH ON THE PINK BOLLWORM 43

work is needed to develop techniques for mass treating the moths ;

however, the topical treatment has been satisfactory for experimental purposes. When metepa was received from different production batches and was used by workers with other insects,

difficulties were encountered because of variation among the

different batches.

Eradication of Confined Population

With Sterile-Male Releases

Male pink bollworm moths treated with 15 fxg, of metepa per

moth were released in field cages with normal moths of both

sexes to determine the effects of sterile-male releases on the Fi

generation. A single release in each cage at a ratio of nine sterile

to one normal male reduced the Fi population an average of 81

percent compared with that in untreated check cages. Despite

this reduction, the Fi population increased 2.6 times the parent

population. Data on pink bollworm population dynamics indicate

that in the lower Rio Grande Valley an increase of fivefold to

sevenfold per generation is required to overcome winter mortality,

including that resulting from cultural practices, and yet maintain

a steady population from year to year.

An experiment conducted in a large field cage during 1964

and 1965 demonstrated that a pink bollworm population can be

eradicated through effects of sterile-male releases combined with

mortality from winter cultural practices. A screen partition divided the cage into two equal sections, into which equal populations of overwintered pink bollworms were introduced in the

spring of 1964. Sterile males were introduced into the natural

population of one section and the other section was used as an

untreated check.

In 1964 the treated population was reduced 80 to 90 percent,

compared with the check, by an estimated seasonal release ratio

of 7:1 sterile males to normal males. However, the treated population continued to increase slightly during the growing season.

In 1965 an estimated higher seasonal release ratio of sterile to

normal males (probably more than 25:1) reduced the population

98 percent, despite some entry of moths from the check section.

No larvae were found in the cage from June 20 to July 27, and

the population is believed to have been eradicated before this

entry of moths from the check section.

Chemical Attractants

Work was undertaken in the 1950's to find a chemical highly

attractive to pink bollworm moths that might be used for detecting incipient infestations, for measuring insect abundance in the

generally infested area from year to year, and for increasing the

effectiveness of insecticide applications. Such a chemical could

be used to attract the moths to a poison bait or possibly to treated

plants where only parts of a field would be treated with the
44 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

attractant and an insecticide and thus reduce the amount of insecticide needed.

Olfactory tests were conducted in the laboratory to screen

compounds for attractancy to pink bollworm moths. The m-isopropoxybenzyl ester of chrysanthemumic acid was soon found to

have greater attractancy than the cotton boll and was adopted

as a standard for evaluating other materials. Of nearly a thousand compounds tested, none were found to be more attractive

than the standard. Several compounds related to the standard

were about equal to it but not sufficiently attractive for any

practical purpose.

Sex Lure

Discovery in 1962 of a substance extracted from female pink

bollworm moths that is highly attractive to the male has resulted

in new methods for detecting and controlling the insect. The sex

attractant occurs in the terminal two to three segments of the

female abdomen. It can be extracted from clipped abdomens with

méthylène chloride or other solvents. Insect traps baited with this

extract will attract and catch male pink bollworm moths. A component of the sex attractant has been isolated in pure form, identified, and synthesized. The synthetic material (propylure) produced and tested to date is not as eifective as the crude natural

extract, and work is in progress to improve its effectiveness.

A trap has been developed for utilizing the pink bollworm sex

attractant to catch and kill the male moth. Calcium cyanide used

as a killing agent does not affect the number of moths caught.

This trap has been used to detect the pink bollworm in areas not

previously known to be infested. In an experiment comparing

diiferent kinds of traps, light traps baited with the sex attractant

caught more males than did untreated light traps.

One of the most exciting potential uses of the pink bollworm

sex attractant is control of the insect population through male

annihilation. This method of insect control reduces the male population to such an extent that the number of mated females is

reduced and likewise the number of fertile eggs. A study to

develop this method of control was undertaken during the 1964

cotton-production season.

Traps baited with pink bollworm sex attractant failed to reduce

the infestation in the 1964 experiment though the moth catch

in 6 months averaged 1,341 males per trap. Movement of moths

into the field, due to lack of field isolation, and too few traps

were probably responsible for the failure. The study poses many

questions for further investigations: To what extent must the

malerfemale ratio be reduced to achieve a reduction in population? What is the range of the sex attractant at different concentrations, and what factors affect the attractive radius? What

is the behavior of the moths in the field, and how does this vary

with the season and stage of plant growth? Can the design of

the traps be improved, or is there a more effective way to use the
FIFTY YEARS OF RESEARCH ON THE FINK BOLLWORM 45

sex attractant? Studies are underway to answer some of these

questions.

Another use of the pink bollworm sex attractant, provided

practicable techniques could be developed, would be to attract

males to a chemosterilant, where they would be sterilized and

then released back into the field population to mate with the

normal females.

REARING

Development of an artificial diet and rearing techniques has

made possible the rearing of the pink bollworm in the laboratory

for experimental use. Larvae may be reared individually on the

medium in small vials stoppered with cotton. Although this method is expensive, there are no difficulties other than the tedious

task of dispensing the rearing medium into the vials, introducing

the larvae, and inserting the cotton stoppers.

Difficulties encountered in early attempts to rear large numbers

of pink bollworms in a container involved measures to prevent

the larvae from wandering away from the medium and escaping.

Using a tightly closed container to prevent escape of newly hatched

larvae resulted in condensation of moisture and drowning of the

larvae. Later it was found that newly hatched larvae could be

confined on the medium when they were placed on 14-inch cubes

of the medium spread in layers interspersed between layers of

cotton fibers.

Preparation of Rearing Medium

The rearing medium is prepared in batches of approximately

1 gallon in a blender of the Waring type. The ingredients for

such a batch in the order in which they are added to the

blender are as follows :

Material Amount

Water (distilled) ___ _ 880 ml.

Potassium hydroxide (4M) 18 ml.

Casein (vitamin free) 126 grams

Salts, Wesson's - . _ . ^ ... 36 grams

Sucrose ^ _ _ _ 126 grams

Wheat germ _ „ _ _ 108 grams

a-Cellulose 18 grams

Choline chloride (10 percent v/v in water) -_ . ^^ _ 36 ml.

Formaldehyde ( 10 percent v/v in water) 13 ml.

Methyl p-hydroxybenzoate (15 percent w/v in 95 percent

alcohol) 36 ml.

Vitamin stock ^ 6 ml.

Agar (dissolved in 2,200 ml. of boiling distilled water) 90 grams

^ Contains 300 mg. riboflavin, 150 mg. pyridoxine, 150 mg. thiamine, 150

mg. folie acid, 600 mg. niacin, and 600 mg. calcium. The mixture should be

stored under refrigeration.

When preparing a batch of this size, the potassium hydroxide

and casein are blended in 880 ml. of water. All solids are then
46 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

added and blended. The choline chloride, formaldehyde, methyl

p-hydroxybenzoate, and vitamin stock are successively added with

continuous blending. The hot dissolved agar is added and the

entire mixture blended for about 2 minutes or until a homogeneous color is obtained.

After blending, the hot medium may be dispensed into vials

with a plastic '^squeeze" bottle of the type used to eject mustard

or catsup, or it may be poured into a tray to solidify as a cake

about one-fourth inch thick. The cake is cut into cubes by pressing

it through a l^-inch mesh hardware cloth mounted on a wooden

frame.

Equipment and Rearing Procedure

During the early rearing of the pink bollworm, considerable

difficulty was experienced in getting the moth to lay eggs where

they could be recovered without using parts of the cotton plant

as an egg-laying site. Later it was found that the female can be

induced to insert her ovipositor through a screen to deposit eggs

on a rough-surface paper pressed against the screen if all other

surfaces of the oviposition cage are smooth and therefore offer

no alternative egg-laying site. A 1-quart cylindrical ice cream

carton will serve as such a cage if it is treated inside with

paraffin and the cardboard disk in the lid is replaced with a

screen disk. It will accommodate about 50 pairs of moths.

Eggs adhering to laying pads from several oviposition cages

are held for incubation in a 250-cc. Erlenmeyer flask stoppered

with cotton. The flasks are inverted in a holding rack until hatching takes place and the larvae are ready for transfer to rearing

containers. Since newly hatched larvae are attracted to light,

proper exposure to a 40- or 60-watt light bulb will cause them

to crawl to the lip of the flask, where they may be removed

with a cameFs hair brush or small tuft of cotton and placed in

the rearing vials or cups.

A 9-ounce waxed paper cup with a plastic snap-on lid has been

found convenient for rearing large numbers of larvae. A thin

layer of sterile plucked cotton is placed at the bottom of the

cup followed with a layer of medium consisting of about twentyfive l/i-inch cubes. About 25 newly hatched larvae collected on a

small tuft of cotton are placed on this medium, and another layer

of cotton, which serves as a barrier, is added. Successive layers

of medium and cotton, with 25 larvae per layer of medium, are

added until the cup is filled. Usually four to five layers of medium

per cup are used. After a layer of cotton is applied to the top

layer of medium, the lid is placed on the cup. Eggs instead of

larvae may be placed in the cups. However, better yields have

been obtained from newly hatched larvae implanted on the medium.
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 47

SURVEYS

Need for Surveys

Surveys for the pink bollworm are made by both the cotton

producers and quarantine regulatory agencies. When the population control resulting from cultural practices and natural factors

fails to hold the infestation below the economic damage level,

grov^ers must make infestation counts to determine when insecticide control is needed. Fall, winter, and spring surveys are useful

as an index to the potential infestation of the next season's crop.

Regulatory agencies conduct surveys to detect the pink bollworm in areas not previously known to be infested and to determine when an isolated infestation has been eradicated. Also,

they make surveys to provide information that may be used in

planning control or suppressive programs for retarding or preventing spread, and to evaluate the effectiveness of these programs.

Survey Methods

Surveys to determine the degree of pink bollworm infestation

in individual fields may be made early in the season by inspecting

blooms and later by inspecting bolls. Bloom infestation ceases

to be a reliable index of the larval population after bolls form,

because the insect then attacks bolls in preference to squares

and very few larvae are found in blooms.

Bloom Inspection

The spring pink bollworm population developing in squares

reaches a peak 2 weeks after blooms first appear and then decreases rapidly. In an experiment with two planting dates during

a 3-year study, all blooms on a measured acreage were inspected

daily during the first 3 weeks after blooming commenced.

The daily number of infested blooms found on this acreage

increased from three on the first day to 186 on the seventh day,

reached a peak of 347 on the 14th day, and decreased to 125 on

the 21st day. The daily counts showed that the most reliable

time to estimate the larval population is from about the eighth

through the 17th day. However, the larger plants and greater

number of blooms present during the last part of this period

make the inspection more difiicult. The number of blooms opening daily increased from 11 to 1,059 the first week, to 3,904 the

second week, and to 5,321 the third week. The percent of blooms

infested decreased continuously from 27 to 18, to 9, and to 2

during the respective weeks. Therefore a count to determine the

percentage of blooms infested is a less reliable index than one

showing the number of blooms infested on a measured sample

area.
48 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

A survey for detecting a light pink bollworm infestation is

easiest accomplished early, when the plants are small and the

larval population is concentrated in a few blooms. Also, at that

time persons fully familiar with the insect can estimate fairly

accurately the potential seasonal infestation from a count made

to determine the percentage of blooms infested. However, a better

criterion for comparing yearly early-season populations in blooms,

or to determine when early insecticide applications are needed,

is obtained when inspections are made to estimate the number

of larvae per acre.

Recommended rnethod.—Five days after the first blooms appear, but not later than 15 days, check the number of larvae per

acre as follows: Step off 300 feet of row (100 steps) and count

the number of rosetted^ blooms at five representative locations in

a field (1,500 feet). Add the number of rosetted blooms from the

five locations and multiply by 10 to obtain the number of larvae

per acre. To increase the sample size, two rows may be inspected

simultaneously instead of one row and the number of rosetted

blooms multiplied by 5 instead of 10.

Boll Inspection

In most field investigations of the pink bollworm, it is desirable to count boll infestations so as to estimate the larval population per acre. The timing of late-.season insecticide applications

is based on the percentage of bolls infested. A count of pink bollworm exit holes in green bolls should not be used as an index

to abundance of the insect, because the larvae that have emerged

represent only a small proportion of the population present. Also,

the timing of insecticide applications based on exit holes is dangerous, because this may result in serious population buildup before

the treatment begins.

Recommended methods.—When determining the time to apply

insecticides, walk diagonally across the field and collect at random

100 firm bolls. Crack the bolls or cut each section of the carpel

(hull) lengthwise so that the locks can be removed, and examine

the inside of the carpel for mines made by the young larvae

when entering the boll Record the number of bolls infested on

a percentage basis.

When it is desirable to know the larval population, the number

of mines in each infested boll should also be recorded for determining the total mines in the sample or average number per

boll. The number of bolls per acre at the time the sample is

collected may be estimated by counting th^ firm bolls on 10 rowfeet at representative points in the plot or field sampled. The

average number of bolls per row-foot multiplied by 13,000 equals

approximately the number of bolls per acre, and this figure multiplied by the average mines per boll equals the larval population

per acre.
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 49

Other Inspection Techniques

Other inspection methods are helpful in directing control activities against the pink bollworm. They make possible the detection of infestations in previously uninfested areas and the evaluation of increases or decreases as they occur in infested areas.

They are also used to determine the population of larvae in hibernation and their carryover to infest the new cotton crop.

Inspection of gin trash.—Arrange with ginners to install traps

where possible to procure freshly ginned **first cleaner" trash,

which has not been passed through a fan, from as many gins as

possible in the area. Maintain the identity of each sample. A gin

trash machine is used to separate mechanically all parts of the

trash larger and all parts lighter than the pink bollworm. A small

residue is left, which must be examined by hand. This method

is very efficient for detecting the presence and abundance of the

pink bollworm in any given area. One may locate the exact field

by taking a separate trash sample from each grower's cotton.

Inspection of lint cleaner.—During the ginning process the

free larvae remaining in the lint are separated in the lint cleaners,

and a substantial number of them are smashed against the glass

inspection plates where they stick on the glass and may be

counted. For constant examination at a single gin, wipe off the

plates and examine after each bale is ginned. In this way the

individual field that is infested may be determined. For a general

survey, examine periodically to detect the presence of the pink

bollworm in a general area.

Examination of debris.—Between January and the time squares

begin to form in the new crop, examine old bolls or parts of bolls

from the soil surface in known infested fields. Examine the cotton

debris from 50 feet of row at five representative points in the

field for the number of living pink bollworms. Multiply by 50

to determine the number of living larvae per acre. Such records

when maintained from year to year provide comparative data

that may be used in determining appropriate control measures.

Use of light traps,—Light traps containing argon bulbs or

mercury vapor (blacklight fluorescent) bulbs will attract pink

bollworm moths. Such traps may be used to discover new infestations and to compare yearly population trends. The argon

trap is generally used in pink bollworm surveys because it is more

selective than the blackUght. Although it attracts smaller numbers

of pink bollworms, the collections of orders other than Lepidoptera are decreased compared with those by the blacklight,

and thus the argon trap reduces the time required for examining

the collections.

Use of sex-lnre traps.—Traps containing the sex attractant

extracted from the tips of abdomens of female pink bollworm

moths have been highly effective in trapping male moths. Such

traps are being used in surveys for detecting insect spread, Propylure is sometimes mixed with the natural attractant ; however, the

synthetic material currently available is of questionable value in

the mixture.
50 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

PRESENT STATUS

The cotton-producer reaction to the pink bollworm in the

United States has varied from panic to apathy. In the extreme

eastern cotton area, growers have been lulled into a state of

apathy because for many years they have anticipated an invasion

that has not materialized. Growers in Texas, New Mexico, and

Oklahoma have become accustomed to the pink bollworm and

find its presence not so bad as they feared in the beginning so

long as they follow recommended cultural and other control methods. Arizona growers have reappraised the insect they had begun

to consider as a minor pest in their area; now they know its

potential demands a great deal of concern. Growers in California

know they have a serious new pest in their midst, but they have

not had time to experience the full impact of its invasion into

their area.

The dynamics of pink bollworm populations is governed by an

interacting complex of environmental factors over which man

has considerable influence. In the eastern part of the infested

area of this country man has the upper hand on this insect

with his effective winter cultural practices and his intensive insecticide program for control of other insects. A great danger

looms in the Far West, where the winter environment is favorable to the species, insecticides are used in less quantity than

in the East, and production of high yields resulting from a long

growing season with a late harvest is customary. Apparently

man's ultimate goal concerning this insect should be to eliminate

it completely.

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FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 51

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1962. PLANTING DATE AS A FACTOR INVOLVED IN PINK BOLLWORM CONTROL. In Martin, D. F., and Lewis, R. D., A Summary of Recent

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1960. A WHEAT GERM MEDIUM FOR REARING THE PINK BOLLWORM. Jour.

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1962. EFFECT OF DDT POISONING ON THE FECUNDITY AND LONGEVITY OF

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WiLKEs, L. H., and JOHNSON, S. P.

1958. CHEMICAL, CULTURAL, AND MECHANICAL CONTROL OF THE PINK

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1966. CERTAIN ASPECTS OF THE GENETIC FACTORS INVOLVED IN THE LARVAL

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BECKMAN, H. F.

1953. LABORATORY CULTURE OF THE PINK BOLLWORM ON CHEMICALLY

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52 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

BELL, R. A., and ADKISSON, P. L.

1964. PHOTOPERIODIC REVERSIBILITY OF DIAPAUSE INDUCTION IN AN INSECT. Science 144: 1149-1151.

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1964. SOME PROPERTIES AND THE FIELD EVALUATION OF THE PINK BOLLWORM SEX ATTRACTANT. Amer. Ent. Soc. Ann. 57: 606-609.

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1941, SECONDARY HOSTS OF THE PINK BOLLWORM IN THE LOWER RIO

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736-737.

BiSHOPP, F. C.

1956. INSECTS LOWER THE QUALITY OF COTTON LINT AND SEED. Jour.

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1958. LABORATORY AND FIELD TESTS WITH SEVIN AGAINST COTTON INSECTS. Jour. Econ. Ent. 51: 236-239.

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1964. RELATION OF GOSSYPOL CONTENT OF COTTON PLANTS TO INSECT

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BRAZZEL, J. R.

1955. THE PINK BOLLWORM AS A FACTOR IN COTTON BOLL ROT. U.S. Agr.

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1956. THE EFFECTS OF PINK BOLLWORM INPESTATIONS ON YIELD AND

QUALITY OF COTTON. Jour. Econ. Ent. 49: 852-854.

— and GAINES, J. C.

1957. COTTON YIELD AND QUALITY LOSSES CAUSED BY VARIOUS LEVELS OF

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and GAINES, J. C.

1959. THE TOXICITY OF SEVERAL INSECTICIDES TO THE EGGS AND LARVAE

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1955. BEHAVIOR OF PINK BOLLWORM LARVAE. Jour. Econ. Ent. 48:

677-679.

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1956. RESISTANCE OF COTTON TO PINK BOLLWORM DAMAGE. Tex. Agr.

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and MARTIN, D. F.

1957. OVIPOSITION SITES OF THE PINK BOLLWORM ON THE COTTON PLANT.

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and MARTIN, D. F.

1959. WINTER SURVIVAL AND TIME OF EMERGENCE OF DIAPAUSING PINK

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and MARTIN, D. P.

1959, PINK BOLLWORM RESISTANCE IN COTTON. Jour. Econ. Ent. 52:

385-390.

BULL, D. L., and ADKISSON, P. L.

1960. CERTAIN FACTORS INFLUENCING DIAPAUSE IN THE PINK BOLLWORM.

Jour. Econ. Ent. 53: 793-798.

and ADKISSON, P. L.

1962. FAT CONTENT OF THE LARVAL DIET AS A FACTOR INFLUENCING

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Soc. Ann. 55: 499-502.

and ADKISSON, P. L.

J1963. ABSORPTION AND METABOLISM OF C"-LABELED DDT BY DDT-SUSCEPTIBLE AND DDT-RESISTANT PINK BOLLWORM ADULTS. Jour. Econ.

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BUSK, A.

1917. THE PINK BOLLWORM, PECTINOPHORA GOSSYPIELLA. Jour. Agr.

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FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 53

CHAPMAN, A. J., and CAVITT, H. S.

1934. THE INFLUENCE OF SOIL MOISTURE UPON THE SURVIVAL OF THE

PINK BOLLWORM. Jour. Econ. Ent. 27: 820-827.

and CAVITT, H. S.

1938. POSSIBILITIES OF REDUCING OVER-V^^INTERING PINK BOLLWORM

POPULATION IN THE SOIL AS SHOWN BY STRIPPING TESTS. Jour.

Econ. Ent. 30: 837-838.

and COFFIN, L. B.

1964. PINK BOLLWORM RESISTANCE TO DDT IN THE LAGUNA AREA OF

MEXICO. Jour. Econ. Ent, 57: 148-150.

FIFE, L. C, SMITH, G. L., and CLARK, J. C.

1950. DDT FOR CONTROL OF PINK BOLLWORM IN MEXICO IN 1946. Jour.

Econ. Ent. 43: 491-494.

and HUGHES, M. A.

1941. FACTORS INFLUENCING THE FORMATION OF RESTING PINK BOLLWORM LARVAE. Jour. Econ. Ent. 34: 493-494.

and LowRY, W. L.

1941. CONTROL OF THE PINK BOLLWORM WITH INSECTICIDES. Jour.

Econ. Ent. 34: 490-492.

and MORENO, I.

1945. FURTHER OBSERVATIONS ON HOST PLANTS' OF THE PINK BOLLWORM

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and NoBLE, L. W.

1954. HIBERNATION EXPERIMENTS ON THE PINK BOLLWORM IN TEXAS AND

OKLAHOMA. U.S. Bur. Ent. and Plant Quar. E-879, 3 pp.

NOBLE, L. W., ROBERTSON, 0. T., and FIFE, L. C.

1960. SURVIVAL OF THE PINK BOLLWORM UNDER VARIOUS CULTURAL AND

CLIMATIC CONDITIONS. U.S. Dept. Agr. Prod. Res. Rpt. 34, 21 pp.

NOBLE, L. W., ROBERTSON, 0. T., and SMITH, G. L.

1963. EARLY-SEASON APPLICATION OF DDT FOR PINK BOLLWORM CONTROL.

Jour. Econ. Ent. 56: 900-901.

ROBERTSON, 0. T., and NOBLE, L. W.

1961. EVALUATION OF STALK SHREDDERS AND CUTTERS FOR PINK BOLLWORM CONTROL. Jour. Econ. Ent. 54: 791-792.

CLARK, E. W.

1957. THE EFFECT OF THE HOT WATER TREATMENT FOR HARD COTTONSEED

ON A PINK BOLLWORM INFESTATION. Jour. Econ. Ent. 50: 795-796.

1960. A COMPARATIVE STUDY OF THE FREE AMINO ACIDS AND CARBOHYDRATES OF PECTINOPHORA GOSSYPIELLA (SAUND.). Amer. Ent.

Soc. Ann. 53: 439-441.

— and CHADBOURNE, D. S.

1960. THE HAESMOCYTES OF NONDIAPAUSE AND DIAPAUSE LARVAL AND

PUPAL PINK BOLLWORM (PECTINOPHORA GOSSYPIELLA (SAUND.)).

Amer. Ent. Soc. Ann. 53: 682-685.

— and CHADBOURNE, D. S.

1962. A COMPARATIVE STUDY OF THE WEIGHT, AND LIPID AND WATER

CONTENT OF THE PINK BOLLWORM, PECTINOPHORA GOSSYPIELLA

(SAUND.). Amer. Ent. Soc. Ann. 55: 225-228.

— and GLICK, P. A.

1961. SOME PREDATORS AND SCAVENGERS FEEDING UPON PINK BOLLWORM

MOTHS. Jour. Econ. Ent. 54: 815-816.

— and LuKEFAHR, M.

1956. A PARTIAL ANALYSIS OF COTTON EXTRAFLORAL NECTAR AND ITS

APPROXIMATION AS A NUTRITIONAL MEDIUM FOR THE ADULT PINK

BOLLWORM. Jour. Econ. Ent. 49: 875-876.

— and RICHMOND, C. A.

1961. THE EFFECT OF CENTRIFUGAL FORCE ON PINK BOLLWORM LARVAE.

Jour. Econ. Ent. 54: 1262-1263.

— and RICHMOND, C. A.

1962. THE EFFECT OF AQUEOUS SUBMERSION ON LARVAL AND PUPAL PINK

BOLLWORM. Jour. Econ. Ent. 55: 167-169.
54 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

CLARK, E, W., and RICHMOND, C. A.

1964. CHANGES IN WEIGHT OF ABRADED AND UNABRADED LARVAL PINK

BOLLWORM UNDER SUBMERSION AND DESICCATION. Jour. Econ.

Ent. 57: 14-16.

RICHMOND, C. A., and MCGOUGH, J. M.

1961. ARTIFICIAL MEDIA AND REARING TECHNIQUES FOR THE PINK BOLLWORM. Jour. Econ. Ent. 54: 4-9.

WILLIAMSON, A. L., and RICHMOND, C. A.

1959. A COLLECTING TECHNIQUE FOR PINK BOLLWORMS AND OTHER INSECTS USING A BERLESE FUNNEL WITH AN IMPROVED HEATER. Jour.

Econ. Ent. 52: 1010-1012.

COAD, B. R.

1929. ORGANIZATION AND PROGRESS OF PINK BOLLWORM INVESTIGATIONS.

Jour. Econ. Ent, 22: 743-750.

and FENTON, F. A.

1928. PRELIMINARY REPORT OF STUDIES CARRIED ON IN 1928 ON THE

MIGRATION OF MOTHS OF THE PINK BOLLWORM. Mex. See. de Agr.

y Fórmente Bol. Mens. 2:878-893.

COCHRAN, B. J., WiLKES, L. H., and ADKISSON, P. L.

1961. PRIMARY TILLAGE PRACTICES FOR PINK BOLLWORM CONTROL. Tex.

Agr. Expt. Sta. Prog. Rpt. 2194, 3 pp.

CURL, L. F.

1938. PINK BOLLWORM CONTROL IN SOUTHEASTERN STATES. Jour. Econ.

Ent. 31: 652-656.

ENKERLIN, D., and HANNA, R. L.

1956. THE DILUTION OF DUST CONCENTRATES IN PINK BOLLWORM CONTROL.

Jour. Econ. Ent. 49: 560.

PENTON, P. A.

1929. BIOLOGICAL NOTES ON THE PINK BOLLWORM IN TEXAS. 4th Internatl. Cong. Ent., Ithaca, Trans. 1928 (2), pp. 439-447.

and OWEN, W. L., JR.

1931. HIBERNATION OF PECTINOPHORA GOSSYPIELLA IN TEXAS. Jour.

Econ. Ent. 24: 1197-1207.

and OWEN, W. L., JR.

1953. THE PINK BOLLWORM OF COTTON IN TEXAS. Tex. Agr. Expt. Sta.

Misc. Pub. 100, 39 pp.

and WAITE, W. W.

1932. DETECTING PINK BOLLWORMS IN COTTONSEEDS BY THE X-RAY.

Jour. Agr. Res. 45: 347-348.

FIFE, L. C.

1934. TEMPERATURE STUDIES IN A COTTON FIELD, PRESIDIO, TEXAS, 19 32.

Ecology 15: 298-305.

1937. NUMBER OF INSTARS OF PINK BOLLWORM COLLECTED IN SQUARES

AND IN BOLLS OF COTTON. Amer. Ent. Soc. Ann. 30: 57-63.

1937. THE PINK BOLLWORM OF COTTON IN PUERTO RICO DURING 19 8 6 AND

RECOMMENDATIONS FOR ITS CONTROL. Puerto Rico Agr. Expt.

sta. Agr. Notes 81, 9 pp.

1938. ALTERNATE HOST PLANTS OF THE PINK BOLLWORM, PECTINOPHORA

GOSSYPIELLA (SAUND.) IN PUERTO RICO. Puerto Rico Univ. Jour.

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1949. STUDIES OF THE DIAPAUSE IN THE PINK BOLLWORM IN PUERTO RICO.

U.S. Dept. Agr. Tech. Bui. 977, 26 pp.

1956. SEASONAL OCCURRENCE OF RESTING LARVAE OF THE PINK BOLLWORM

IN CENTRAL TEXAS. Jour. Econ. Ent. 49: 562-563.

1961. FACTORS INFLUENCING PINK BOLLWORM PUPATION AND MOTH EMERGENCE FROM OVERWINTERING LARVAE IN CENTRAL TEXAS. Jour.

Econ. Ent. 54: 908-913.
FIFTY YEARS OF RESEARCH ON THE PINK BOLLWORM 55

COWAN, C. B., JR., and DAVIS, J. W.

1957. FACTORS INFLUENCING PINK BOLLWORM WINTER CARRYOVER IN

CENTRAL TEXAS. Jour. Econ. Ent. 50: 642-644.

and GRAHAM, H. M.

1965. SEASONAL ACTIVITY OF BURIED OVERWINTERING PINK BOLLWORM

LARVAE IN CENTRAL TEXAS, Jour. Econ. Ent. 58: 688-690.

—- and GRAHAM, H. M.

1966. INFLUENCE OF MOISTURE ON WINTER SURVIVAL OF THE PINK BOLLWORM, Jour. Econ. Ent. 59: 430-432.

— and MORENO, L

1943. ADDITIONAL NOTES ON HOST PLANTS OF THE PINK BOLLWORM IN

TEXAS AND MEXICO. Jour. Econ. Ent. 36: 478-479.

— ROBERTSON, 0. T., and GRAHAM, H. M.

1963. WINTER CARRYOVER OF THE PINK BOLLWORM UNDER VARIOUS CULTURAL PRACTICES IN CENTRAL TEXAS. Jour. Econ. Ent. 56:

172-175.

— SHILLER, L, and CHAPMAN, A. J.

1947. PINK BOLLWORM CARRYOVER FROM ONE COTTON CROP TO THE NEXT

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545.

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1962. WINTER CULTURAL PRACTICES FOR PINK BOLLWORM CONTROL. In

Martin, D. F., and Lewis, R. D., A Summary of Recent Research

Basic to the Cultural Control of the Pink Bollworm. Tex. Agr.

Expt, Sta, Misc. Pub. 579, pp. 25-28.

FLITTERS, N. E., MESSENGER, P. S., and HUSMAN, C. N.

1956. BIOCLIMATIC CABINETS USED IN STUDIES ON THE MEXICAN FRUIT

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CLICK, P. A.

1939. THE DISTRIBUTION OF INSECTS, SPIDERS, AND MITES IN THE AIR.

U.S. Dept. Agr. Tech. Bui. 673, 150 pp.

1955. PINK BOLLWORM MOTH COLLECTIONS IN AIRPLANE TRAPS. Jour.

Econ. Ent. 48: 767.

1957. COLLECTING INSECTS BY AIRPLANE IN SOUTHERN TEXAS. U.S.

Dept. Agr. Tech. Bui. 1158, 28 pp.

1967. AERIAL DISPERSAL OF THE PINK BOLLWORM IN THE UNITED STATES

AND MEXICO. U.S. Dept. Agr. Prod. Res. Rpt. 96, 12 pp.

— and GRAHAM, H. M.

1961. EARLY-SEASON COLLECTIONS OF THREE COTTON INSECTS BY ARGONGLOW LAMP AND BLACK LIGHT TRAPS. Jour. Econ. Ent. 54:

1253-1254.

— and GRAHAM, H. M.

1965. SEASONAL LIGHT TRAP COLLECTIONS OF LEPIDOPTEROUS COTTON INSECTS IN SOUTH TEXAS. Jour. Econ. Ent. 58: 880-882.

— GRAHAM, H. M., and BILLINGSLEY, C. H.

1964. EVALUATION OF A BLOWER ATTACHMENT FOR LIGHT TRAPS. Jour.

Econ. Ent. 57: 169-170.

— and HOLLINGSWORTH, J. P.

1954. RESPONSE OF THE PINK BOLLWORM MOTH TO CERTAIN ULTRAVIOLET

AND VISIBLE RADIATION. Jour. Econ. Ent. 47: 81-86.

— and HOLLINGSWORTH, J. P.

1955. RESPONSE OF MOTHS OF THE PINK BOLLWORM AND OTHER COTTON

INSECTS TO CERTAIN ULTRAVIOLET AND VISIBLE RADIATION. Jour.

Econ. Ent. 48: 173-177.

— HOLLINGSWORTH, J. P., and EITEL, W. J.

1956. FURTHER STUDIES ON THE ATTRACTION OF THE PINK BOLLWORM

MOTH TO NEAR ULTRAVIOLET AND VISIBLE RADIATION. Jour. Econ.

Ent. 49: 158-161.

— and LATTIMORE, W. B., JR.

1954. THE RELATION OF INSECTICIDES TO INSECT POPULATIONS IN COTTON

FIELDS. Jour. Econ. Ent. 47: 681-684.
56 AGRICULTURE HANDBOOK 357, U.S. DEPT. OF AGRICULTURE

GLICK, P. A., and NOBLE, L. W.

1961. AIRBORNE MOVEMENT OF THE PINK BOLLWORM AND OTHER ARTHROPODS. U.S. Dept. Agr. Tech. Bui. 1255, 20 pp.

GRAHAM, H. M., FIFE, L. C, and BRYAN, D. E.

1965. DYNAMICS OF CAGED PINK BOLLWORM POPULATIONS IN TEXAS AND

OKLAHOMA. Amer. Ent. Soc. Ann. 58: 658-663.

FIFE, L. C, ROBERTSON, 0. T., and ADKISSON, P. L.

1962. PINK BOLLWORM POPULATION DYNAMICS. In Martin, D. F., and

Lewis, R. D., A Summary of Recent Research Basic to the

Cultural Control of the Pink Bollworm. Tex. Agr. Expt. Sta.

Misc. Pub. 579, pp. 5-10.

GLICK, P. A,, and HOLLINGSWORTH, J. P.

1961. EFFECTIVE RANGE OF ARGON GLOW LAMP SURVEY TRAPS FOR PECTINOPHORA GOSSYPIELLA (SAUND.) ADULTS. Jour. Econ, Ent. 54:

788-789.

GLICK, P. A., and MARTIN, D. F.

1964. NOCTURNAL ACTIVITY OP ADULTS OP SIX LEPIDOPTEROUS PESTS OF

COTTON AS INDICATED BY LIGHT TRAP COLLECTIONS. Amer. Ent.

Soc. Ann. 57: 328-332.

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1967. TEMPERATURE EFFECT ON REPRODUCTION AND LONGEVITY OF LABORATORY-REARED ADULT PINK BOLLWORM ( LEPIDOFTERA : GELECHiiDAE). Amer. Ent. Soc. Ann. 60: 1211-1213.

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