s; nmmww {O_‘_.{_§[,LBGE (I? TEYXIQE ‘EJERR A??? A115-729-8,000-L180 TEXAS AGRICULTURAL EXPERIMENT STATION A. B. CONNER, DIRECTOR College Station, Brazos County, Texas BULLETIN NO. 401 ' SEPTEMBER, 1929 DIVISION OF ENTOMOLOGY THE COTTON-SQUARE BORER AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS T. O. WALTON, President - STATION STAFF’; I ADMINISTRATION: A. B. CoNNER, M. S., Director R. E. KARPER, M. S., Vice-Director CLARIcE MIxsoN, Secretary M. P. HoLLEMAN, JR., Chief Clerk J. K. FRANCKLOW, Assistant Chief Clerk CHESTER HIGGS, Executive Assistant C. B. NEBLETTE, Technical Assistant CHEMISTRY: G. S. FRAPS, Ph. D., Chief; State Chemist S. E. AsBURY, M. S., Assistant Chemist E. C. CARLYLE, B. S., Chemist WALDo H. WALKER, Assistant Chemist VELMA GRAHAM, Assistant Chemist T. L. OGIER, B. S., Assistant Chemist ATI-IAN J . STERGES, B. S., Assistant Chemist JEANNE M. FUEGAS, Assistant Chemist RAY TREIcRLER, M. S., Assistant Chemist J. K. FARMER, M. A., Assistant Chemist RALPH L. SCHWARTZ, B. S,. Assistant Chemist HORTICULTURE: HAMILTON P. TRAUE, Ph. D., Chief ——-——————-——-, Berry Breeder RANGE ANIMAL HUSBANDRY: J. M. JoNEs, A. M., Chief; Sheep and Goat Investigations J. L. Lvsn, Ph. D., Animal Husbandman; Breeding Investigations STANLEY P. DAvIs, Wool Grader EN TOMOLOGY: F. L. THOMAS, Ph. D., Chief; State Entomologist H. J . REINRARD, B. S., Entomologist R. K. FLETcRER, Ph. D., Entomologist W. L. OWEN, JR., M. S., Entomologist FRANK M. HULL, M. S., Entomologist J. C. GAINEs, JR., M. S., Entomologist C. J. T0DD, B. S., Entomologist F. F. BIBBY, B. S., Entomologist CECIL E. HEARD, B. S., Chief Foulbrood Ins ector Orro ACKENSEN, Foulbrood Inspector AGRONOMY: E. B. REYNoLDs, Ph. D., Chief _ R. E. KARPER, M. S., Agronomist; Grain Sorghum Research _ C. MANaELsDoRF, Sc. D., Agronomist; in chargeof Corn and Small Grain Investi- gations . T. KILLOUGH, M. S., Agronomist; Cotton i 1 Breeding H. E. REA, ._S., Agronomist; Cotton Root Rot Investigations W. E. FLINT, B. S., Agronomist _ B. C. LANGLEY, B. S., Assistant in Soils PUBLICATIONS: A. D. JAcKsoN, Chief VETERINARY SCIENCE: *M. FRANcIs, D. V. M., Chief H. SCHMIDT, D. V. M., Veterinarian F. E. CARROLL, D. V. M., Veterinarian PLANT PATHOLOGY AND PHYSIOLOGY: J. J. TAUBENHAUS, Ph. D., Chief ' W. N. EzEKIEL, Ph. D., Plant Pathologist and Laboratory Technician W. J. BACH, M. S., Plant Pathologist B. F. DANA, M. S., Plant Pathologist FARM AND RANCH ECONOMICS: L. P. GABBARD, M. S., Chief W. E. PAULsoN, Ph. D., Marketing Research Specialist C. A. BoNNEN, M. S_., Farm Management Research Specialist _ V. L. CoRY, M. S., Grazing Research Botanisi J. F. CR1swELL, B. S., Assistant; Farm Records and Accounts **J. N. TATE, B. S., Assistant; Ranch Record: and Accounts RURAL HOME RESEARCH: JEssiE WRITAcRE, Ph. D., Chief MAMIE GRIMEs, M. S., Textile and Clothing Specialist _ _ _ EMMA E. SUMNER, M. S., Nutrition Specialist SOIL SURVEY: "W. T. CARTER, B. S., Chie E. H. TEMPLIN, B. S., Soi Surveyor T. C. REITcH, B. S., Soil Surveyor L. G. RAGSDALE, B. S., Soil Surveyor BOTANY: ——————————-, Chief . SIMoN E. WoLFF, M. S., Botanist SWINE HUSBANDRY: _ FRED HALE, M. S., Chief DAIRY HUSBANDRY: _ O. C. CoPELAND, B. S., Dairy Husbandman POULTRY HUSBANDRY: _ R. M. SHERWOOD, M. S., hief ***AGRICULTURAL ENGINEERING: MAIN STATION FARM: G. T. McNEss, Superintendent APICULTURE San Antonio): H . S., Chief A. H. ALEX, B. S., Queen Breeder FEED CONTROL SERVICE: F. D. FULLER, M. S., Chief . D. PEARcE, Secretary . H. ROGERS, Feed Inspector . H. W000, Feed Inspector . L. KIRKLAND, B. S., Feed Inspector . D. NORTHCUTT, JR., B. S., Feed Inspector IDNEY D. REYNQLDS, JR., Feed Inspector P. A. M0oRE, Feed Inspector méxéhm SUBSTATIONS No. 1, Beeville, Bee County: P R. A. HALL, B. S., Superintendent No. 2, Troup, Smith County: P. R. JoRNsoN, B. S., Act. Superintendent No. 3, Angleton, Brazoria County: . H. STANSEL, M. S., Superintendent No. 4, Beaumont, Jeiferson County: . H. WYCHE, B. S., Superintendent No. 5, Temple, Bell County: HENRY DUNLAvY, M. S., Superintendent B. F. DANA, M. S., Plant Pathologist H. E. REA, B. S., Agronomist; Cotton Root Rot Investigations ' SIMoN E. WQLFF, M. S., Botanist; Cotton Root Rot Investigations No. 6, Denton, Denton County: P. B. DUNKLE, B. S., Superintendent No. 7, Spur, Dickens County: R. E. DICKSON, B. S., Superintendent W. E. FLINT, B. S., Agronomist No. 8, Lubbock, Lubbock County: D. L. JoNEs, Superintendent FRANK GAINEs, Irrigationist and Forest Nurseryman No. 9, Balmorhea, Reeves County: J. J. BAYLEs, B. S., Superintendent No. l0, Feeding and Breeding Station, near Colle e Station, Brazos County: R. MJgfiERwOOD, S., Animal Husband- man in Charge of Farm_ L. J . McCALL, Farm Superintendent No. 11, Nacogdoches, Nacogdoches County: H. F. MoRRis, M. S., Superintendent **No. 12, Chillicothe, Hardeman County: J. R. QUINBY, B. S., Superintendent _ **J. C. STEPHENS, M. A., Assistant Agronomist No. 14, Sonora, Sutton-Edwards Counties: W. . AMERoN, B. S., Superintendent E. A. TUNNICLIFF, D. V. M., M. S., Veterinarian V. L. CoRY, M. S., Grazing Research Botanist **O. G. BABCOCK, B. S., Collaborating Entomologist O. L. CARPENTER, Shepherd No. 15, Weslaco, Hidalgo County: W. H. FRIEND, B. S., Superintendent _ SHERMAN W. CLARK, B. S., Entomologist W. J . BAcR, M. S., Plant Pathologist No. 16, Iowa Park, Wichita County: E. J. WILsoN, B. S., Superintendent Teachers in the School of Agriculture Carrying Cooperative Projects on the Station: G. W. ADRIANcE, M. S., Associate Professor of Horticulture S. W. BILSING, Ph. D., Professor of Entomology _ V. P. LEE, Ph. D., Professor of Marketing and Finance D. ScoATEs, A. E., Professor of Agricultural Engineering _ _ H. P. SMITH, M. S., Associate Professor of Agricultural Engineering ' R. H. WILLIAMS, Ph. D., Professor of Animal Husbandry A. K. MAcKEY, M. S., Associate Professor of Animal Husbandry J . S. MocFoRD, M. S., Associate Professor o Agronomy F. S. JAMIsoN, M. S., Associate Pro essor o Horticulture TAs of September 15, 1929. *Dean, School of Veterinary Medicine. **In cooperation with U. S. Department of Agriculture. ’ ***In cooperation with the School of Agriculture. The cotton-square borer, Strymon melinus Hubner, is one of the common insect enemies of cotton in Texas. The larva or caterpillar of this insect feeds principally upon the squares. Under favorable conditions the number of squares destroyed by this species may become quite serious over limited areas, especially during the early portion of the growing season. The insect is widely distributed within the State and is active in the field from March to November. Locally, the larvae have been recorded feeding on cotton, cowpea, bean, okra, field corn, and goatweed. In the field, oviposition begins about April 1 and extends throughout the season as long as suitable food plants remain available. Rearing records indicate that three complete generations or broods of this insect are pro- duced during a season. Data on the developmental stages of the cotton-square borer are presented. Under average laboratory conditions from June to August, 1928, it required 38.25 days to complete development from egg to adult. The eggs are laid singly and promis- cuously upon the food plant, and during the summer months require approximately 5.5 days for incubation. Normally, the larva molts five times and requires about 23 days during warm weather to attain full growth. Pupation ordinarily occurs in the open upon the food plant, and approximately 9.5 days are required for pupal development during the summer months. Usually multiplication of the cotton-square borer is elfec- tively checked by natural enemies, and combative measures to reduce infestations are rarely required. When control measures appear necessary, dry applications of calcium arsenate, five to seven pounds per acre, are recommended. To be most effective the poison should be applied when the majority of the cater- pillars are in the early stages of development. 6782i CONTENTS PAGE Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Systematic History . . '. . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . 6 Common Names . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 . . . . . , . . . . . . . . .. 6 Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . '7 Food Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8 Economic Importance . . . . . . . . . . . . . . . ‘ . . . . . . . . . . . . . . . . . . . . . .. 8 Methods of Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9 Seasonal History . . . . . . . . . . . . . . . . . . . . . . . . I , . . . . . . . . . . . . . . . .. 10 Description . . . . . . . . . . . . . . . . _ . . . . . . . . . . . . . . . I . . , . . . . . . . . . . . . 10 Egg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . .. 10 Larva . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 13 Pupa . . . . . . . . . . . . . . . . . . . . . _ . . . . . . . . . . . . . . 4 . . . . . . . . . . . . .. 14 Adult . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 15 Life. History . . . . . . . . . . . . _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Mating and Fertility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Oviposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1'7 Incubation Period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 18 Hatching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 20 Larval Development . . . . . . . . . . . H . . . . . . . . . . . . . . . . ; . . . . . . . . . . 20 Prepupal Period . . . . . . . . . . . . . . . . . . . _ 4 . . . . . . . . . . . . . . . . . . . . . 25 Pupation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 26 Pupal Period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 26 Summary of Developmental Periods . . . . . . . . . . _ . . . . . . . . . . . . .. 30 Emergence of Adults . . . . . . I . . . . . . . . . . . . . . . . I . . . . . . . . . . . . . _ . . . 3O Sexual Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3'1 Longevity of Adults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 31 Number of Generations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Hibernation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 32 Natural Enemies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Control Measures . . . . . . . . . I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I . . . . . . .. 35 Literature Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 BULLETIN NO. 401 SEPTEMBER, 1929 THE COTTON-SQUARE BORER H. J. REINHARD The cotton-square borer, Strymon melinus Hubner, is one of the common insects encountered in the cotton fields of Texas. Although this species is not classed among the most economically important insect pests of cotton,_ nevertheless it attracts the attention of some growers practi- cally every season by the injury it produces while feeding on the squares. The insect is m.ost abundant during the early part of the growing sea- son, and usually by midsummer its numbers have been greatly reduced by natural enemies. Invariably this natural-control factor is so effective that only a. small per cent of the larvae and pupae escape the attack of parasites during June and July. Consequently, the squares produced early in the season are most subject to attack by the cotton-square borer. Although this insect‘ is widespread within the State, there are no cases on record where the larvae have caused extensive injury to the crop. Sanderson (17) reports having seen 10 per cent of the stalks entirely denuded of squares in small fields in Texas where this insect was abundant. This extent of injury probably approximates the maximum and normally it is considerably less, although the extent of annual toll from the cotton crop of Texas is undoubtedly sufficient to class it as a cotton pest. . , The nature of the injury done by the cotton-square borer is very similar in appearance to that done by the cotton bollworm. Both insects bore into the squares and eat the contents, after which the hollowed squares flare and are shed by the plant. For this reason the two insects oftentimes are confused by the layman. However, the two species are quite distinct. The cotton-square borer larva may be distinguished readily from the cotton bollwonn by its flattened, oval-shaped body, that is densely covered with short hairs, giving it a velvety appearance. Its normal color varies from light-green to foliage-green without any con- trasting color pattern. The adult or mature insect is a small, bluish-gray or slate-colored butterfly illustrated in Figure 4. There are numerous references to this species in economic literature in which the insect is listed incidentally or mentioned in conjunction with other cotton insect pests. A few preliminary observations on its life history and habits have been published, but no details in this. con- nection have been presented heretofore. The observations and data presented in this Bulletin have been taken at College Station as time and opportunity permitted during the past three or four years. 6 BULLETIN NO. 401, TEXAS AGRICULTURAL EXPERIMENT STATION SYSTEMATIC HISTORY The cotton-square borer was first described as Strymon melinus by Hubner (14) in 1818. The following year Godart (10) described the same species as Polyommatus ergeus. In 1833 Boisduval and Leconte (2) placed the species in the genus Thecla, describing it as new under two specific names, hyperici and fammzius. Harris (11), during the same year, described it as Theda pan, and again in 1841 (12) as Thecla hu-mil/i. In 1847 Doubleday (5) described the same species new as Theda silenus, but in 1852 (6) made this name a synonym of Thecla melinus. Henry Edwards (8) 1877 described a western variety as Thecla Pltdica». Scudder (18), in 1872, treated the species under the name Uallipareus melinus, and in 1876 (19) erected the genus Uralwtes with melinus as the type species. The combination Uranotes melinus obtained for many years and was used by practically all writers until 1917, when Barnes and McDunnough (1) again referred the species to the genus Strymon. According to Scudder (20), Dyar (7), and Barnes and McDunnough (1), the synonymy of Stry-mon melinus Hubner stands as follows: P0Zy0nz1rzatus ergeus Godart, 1819. Thecla hyperici Boisduval and Leconte, 1833. Thecla favonius Boisduval and Leconte, 1833. Thecla pan Harris, 1833. Thecla humiZi Harris, 1841. Theda silenus Doubleday, 1847. Calilipareus melinus Scudder, 1872. Thecla melinus var. pudica Hy. Edwards, 1876. Uranotes melinus Scudder, 187 6. COMMON NAMES The adult stage of Strymon melinus has been referred to in literature by several common or popular names. The species is a member of a family of butterflies, commonly designated as the gossamer-winged or hair-streak butterflies. To differentiate‘ it from related forms in this group, authors have called it “red spotted hair-streak butterfly,” “gray hair-streak,” “allied hair-streak,” and “gray-streaked butterfly.” When the larvae of this species were discovered feeding upon hop vines such common names as “hop-vine Thecla,” “hopeating Thecla,” and “hop but- terfly” were also applied to the insect. In recent literature, however, the adult insect is most frequently referred to as “the gray hair-streak.” In the Southern States where the larva of the insect attacks cotton squares the common name “cotton-square borer” has been generally used for the species. Although this common name has not been officially adopted by the American Association of Economic Entomologists, it appears to be a very suitable and descriptive name, applicable throughout THE COTTON-SQUARE BORER T 1e section of the country where the insect may be classed as an eco- Jmic pest. DISTRIBUTION The counties within the State from which the cotton-square borer has een definitely recorded are indicated in Figure 1. The Widespread (zalities where the insect is known to occur indicate that its general g. 1.—Distribution of the cotton-square borer in Texas. Counties from which the insect. has been recorded are indicated by dots. nge of distribution probably includes many additional counties from iich it has not been reported. Its distribution in West and Northwest zxas is represented by only a few authentic records; however, field servations in Northwest Texas during August, 1928, showed that uare borer butterflies were rather abundant in cotton fields in the zinity of Spur and Lubbock. In Brazos and the adjoining counties the ecies is common practically every year, especially during the spring d early summer months. 8 BULLETIN NO. 401, TEXAS AGRICULTURAL EXPERIMENT STATION Holland (13) defines the general distribution of the cotton-square borer as temperate North America, ranging southward into Mexico and Central America at suitable elevations. Comstock (4) states the species occurs throughout the United States. French (9) includes the Atlantic States, Mississippi Valley, and Montana in its range of habitat. Leonard (15) lists it from New York; Britton (3) from Connecticut; Smith (21) from New Jersey; and Maynard (16) from California, Nevada, and Arizona. In addition to these states, the insect has also been reported from Oklahoma, Florida, Alabama, Mississippi, Louisiana, and New Mexico. FOOD PLANTS Under natural conditions the larvae of the cotton-square borer feed upon a number of remotely related plants, which indicates that the species is more or less a general feeder. In Texas, the larvae apparently are most frequently encountered feeding upon cotton, cowpea, bean, and okra. The insect shows a decided preference for the fruit or seedpod of each of these food plants, but also feeds upon the foliage, especially during the early instars of its development. Occasionally individuals have been observed in the field during midsummer hollowing out the seedpods of goatweed, Omton capitatus. Locally, this plant is a very common weed, but it does not appear to be an especially attractive source of food for the insect. During June, 1928, a cotton-square borer larva was collected on the silk of field corn, Zea mag/s, and reared to maturity in the laboratory on this source of food. Eggs of the insect have also been noted in the field on henbit, Lamalum wmpilesmlcaule, although no larvae were reared on this plant. In Florida, Watson (22) reports this insect attacking loquat, Eri0— botrya, and rearing it on this food plant. Hops, beans, and hawthorn, Cratazgus, have been recorded as the most common food plants of the insect in the Northeastern States. Additional plants attacked by the cotton-square borer in this region include hound’s tongue, Oynoglossum; St. John’s-wort, Hypericumr; cactus, Echinocaictwas tnteriervfus; kidney bean, Phczseolus“; bush clover, Lespedeza; and other legumes. The adult insect or gray hair-streak butterfly apparently is attracted to any nectar-producing cultivated crop or weed. Locally, individuals have been commonly observed feeding in the blooms of cotton, bean, okra, cowpea, wild aster, pepper-vine, Ampelopsis arborea; trumpet weed, Eupatorium purpureum; mistletoe, Phoiradendron flavescens; goatweed, Croton capitatus, and to a lesser extent on many other flowering plants. ECONOMIC IMPORTANCE Although the cotton-square borer does not rank among the most im- portant insect enemies of cotton in Texas, yet it is capablerof producing considerable injury to the crop when the optimum combination of favor- able climatic conditions prevails for multiplication of the insect and repression of its natural enemies. THE COTTON-SQUARE BORER 9 The squares produced by cotton plants early in the season are most subject to injury by square borer larvae. However, there are no records available by which the extent of injury can be accurately measured. Local growers often improperly ascribe the injury done by this species _ 6o the cotton bollworm and ignore or completely overlook the potential destructive power of the larvae of the cotton-square borer. Rearing records in the laboratory show that the larvae 9f this species are voracious itegdgzrs, and each individual capable of destroying at least twenty to thirty squares ‘during the course of its development. With this destruc- tivecapacity the insect, under favorable conditions, may become a cotton pest of considerable economic importance. According to Sanderson (17) 10 per cent of the cotton stalks in small fields in Texas have been completely denuded of squares by this insect. This extent of injury is not a common occurrence and ordinarily it is considerably less. The destruction of three to six squares per plant over small areas has frequently been noted in local cotton fields. METHODS OF STUDY Detailed observations on the life history of the cotton-square borer Were made in anopen laboratory Where the temperature and the humidity closely approximated natural conditions. Cotton was used as the food plant in rearing all individuals included in the life-history studies. For the purpose of making observations on oviposition and securing material of known ancestry for other phases of the work, individual pairs of field-collected butterflies were placed in metal 16-mesh screen cages 6"x6”x10" with a small branch of cotton inserted in a container of water to keep it fresh. The confined insects were fed at regular intervals in the morning and afternoon by placing small pieces of ster- ilized sponge soaked in a weak sugar solution on the top of the cage or by spraying the sweetened mixture directly onto the cage. At the end of each 24-hour period the insects were transferred to another thoroughly cleansed cage with a fresh cotton branch. supplied for oviposition. The eggs deposited during each day were carefully removed from the plant and cage for observations on the duration of this stage. All eggs laid during the same 24-hour period were placed collectively in a glass vial (23x11 mm.) with the "open end covered with one thickness of ordinary cheese-cloth. As soon as the eggs hatched the individual larva was isolated on fresh food placed in similar vials. Fresh food was supplied to each larva during the morning and afternoon of each day of its development. At the time of these semi-daily operations every indi- vidual was carefully noted for molts until the date of pupation. The pupae were also kept isolated in individual vials and noted twice daily for emergence of adults. In addition to the small metal screen cage used in the laboratory, two other types of larger wood frame 16-mesh screen cages measuring 3’x2’x4’ and 4’x4’x4' were used in the field in attempting to mate the “Scudder (20) states that it probably hibernates in the pupal stage. 1O BULLETIN NO. 401, TEXAS AGRICULTURAL EXPERIMENT STATION species in captivity. Apparently many of the insects reached sexual maturity; yet all efforts to secure fertile eggs from females reared in the laboratory were unsuccessful in all the types of cages used. Throughout the warm season incidental field observations on the cotton-square borer were mad.e locally by the Writer. Other members of the Station Staff, as time and opportunity permitted, contributed general field notes on the insect in other sections of the State. SEASONAL HISTORY In the latitude of College Station adult cotton-square borers are active throughout the year, excepting December and January. Butterflies of i. the overwintering brood begin to appear during the latter part of ‘- February; the bulk of the brood appears during March and the first two weeks of April, and some belated stragglers after April 15. The available records on earliest oviposition in the field by females of the overwintering brood include the last week of March and the first week of April. It appears likely that with favorable climatic conditions eggs ’ may be laid prior to that time. The major portion of the first generation of insects has matured by the latter part of May and the first week of June, and the adults of the cotton-square borer are usually present in maximum numbers at this time. Subsequent to this date the insect is continuously active and oviposition extends uninterruptedlyr through- i out the warm season. The second generation, which develops during i- June and J uly, invariably 151E551; parasitized. This results in a great reduction in the members of this generation which reach maturity, and adults become less noticeable in the field as the season advances. Most writers state that this species has two generations in the North, but it appears safe to assume that three complete generations may occur in this latitude and southward, Where the insect continues to breed in the fall as long as suitable food plants remain available. In the vicinity ‘ of San Antonio the butterflies are active during warm days throughout y the winter months, indicating that the winter may be passed in the adult p stage as Well as the pupal stage. This point has not been definitely - established for the species in the latitude of College Station. In the northern limits of its distribution the insect is active in the - field from May to September, and produces two broods during a season. " DESCRIPTION Egg In dorsal aspect the egg is circular in outline with a slight depression in the central area. The diameter is greatest about one-third the dis- , tance above the base, and from this point decreases rather sharply above ‘ and to a lesser extent below. The attached or under surface is irregularly flattened. ‘ THE COTTON-SQUARE BORER 11 Fig. 2.——Above, eggs of the cotton-square borer laid in confinement on underside of cotton leaf; below, injury to cotton foliage by young larvae in confinement. 12 BULLETIN NO. 401, TEXAS AGRICULTURAL EXPERIMENT STATION Under magnification the surface is conspicuously sculptured with rather deep and quite regular hexagonal depressions. The shining basal area of each pitlike depression bears a narrow, opaque, white, circular elevation, joined at brief intervals by delicate converging ridges extend- ing inward from the sides of the depressions. These reticulations are smaller in the polar areas and are most apparent on the empty or hatched egg. The shell is opaque, thick, and rather tough, bearing more or less regularly arranged rows of short, blunt bristles. Fig. 3.——At left, mature larva of cotton-square borer; center, prepupal stage; right. pupa, all enlarged. The eggs are pale-green or bluish-vfhite When laid, but within a day or two change to yellowish-white. After the larva has hatched, the egg shell remains opaque an.d is pure white in color. In size the eggs are slightly variable, ranging from 0.62 mm. to 0.72 mm. in diameter, and from 0.28 mm. to 0.32 mm. in height. The THE COTTON-SQUARE BORER 13 ieasurements of fifteen eggs selected at random averaged 0.679 mm. a l’ diameter and 0.301 in height. Larva The caterpillar or larva, illustrated in Figure 3, is the stage in which _ _ insect attacks and destroys cotton squares. The newly hatched larva‘ Ieraes about one millimeter,__i_1_1,__le_ngth and is greenisT-whitelbiitwturns ker in color shortlyilafter feeding begins. The body is slender, sub- adrate in cross-section, and clothed with several rows of long, pale, plated, bristly hairs. In dorsal aspect the head is fully exposed if but slightly narrower than the thorax. The narrow Ipedian dorsal laterodorsal regions of the body are characteristically flattened and . ded by prominent tubercles, which bear clusters of conspicuous tly hairs. On the dorsum the bristles curve uniformly backward i are distinctly longer than the body diameter of the larva. The ral bristles are shorter, less curved, and directed laterally or only ltly backward. The body is paler beneath than above and sparsely _‘ ed with short fine hairs. The legs and prolegs are short and also or light-greenish in color. _ each succeeding molt the larva increases proportionately faster dth than in length, and the body becomes flattened and more fipact as maturity is approached. During the intermediate instars bristly hairs become infuscated and the general color of the larva from reddish-yellow to brown. e full grown larva is short, flattened, about two and one-half times along as wide, and tapers towards each broadly rounded extremity. ,1: general color is variable, usually bright-green without any mark- "', but sometimes pale-green with faint darker stripes along the tum. The under side, including the legs, is uniform light-green in fir. Larvae which were reared in the laboratory for biological observa- H: invariably were much darker in color throughout development, ’;| g from light-brown t0 almost black. The head is small, shining» ish-yellow and retracted beneath. the body in front. The entire j» is densely covered with bristly hairs of varying. lengths, which "t a velvety appearance of the caterpillar as seen in the field. The iture is longer and denser at the body extremities and on the latero- margins. As in the first instar, the hairs are largely pale and 3 microscopic spicules. 5 he mature larvae are subject to some variations in size, depending ely upon the amount and character of food consumed. Measurements ten larvae which were reared in the laboratory ranged from 12 mm. i_16 mm. in length and from 4.5 mm. to 6.5 mm. in width. These surernents were made with slide calipers to the nearest half ‘I imeter. 14 BULLETIN NO. 401, TEXAS AGRICULTURAL EXPERIMENT STATION Pupa The pupa of the cotton-square borer varies in color from pale-yellow to brown and is covered with numerous blackish mottlings, which are variable in position, size, and intensity. Viewed dorsally, the pupa is nearly ovate in outline with both extremi- ties broadly rounded. A median transverse suture clearly defines the junction of the thorax and abdomen. Anterior to the suture the pupa is distinctly constricted or narrowed with the sides sloping sharply downward from a prominent rounded ridge extending along the longi- tudinal axis. Shortly posterior to the median transverse suture the sides bulge to the greatest width and then converge uniformly towards ‘the posterior extremity. The abdominal segments of the insect are ‘indicated by a series of distinct transverse sutures in the pupa case. The dorsum of the abdominal region is broadly convex and slopes abruptly downward towards the distal extremity. The entire dorsal surface of the pupa is more or less granular and sparsely covered with irregular rows of short pale or whitish bristles. In lateral aspect the pupa appears almost straight on the ventral side and arches upward from both extremities, forming a semi-ovate outline. ‘The constriction at the median transverse suture is noticeable above by r~a slight depression shortly before the middle. The rows of bristly hairs ~~on the dorsum are most conspicuous along the median area and at the extremities. A large proportion of the ‘central area of the pupa case is occupied by the insect’s wing, the hind border of which is defined by Ia very definite suture that extends from the median transverse suture rabove diagonally downward towards the posterior, purving beneath at the idistal border of the fourth abdominal segment. Under moderate mag- ‘aification the wing area appears roughened, with faint traces of obscure reticulations present. The blackish mottlings usually do not extend upon the wing area, which is generally somewhat paler and is semi-translucent in appearance. _ From the ventral side the pupa presents the same outline as when viewed from above, except that the posterior extremity is more promi- 'nent and less broadly rounded. The insect’s eyes and head with its "appendages are all clearly defined by distinct sutures. The proboscis extends along the median line to about the middle of the pupa case. At this point it is adjoined on either side by the antennal sutures, which originate near the middle of the anterior of the head. From the base "they bow outwardly for a short distance and thence posteriorly inward, continuing parallel beyond the tip of the median proboscal suture and extend to the hind border of the wing areas. The latter are destitute of bristles or hairs and occupy most of the space outside of the antennal sutures, covering all but the last five abdominal segments, which are noticeably narrowed at the middle. Under magnification the wing areas appear roughened by slightly raised irregular rcticulations. The ab- dominal segments are sparsely covered with irregular rows of pale or THE COTTON-SQUARE BORER i 15 whitish bristles which vary in length. The distal segment is most prom- inent, with the bare central area bordered on each side, and to a lesser extent behind, with a group of minute modified spines. The latter are brownish and usually slightly bent below the enlarged or swollen tips. This specialized vestiture is rather inconspicuous without magnification. The pupa is somewhat variable in size, ranging from 7.5 mm. to 10.5 mm. in length, and from 3.5 mm. to 5.0 mm. in width. The measure- ments of ten individuals which were reared in the laboratory averaged 9.1 mm. in length and 4.5 mm. in width. All measurements were made to the nearest half millimeter with slide calipers. Adult Theadult cotton-square borer is a small, fragile, blue-gray butterfly, with a wing expanse ranging from 25 mm. to 32 mm. Fig 4.——Butterfly of the cotton-square borer, enlarged. 'l‘l1e upper surface of thewings is blackish with a faint blue-gray tinge except on the narrow posterior borders of the hind wings, where the coloration is decidedly paler. This area and anteriorly adjacent to it is rather densely covered with long, fine, gray hairs. The lateral margins of the wings are fringed with'dense rows of scales, which are blackish along the basal area and grayish-white apically. The posterior lateral margins of the hind wings bear two slender tail-like prolongations. The black, briefly white-tipped anterior tail is short and rather inconspicuous 16 BULLETIN NO. 401, TEXAS AGRICULTURAL EXPERIMENT STATION in comparison with the posterior prolongation. The latter is consid- erably elongated, more or less twisted or coiled, black, bordered on the front edge with white, the tip bearing a dense tuft of contrasting white scales. Shortly inward between the bases of the tails a bright orange-red area superimposes a roundish black spot, which is crossed basally by a narrow bluish-white line extending distinctly towards the posterior and becomes obscured at a brief distance toward the anterior wing mar,- gin. Shortly inward from this line and parallel with it the wings are crossed by a series of irregular oblong bluish-white spots, which usually originate near the middle of the lateral margin and extend to the hind border. The outer posterior corner of the hind wing bears a rounded flaplike extension, which is deflected downward and densely fringed with long black and white scales. In the middle it bears an oblong dull orange-red spot, bordered with black on either side and white in front. The under surface of the wings is ash-gray with a linear blackish border along the lateral margins. Both the fore and hind wings are crossed by two interrupted darker lines. The outer one is rather indis- tinct and closely parallels the lateral wing margin. The inner line is more conspicuous, originating near the anterior margin of each wing at a point located about three-fourths the distance between the base and tip. On the fore wing the line extends obliquely outward for approxi- mately two-thirds the wing width and completely crosses the hind wing nearly parallel to the lateral margin, curving sharply inward at the posterior extremity. This line is tricolored. The black median stripe is edged with white externally and with orange-red internally. Extend- ing inward from the base of each tail there is a conspicuous bright orange-red area which, at the basal edge, partially envelops a sharply contrasting round black spot. Located posterior to the latter is a larger spot with intermixed black and white scales effecting a checkered appear- ance. The upturned surface of the fiaplike extension at the outer posterior corner of the hind wing is black, bordered in front largely with irregularly disposed orange scales. The head is small, distinctly broader than long and densely clothed with white scales posterior to the eyes. The latter are blackish-brown and densely covered with whitish hairs except on the narrow hind border. A thick lafyer of white scales intermixed with moderately long white bristly hairs completely covers the face. In the middle of the frons the scales are white and orange and the lateral areas posterior to the antennae are rather scantily clothed with short blackish hairs. The vertex is orange, bordered behind with black scales and long whitish hairs. The slender, straight, black antennae are narrowly ringed with white scales at the base of each segment and the club is conspicuously tipped with orange. The thorax is rather narrow, black above and thickly clothed with grayish hairs on the sides and to a lesser extent on the dorsum. The ventral side is completely covered with a dense vestiture of pure white THE COTTON-SQUARE BORER 17 silky hairs and scales. The legs, except the tarsal joints, are wholly clothed with white scales and concolorous long hairs on the ventral surface of the femora. On the upper side of the tarsal joints the scales are black basally and white on the narrow distal ends. The abdomen is slender, compressed laterally, and strongly arched above along the longitudinal axis, which is more apparent in dried or preserved specimens. The dorsal surface is concolorous with the thorax, at least basally, and sometimes tinged with yellowish-orange and white apically. The venter bears a thick layer of coarse white closely appressed scales. LIFE HISTORY Mating and Fertility In the field, the butterflies of the cotton-square borer have been observed frequently in the process of mating, which usually occurs late in the evening or shortly before sunset. During the act of copulation the insects remain seated on the plant faced in opposite directions with the tips of their abdomens united and the wings held in the normal upright position. They may remain united in this position for a. half hour or more if not disturbed. The maximum time and the average time consumed in the act were not determined. Although mating appears to occur sedentarily with this species, it was not observed to take place among laboratory-reared individuals within the confinement of cages placed over plants growing in the field or in the laboratory. In every case apparently sexually matured virgin females which were confined with active males failed to produce any fertile eggs. Laboratory observations show that when fertilization has been effected in the field the eggs deposited subsequently by females placed in con- finement Without the further presence of any male are fertile. In other words, one mating appears sufficient to insure fertilization of at least the average number of eggs laid by éach female. Oviposition The eggs are laid singly by the female and normally they are attached rather firmly to the foliage of the food plant. Quite often they are deposited also on the blooms, fruits, 0r seedpods. In the laboratory, caged females oviposited most actively after 5 o’clock in the afternoon and before 8 o’clock in the morning. Only rarely has oviposition been observed to occur in the field during that portion of the day when the insects are most active. There is some tendency for females to lay the eggs in protected situations, as along the larger leaf-veins or between the bracts of the squares and similar places. This tendency appears more pronounced among caged individuals. In confinement, field- collected females laid as many, or even more, eggs on the sides and bottoms of the cages as they did s11 the cotton foliage supplied for the 18 BULLETIN NO. 401, TEXAS AGRICULTURAL EXPERIMENT STATION purpose. Occasionally a few eggs were found loose on the bottoms of the cages. ' Shortly after the appearance of the adults in th ' ' ' ' - . . t begins and 1s continued throughout the warm seasogspgliriligceotrllildoildliollf 19§§9I$-_&I_e_ long-lived in nature, the period of ovi osition I’ b b1 extends over a considerable period of time The datla se (fr? athy laboratory on this point are given in Table 1 In this dude tm ‘e should be pointed out that ‘the insect does not withstand O nfic Ion It very readily and usually succumbs Within two Weeks Mcim nemfigt females failed to mate in the cages used and the data represgnfodrdlly a1: illpgpttrplrei 0i ov1pos1t1}pn period of virgin females. It appears Certain _ P 0 Over W lch eggs are laid under natural conditions is considerably longer than indicated by these data. Table 1. Duration of oviposition period in confinement, 1928, Pair number F 1523i (1688 L315; egg Oviposition Temperature DBFIOd, days mean 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. July 29 Aug. 6 9 83.7 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. July 3O Aug. 3 5 83.9 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aug. 1 Aug. 6 6 84.3 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aug. 2 Aug. 8 7 84.8 8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aug. 7 Aug. 15 9 86.2 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aug. 8 Aug. 15 8 86.2 11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aug 7 Aug. 15 9 86.2 l2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aug. 9 Aug. 15 7 86.3 13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Aug. 11 Aug. 18 8 85.7 16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Aug. 15 Aug. 20 6 85.7 The figures secured on the total. number of eggs laid and the daily rate of oviposition in the laboratory are given in Table 2. It should be noted that these data, for the reasons indicated in the preceding paragraph, may not be a. very close approximation of either the rate at which eggs are laid or the total number produced under natural con- ditions. In confinement, oviposition occurred at a rapid rate over a e period of four and five days, shortly after which the infertile females died. Since the insect is long-lived in nature, there is a considerable period of time during which ova may be developed Within the uterus. This point, considered in conjunction With the fact that the eggs are not laid in groups or batches, but singly and generally over plants in the field, may be considered as evidence that fertile females may lay a larger number of eggs at a more uniform rate over a longer period of time than the data indicate for the caged individuals. Incubation Period Laboratory records on the incubation period of thirty-four individual egg lots during June and July are given in Table 3. The mean tem- peratures indicated are the averages of the daily extremes affecting all the eggs of each individual lot. When effective mean temperatures THE COTTON-SQUARE BORER i 19 Table 2. Daily oviposition records of individual pairs of cotton-square borer butterflies in confinement, 1928. Average mean ‘ Pair number Date temper ature 1 3 4 6 8 9 11 12 13 16 July 26 79.5 E M July 27 81.5 0 E M July 28 81.5 0 0 July 29 82.0 9 0 July 30 82.0 20 2 E M July 31 84.0 16 18 O E M Aug. 1 83.5 19 1O 3 0 Aug. 2 85.0 10 17 0 4 Aug. 3 85.0 8 12 0 6 Aug. 4 84.0 0 0 4 4 E M Aug. 5 83.5 0 0 7 7 0 Aug. 6 85.0 5 0 6 14 0 E M E M Aug. 7 86.0 0 . . . . . . 0 10 4 0 2 E M Aug. 8 85.5 0 . . . . . . . . . . . . 11 7 4 9 0 E M Aug. 9 88.5 0 . . . . . . . . . . .. 0 13 0 7 4 0 Aug. 10 87.0 . . . . . . . . . . . . . . . . . . 0 10 0 6 4 0 Aug. l1 85.5 . . . . . . . . . . . . . . . . . . . . . . . . 6 7 8 3 5 Aug. 1 86.5 . . . . . . . . . . . . . . . . . . . . . . .. 12 6 1 7 4 E M Aug. 13 87.0 . . . . . . . . . . . . . . . . . . . . . . .. 4 3 0 10 14 0 Aug 14 85.0 . . . . . . . . . . . . . . . . . . . . . . .. 0 5 0 l1 11 0 Aug 15 85.0 . . . . . . . . . . . . . . . . . . . . . . .. 1 1 1 13 16 2 Aug 16 85.5 . . . . . . . . . . . . . . . . . . . . . . . . 0 . . . . . . 0 0 2 14 Aug 17 86.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 0 4 9 Aug 18 85.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 16 Aug. 19 84.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 2 Aug. 20 88.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 3 Aug. 21 88.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 0 Aug. 22 87.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 E M—Emerged, Mated. Table 3. Duration of egg stage during summer, 1928. Laid Hatched Weighted Total average Temperature Lot N0. eggs egg incubation mean Date No. Date hatched days period days June 21 1 June 25-27 . . . . . . . . . . . . . . . . . . 81 430 5.30 80.6 June 22 2 June 28 . . . . . . . . . . . . . . . . . . .. 14 84 6.00 80.5 June 23 3 June 29-30 . . . . . . . . . . . . . . . . . . 19 118 6 21 80.6 July 1 4 J y 6-7 . . . . . . . . . . . . . . . . . . .. 8 46 5 75 82 0 July 2 5 Julv 6-8 . . . . . . . . . . . . . . . . . . .. 21 116 5 52 81.5 July 3 6 July 8-9 . . . . . . . . . . . . . . . . . . .. 20 116 5 80 81.4 July 4 7 July 9-10 . . . . . . . . . . . . . . . . . .. 11 5 50 81 3 July 5 8 July 10-12 . . . . . . . . . . . . . . . . .. 36 213 5 91 81 4 July 6 9 July 10-12 . . . . . . . . . . . . . . . . .. 20 111 5 55 81.1 July 7 10 July 11-13 . . . . . . . . . . . . . . . . .. 13 73 5 61 81 5 July 8 11 July 12-14 . . . . . . . . . . . . . . . . .. 21 113 5 38 82 3 July 9 l2 Julv 14-15 . . . . . . . . . . . . . . . . .. 11 63 5 72 82 9 July 10 13 July 16 . . . . . . . . . . . . . . . . . . . .. 7 42 6 00 83 1 July 11 14 July 15-17 . . . . . . . . . . . . . . . . .. 6 33 5 50 83 4 July 12 15 July 16-18 . . . . . . . . . . . . . . . . .. 9 52 5 77 83 7 July 13 16 Julyl . . . . . . . . . . . . . . . . . . . .. 8 48 6 00 84 2 July 14 17 July 19-20 . . . . _ . . . . . . . . . . . .. 16 91 5 68 84 5 July 15 18 July 19-21 . . . . . . . . . . . . . . . . .. 22 127 5.77 84 7 July 16 19 July 21-22 . . . . . . . . . . . . . . . . . . 12 69 5.75 85 2 J y 17 20 July 21-23 . . . . . . . . . . . . . . . . .. 11 63 5 72 85 8 July 18 21 July 23-24 . . . . . . . . . . . . . . . . .. 7 40 5 71 85 7 July 19 22 July 24-25 . . . . . . . . . . . . . . . . .. 8 » 45 5 62 85 7 July 20 23 July 24-26 . . . . . . . . . . . . . . . . .. 90 448 4 97 85 6 July 21 24 July 25-_6 . . . . . . . . . . . . . . . . .. 78 383 4 91 85 5 July 22 25 July 26-27 . . . . . . . . . . . . . . . . .. 45 224 4 97 84 1 July 23 26 July 27-28 . . . . . . . . . . . . . . . . .. 25 123 4 92 83 2 July 24 27 July 28-29 . . . . . . . . . . . . . . . . .. 38 189 4 97 82 0 July 25 28 July 29-31 . . . . . . . . . . . . . . . . .. 41 236 5 75 81 8 July 26 29 July 31.: . . . . . . . . . . . . . . . . . .. 32 160 5 00 81 1 July 27 30 July 31-August 2 . . . . . . . . . . . . 80 458 5 72 82 3 July 28 31 August 2-3 . . . . . . . . . . . . . . . .. 97 512 5 27 82 6 July 29 32 August 2-4 . . . . . . . . . . . . . . . . .. 26 155 5 96 83 6 July 30 33 August 3-5 . . . . . . . . . . . . . . . .. 42 221 5 26 83 8 July 31 34 August 3-6 . . . . . . . . . . . . . . . . . 59 327 5 54 84 2 20 BULLETIN NO. 401, TEXAS AGRICULTURAL EXPERIMENT STATION remain fairly uniform, the incubation period of the eggs is not subject to anv marked fluctuations. The Weighted average for the period of incubation of 1025 eggs, in mean temperatures ranging from 80.6 to 85.8 degrees F., was 5.56 days. Lower temperatures early and late in the active season probably are effective in increasing the time required for incubation of the eggs. Some incidental field observations made in this connection during July and August, 1923, indicate that cotton-square borer eggs may hatch within a. period of two or three days. However, these minimum incuba- tion periods were not observed to- occur in the laboratory during June and July, 1928, when the data presented in Table 3 were recorded. Hatching Soon after complete embryonic development has been attained, the larva becomes active and begins eating its way through the egg shell. The exit hole, which is eaten through the upper portion of the egg, is irregular in outline and quite variable in size, sometimes including practically the entire upper portion of the shell. Normally, however, the larva enlarges the exit just to the extent of permitting its body to pass through. When completely emerged it does not continue to feed upon the remains of the egg shell. Under favorable conditions the process of hatching may be completed within a half hour, although some individuals under observation in the laboratory required more than one hour to eat their way through the shell and emerge from the eggs. The empty egg shell remains attached and is pure white in color, which makes it a decidedly more conspicuousobject than the unhatched egg on the foliage of the food plant. Larval Development Records on the development of 134 individuals reared in the laboratory from June 25 to Ailgust 16, 1928, are presented in Table 4. The mean temperatures given are the averages of the daily extremes obtaining dur- ing the development of each larva. Nqlllllally, five molts occur duljng the larval period. The first three instars are approximately of equal duration with the maximum number of individuals completing the growth for these instars in three to four and one-half days. The fourth instar comprises approximately four and one-half days and is subject to greater variations than the preceding instars. About one-third of the time required for complete larval development isjspent in the fifth or final instar, which includes the prepupal period. A summary of the detailed observations on larval development is given in Table 5. It will be noted that considerable variations in the time required for the various instars occurred, especially during the last two periods of larval development. 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THE COTTON-SQUARE BORER 25 cotton squares, it may be assumed that the laboratory technic was responsible, at least, for the greatest departures from the average. In fact, it was noted that when a larva which had prepared to molt was inadvertently removed from the place of its attachment, the time required to cast the skin invariably was increased from one to several days, thus prolonging the duration of the instar. Although a number of these instances are included in the data given above, they are not sufficient to appreciably affect the average periods given for the various instars. The newly hatched larva is active and begins feeding as soon as it has emerged from the egg. The early feeding may be characterized as mere nibbling at the surface of the food supply. In confinement, the tendency to eat into the square does not become pronounced until the third or fourth instar has been attained. As the larva grows it consumes a correspondingly larger amount of food, and during the latter part of its development shows a decided preference for the nutritious contents of the square. The larva may bore into the square from any angle. It usu- ally eats a small circular hole less than the body diameter of the worm through the outer layers of the squares, and gradually moves inward by constricting the body and eats the contents within reach. Frequently the entire contents of large squares are consumed before the larva leaves it to attack other fruits. a Some time before the larva molts, it attaches itself to the surface of the food plant or cage, when confined, by a flimsy layer of silken threads, becomes quiescent, and does not feed. This period of inactivity ranges from twelve to twenty-four hours and usually is more protracted during the fourth and fifth molts. In the process of molting, the skin is rup- tured at either side of the head and gradually splits posteriorly along the lateral margins of the body. Usually the skin is cast off entirely by faint rhythmic contractions of the body before the larva resumes feeding, although occasionally an individual may become active before it is wholly disengaged from the old skin. No larvae were observed to feed upon the cast skins. The exact time required for the process of molting was not determined, but general observations indicate that it occurs within the limits of one to two hours. Prepupal Period When the larva has reached maturity it ceases to feed and attaches itself to any surface upon which it happens to be situated at the time. In this position it remains inactive for two or three days and occasionally for a longer period. During this time the larva gradually becomes dis- tended or swollen by contracting longitudinally. Subsequently, the con- volutions or wrinkles of the body surface disappear and the larva slowly assumes the general outline of the pupa. The reddish-brown color of the pupal case, which has been formed within the body wall of the larva, becomes apparent shortly before the final molt occurs. 26 BULLETIN NO. 401, TEXAS AGRICULTURAL EXPERIMENT STATION Pupation Normally both sexes pupate from the fifth larval instar, althougha few exceptions to this rule were noted in the laboratory. Shortly after the pupal case has been formed the larval skin is ruptured in front and pushed towards the posterior by body contractions of the pupa. Usually the cast skin remains attached to the distal extremity of the pupal case. The time required for completing the final molt is brief, ordinarily ‘occurring in fifteen to thirty minutes. Observations indicate that trans- formation to the pupal stage most commonly occurs during the daytime. In the field, the larva pupates upon the food plant, either fully exposed or in more or less secreted situations. Pupal Period From July 17 to August 26, 1928, records were made on the duration of the pupal period of 153 individuals. The data secured in this con— nection are given in Table 6. In each case the mean temperatures given are the averages of the daily mean temperatures affecting any individual throughout pupal development. It will be noted that the duration of the pupal period is fairly uniform, varying from nine to ten and one-half days for most individuals, when the mean temperature averages about 84 degrees F., and is not subject to marked fluctuations. Lower tem- peratures earlier and later in the season doubtless retard the rate of development and prolong the duration of the stage. Table 6. Records on pupal development, 1928. Duration Average No. Date pupated Date emerged Sex of pu al mean stage, ays temperature 1 July 17, p.m. July 27, a.m 9.5 84.5 2 July 16. p.m. July 25, a m 8.5 85.3 3 July 16, p.m. July 26, a m 9.5 84.6 4 July 19, a.m. July 29, a III 10.0 84.0 5 July 19, a.m. July 29, a m 10.0 84.0 6 July 16, p.m. July 25, p m 9.0 85.3 7 July 18, p.m. July 28, a m 9.5 84.2 8 July 20, a.m. July 31, a m 11.0 83.6 9 July 19, a.m. July 29, a m 10.0 84.0 1O July 19, a.m. July 29, a m 10.0 84.0 11 July 17, p.m. July 27, am 9.5 84.5 12 July 17, p.m. July 26, a m 8.5 84.8 13 July 18, p.m. July 28, a m 9.5 84.2 14 July 17, a.m. July 27, a m 10.0 84.5 15 July 17, a.m. July 27, a m 10.0 84.5 16 July 17, a.m. July 27, a m 10.0 84.5 17 July 17, a.m. July 27, a m 10.0 84.5 18 July 17, a.m. July 27, a m 10.0 84.5 19 July 17, a.m. July 28, a m 11.0 84.2 20 July 18, a.m. July 28, a m 10.0 84.2 21 July 18, a.m. July 28, a m 10.0 84.2 22 July 18, a.m. July 29, a m 11.0 84.0 23 July l9, a.m. July 29, a m 10.0 84.0 24 July 19, a.m. July 29, a m 10.0 84.0 25 Julv 19, a.m. July 29, a m 10.0 84.0 26 July l9, a.m. July 29, a.m 10.0 84.0 27 July 19, a.m. July 29, a m 10.0 84.0 28 July 23. p.m. Aug. 2, p.m 10.0 83.0 29 July 18, p.m. July 29, a.m 10.5 84.0- THE COTTON-SQUARE BORER 27 Table 6. Records on pupal development, 1928 . Duration Average No. Date pupated Date emerged Sex of pu al mean stage, ays temperature 30 July 20, p.m. July 31, a.m. Male . . . . . . . . . . . . . . . . . 10.5 83.6 31 July 20. p.m. July 31, a.m. Male . . . . . . . . . . . . . . . . . 10.5 83.6 32 July 20, p.m. July 31, a.m. Male . . . . . . . . . . . . . . . . . 10.5 83.6 33 July 20, p.m. July 31, a.m. Male . . . . . . . . . . . . . . . . . 10.5 83.6 34 July 20, p.m. July 31, a.m. Male . . . . . . . . . . . . . . . . . 10.5 83.6 35 July 20, a.m. July 31, a.m. Female . . . . . . . . . . . . . . . 11.0 83.6 36 July 21, p.m. Aug. 1, a.m. Female . . . . . . . . . . . . . . . 10.5 83.4 37 July 21, p.m. July 31, a.m. Male . . . . . . . . . . . . . . . . . 9.5 83.4 38 July 17, p.m. July 28, a.m. Male . . . . . . . . . . . . . . . . . 10.5 84.2 39 July 16, p.m. July 26, a.m. Male . . . . . . . . . . . . . . . . . 9.5 84.6 40 July 19, p.m. July 30, a.m. Male . . . . . . . . . . . . . . . . . 10.5 83.8 41 July 18, a.m. July 27, a.m. Female . . . . . . . . . . . . . . . 9.0 84.5 42 July 17, p.m. July 27, a.m. Male. 9.5 84.5 43 July 18, p.m. July 29, a.m. Male . . . . . . . . . . . . . . . .. 10.5 84.0 44 July 18, p.m. July 29, a.m. Male . . . . . . . . . . . . . . . . . 10.5 84.0 45 July 16, p.m. July 25, p.m. Female . . . . . . . . . . . . . . . 9.0 85.3 46 July 17, p.m. July 27, a.m. Female . . . . . . . . . . . . . . . 9.5 84.5 47 July 20, p.m. July 30, a.m. Female . . . . . . . . . . . . . . . 9.5 83.5 48 July 22, a.m. Aug. 1, a.m. Female . . . . . . . . . . . . . . . 10.0 83.1 49 July 25, p.m. Aug. 4, a.m. Female . . . . . . . . . . . . . . . 9.5 82.9 50 July 18, a.m. Jul 27, a.m. Female . . . . . . . . . . . . . . . 9.0 84.5 51 July 24, p.m. Aug. 3, a.m. Female . . . . . . . . . . . . . . . 9.5 82.8 52 July 19, a.m. July 29, a.m. Male. 10.0 84.0 53 July 19, a.m. July 29, a.m. Male . . . . . . . . . . . . . . . . . 10.0 84.0 54 July 18, p.m. July 28, a.m. Female . . . . . . . . . . . . . . . 9.5 84.2 55 July 18, p.m. July 28, a.m. Female . . . . . . . . . . . . . . . 9.5 84.2 56 July 17, p.m. July 26, a.m. Female . . . . . . . . . . . . . . . 8.5 84.8 57 July 18, p.m. July 28, a.m. Female . . . . . . . . . . . . . . . 9.5 84.2 58 July 17, p.m. July 27, a.m. Male. 9.5 84.5 59 July 19, p.m. July 29, a.m. Female . . . . . . . . . . . . . . . 9.5 84.0 60 July 18, p.m. July 28, a.m. Female . . . . . . . . . . . . . . . 9.5 84.2 61 July 19, a.m. July 29, a.m. Female . . . . . . . . . . . . . . . 10.0 84.0 62 July 17, p.m. July 27, a.m. Male. 9.5 84.5 63 July 18, a.m. July 28, a.m. lVlale . . . . . . . . . . . . . . . . . 10.0 84.2 64 July 19, a.m. July 29, a.m. Female . . . . . . . . . . . . . . . 10.0 84.0 65 July 17, p.m. July 26, a.m. Female . . . . . . . . . . . . . . . 8.5 84.8 66 July 18, p.m. July 28, a.m. Female . . . . . . . . . . . . . . . 9.5 84.2 67 July 20, a.m. July 30, a.m. Male. 10.0 83.5 68 July 21, p.m. July 31, a.m. Female . . . . . . . . . . . . . .. 9.5 83.4 69 July 21, a.m. July 30, a.m. Female . . . . . . . . . . . . . . . 9.0 83.3 70 July 20, p.m. July 31, a.m. Male. 10.5 83.6 71 July 20, p.m. July 31, a.m. Male . . . . . . . . . . . . . . . .. 10.5 83.6 '72 July 20, p.m. July 31, a.m. Male. 10.5 83.6 73 July 20, p.m. July 31, a.m. Male . . . . . . . . . . . . . . . .. 10.5 83.6 74 July 20, p.m. July 31, a.m. Male. 10.5 83.6 75 July 20, p.m. July 31, a.m. Female . . . . . . . . . . . . . . . 10.5 83.6 76 July 24, p.m. Aug. 4, a.m. Male. 10.5 82.9 77 July 25, a.m. Aug. 3, p.m. Male. 9.5 82.8 78 Aug 2, a m Aug. 11, a.m. Female . . . . . . . . . . . . . . . 9.0 85.5 79 July 31, p.m Aug. 9, a.m. Female . . . . . . . . . . . . . . . 8.5 85.0 80 July 29, p m Aug. 7, a.m. Female . . . . . . . . . . . . . . . 8.5 84.0 81 July 30, p m Aug. 8, a.m. Female . . . . . . . . . . . . . . . 8.5 84.3 82 July 31, p.m Aug. 10, a.m. Male. 9.5 85.1 83 July 30, p.m Aug. 8, a.m. Female . . . . . . . . . . . . . . . 8.5 84.3 84 July 30, a.m Aug. 8, a.m. Male . . . . . . . . . . . . . . . . . 9.0 84.3 85 July 30, p.m Aug. 9, a.m. Male . . . . . . . . . . . . . . . . . 9.5 84.7 86 July 31, a.m Aug. 10, a.m. Male. 10.0 85.1 87 Aug 3, p.m Aug. 17, a.m. Male. 13.5 85.6 88 July 29, p.m Aug. 8, a.m. Male . . . . . . . . . . . . . . . . . 9.5 84.1 89 July 29, a.m Aug. 8, a.m. Male . . . . . . . . . . . . . . . . . 10.0 84.1 90 July 29, a.m Aug. 7, a.m. Male . . . . . . . . . . . . . . . . . 9.0 84.3 91 July 30, a.m Aug. 8, a.m. Female . . . . . . . . . . . . . . . 9.0 84.3 92 Aug 1, a.m Aug. 9, a.m. ale . . . . . . . . . . . . . . . . . 8.0 85.1 93 Aug 1, p.m Aug. 10, a.m. Female . . . . . . . . . . . . . . . 8.5 85.3 94 Aug 1, p.m Aug. 11, a.m. ale.. 9.5 85.3 95 July 30, p.m Aug. 9, a.m. Male.. 9.5 84.7 96 July 29, p.m Aug. 7, a.m. Female . . . . . . . . . . . . . . . 8.5 84.0 97 July 31, a.m Aug. 10, a.m. ale.. 10.0 85.1 98 July 29, a.m Aug. 7, a.m. Female . . . . . . . . . . . . . . . 9.0 84.0 99 July 31, a.m Aug. 10, a.m. Male . . . . . . . . . . . . . . . . . 10.0 85.1 100 July 30, p.m Aug 9, a.m. Male. 9.5 84.7 _ 28 BULLETIN NO. 401, TEXAS AGRICULTURAL EXPERIMENT STATION Table 6. Records on pupal development, 1928. Duration Average No. Date pupated Date emerged Sex of pu al mean stage, ays temperature 101 July 31, a.m. Aug. 9, a.m. Female . . . . . . . . . . . . . . . 9.0 85.0 102 July 30, a.m. Aug. 8, a.m. Female . . . . . . . . . . . . . . . 9.0 84.3 103 July 31, p.m. Aug. 10, a.m. Male . . . . . . . . . . . . . . . . . 9.5 85.1 104 July 30, a.m. Aug. 8, a.m. Male . . . . . . . . . . . . . . . . . 9.0 84.3 105 Aug. 1, a.m. Aug. 11, a.m. Male . . . . . . . . . . . . . . . . . 10.0 85.3 106 July 31, a.m. Aug. 10, a.m. Female . . . . . . . . . . . . . . . 10.0 85.1 107 July 31, a.m. Aug. 9, a.m. Female . . . . . . . . . . . . . . . 9.0 85.0 108 July 31, p.m. Aug. 10, a.m. Male . . . . . . . . . . . . . . . .. 9.5 85.1 109 July 31, p.m. Aug. 10, a.m. Female . . . . . . . . . . . . . . . 9.5 85.1 110 Aug. 4, a.m. Aug. 14, a.m. ale . . . . . . . . . . . . . . . . . 10.0 85.7 111 Aug. 2, a.m. Aug. 12, a.m. Female . . . . . . . . . . . . . . . 10.0 85.5 112 Aug. 3, a.m. Aug. 12, a.m. Female . . . . . . . . . . . . . . . 9.0 85.6 113 Aug. 2, a.m. Aug. 11, a.m. Female . . . . . . . . . . . . . . . 9.0 85.5 114 Aug. 4, a.m. Aug. 14, a.m. ale . . . . . . . . . . . . . . . . . 10.0 85.7 115 Aug. 2, a.m. Aug. 12, a.m. Female . . . . . . . . . . . . . . 10.0 85.5 116 Aug. 1, a.m. Aug. 11, a.m. Male . . . . . . . . . . . . . . . .. 10.0 85.3 117 Aug. 5, a.m. Aug. 14, a.m. Female . . . . . . . . . . . . . . . .0 85.9 118 Aug. 3, p.m. Aug. 13, a.m. ale . . . . . . . . . . . . . . . . . 9.5 85.7 119 Aug. 4, a.m. Aug. 14, a.m. Male . . . . . . . . . . . . . . . . . 10.0 85.7 120 Aug. 1, a.m. Aug. 10, a.m. Female . . . . . . . . . . . . . . . 9.0 85.3 21 Aug 1, a.m. Aug. 10, a.m. ale . . . . . . . . . . . . . . .. 9.0 85.3 122 Aug 1, p.m. Aug. 11, a.m. Female . . . . . . . . . . . . . . . 9.5 85.3 123 Aug 1, p.m. Aug. 11, a.m. Female . . . . . . . . . . . . . . . 9.5 85.3 124 Aug 2, p.m. Aug. 12, a.m. ale . . . . . . . . . . . . . . . . . 9.5 85.5 125 Aug 1, a.m. Aug. 10, a.m. Female . . . . . . . . . . . . . . . 9.0 85.3 126 Aug 3, a.m. Aug. 12, a.m. ale . . . . . . . . . . . . . . . . . 9.0 85.6 127 Aug 3, a.m. Aug. 12, a.m. Male . . . . . . . . . . . . . . . . . 9.0 85.6 128 Aug 1, p.m. Aug. l0, a.m. Female . . . . . . . . . . . . . . . 8.5 85.3 129 Aug 5, a.m. Aug. 15, a.m. Male . . . . . . . . . . . . . . . . . 10.0 85.8 130 Aug 4, a.m. Aug. 14, a.m. Male . . . . . . . . . . . . . . . . . 10.0 85.7 131 Aug 2, a.m. Aug. 12, a.m. Male . . . . . . . . . . . . . . . . . 10.0 85.5 132 Aug 4, a.m. Aug. 14, a.m. Male . . . . . . . . . . . . . . . . . 10.0 85.7 133 Aug 5, a.m. Aug. 14, a.m. Female . . . . . . . . . . . . . . . 9.0 85.9 134 Aug 5, a.m. Aug. 15, a.m. ale . . . . . . . . . . . . . . . . . 10.0 85.8 135 Aug 6, p.m. Aug. 16, a.m. Male . . . . . . . . . . . . . . . . . 9.5 86.0 136 Aug. 5, a.m. Aug. 14, a.m. Female . . . . . . . . . . . . . . . 9.0 85.9 137 Aug. 7, a.m. Aug. 18, a.m. ale . . . . . . . . . . . . . . . . . 11.0 86.0 138 Aug 8, a.m. Aug. 15, a m Female . . . . . . . . . . . . . . . 7.0 86.2 139 Aug. 11, p.m. Aug. 24, a m ale . . . . . . . . . . . . . . . . . 12.5 86.1 140 Aug 8, a.m. Aug. 18, a m Female . . . . . . . . . . . . . . . 10.0 86.0 141 Aug 8, p.m. Aug. 18, a.m Male . . . . . . . . . . . . . . . . . 9.5 86.0 142 Aug 5, a.m. Aug. 14, a.m. Female . . . . . . . . . . . . . . . 9.0 85.9 143 Aug 3, a.m. Aug. 9.0 85.6 144 Aug 4, a.m. Aug. 10.0 85.7 145 Aug. 5, p.m. Aug. 9.5 85.8 146 Aug. 10, p.m. Aug. 8.5 85.7 147 Aug. 8, a.m. Aug. . . 9.0 86.1 148 Aug. 10, a.m. Aug. 20, a.m. Male . . . . . . . . . . . . . . . . . 10.0 85.9 149 Aug. 6, p.m. Aug. 15, a.m. Female . . . . . . . . . . . . . . . 8.5 86. 1 150 Aug 8, a.m. Aug. 19, a.m. Male . . . . . . . . . . . . . . . . . 11.0 86.6 151 Aug. 10, a.m. Aug. 20, a.m. Male . . . . . . . . . . . . . . . . . 10.0 85.9 152 Aug. 5, a.m. Aug. 13, a.m. Female . . . . . . . . . . . . . . . 8.0 86.0 153 Aug. 16,a.m. Aug. 26, a.m. Male................. 10.0 85.9 The detailed records on the duration of the pupal period are sum- marized in Table '7. The proportion of sexes was about equal among the total number of individuals which were reared in the laboratory. According to these data, the time required by the male sex to complete pupal development averages slightly more than one-half day longer than is the case with the female individuals. The majority of males remained in the pupal stage from nine to ten and one-half days, and the females from eight andone-half to ten days. The extremes in duration of the pupal period for both sexes ranged from seven to thirteen and one-half 29 THE COTTON-SQUARE BORER mmd o o o o o o w fin .2 om 2 ~ o ~ E. .. . . 638mb Ma . a M o fi o o m 2 mm .5 n o ~ o o w“. . . . . . 1.3.32 £2. ma: 0A3 9Q ofifi 9: 9: #2 odfi ma 0d w; 9w m.» o5 mzzzkéqfi 5w awake?» E hwflriflz wfiafiw? wvmmooaw 9C3. “om owfiw E @925 mo “M5552 .fi$fiao_v>ww Rana we hpwfifisw S Esau. 3O BULLETIN NO. 401, TEXAS AGRICULTURAL EXPERIMENT STATION days, but the majority of individuals completed pupal development within the limits of eight and one-half and eleven days. Summary of Developmental Periods The data accumulated on the various developmental stages of the cotton-square borer are briefly summarized in Table 8. All stages from the egg to the pupa, inclusive, are subject to considerable variations. Table 8. Summary of developmental periods. Number of Minimum Maximum Avera e individuals period period perio observed days days days Egg . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1025 4.9 6.2 5.55 First instar . . . . . . . . . . . . . . . . . . . . . . . 134 2.5 5.0 3.61 Second instar . . . . . . . . . . . . . . . . . . . . . 134 2.5 9.5 3.36 Third instar . . . . . . . . . . . . . . . . . . . . . . 134 2.5 8.5 ' 3.55 Fourth instar . . . . . . . . . . . . . . . . . . . .. 131 3.0 11.5 4.84 Fifth inskar . . . . . . . . .. . . . . . . . . . . . .. 128 5.0 14.0 7.69 Pupa . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 153 7.0 13.5 9.65 Theoretically, it appears possible for an individual to reach maturity within twenty-eight days, as is indicated by the sum of the minimum periods secured for each developmental stage. Under average laboratory conditions, however, approximately thirty-eight days are required during the summer months for complete development. The egg stage comprises about five and one-half days, the larval stage, including the prepupal period, twenty-three days, and the pupal stage about nine and one-half days. EMERGENCE OF ADULTS When the insect has attained maturity within the pupal case it emerges from the latter through a T-shaped split in the anterior end. The split originates at the base of the anterior extremity of the pupal case and extends posteriorly along the dorsomedian line of the thorax. Laterally, from this point of origin a secondary split extends 011 either side of the pupal case along the antennal sutures to the point where the latter are joined by the suture defining the hind margin of the prothorax. As the adult squeezes through the exit thus formed, the divided anterior wall of the pupal case is pushed outwardly, assuming more or less its original position after emergence has been effected. Laboratory observations made at 30-minute intervals show that the adult may emerge from the pupa and completely expand the wings within this period of time. The newly emerged individuals hang quietly to any available support, rubbing the wings together with a shearlike movement THE COTTON-SQUARE BORER 31 until they have attained complete expansion. At this time, although the wings are not fully hardened, the adult is capable of making at least short flights, and becomes very active, especially when confined 1n a cage. In the laboratory practically all of the adults of both sexes emerged from the pupae between 8 and 10 o’clock in the morning. In fact, only four cases of adult emergence were noted in the afternoon in a total of 153 individuals under observation. The detailed observations made in this connection are presented in Table 6. SEXUAL DEVELOPMENT Newly emerged females do not attain sexual maturity until a feeding period of one to three days has elapsed. After this time, in confinement, they begin to lay eggs, even though fertilization has not been effected. As has already been pointed out, mating does not occur readily with this species in captivity. In the laboratory, virgin females, confined with active field-collected males or with reared male individuals, con- tinued to deposit only infertile eggs. Although the females attained sexual maturity within the cages, it appears likely that freedom of flight or other factors not imposed by laboratory conditions are essential for fertilization and subsequent reproduction. LONGEVITY OF ADULTS The normal life period of the adult cotton-square borer in nature cannot be determined accurately. Since the insect is a strong flier and is very active, individuals cannot be followed readily through their entire life period. Moreover, there is a considerable overlapping of generations in this latitude, which makes it practically impossible to decide to which generation any given individual may belong or approximate the time when it attained maturity. In the vicinity of College Station the extremes of adult activity range from February to September, but the reproductive period is confined largely to the summer months. Judging from these observations, adult longevity may comprise a periodof two months or more. At least, it appears certain that the butterflies are normally long-lived under natural or field conditions. The data secured on adult longevity under laboratory conditions are given in Table 9. Referring to these data, it will be noted that this insect does not readily withstand confinement. Although supplied with suflicient food, most of the caged individuals of both sexes died in less than two weeks. The average life period of the thirteen pairs of but- terflies under observation was approximately nine days for males and ten days for females. s2 BULLETIN NO. 401, TEXAS AGRICULTURAL EXPERIMENT STATION Table 9. Records of longevity of adults in confinement. Male Female Number Date D_ate Number Date Date Number emerged died days emerged died days 1 . . . . . . . . . . . . . . . . .. July 26 Aug. 1 6 July 26 Aug. 14 2 . . . . . . . . . . . . . . . . .. July 27 Aug. 9 13 July 26 Aug. 10 l5 3 . . . . . . . . . . . . . . . . .. July 27 Aug. 5 9 July 27 Aug. 6 10 4 . . . . . . . . . . . . . . . . .. July 31 Aug. 6 6 July 30 Aug. 7 5 . . . . . . . . . . . . . . . . .. July 3O Aug. 5 6 July 30 Aug. 9 6 . . . . . . . . . . . . . . . . .. July 31 Aug. 1O 10 July 31 Aug. 10 l0 7 . . . . . . . . . . . . . . . . .. Aug 4 Aug. 14 10 Aug 4 Aug. 16 12 8 . . . . . . . . . . . . . . . . .. Aug. 6 Aug. 15 Aug. 6 Aug. l6 1O 9 . . . . . . . . . . . . . . . . .. Aug. 6 Aug. 19 13 Aug. 6 Aug. 16 10 1O . . . . . . . . . . . . . . . . .. Aug 7 Aug. 17 10 Aug. 7 Aug. 17 1O 11 . . . . . . . . . . . . . . . . .. Aug. 8 Aug. 16 8 Aug. 8 Aug. 21 13 12 . . . . . . . . . . . . . . . . .. Aug. 11 Aug. 22 11 Aug. 11 Aug. 1a 4 13 . . . . . . . . . . . . . . . . .. Aug. 12 Aug. 2O 8 Aug. 12 Aug. 22 10 NUMBER OF GENERATIONS The available data on the seasonal history of this species indicate that three complete generations may be produced in this latitude. However, it should be stated that the generations or broods are not clearly defined. The first generation of cotton-square borers is produced from the eggs laid during March and April by adults of the overwintering brood. The bulk of the first generation reaches maturity by the latter part of May and the first week in June. The second generation develops during June and July. It is subject to very heavy parasitism, and only a small per cent of the second brood reaches maturity. The remnant of this brood con- tinues reproduction during August and September, and rearing records show that there is ample time before the first frost occurs for the develop- ment of the third generation of insects. In the North, Where the adults of the overwintering brood emerge later in the spring, only two generations of insects are produced during a SGEISOII. \ 2L1 HIBERNATION The cotton-square borer does not pass through a protracted period of hibernation in this latitude. With the advent of frosts and lower tem- peratures, the insect disappears from the fields and is rarely seen through- out December and January. However, during brief periods of mild weather in these months, active individuals have been noted, indicating that the insect may pass through the winter in the adult stage. Although pupae were not kept under continuous observation during the entire Year, it appears more than likely that locally the species also passes through the winter in this stage as is the case in the more northern limits of its distribution. Emergence from the dormant or semi-dormant period normally begins during the latter part of February and extends throughout March. By the middle of April the butterflies are again common in the field, and it appears safe to assume that the emergence of the major portion of the overwintering brood has been completed. THE COTTON-SQUARE BORER 33 NATURAL ENEMIES The cotton-square borer is attacked by several species of insect para- sites which effectively reduce the numbers of this insect in the field. In fact, the work of the parasites limits the multiplication of the square borer to such an extent that combative measures against it» rarely are necessary. During the course of these studies, four different species of parasites were reared from the larva and pupa of this insect. Two of these were Hymenoptera determined by A. B. Gahan, Bureau of Ento- mology, United States Department of Agriculture, as Apainteles theclw Riley, and Octosmicra sp., of the family Braconidae and Chalcididae, respectively. Two of the species were Diptera, Z enillia confinis Fallen, and Frontina sp. The latter determinations were made by the writer. Data on the extent of parasitism by these species are given in Table 10. Table 10. Rearing records of cotton-square borer parasites. _ No. of square No. Locality borers specimens collected, Stage collected Name of parasite reared collected Texas Para- Emerged sitized 1* College Station 5th instar larva. . . . . 0 1 Frontina sp. 1 College Station 3rd instar larva. . . . . 0 1 Zenillia confinis Fallen 3 Gauze . . . . . . . . . 4th instar larvae . . . . 0 3 Zenillia confinis Fallen 1 College Station Pupa . . . . . . . . . . . . . . 0 1 Octosmicra sp. 10 College Station 1st-5th instar larvae. 1 9 A panteles theclae Riley 21 College Station 2nd-5th instar larvae. O 21 Apanteles theclae Riley 2 Mart . . . . . . . . . 3rd instar larvae. . . . O 2 Zenillia conjinis Fallen 1 College Station Pupa . . . . . . . . . . . . . . 0 1 Octosmicra sp. 20 College Station 2nd-5th instar larvae. 0 20 A pantcles theclae Riley i Zenillia confims Fallen 2 Brazoria Co. . . 3rd instar larvae. . . . 0 2 Zenillia confinis Fallen 1 oun . . . . . . . . 3rd instar larva . . . . . . O 1 Apanteles theclae Riley 1 Rusk . . . . . . . . . 5th instar larva. . . . . 0 1 Apanteles theclae Riley 5 College Station 3rd-5th instar larvae. 0 5 Apanteles theclae Riley 12 College Station 2nd-5th instarlarvae. 0 12 Apanieles lheclae Riley 1 Trinity . . . . . . . . 5th instar larva . . . . . . 0 1 Zenillia confinis Fallen 1 Jasper Co. . . . . 5th instar larva . . . . 0 1 Apanteles theclae Riley 5 College Station 2nd-3rd instar larvae. 0 5 A panteles theclae Riley Zenillia confinis Fallen 12 College Station 3rd-5th instar larvae. O 12 A panteles theclae Riley ' Zenillia confims Fallen 1 Balmorhea. . . . . 3rd instar larva. . . . . O 1 Apanteles theclae Riley 1 Clarksville. . . . . 5th instar larva.. . . . . 0 1 Zenillia confinis Fallen 8 College Station 3rd-5th instar larvae. 0 8 Apanteles theclae Riley _ Zenillia confinis Fallen 1 Grand Saline.. . 5th instar larva . . 0 1 Zenillia confinis Fallen 1 Oletha . . . . . . . . 3rd instar larva. . . . . 0 1 Zenillia confinis Fallen 1 Lott . . . . . . . . . . 4th instar larva. . . . . 0 1 Zenillia confnis Fallen 8 College Station 2nd-5th instar larvae. 0 8 Apanteles theclae Riley 17 College Station 4th-5th instar larvae. 6 11 Apanteles theclae Riley 3 College Station Pupae . . . . . . . . . . . . . 2 1 Octosmicra sp. _ 4 College Station 5th instar larvae. . . . 1 3 Apanleles theclae Riley Rearing records show that Apanteles theclae Riley is the most common and important parasite of the square borer larvae. This species oviposits within the body of its host, where the maggots complete their develop- ment before emerging therefrom. When fully fed, the parasitic mag- gots emerge from the host larva. and pupate in loose clusters upon its body, each individual enveloping itself in a tiny white cocoon. Seven 34 BULLETIN NO. 401, TEXAS AGRICULTURAL EXPERIMENT STATION to nine days are required for pupal development and emergence of the adult parasite. The host larva parasitized by this species does not succumb until the maggots have emerged from its body, but invariably it dies shortly thereafter and always before pupation-occurs. Four specimens of Octosmicra sp. were reared from the pupae of the cotton-square borer. None of the host individuals from which this parasite was reared showed any external evidence of parasitism when collected in the field. Apparently this species also attacks the host larva in the latter instars, but does not attain maturity until some time after pupati.on of the host larva has occurred. In other Words, the parasite passes through its entire developmental stages within the host and emerges from the pupal case of the latter in the adult stage. The available records on this species indicate that only one parasite develops to maturity within the body of each host specimen. In every instance noted the host insect was killed when attacked by this parasite. The economic importance of this parasite appears to be limited by its slow rate of multiplication. Only (me of the Qipterous parasites reared from the cotton-square borer proved to be economically important. This species, Z enillia con- finis Fallen, was commonly reared from host larvae collected locally and in various other sections of the State. The fly deposits its eggs upon the surface of the host larva’s body, usually near the anterior extremity. The tiny maggots which hatch from the ventral side of the eggs bore into the body of the caterpillar, where they feed without attacking the vital organs until practically matured. When fully fed, the maggots A emerge from the host larva and normally enter the soil for pupation. In the absence of any soil the parasitic maggots pupate in the open without any protection. An average period of seven or eight days is required for pupal development and emergence of the adult fly. In- variably the host larva dies about the time when the parasitic maggots have reached maturity and emerge from its body. Usually only one or two maggots attain full development within a single host specimen. This parasite is a common species within the State and doubtless is an important factor in the natural control of the cotton-square borer. A single specimen of a species of Frontina emerged from a practically matured cotton-square borer larva, which, at the time of collection in the field, showed no external indication of parasitism. The host died shortly after the maggot emerged and the latter pupated in moist sand supplied in the bottom of the cage. The fly issued from the puparium eight days after pupation occurred. No predacious enemies of the developmental stages of this insect were noted. However, robber flies belonging to the genera Asilus and Eras: were frequently observed capturing butterflies of the cotton-square borer. Aside from these observations there are no available records on any other important predacious enemy of the insect. THE COTTON-SQUARE BORER 35 CONTROL MEASURES During the time covered by these studies on the cotton-square borer no local infestation developed on cotton to the extent of making serious inroads on the crop and requiring applications of poison for controlling the insect. As has already been stated, the agencies of natural control are so effective in checking the multiplication of this species that it is rarely necessary to employ any measures for combating it. When conditions warrant the use of control measures against this insect, applications of calcium arsenate, made at the rate of five to seven pounds per acre, are effective in destroying_the younger larvae which have not yet eaten their way into the squares. This recommenda- tion is based upon the observations made on cotton-square borer mortality in fields of cotton which were dusted with calcium arsenate for the pur- pose of controlling the boll weevil. The results secured in the laboratory from feeding square borer larvae cotton foliage dusted with either calcium ‘or lead arsenate indicate that the larvae in any instar of development are susceptible to the poison. Under field conditions, however, larvae of the later instars feed largely within the squares and consequently cannot be so effectively reached by poison applications. Thus it should be noted that applications of poison made when most of the larvae are still small will result in the maximum degree of control. SUMMARY Strymon me-lrinus is one of the “hair-streak” butterflies, the larva of which commonly feeds upon cotton squares and is popularly known as the cotton-square borer. _ The distribution of the species extends over temperate North America. Although a very common species in Texas, this insect is not an especially injurious pest on cotton. Locally, the larvae also feed commonly upon the seed pods of cowpeas, beans, okra, and to a lesser extent upon corn and goatweed, Croton capitatus. The butterfiy’s wings expand about one inch, and are blackish-gray above and ash-gray with darker wavy streaks beneath. The hind wings bear two slender tail-like prolongations between the bases of which above and beneath are roundish black spots crowned with orange-red crescents. Adults of the overwintering brood emerge during February and March and oviposition begins soon thereafter, extending continuously throughout the warm season. The eggs are laid singly and promiscuously upon the food plants. The incubation period during June and July, 1928, averaged about five and one-half days. The larvae normally molt five times and require about twenty days during warm weather to attain full growth. Pupation occurs in the open, usually upon the food plant, and approximately nine and one-half days are required for pupal devel~ opment during the summer months. Rearing records indicate that three complete generations or brood»: 36 BULLETIN NO. 401, TEXAS AGRICULTURAL EXPERIMENT STATION of the cotton-square borer may be produced during a season. In this latitude the insect does not pass through a protracted hibernation period. It is dormant or semi-dormant throughout December and January. This period apparently is passed in both the pupal and the adult stage. Usually the cotton-square borer is effectively held in check by natural enemies and combative measures rarely are required. When the tuse of the latter appear necessary, dry applications of calcium arsenate, five to seven pounds per acre, will produce a satisfactory control, especially if the poison is applied when most of the larva are still small. LITERATURE CITED Barnes, W., and McDunnough, J. H. 1917. Check List of the Lepidoptera of Boreal America, p. 17. Boisduval, J. A., and Leconte, J. E. 1833. Histoire Generale et Monographie des Lepidopteres et des Cheonilles de l’Amerique Septentrionale, DD- 90, 95 Britton, W. E. 1920. Check List of the Insects of Connecticut, p. 156. Comstock, J. H., and Comstock, A. B. 1915. How t0 Know the Butterflies, pp. 223-24. - Doubleday, E. 1847. List Lepidoptera British Museum, p. 31. Doubleday, E., and Westwood, J. O. 1852. Genera Diurnal Lepidoptera, II. p. 486. Dyar, H. G. 1902. Literature of this Order of Insects. Edwards, Henry. 1877. A List of North American Lepidoptera and Key to the Bull. 52, U. S. Nat. Mus., p. 36 Transactions California Academy of Science, VI. French, G. H. 1886. The Butterflies of the Eastern United States, p. 259. Godart, J. B. 1819. Encyclopedic Methodique, IX, DD. 635-6. Harris, T. W. 1833. Report Geologist, Mineralogist, etc., Massachusetts, p 590 Harris, T. W. 1841. Insects injurious to Vegetation. First Edition, pp. Holland, W. J. 1902. The Butterfly Book, p. 242. Hubner, J. 1818. Zutrage zur Sammlung Exotischer Schmetterlinge, I, p. 22. Leonard, M. D. 1928. A List of the Insects of New York, p. 678. Maynard, C. J. 1891. Manual 0t North American Butterflies, p. 133. Sanderson, E. D. 1912. Insect Pests of Farm, Orchard, and Garden, p. 248. Scudder, S. H. 1872. A Systematic Revision of Some of the American Butterflies, etc., p. 30. Scudder, S. H. 1876. Bulletin Bufialo Society Natural Science, III, p. 107. Scudder, S. H. 1889. Butterflies of the Eastern United States and Canada, II, p. 850-5. Smith, J. B. 1910. The Insects of New Jersey, p. 414. Watson, J. R. 1913. Annual Report Florida, p. LXX.