es-szal TEXAS‘ AGRICULTURAL EXPERIMENT STATION B. ‘YOUNGBLOOD, DIRECTOR COLLEGE STATION, BRAZOS COUNTY, TEXAS A I ' BULLETIN NO. 328 - APRIL, 1926 DIVISION OF EN TOMOLOGY THE LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS T. O. WALTON, President STATION STAFFT ,1. S., Ph. D., Director .1. S., Vice-Director _, B. S., Assistant Director ., Secretary _ LLEMAN, JR., Chief Clerk .ANcKLow, Assistant Chief Clerk .~-_>cnAEnEL, Executive Assistant 2 NEBLETTE, Technical Assistant ETERINARY SCIENCE: _ *M. FRANcIs, D. V. M., Chief_ _ H. SCHMIDT, D. V. M., Veterinarian W. L. BLAcK, D. V. M., Veterinarian CHEMISTRY: _ _ G. S.'FRAPs, Ph. D., Chief; State Chemist S. E. AsEURY, M. S., Assistant Chemist WALDO H. WALKER, Assistant Chemist J. K. BLUM, B. S., Assistant Chemist J. E. TEAGUE, B. S., Assistant Chemist VELMA GRAHAM, Assistant Chemist _ AnAn E. PRocToR, B. S., Assistant Chemist N. J. VOLK, M. S., Assistant Chemist E. C. CARLYLE, B. S., Assistant Chemist R. O. BROOKE, M. S., Assistant Chemist HORTICULTURE: W. B. LANHAM, M. A., Chief H. NEss, M. S., Berry Bree er RANGE ANIMAL HUSBANDRY: J. M. JoNEs, _A. M., Chief; Sheep and Goat Investigations _ J. L. Lusn, Ph. D_., Animal Husbandman; Breeding Investigations FRANK GRAYsoN, Wool Grader ENTOMOLOGY: F. L. THOMAS, Ph. D., Chief; State Entomologis _ H. J. REINHARD, B. S., Entomologist W. L. OwEN, M. S., Entomologist S. E. McGREcoR, JR., Acting Chief Foulbrood Inspector _ GILLIS GRAHAM, Apiary Ins ector OTTo MACKENSEN, Foulbroo Inspector AGRONOMY: _ E. B. REYNoLns, M. S., Chief _ _ A. B. CoNNER, M. S., Agronomist, Grain Sor hum Research _ R. E. _ARPER, B. S., Agronomist, Small Grain Research _ D. T. KxLLoUcn, M. S., Agronomist, Cotton Breeding ~ R. H. STANsEL, B. S., Assistant in Crops SUBSTATIONS N of.‘ 1, Beeville, Bee County: . A. HALL, B. S., Superintendent No. 2, Troup, Smith County:- W. S. HOTCHKISS, Superintendent No. 3, An leton, Brazoria County: V. E. AENER, B. S., Superintendent No. 4, Beaumont, J efierson County: R. H. WYCHE, B. S., Superintendent No. 5, Temple, Bell County: H. E. REA, B. S., Superintendent No. 6, Denton, Denton County: P. B. DUNKLE, B. S., Superintendent No. 7, Spur, Dickens County: _ R. E. DICKSON, B. S., Superintendent No. 8, Lubbock, Lubbock County: D. L. JoNEs, Superintendent FRANK GAINEs, Irrigationist and _ Forest Nurseryman No. 9, Balmorhea, Reeves County: J. J. BAYLES, B. S., Superintendent 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 F. A. BUECHEL, Ph. D., Professor of_ Agricultural Economics G. P. GRoUT, M._S., Professor of Dairy Husbandry V. P. LEE, Ph. D., Professor of Agricultural Economics E. O. POLLOCK, A. M., Assistant Professor o Agronomy . ScoATEs, A. E., Professor o . P. SMITH, B. S., Associate TAs of May 1, 1926. _ _ *Dean, School of Veterinary Medlcine. “In cooperation‘ wlth EU A ricultura Engineering _ ro essor of Agricultural Engineering _ U. S. Department of Agriculture. ***In cooperation Wlfllt‘), e School of Agnculture. PLANT PATHOLOGY AND PHYSIO J. J. TAUBENHAUS, P . D., Chief FARM AND RANCH ECONOMICS: _ L. P. GAERARn, M. S., Chief . B. YOUNGBLOOD, _ S., Ph. D., Farm K Ranch Economist a G. L. CRAvsfFoRn, B. S., Research Mark Specialist . **GLAnYs D. LINDSEY, M. S_., Assistant Farm and Ranch Economics J V. L. CoRY, M. S., Grazing Research Bot -_ **T. L. GAsToN, JR., B. S., Assistant, Records and Accounts -’ "J. N. TATE, B. S., Assistant, Ranch L, and Accounts SOIL SURVEY: **W. T. CARTER, B. S., Chief H. W. HAWKER, Soil Surveyor E. H. TEMPLIN, B S., S_oil Surveyor T. C. REITCH, B. S., Soil Surveyor BOTANY: HQNEss, M. S., Chief PUBLICATIONS: A. D. JACKSON, Chief SWINE HUSBANDRY: FREn HALE, M. S., Chief DAIRY HUSBANDRY: Chief POULTRY HUSBANDRY: R. M. SHERWOOD, M. S., Chief ***AGRICULTURAL ENGINEERING: MAIN STATION FARM: G. T. McNEss, Superintendent APICULTURAL RESEARCH LABORATO r: (San Antoniog _ _ H. B. PARKS, B. ., Apiculturist in Charge? A. H. ALEx, B. S., Queen Breeder y FEED CONTROL SERVICE: . D. FULLER, M. ., Chief . D. PEARcE, Secretary . H. ROGERS, Feed Inspector . H. Woon, Feed Inspector . L. KIRKLAND, B. S., eed Inlspector a ' . D. NORTHCUTT, JR., B. S., eed Inspew . C. GLAss, B. S., Feed Inspector a E. H. GARRETT, Feed Inspector <2we~wa No. l0, Feeding and Breeding Station, College Station, Brazos County: R. M. SHERWOOD, M. S., Animal Husba man in Charge of Farm_ - L. J. McCALL, Farm Superintendent No. 11, Nacogdoches, Nacogdqches County: H. F. MoRms, M. S., Superintendent i **No. 12, Chillicothe, Hardeman County: J. R. QUINBY, B. S., Superintendent **JOSEPH' C. STEPRENs, Junior Agronomist . ‘ No. 14, Sonora, Sutton-Edwards Counties: E. W. THOMAS, B. S., sfilferliilf6lltlefll_ D. H. BENNETT, D. V. _ ., Veterinarian ‘ V. L. CoRY, M. S. Grazin Research Botani **O. G. BABCOQK, B. S., ollaborating Entomologist - O. L. CARPENTER, Shepherd No. 15, Weslaco, Hidalgo County: W. H. FRIEND B. S., Su erintendent E. HoBRs, B. S., Entomo ogist No. 16, Iowa Park, Wichita County: ' E. J. WILSON, B. S., Superintendent SYNOPSIS This Bulletin is a summary of a study of the, life history, 0f the pecan nut case bearer, and of experiments conducted to obtain a suitable method 0f control. The observations here recorded extended over a period of six years and were con- tinuous over that length of time. A study of the life history and habits is necessary to the formulation of control methods. It is necessary first to understand as fully as possible the biology and relationships of an insect in order to Work out methods of control. It is with that end in view that these observations are presented. This Bulletin contains a discussion of the more important points on the life history of the pecan nut case bearer. There are four generations of this insect annually when there is a sufficient food supply; but due to a shortage in‘ the food supply or some unknown factor there were but two generations in three of the years in which observations were made. Each generation consists of four stages, the egg, the larva or worm, the pupa or resting stage, and the adult or moth. This Bulletin gives a description of each of the four stages together with suitable illustrations; a discussion concerning the food plants; methods by which the studies on the life history were conducted; habits of the adults and larvae; a summary of the life history studies by generations, and a summary of the life history for each of the years 1918-1923, inclusive. ‘ This Bulletin also contains a discussion of the nature and extent of injury to pecans; tables giving the results of spray- ing tests for the years 1919, 1920, 1921, and 1922; and a gen- eral summary of the experiments conducted on control. Spraying with arsenate of lead at the proper time has been found most effective. Full details are given in the Bulletin. CONTENTS. PAGE Synopsis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Life History Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .' . . . . . . . . . . . 5 Food Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Outline of the Life History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Adult . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7 Egg . . . .' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Larva . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Pupa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 11 Number of Generations . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 11 Method of Hibernation. ., . . . . . . . . . . . . . . . . . . , . ; . . . . . . . . 11 Explanation of Terms Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 12 Number of Annual Generations . . . . . . . . . . . . . . . . . . . . . . . . . .. 13 Methods of Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 16 Habits of the Adults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Habits of the Larvae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 22 Summary of the Life History by Generations . . . . . . . . . . . . . . . . 26 Spring Brood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 26 First Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Second Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Third Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 31 Fourth Generation . . . . . . . . . . . . . . . . . . . . . . . . . . .' . . . . . . . 32 Summary of the Life History Studies by Years . . . . . . . . . . . . . . 32 1918 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 32 1919 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 1920 . . . . . . . . . . . . . . .' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 1921 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 39 . 1922 . . . . . . . . . . . . . . . . . . . . '. . . . . . . . . . . . . . . . . . . . . . . . . . 42 1923 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 44 Nature and Extent of Damage. .- . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Studies on Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 Method of Conducting the Spraying Tests . . . . . . . . . . . . . . . . . . . 51 Preliminary Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Spraying Tests at College Station in 1919 . . . . . . . . . . . . . . . . . . 53 Spraying Tests at College Station in 1920 . . . . . . . . . . . . . . . . .. 54 Spraying Tests at Corsicana in 1920 . . . . . . . . . .* . . . . . . . . . . . . . 57 Spraying Tests at College Station in 1921 . . . . . . . . . . . . . . . . .. 67 Spraying Tests at Corsicana in 1921 . . . . . . . . . . . . . . . . . . . . . .. 69 Spraying Tests at Winona in 1921 . . . . . . . . . . . . . . . . . . . . . . . . . 69 Spraying Tests at Corsicana in1922 . . . . . . . . . . . . . . . .' . . . . . . . 71 Spraying Tests at Winona in 1922 . . . . . . . . . . . . . . . . . . . . . . . . . 72 Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . 74 Summary of Life History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 74 General Conclusions on Spraying . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 75 BULLETIN No. 328 APRIL, 1926 THE LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER (Acrobasis caryae, Grote) S. W. BILSING The pecan nut case bearer is the most destructive insect pest of the pecan in Texas at the present time. It is a native insect and is widelydistributcd Wherever the pecan is indigenous. Inmost cases, it is also found wherever improved varieties are grown. Its abun- dance depends upon the extent of the crop the previous year, the number and kinds of parasites present, and the climatic conditions during March, April, and May. These studies covered a period of six years, during which time ob- servations were made over a considerable extent of territory. Larvae were collected at various places. The major part was collected in Brazos and Grimes Counties; and the minor part in the vicinity of Corsicana, Winona, Westfield, and Olarksville, Texas. There is some confusion in regard to the correct scientific name of this insect. Dr. Harrison G. Dyar compared specimens of this insect with the collection of Acrobasis in the U. S. National Museum and’ identified them as Acrobasis caryivorella, Rag. _ In 1913 Dr. J. H. McDunnough visited Europe and examined Rago- not’s type specimens in the National Museum at Paris. He also studied Grote’s types in the British Museum at London. From these studies he concluded that the “true caryae is what Dyar identified as caryivorella, Rag, a much larger species, With no trace of red on the primaries; the type of the latter species being a female, we had no means of determining the sex marks of the male.” (Contrib. Nat. Hist. of the Lepidop of N. A., Vol. II, No. 5, page 222.) A. caryae was first described in 1881 by Grotefrom material col- lected by Coquillet. Illinois was given as the type locality. (Bull. Geol. Survey, VI, 590). - ' In view of this seeming confusion the name has been changed from Acrobasis caryivorella, which was used by the author in two former publications (Journal Economic 'Ent., Vol. 14, No. 2, April, 1921; Journal Economic Ent, Vol. 18, No. 1, Feb., 1925) to that of Acro- basis caryae. With the information available it is not possible to determine the correct scientific name of this insect. In order to assist in clarifying this situation a technical study has been made of the various stages of the insect. These studies will be included in a succeeding bulletin. ' BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION Fig. 1. Adult moths, male and female. LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 7 FOOD PLANTS So far as is ‘known the only food plant is the pecan (Hicoria pecan). The larvae of the spring brood feed upon the inside of the tender branches and upon buds; occasionally some of them also feed upon the leaves and catkins. In the first and second generations the larvae feed upon the interior of the nuts. Most of the third generation larvae feed in the shucks but some of them enter the nuts. The fourth-generation larvae feed in the shucks of the nuts, but if nuts are not available they feed in the axils of the leaf stems and on buds. OUTLINE OF THE LIFE HISTORY There are four stages in the life history of this insect; the adult or moth, the egg, the larva or worm, and the pupa or resting stage. Adult The adult is a small gray moth which is '7 to 9 mm. or about one- third of an inch in length. It has a wing expanse of 20 to 22 mm. or about an inch. The width at the extremity of the wings when the moth is at rest (Fig. 1) is 5 to 6 mm. or about one-fifth of an inch. The ground color is pale gray, which is intermixed with black- ish. The most distinctive character by which this moth may be recog- nized is a ridge of scales which extends horizontally across the wings about on.e-third the distance from the head to the extreme tip of the wings. This ridge of scales is easily rubbed oif and may be entirely absent in old specimens. The moths fly only at night and are not at- tracted to light. They are very adept at hiding and are seldom seen in the field. One can easily obtain a few specimens for study by placing pupae in a box or jar and then examining it daily until the moths emerge. The moth is well protected by its coloration and is very difficult to locate when at rest on a branch. When disturbed, it flies with a quick darting flight which is difficult for the eye to follow, but after alighting it remains perfectly quiet. The two sexes are very similar in appearance. The male may be distinguished from the female by a black streak on the underside of the fore wing near its outer border. The female can be most easily distinguished by the rounded genital opening, which is surrounded by a ring of yellowish hairs. Both sexes are very active and are dilficult to handle. The length of life of the adult is very short and is probably not more than five to eight days. When kept in experimental cages most of the moths died within three to five days. Egg The eggs are elliptical in shape (Fig. 2) and are finely reticulated. They are just large enough (.65 mm. long and .36 mm. wide) to be T seen without the aid of a lens, but it is necessary to use a lens to 8 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION . form an idea of their appearance. Whenfirst laid they are bluish- white but in a few hours small red spots appear, which later increase in size, and the egg is pinkish to reddish in color up to the time of hatching. The eggs are convex above and flattened below and are firmly fastened to the nut with a sticky substance which makes it ‘difficult to remove one without injuring it. In hatching, the larva cuts its way out of one end of the egg, after which the shell has a snowy white appearance. The egg shell may remain intact for a long timeand can be seen for several days and sometimes for weeks Fig. 2. The eggs of the pecan nut case bearer, showing their position on the nuts. A. Shows position of egg when deposited below calyx. . B.-C. Shows a single egg much enlarged. D. Shows position of egg both below calyx and at base of nut. LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 9 after hatching when the eggs are deposited in grooves on the sides of the nuts or where they may be readily seen. The eggs aredeposited singly in the tip of the pistil or on top or under the calyx lobes by the moths of the spring brood. When the pmoths ofxthe first and second generations emerge, the nuts arerlarger, the pistil is dry, and the calyx lobes have usually fallen ofiY. For that reason the eggs are deposited in grooves at the tips and bases of the nuts or on the buds below the nut clusters. The moths of the third generation usually deposit their eggs as in the preceding generations. Ifnoenuts are available, the eggs are deposited on buds between the bud and the branch. The duration of the egg stage is four to nine days, depending upon the temperature; except in early spring or late fall, the eggs hatch in four or five days. Larva The larva or worm (Fig. 3) is the stage of the life history which is familiar to most people. This is the only stage of the insect which is injurious. When first hatched from the egg, the larva is whitish to pinkish in color. Later it becomes an olive gray and remains that color until just before pupating, when it turns to a jade green. The mouth parts, and the thoracic and anal shields are yellowish brown. The surface of the body is much wrinkled and sparsely covered with white hairs. There are four pairs of abdominal and one pair of anal prolegs in addition to the regular number of legs on the thorax. The larva is cylindrical and tapers slightly near the posterior end. When full grown it is 11 to 13 mm. or about one-half inch in length; occasional specimens reach a length of 15 mm. Soon after hatching, the larva begins to wander about in search of a place to hide and then beginsfeeding. A location is preferred where two or three nuts touch and form a dark and protected place. At first they also ‘feed on the buds below the nuts but l.ater enter the nuts by cutting circular holes at their bases. Before entering a nut a larva usually spins a pro- tective sheet of silk, attaching it to two or three nuts. This protects the larva from parasites and predacious enemies and also prevents it from falling to the ground with nuts which would drop from the trees if not fastened to nut stems or other nuts with the silken thread. After hollowing out one nut a larva goes to another and when most of the nuts in a cluster have been destroyed, it goes to still another cluster. Many of the larvae of the third generation do not enter the nuts but feed on the interior of the shucks. The duration of the larval stage varies from 1'7 to 51 days. a Before pupating, a larva spins a flimsy cocoon which is composed ‘of silk and excrement. It is due to this habit that the name “pecan nut case bearer” has been applied. 1O BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION Fig. 3. Antenlarged view of the larva and a larva resting on the side of a mature nut“ LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 11 Pupa The pupa (Fig. 4;) is similar to that of many other small moths. It is 8 to 1O mm. in length, and when first formed is jade green in color, but a few hours after pupation turns to a brownish-yellow color and later to a blackish-brown. The two most distinctive characters are four golf-club-like setae and the cremasters or hooks both located at the posterior end, the latter at right angles to the longitudinal axis. In the spring brood the pupal stage is passed Within the larval bur- row in the new growth; in the first and second generations it is passed inside the nut; in the third generation, in the larval burrow in the shuck of the nut or in a cavity which the larva has hollowed out where three or four nuts touch at their bases. The duration of the pupal stage varies from 5 to 24 days, averaging about 9 days in summer and 12 to 14 days in the spring. Number of Generations The number of generations of the pecan nut case bearer varies. In three of the siX years in which detailed observations were made there were four generations each year; in the other three years there were two generations. . Method of Hibernation The winter is passed in the larval stage in a thick tough silken hibernaculum (Fig. 7) which is made by the larva and is usually situated between a bud and a branch. At the approach of winter or under adverse food conditions a larva constructs its hibernaculum and remains in it until the spring of the following year. The hibernac- ulum is more or less saucer-shaped and about 3 mm. in diameter. Fig. 4. The outer shell of a nut is removed to show the position of a pupa in a mature nut. 12 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION EXPLANATION OF TERMS USED The term “hibernaculum” (Fig. '7) is applied to the tough silken case which the larva spins at the approach of winter or when there is a shortage in the food supply. Tbe larvae remain in the hibernacula until the following spring. All of the larvae which pass the winter are known as “overwintering larvae.” The “overwintering larvae” comprise all the larvae of the fourth generation, some of the larvae of the third generation, and, in some cases, larvae of the second generation and probably also some of the first generation. None of the larvae of the fourth generation transform to pupae until the following spring. When there are but two generations, the larvae of the second generation spin hibernacula, and probably part of those of the first generation do so, too. The “spring brood larvae” are those which have successfully passed the winter and begin feeding in the spring. The term “brood” is applied only to the larvae which have passed the winter and to the resulting pupae and moths. - The overwintering generation or spring brood includes: 1. All the non-transforming larvae of the first, second, and third generations and all of the larvae of the fourth generation of the previous year. 2. All the pupae from the spring broad larvae. 3. All of the moths from the spring-brood pupae. The first generation includes: 1. The eggs laid by spring-brood moths. 2. The larvae of the first generation. (a) Transforming firstegeneration larvae. (b) Non-transforming first-generation larvae. 3. The pupae of the first generation. i 4. The moths of the first generation. The second generation includes: 1. The eggs laid by moths of the first generation. 2. The larvae of the second generation. v (a) Transforming second-generation larvae. b) Non-transforming second-generation larvae. 3. The pupae of the second generation. 4. The moths of the second generation. The third generation includes: 1. The eggs laid by moths of the second generation. 2. The larvae of the third generation. - LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 13 (a) Transforming third-generation larvae. (b) N on-transforming third-generation larvae. 3. The pupae of the third generation. 4. The moths of the third generation. The fourth generation (not completed) includes: 1. The eggs of the fourth generation. - 2,. The larvae of the fourth generation, all of which are non- transforming larvae. NUMBER OF ANNUAL GENERATIONS The ‘number of annual generations varies. There were four gen- erations in 1919, 1921, 1923, 1924, and 1925; in 1920 there were practically only two generations, the third being negligible; in 1918 and 1922 there were also two generations. Field observations indicate that the cause of this variation in the number of generations is the scarcity or abundance of nuts. In addi- tion to the food supply, climatic conditions and the presence of a large number of parasites and predacious enemies also play some part in determining the number of generations. In the years 1919, 1921, and 1923, in which heavy crops of nuts matured, there were four gen- erations. But in 1920 and 1922, following years of heavy crops, there were but two generations. An analysis of the estimates of a full crop compared with the data on number of generations indicates that: when there was more than 20 per cent of a crop of nuts matured there were four generations; if less than 20 per cent of a _crop ma- tured there were but two generations. In 1919 it was estimated that 98 per cent of a full crop matured and there were four generations of the pecan nut case bearer; the third and fourth being the larger gen- erations. In the spring of 1920 nut case bearer larvae were very abundant and a large crop of nuts was set at both College and Cor- sicana; the first-generation larvae were numerous enough to destroy the entire crop on trees which were not sprayed at these places; that yea-r there were but two generations with a few stragglers in the third. In 1921, on account of cool weather, the pupal period of the spring brood extended over a long period of time with the result that there was no great emergence of moths at any one time. The larvae of the first and second generations were not numerous, but in the third, and fourth generations they were abundant. In addition the weather was warm in October and many larvae of the fourth generation fed until the last of the month before going into winter quarters. Finally it v may be stated that in 1921' the temperature was unfavorable during the development of the spring brood; therefore the insect did not be- come abundant until the third generation. Since there was a good crop of nuts set, four generations resulted anda large number of the fourth-generation larvae spun hibernacula. 14 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION The spring of 1922 was favorable to the development of the large number of larvae which passed the winter; the spring-brood moths emerged over a short period of time; there was not as large a crop of nuts set as in the two previous years, hence there was not a suffi- cient supply of‘ nuts and there were only two generations. In 1923 very few spring-brood larvae could be found; the number of larvae increased in the first and second generations, and in the third generation the larvae were also abundant, decreasing in number in the fourth generation. From 1918 to 1923, inclusive, climatic conditions and the food supply are thought to have been the determining factors inregulating the number of generations over a wide extent of territory. In addi- tion, the large number of parasites and predacious enemies operated much the same as the lack of food supply and unfavorable weather conditions in some localities where extensive collections of larvae were made. In 1924 and 1925 there Were four generations. Larvae were col- lected at College in both years but no detailed life history studies were made and on that account it is possible to make only general comparisons with the previous years. A plentiful supply of nuts seems to have been the explanation for four generations in 1924. Probably some other factor affecting the number of generations has not been determined. Although the Bureau of Agricultural Economics re- ported the size of the crop of 1925 to be about the same as that of 1924, estimates and observations indicate that the yield was much smaller in the sections where the investigations were conducted. How- ever, in spite of the small crop of 1925, there were four generations. Table 1. Summary of the Number of Alngnligallggnerations of ‘the Pecan Nut Case Bearer, Generation ' Year Spring brood First I Second Third | Fourth 1918 . . . . . . .. Spring First Second (incomplete) . . . . . . . . . . . . . . . . . . . . . . . . . ._ . . . . . . . . . . 1919 . . . . . . . . Spring First Second . . . . . . . . . . . . Third . . . . . . . . . . . .. Fourth (incomplete) 1920 . . . . . . . . Spring First Second (partial). . . . Third (incomplete) . . . . . ._ . . . . . . . . . . 1921 . . . . . . .. Spring First Second ._. . . . . . . . _ . Third . . . . . . . . . . . . . Fourth (incomplete) 1922 . . . . . . . . Spring First Second (incomplete) . . . . . . . . .- . . . . . . . . . . . . . . . . ._ . . . . . . . . . . 1923 . . . . . . . . Spring First Second . . . . . . . . . . . . Third . . . . . . . . . . . . . Fourth (incomplete) The percentage of a full crop in the following table is compiled from estimates made by the Bureau of Agricultural Economics of the U. S. Department of Agriculture. An estimate of the number of cars shipped is difficult to make, as the reports from different large ship- pers vary greatly. The calculated number of “cars shipped” is based upon the number of cars shipped in 1919, when the census bureau reported that Texas produced 16,755,424 pounds of pecans, and the most authentic reports show that shippers of pecans estimated that Texas shipped 500 carloads of pecans in that year. The number of LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER . 15 cars shipped in the other years given was calculated on the basis that 500 cars were 98 per cent of a full crop. For example, the crop in 1920 was 8 per cent of 510 cars. Table 2. Relation of the Number of Annual Generations to Pecans Produced. 1 1 Estimated Number of Number Per cent of , Cars Shipped generations of Year a full crop the pecan nut 1 Estimate of case bearer g Calculated I shippers 191s . . . . . . . . . . . . . . . . . . . .. 18 90 1 . . . . . . . . . . . . .. 2 1919 . . . . . . . . . . . . . . . . . . . . . 98 500 500 4 1920 . . . . . . . . . . . . . . . . . . . .. s 4o 1 2 , fig; . . . . . . . . . . . . . . . . . . . .. 4g 238 2Z5 g 19231111IFIIIIIIIIIIIIIII 49 250 355 4 1924 . . . . . . . . . . . . . . . . . . . . . 3O 150 250 4 1925 . . . . . . . . . . . . . . . . . . . . . 3O 150 60 4 1918 1919 , 1920 1921 192.2 1925 500 CATZC. ENE! El EFig. 5. Comparison of annual nut production and number of generations per year. The “estimates of shippers” Were calculated from estimates furnished by shippers at various points. According t0 some of the largest shippers of pecans, the number of cars shipped in 1923, 1924;, and 1925 does not correspond with the 16 D BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION _ calculated estimates. One shipper who handles a large part of the crop estimated that 325 cars were shipped in 1923; 250 in 1924; and only 60 cars in 1925. That being the case, the number of generations in 1925 was an exception, according-to the deduction made as a result of the investigations from the years 1918 to 1923, inclusive; but if the estimate on the per cent of a full crop made by the Bureau of Agricultural Economics is more nearly correct, then the number of generations is correlated with the annual production as in the vears 1918-1923, inclusive. METHOD OF STUDY A The problem of working out the life history of the pecan nut case bearer has been largely one of technique. Many difficulties were en- countered and it was necessary to collect a large number of larvae in order to secure a sufficient supply of moths to carry on the life history work. Larvae were collected from both native and cultivated trees in the vicinities of College Station and Oorsicana; at Winona they were collected from cultivated trees only. Each year When the buds of the pecan tree began to swell, the collecting of larvae was com- menced and was continued as long as it was possible to find them in the field. The larvae of the spring brood were reared in four-ounce salve boxes—a circular piece about an inch in diameter was cut out of the lid of each box and a piece of fine-mesh copper screen wire was soldered over the hole on the inside of the lid. The ventilation thus provided kept the boxesfree from moisture and the temperature within was an approximation to that of the surrounding air. The larvae were supplied daily with leaves and twigs which were placed on the bottom of the box and the twigs containing the larvae were placed on the fresh food. To secure normal development it was necessary to keep the larvae supplied with food continuously, for if the supply of food became stale or dry for a single day many of them died. The larvae were left in the four-ounce salve boxes until pupation occurred. The pupae were then placed in two-ounce pasteboard pill boxes and kept in a large screen-wire breeding cage, where they were examined daily. Only a single larva was placed in a salve box, because if two or more were confined in the same place frequently one ate the others. The larvae were disturbed as little as possible after entering the twigs and were allowed to remain in their burrows until they left them of their own accord. All the moths which emerged on the same day were placed in an- other large breeding cage. The moths do not mate readily in cap- tivity and it was necessary to place a large number in the mating cages at one time to get any considerable. number of females fertilized. Observations on oviposition were made in a photographic dark room with the aid of a red light suspended by the side of a screen-wire LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 17 Fig. 6. Method of feeding the adulf with a medicine dropper. 18 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION ‘ mating cage having a glass door. The. light was suspended on the side opposite to the glass door so that the moths within could be observed by looking through it. " It was necessary to solve the problem of keeping the adults alive in captivity before any progress could be made with the life history work. They were fed on a dilute solution of sugar water. Few of the moths would feed the first day after emergnce, but on the second day most of them could be induced to feed by holding a medicine dropper with a drop of the solution on the end of it near the proboscis. (Fig. 6.) After they had fed once it was not difficult to get them to feed again, for as soon as the medicine dropper was held in the vicinity of the moth it began hunting about until the drop of sugar water was located. Sometimes a drop of liquid was placed in the vicinity of the moth, which was then touched with the medicine dropper. It responded to this and searched about until the drop of liquid was located. They were fed early in the morning and again in the afternoon. In addition to this they had access to water, which _ was sprayed on the cages every evening just before dark. The tem- perature in the large cages was regulated by spraying them with water several times a day and on exceptionally hot days this was done once an hour. The moths were usually kept inthe large mating cages for two nights after emergence. On the second or third afternoon after emergence the moths were taken from the large breeding cages and placed in cylindrical wire cages which were six inches long and two inches in diameter. One end of these cages was open and the other was a solid piece of tin. If allowed to come in contact with screen wire the moths frequently thrust the tibial spurs through the meshes and often pulled off a leg. For this reason the inside walls and tops of the large cages were lined with fine muslin and the small cages were lined with press board, which was made in the shape of cylinders and inserted in the wire cages. It was necessary to firmly push each press-board ‘fcylinder against the closed end of the wire cage; otherwise the moths would crawl around the bottom end of the press-board cylinder and be killed by the pressure of the press board against the wire. A single pair was placed in each small cage, after which the open end was then closed with a plug of moistened cotton and the cages were numbered and tagged with the date of emergence of the moths. A pair was put in each small wire cage, which was then placed over a cluster of nuts which hadypreviously been examined to see that no eggs had been deposited by free-flying moths. The open end was then plugged with cotton. The cages were removed from the trees early in the morning and the nut clusters were examined for the presence of eggs. If any were found, the information was recorded on a tag which was attached to the cluster; it was also recorded in a ledger. The nut clusters were left uncovered in the beginning of the work but so many eggs were destroyed that it was necessary to protect them LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 19 from other insects and mites. This protection was secured by the use of six-ounce gelatin capsules and caps of press board, made in the form of cylinders. To make a cap, one end of each cylinder was pressed together and firmly stapled. These caps were placed over the nut clusters and the open ends closed with cotton plugs. Due to the fact that many larvae became entangled in the cotton, this was later rolled in a piece of tissue paper and Wrapped around the limb six or eight inches below the cluster, after which the press-board cap was forced down over the cotton and tissue paper. Some larvae escaped between the plug and the sides of the press board, and six-ounce gel- atin capsules were later used to prevent their escaping. The leaves nearest to the nut clusters were cut 0E, after which the nut clusters - were covered with the capsules, which previously had been perforated in order to allow moisture to escape. The capsules were then covered with press-board caps, the open ends of which were closed with a roll of cotton and tissue paper. After the eggs hatched, the larvae were kept for one or two days on the cluster where the eggs had been deposited and then transferred singly to separate clusters with a camePs-hair brush. In order that the larvae from eggs of free-flying moths might not gain access to the nut clusters, a piece of muslin was wrapped around the limb one or two feet below the cluster and a ring of tanglefoot applied on the muslin. This had an added advantage in that it served as a barrier against ants which attack both eggs and larvae. It was necessary to examine the clusters daily because some of the nuts became detached as a result of malnutrition following the removal of the leaves. For this reason the nuts containing the larvae were changed to new nut clusters every two or three days. The nuts containing the larvae were removed from the cluster and tied to new nut clusters with a piece of thread. Just before the larvae pupated, the infested nuts were removed from the trees and taken to the laboratory. The same procedure was used in rearing the first-generation larvae in the laboratory that was used in the field. A supply of pecan twigs with nut clusters was gathered daily and the larvae were confined to these nut clusters by the use of gelatin capsules. After pupation, the pupae were placed in two-ounce pasteboard pill boxes and the same procedure followed as has already been given for the spring brood. The life history work of the second and third generations was con- ducted similarly to that of the first, except that the nuts were too large to be covered with gelatin capsules; hence press-board cylinders were used instead. These cylinders were six inches long and three- inches in diameter, one end being closed with a cork stopper. These‘ were placed over the nut clusters and the open ends closed with rolls of cotton wrapped in tissue paper. After the larvae of the fourth generation had gone into hibernation they were protected from enemies during the winter with fine-mesh 20 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION copper-wire cylinders, used in the same way as the press-board cylin- ders were used in the second and third generations. HABITS OF THE ADULTS The moths fly only at night. They are repelled by a strong light, but are attracted toward diffused light of a moderate intensity. When an electric light bulb was inserted in a breeding cage the moths flew against the sides of the cage with suflicient violence to injure them- selves. Several attempts to attract the adults to a two hundred candle power gas lamp in the pecan orchard failed; but when the large breed- ing cages were placed inside of a building with one side of the cage near a window, the moths collected on the side nearest the light. Advantage was taken of their reaction to different light intensities in ' putting the small cages on the nut clusters. The cotton plug was removed slowly and replaced quickly when the cages were put on the trees. If this was done in the afternoon while the light intensity was still great the moths were less liable to dart out than when the cage were put on the trees at dusk. * The adults have two characteristic modes of flight, a short dart, which is their preference, and a flutter for long distances. When dis- turbed in a breeding cage or liberated in the vicinity of trees or other objects, the moths dart swiftly and one must watch very closely to find them after they have alighted. When liberated in an open space a long distance from trees or other upright objects, they flutter up- ward and are lost to sight in a few seconds. During the day the moths assume a characteristic pose, remaining motionless and in the same place for hours at a time. ‘When in this position the antennae lie parallel on the median line of the body and are covered by the wings, which are held roof-like ; the head is extended forward and upward. This position and their protective coloration cause‘ the moths to closely resemble buds, small twigs, and protuber- ances on the bark. It is because of this fact that individualshave been seen in the field only a few times. On several occasions seventy or eighty moths were liberated in a tree in the evening. A diligent search_ was made the next morning but only two or three moths were found after they had been set free. On the other hand, this habit of repose seems to be a disadvantage to the moths, as they are more easily caught by predacious enemies. When spiders gained entrance to the mating cages they killed many moths. For that reason the mating cages could not be placed in the vicinity of leaves and grass. In the breeding cages the moths often concealed themselves by crawl- ing into small cracks and it was necessary to keep all openings and cracks tightly closed with cotton. The adults were fed on a dilute solution of sugar and water; the females and some of the males would usually feed the second day after emergence but it was not always possible to get the males to feed. LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 21 Fig. 7. An enlarged drawip of a hibernaculum or overwintering cocoon. Shows the pos;t1on of a hnbernaculum on a bud. B. An enlarged vlew of the same. (Drawn by J. F. Knull.) 22 BULLETIN NO. 328,, TEXAS AGRICULTURAL EXPERIMENT STATION When the moth is feeding, the proboscis is extended forward and the antennae are held in front of the head and slowly moved up and down. As soon as they have finished feeding the antennae are brought to lie on the median line of the body and the moths assume the posi- tion of repose previously mentioned. When placed on a pecan leaf the proboscis is first extended and then moved about here and there over the surface of the leaf. The moths do not mate readily in captivity, and only about 20 per cent of the females were fertilized in cages. Many unfertilized females oviposited but usually laid only a few eggs. A few females began egg deposition on the second night after they emerged but most of them began to oviposit on the third and fourth nights. In most cases the eggs were deposited in a few nights, and sometimes all of them were deposited in one night. In the fourth generation the moths did not oviposit as soon after they emerged as they did in the preceding generations, which was probably due to the cool nights at that time of the year. In 1923, after many_failures to get egg deposition from moths of the fourth generation, some females were placed in small breeding cages, together with clusters of nuts and, at night kept in a room in which a constant temperature of '70 degrees Fahrenheit was main- tained. Some moths laid as many as two hundred and fifty eggs under these conditions but most of these eggs were infertile. HABITS OF THE LARVAE The larvae pass the winter in hibernacula (Fig. 7), which they spin at the approach of winter or when the food supply is about ex- hausted. Each hibernaculum is usually attached to a bud and lies between the bud and a branch. At the approach of the first warm days in the spring the larvae begin activity and commence to feed while still in the hibernacula. The larvae remain in the wintering hibernacula for some time after they begin feeding and cut small holes through the hibernacula, through which frass and excrement are pushed to the exterior. Later they come out of the hibernacula and enter the growing branches at the junctures of the leaf stem and the main branches to which the leaf stems are attached (Fig. 8). The places at which the larvae enter the branches may easily be detected by the frass and excrement pushed out at those points. Some of the spring-brood larvae also feed on buds and catkins. When a larva has become full grown it closes the place where it entered the branch with silk and excrement and then spins a flimsy cocoon within the larval burrow. It then turns to a jade green color, after which pupation occurs. When the larvae of the first generation hatch, they crawl about rapidly until a place is found which affords protection from enemies and the heat of the ‘sun. A few minutes after hatching, a young LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER .23 Fig. 8. Twig showing whereidlarvaihas entered a growing branch. (after J. B. Gill, U. S. D. A.) 24 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION ‘larva may be several feet from the place Where it was hatched. Some larvae select enclosures which are formed by three or four nuts of a cluster touching at their bases; others begin feeding in the axils of buds, later entering them. The habit varies, depending to some extent upon the variety of nuts. Most of the larvae in the cages fed upon It buds for two or three days and then entered the young nuts, which were about the size of a garden pea, by cutting round holes at their bases. A few larvae entered the nuts immediately upon hatching, but most of them fed on the buds below the nuts beforeentering. Before entering a nut cluster, a partly grown larva spins a series of silken threads (Fig. 9), which are attached to the individual nuts in a cluster and also to the nut stems and occasionally to leaves or branches. The larva does this by raising the fore part of its body until the head and about half the body is‘ at right angles, or nearly so to the remainder of the body. In this position the fore part is free to move over a considerable radius, while the other part clings to the branch or nut on which it is resting. The larva then attaches one end of a strand of silk to a nut and as it moves its head continues spinning the silken thread- until the head reaches the nearest nut or nut stem to which the other end is to be attached. This process is repeated again and again until a sheet of silk is formed, after which the larva changes its position and continues the process. A larva will seldom enter a nut when it is the only one of a cluster left unless there are no more nuts to be found. Within this silken enclosure the larva cuts a round hole at the base and then hollows out the in- terior of one of the nuts, going to another after it has eaten the "interior of the first. When nuts are plentiful, a larva seldom destroys all the nuts in a cluster but usually goes to another cluster when there are still one or two nuts which have not been attacked. These silken enclosures probably serve several purposes. Shortly after being attacked by the larva a nut may become detached from the nut stem and fall to the ground. If the nuts containing larvae were not attached to something, many larvae would fall to the ground and be killed by ants. When they are not feeding the larvae prefer to stay in dry hollow nuts, which serve as domiciles. The silken enclosure also serves to some extent as a protection against predacious and parasitic enemies. A larva travels from cluster to clusterluntil full grown; then it enters a dried nut, the interior of which has pre- viously been hollowed out. The entrance is then closed with frass and silk, after which a flimsy cocoon is constructed and pupation takes place. In entering nuts, the larvae seldom feed on the chips which are cut in making the entrance hole but usually cast these aside. The second generation larvae enter the nuts and construct silken enclosures similar to those of the first generation. The. nuts at this time are much larger and are not detached from the nut stems as easily, and for this reason the larvae sometimes enter nuts without tying them fast with silken threads. Fewer nuts are destroyed by one larva in LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER Fig. 9. “The larvafusually spins a series of silken threads before entering ainut. a ;:\—“— >26 BULLETIN NO. 328, TEXAS AGRICULTRAL EXPERIMENT STATION the second generation than are destroyed by a larva in the first generation. The greater number of larvae of the third generation tunnel about in the shucks of the nuts or feed at the bases of the clusters where three or four nuts touch. Some enter and hollow out the interior of nuts as in the first and second generations, but most of them feed in the shucks. When they are feeding in the shucks, excrement and frass are pushed out at the places of entrance. This distinguishes the work of the pecan nut case bearer from the shuck worm, which feeds in the shuck at the same time of the year but does not push the excrement out of the tunnel. Some of the larvae of the third generation feed for a while on the nuts and then construct their overwintering hibernacula even when there is a supply‘of nuts.- Others feed until full grown and then construct their cocoons in the shucks or interior of the nuts or in cavities that have been hollowed out where the bases of several nuts touch, after which they pupate. _ The larvae of the fourth generation feed in the shucks if these are still on the trees, but if none are to be found they feed at the bases of leaf stems and buds, after which they, too, construct their over- wintering hibernacula. . I SUMMARY OF THE LIFE HISTORY STUDIES BY . GENERATIONS Spring Brood At the approach of the first warm days of spring, the larvae become active and begin to feed on the buds to which the hibernacula (Fig. 7) have been attached. At first they do not go outside of the hiber- nacula but feed by cutting a hole through the side attached to the bud. The first larvae begin feeding from the first to the fifteenth of March, depending to a great extent upon climatic conditions. Later they enter the succulent new growth at the juncture of the leaf stems and branches. (Fig. 8.) The places where they have entered may be detected by the frass and excrement which are pushed out of the burrows at those places. The larvae feed in the interior of the branches until full grown and then they spin their cocoons and pupate in these larval burrows. Pupation begins the latter half of March or the first few days of April. The duration of the pupal period is 12 to 18 days, depending upon the temperature. The spring-brood moths commence to emerge about the middle of April and continue to emerge until the middle or latter part of May. The greater num- ber of moths emerge between May 9 and May 13. The females begin to lay eggs on the second, third, or fourth night after emergence, one moth laying fifty to one hundred eggs. The eggs are usually de- posited in the tip of the nuts but may be laid on the upper or under side of the calyx and occasionally on the side of the nuts. These eggs are the beginning of the first generation. LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 27 Table 3. Summary of the length of the pupal period of the pecan nut case bearer. Spring brood. 1918-1923. \ Date of Period . _ ov_er _Number Length of pupal Year Place First Max. Last which fmdividuals stage, days . pupa- pupa- pupa- pupation observed ——————————-— tron tion tion occurred Avg. Max. Min. 1918 College . . . . . . . .. April .~1 April 17 April 27 27 132 17.5 24 l9 1919 College . . . . . . . . . April 12 April 22 May 3 22 235 13.6 18 11 1920 College . . . . . . . . . April 12 April 24 May 8 27 405 12. 1 16 8 1921 College . . . . . . . . . Mar. 27 April_25 May 6 41 228 18.5 24 14 Clarksville*. . .. . April 18 April 26 May 12 25 133 17.3 20 14 1922 College . . . . . . . . . April 16 April 25 May 14 29 663 13.8 21 9 Winona* . . . . . . . April 20 April 26 May 14 25 231 14.9 19 11 1923 College . . . . . . . . . April 27 April 28 May 16 20 123 14.4 18 10 Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2150 . . . . . . . . . . . . . . . . . . *Larvae collected at Clarksville and Winona but bred through at College Station. Table 4. Summary of the emergence records of the spring-brood moths of the pecan nut case bearer. 1918-1923. Date of Number days on No. Year Place First Max Last which moths No. No. emerg- emerg- emerg- emergence observed males females ence ence ence occurred ""4 1918 College . . . . . . . . . . . . . April 16 May 7 May 14 2 106 56 50 1919 College . . . . . . . . . . . . . April 27 May 5 May 17 21 187 84 103 1920 College. . . . . . . . . . . . . April_'26 May 7 Mayr2l 26 380 178 202 1921 College . . . . . . . . . . . . . April 15 May 13 May 20 36 202 w. 116 86 College . . . . . . . . . . . . . I Corsicana* . . . . . . . . . April 15 May 13 May 23 39 333 165 168 Clarksville* . . . . . . . . v 1922 College . . . . . . . . . . . . . May 3 May 9 May 24 22 639 298 341 College . . . . . . - . . . . . . . Winona* . . . . . . . . . .. May 3 May 10 May 24 22 820 395 425 1923 College . . . . . . . . . . . . . May 7 May 13 May 28 22 196 71 ‘125 Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2022 949 1073 *I_.arvae collected at Corsicana, Clarksville, and Winona, but bred through at College Station. A. A First Generation The eggs laid by the wring-brood moths hatch in 4 or 5 days into pinkish-white larvae or Worms which feed for 1 or 2 days on the buds below the clusters. These larvae soon turn to an olive-gray color, and after feeding on the buds for a short time generally enter the young nuts by cutting entrance holes near the bases of the nuts, but 28 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION occasionally at other points. When one nut has been hollowed out a larva goes to another and may attack several clusters before it is full grown. A nut which has been. hollowed out for some time and has become dry and hard is selected as a location in which the pupal period is to be passed. The point of entrance is closed with frass and excrement, after which the larva spins a flimsy cocoon and pupates. Before pupating, the larva turns to a jade green color and the pupa when first formed is of the same color. The duration of the larval period is about 25 days and that of the pupal period about 9 days. ‘The moths of the first generation begin to emerge the first week in July. On the second or third night after emerging the females begin to oviposit. The eggs are deposited in grooves near the tips and bases of the nuts or on buds below the nut clusters, because by the time the moths of this generation have emerged the pistil and calyx have dried up and the most suitable places are the grooves on the sides. Table 5. Summary of the length of the pupal eriod of the pecan nut case bearer. First Generation. 1 18-1923. Date of Period over Number Length of pupal Year Place First Max. Last which individuals stage. days pupa- pupa- pupa- pupation observed —-————-i——— tron tion tion occurred Avg. Max. Min. 1918 College . . . . . . . . . May 29 June 12 June 18 21 161 8.5 12 I5 1919 College . . . . . . . .. May 31 June 16 July 2 33 229 .6 13 7 June 19 1920 College . . . . . . . . . May 31 June 5 June 29 30 " 249 9.0 11 i5 C0rsicana*. . . .. June 18 June 20 July 3 16 101 9.8 13 l7 1921 College . . . . . . . . . June 6 June 12 June 28 23 58 9.5 12 l 7 Winona* . . . . . . . June 8 June 2O July 2 25 230 10.6 13 I 6 1922 College . . . . . . . . . June 6 June 6 June 28 23 196 9.0 13 v 6 Corsicana*. . . . . June 21 June 24 July 4 14 78 9.8 12 8 Winona*. .. . . .' . June 13 June 26 July 8 26 T 240 9.7 v 13 6 1923 College . . . . . . . . . June 12 June 18 July 8 27 206 9.4 16 l 8 Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1748 F V.‘ *Larvae collected at Corsicana and Winona but bred through at College Station. LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 29 Table 6. Summary of the emergence records of the first generation moths of the . pecan nut case bearer. 1918-1923. Date of Number ~', _ da s‘ on No. 1 Year Place First Max. Last w ich moths No. No. . - emerg- emerg- emerg- emergence observed males females ence ence ence occurred 11918 College . . . . . . . . . . . . . June 5 June 14 June 28 24 p333 145 188 l: 1919 College . . . . . . . . . . . .. June 13 June 28 July 10 28 222 103 119 . 1920 College . . . . . . . . . . . . . June 6 June 15 July 8 33 389 219 _ 170 g College ........... .. Corsicana* . . . . . . . .. June 6 June 15 July 13 38 537 289 248 '; 1921 College . . . . . . . . . . . . . June 11 June 11 July 8 28 152 56 96 . College . . . . . . . . . . . . . “Y! Winona* . . . . . . . . . . . June 11 June 23 July 14 34 456 209 47 College . . . . . . . . . . . .. June 13 June 19 July 8 25 245 106 139 ~' June 27 ,:1922 College . . . . . . . . . . . . . Corsicana* . . . . . . . . . June 13 June 30 July 14 32 1108 478 630 p W1nona* . . . . . . . . . . . _ 11923 College . . . . . . . . . . . . . June 15 June 22 July 16 32 519 231 288 Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3175 1455 1720 *Larvae,_collected at Winona and Corsicana but bred through at College Station. Second Generation The eggs of the second generation hatch in 4 or 5 days after de- position and the larvae feed on the buds below the clusters and then enter the bases of the nuts and hollow out the interior as in the first generation. Due to the fact that by this time the nuts have increased jvery much in size, one larva does not destroy as many nuts as does a single larva of the first generation. A‘ larva, when mature, selects “a dried nut, the interior of which has previously been hollowed out, and closes up the entrance with silk and frass, after which it spins '11 flimsy silken cocoon and pupates. The larval period is about 33 days and the pupal period 9 days in length. The first larvae begin to pupate about the 15th of July and the last pupate during the first week in August. The moths of this generation begin to emerge the last week in July and the first week in August and continue to emerge until the last week in August or the first week in September. Three ‘or four nights after they emerge, the females begin oviposition, de- ‘positing the eggs in the grooves on the sides of the nuts or on buds in Ya manner similar to that described for the moths of the first generation. 30 Table 7. Summary o BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION f the length of the p Second generation. 1919-1920-1921-1923. upal period of the pecan nut case bearer. Date of Period a over Number Length of pupal Year Place First Max. Last which individuals stage, ays pupa- pupa- pupa- pupatlon observed _ tion tion tion occurred Avg. Max. Min. 19181‘ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1919 College . . . . . . . . , July 27 Aug. 6 Aug 12 17 111 9.0 12 6 Corsicana*. . . .. Aug. 16 Aug 19 Aug 25 - 1O 165 11.6 14 19201 College . . . . . . . . . July 17 July 17 Aug 11 26 20 9.2 12 8 July 29 1921 College . . . . . . . .. July 13 July 20 Aug. 11 30 369 9.0 11 Winona* . . . . . . . July 27 Aug. 9 Aug 14 19 127 9.3 17 19221 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1923 College . . . . . . . . . July 18 July 26 Aug. 27 41 508 9.0 12 5 Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1300 . . . . . . . . . . . . . . . . . . *Larvae collected at _Corsicana and Winona but bred through at College Station. TNo second generation pupae. IPartlal second generation. Table 8. Summary of the emergence records of the secondigeneration moths of the pecan nut case bearer. 1919-1920-1921 23- Date of Number _ da s on No. Year Place First Max. Last w ich moths No. No. emerg- emerg- emerg- emergence observed males females ence ence ence occurred 19181 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. College . . . . . . . . . . . .. Aug. 4 Aug. 14 Aug. 22 19 91 52 39 1919 Hg‘ College . . . . . . . . . . . . . Corsicana* . . . . . . . .. Aug. 4 Aug 24 Sept. 5 33 725 370 355 College . . . . . . . . . . . .. July 26 . _ . . . . . . Aug. 2O 26 16 5 11 1920i College . . . . . . . . . . . . . Corsicana* . . . . . . . .. July 26 . . . . . .. Aug. 21 27 28 13 15 1921 College . . . . . . . . . . . .. July 22 Aug. 5 Aug. 17 27 784 369 415 College . . . . . . . . . . . . .' a Corsicana* . . . . . . . . . July 22 Aug. 3 Aug. 28 38 978 473 505 Winona* . . . . . . . . . . . 1922T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1923 College . . . . . . . . . . . ..July 24 Aug. a Sept. 7 4s | s93 464 429 Total . . . . . . . . . . . . . . . .' . . . . . . . . . . . . . . . . . . . . . . . . . . . 2624 1320 1304 *Larvae collected at Corsicana and Winona but bred through at College Station. xNo second generation rnoths. Partial second generation. LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 31 Third Generation The eggs of the third generation hatch in 4 to 6 days. By this time theshells of the nuts have become hard and it is more diflicult for the larvae to gain access to the interior of the nuts. For this reason most of them feed in the shucks (Fig. 16-0). The placemost preferred is at the base of a cluster where three or four nuts touch and form an enclosure. If such a place is not available, the larvae tunnel about in the shucks or enter the interior of the nuts by cut- ting round holes at their bases. When they are feeding in the shucks, the excrement is pushed out of the burrows just as it is pushed from the burrows in the branches by the spring-brood larvae. Some of the larvae of this generation feed for a short time in the nuts and then spin overwintering hibernacula. Others live in the shucks until full grown and then close up the larval burrows and pupate. Whether the larvae enter the nuts depends on both the variety and the degree of maturity of the nuts. This generation overlaps the fourth generation.‘ Pupation begins the last week in August or first week in September, and the last larvae pupate the last week in September and the first days of October. The duration of the larvalperiod of this generation is about 28 days. The pupal period varies from 9 to‘12 days, depend- ing on temperature._ The moths of this brood begin emerging about the third week in September and continue to emerge until the 10th or 20th of October. If the nights are warm, the females begin t0 lay eggs on the fourth or fifth night after they emerge, but when the nights are cool oviposition is delayed for several days. The eggs are deposited in the grooves on the sides of nuts, at the bases of buds, and between buds and the branches to which the buds are attached. Table 9. Summary of the length of the pupal period of the pecan nut case bearer. Third generation. 1918-1923. _ Date of Period over Number Length of pupa] Year Place First Max. Last which individuals stage, days pupa- pupa- pupa- pupation observed —i——i——- tion tion tion occurred Avg. Max. Min. '1918*College......... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 51919 College . . . . . . . .. Sept. 17 OCL 5 00L 11 25 151 -12.9 1s e 1920* College. . .. . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. E1921 C0llege......... Sept. 12 Sept. 13 Sept. 2s 17 26s 9.5 13 s §1922*co11ege................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. £1923 College......... Aug. 22 Sept. 4 Sept. 29 s9 35s 12.9 17 s ‘ Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 770 . . . . . . . . . . . . . . . . . . ‘No third generation pupae. I 32 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION Table. 10. Summary of the emergence records of the third-generation moths of the pecan nut case bearer. 1918-1923. Date of Number days on N0. Year Place First Max. Last which moths No . No. emerg- emerg- emerg- emergence observed males females ence ence ence occurred 1918* College . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1919 College . . . . . . . . . . . . . Sept."29 Oct. 5 Oct. 25 27 348 159 189 Oct. 6 . 1920* College . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1921 College . . . . . . . . . . . . . Sept. 16 Sept. 24 Oct. 11 26 562 234 328 1922* College . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1923 College . . . . . . . . . . . . . Aug. 29 Sept. 17 Oct. 13 46 662 290 372 Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1572 683 889 ' *No third generation moths. Fourth Generation The duration of the egg stage varies from 4 to 9 days, depending upon the temperature. The larvae prefer to feed in the shucks of the nuts, but if these are not available they feed at the bases of buds and leaf stems. After feeding for a few days they spin overwintering hibernacula. The last date on which a larva has been observed to spin its hibernacula was the 10th of November. Theyaremain in these hibernacula until the following spring. SUMMARY OF THE LIFE HISTORY STUDIES BY YEARS 1918 In 1918 there were two generations. A representative number of records was obtained on pupation and emergence, but at that time the technique for studying the life history had not been perfected sufficiently to get egg deposition from moths in captivity, and for that reason the records on the time of egg deposition were obtained from free-flying moths. A large number of records was difficult to obtain in that manner for the reason that it was impossible to examine enough nuts daily to find a large number of eggs. The time of egg deposition and the duration of the egg stage were observed by select- ing certain nut clusters which" were easily accessible from the ground, marking them by tying a tag around the limb below each cluster and then examining the clusters daily. The larvae of the spring brood or overwintering generation began to pupate on April 1, the greater number pupated between April 16 and April 19, and the last ones pupated on April 27. The date of pupation was obtained on 132 individuals; moths emerged from 85, and 47 died as pupae. The minimum duration of the pupal period LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 33 was 9‘ days and the maximum duration 24 days, the average length being 17.5 days. The spring-brood moths began emerging on April 16, and continued to emerge until May 14, the maximum number emerging on May 7.. Emergence records were obtained 0n 106 moths, of which 56 were males and 50 were females. MARCH APRIL M4 F \V'A m‘ fir" o o .om<3.~ he@3£%o&2N£%m22~£%o°“ ~~I r ||IIIIIII| PLI/PIAFI/ ON . I I I I I k ‘TA1‘~TR“F.”Q@ I I I r DE:P|O5'/ T/o/vl a c/Ifit/t/re I . 51v TERM/Q‘ ‘NUT SF¥%N6 BROOD 1 i’ C; ENE FPA T/ON x _ h ‘J t Fig. 10. Diagram of the life history of the pecan nut case bearer at College Station, 1918. Length of life records were obtained on '79 moths, of which <10 were, males and 39 were females. The average length of,life was 6.45 days ;; the average length of life of the males 6.4 days and that of the females‘ 6.5 days. The maximum length of life of the males was 19 days andi that of the females 18 days. The period from the time when the first larvae were observed until the last moth died-was 63 days, which was approximately the length of the spring brood. Thefirst-generation larvae began to pupate on May 29, the greater- number pupated between June 8 and June 13, and the last ones pupated on June 18. The date of pupation was obtained on 161 in» 34 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION dividuals; moths emerged from 117, and 44 died as pupae. The mini- mum duration of the pupal period was 5 days, the maximum 12 days, and the average 8.5 days. . The moths of the first generation began emerging on June 5, and continued t0 emerge until June 28, the maximum number emerging on June 14. Emergence records were obtained on 333 moths, of which .145 were males and 188 females. Length of life records were obtained on 193 moths, of which 95 were males and 98 were females. The average length of life was 3.1 days, the average life of the males 3.2 days, and the average life of the females 3 days. The maximum length of life of the m-ales was 9 days and that of the females 7 days. 1919 There were four generations in 1919. From April 12, the date when the first larva of the spring brood’ pupated, until October 25, the date the last moth of the third generation emerged, was 197 days, which was the length of time large numbers of the insect were under observation. The insect was active for a considerably longer period. Field observations indicated that the first larvae began feeding about March 25, and the last larvae of the fourth generation spun their hibernacula about November 10. Thus it will be seen that the insect was active for approximately 230 days in 1919. The first larva of the spring brood pupated on April 12, the greater number pupated between April 21 and_ April 25, and the last one pupated on May 3. The date of pupation was observed for 235 in- dividuals; moths emerged from 186, and 49 died as pupae. The min- imum duration of the pupal period was 11 days, the maximum dura- tion 18 days, and the average 13.6 days. The spring-brood moths began to emerge on April 27, and emer- gence continued until May 17, maximum emergence occurring on May 5. Emergence records were obtained on 187 moths, of which 84 were males and 103 were females. Length of life records were obtained on 110 moths; of these 55 were males and 55 were females. The average length of life was 4.4 days, the average life of the males _ was 5 days, and the average life of the females 3.8 days. The maxi- mum length of life was 12 days for both males and females. The first larva of the first generation pupated on May 31, the greater number pupated between June 15 and June 23, and the last ones on July 2. The date of pupation was observed for 229 individuals; moths v emerged from 170, and 59 died as pupae. The minimum length of the pupal period was 7 days, the maximum 13 days, and the average length 9.6 days. - The first-generation moths began to emerge on June 13, and emer- gence continued until July 10, the maximum number emerging on LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 35 June 28. Emergence records were obtained on 222 moths, of which 103 were males and 119 were females. ' The number of larvae of the second generation at College was lim- ited but-they were plentiful at Corsicana. The first larva of this generation at College pupated on July 17, and the last one on August 12. The first moth emerged on August 4, and the last one on August 22. Emergence records were obtained on 91 moths, of which 52 were males and 39 were females. Because of the limited number at College about 1200 larvae were collected at Corsicana from which pupation and emergence records were obtained. A large number had already pupated when the col- lecting was done; hence the first date of pupation is not known; the last larvae pupated on August 25. "The date of pupation was recorded on 165 individuals, of which 132 emerged as moths and 33 died as pupae. The minimum length of the pupal period was 6 days, the maximum 14 days, and the average 11.6 days. Emergence records were obtained on 634 moths from the larvae and pupae collected at Corsicana; of these 318 were males and 316 were females. The last moth from this material emerged on September 5, the maximum emer- gence occurring on August 24 when '74 moths emerged. Length of life was obtained on 604 moths; of these, 290 were males and 314 were females. The average length of life was 4.6 days, aver- aging 4.5 days for the males and 4.7 days for the females. The maxi- mum life of the males was 13 days; that of the females 14 days. The larvae of the third generation began to pupate on September 1'7, the greater number pupated between September 18 and October 6, and the last one pupated in the laboratory on October 11. The date of pupation was obtained on 151 individuals; moths emerged from 125, and 26 died in-the pupal stage. The minimum length of the pupal period was 6 days, the maximum 18 days, and the average length 12.9 days. The moths of the third generation began to emerge on September 29, and emergence continued until October 25, the maximum number emerging on October 5 and 6. Emergence records were obtained on 348 moths, of which 189 were females and 159 were males. Length of life records were obtained on 125 moths; of these 63 were males and 62 were females. The average length of life was 4.7 days, the average life of the males was 4.6 days, and the average life of the females 4.8 days. The maximum length of life of the males was 13 days and the maximum length of life of the females was 11 days. The fourth generation of 1919 was represented by the egg and larval stages only. The larvae passed the winter in hibernacula and trans- formed the next year. These, together with the overwintering larvae of other generations formed the spring brood of 1920. - '36 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION IVLAPR/L MAY JUNE JULY Auc. SEPT 0C7? N. TTTTLT/TLT h, . ~~°$v9i><$£ “$23K: ~v£fifihébfifi9w9b° w°i>° M92“ ‘o? SPRING B9000 ME POS/T HA TCH/ ms ' P E E EPOS/T HA E/VT /V P v/N '4” GEA/ERAT/ON 1i’. ct/vf/é/a T/O/V % MEI? F 5P0: H TCHI A VAE E E/P/Né‘ N071; MERG zvce D Pas HA TC ' zva m/ma 4IHCE/v. 3R?’ ct/vsmar/om 2 L/l/PVA 'Fig. 11. Diagram of the life history of the pecan nut case bearer at College Station, 1919. LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 37 1920 Climatic conditions in the spring of 1920 were very favorable to larval development and a large number of spring-brood larvae was collected. - In the laboratory the first larva pupated on April 12. A consider- able number pupated each day from April 16 to May 4, and the last larvae pupated on May 8. Records were obtained on the date of pupation of 405 individuals; moths emerged from 314, and 91 died as pupae. A much larger number of larvae was collected than shown by the pupal records. This was due to the fact that a large number of larvaewere parasitized and died before they pupated. The mini- mum duration of the pupal period was 8 days, the maximum 16 days, and the average 12.1 days. p The first moth of the spring brood emerged on April 26, the last one on May 2, the maximum emergence occurred on May '7. Emer- gence records were obtained on 380 moths, of which 1'78 were males and 202 were females. Length of life records were obtained on 156 moths, of which '72 were males and 84 were females. The average length of life was 2.59 days; the average life of the males was 2.52 days, of the females 2.65 days. The maximum length of life for both males and females was 6 days. The first larva of the first generation pupated May 31, the larger number pupated between June 2 and June 14, and the last one on June 29. Records were obtained on the date of pupation of 249 in- dividuals; moths emerged from 196, and 53 died as pupae. The mini- mum duration of the pupal period was 5 days, the maximum 11 days, and the average 9 days; Pupation records were obtained from 101 larva collected at Corsi- cana; moths emerged from 6'7, and 34 died as pupae. The minimum duration of the pupal period was '7 days, the maximum 13 days, and the average 9.8 days. The moths of the first generation began to emerge on June 6, and emergence continued until July 8, the maximum emergence taking place on June 15, when 62 moths emerged. Emergence records were obtained on 389 moths at College Station; of which 219 were males and 1'70 were females. Emergence records were obtained on 148 moths from larvae and pupae collected at Corsicana, '70 of these were males and '78 were females. A total of 53'7 emergence records were made. Length of life records were obtained on 210 moths, of which 10'7 were males and 103 were females. The average length of life was 3.2 days; the average length of life of the males was 3.2 days and that of the females 3.1 days. The maximum length of life for both males and females was '7 days. The larvae of the second generation were so few in number that several days of continuous searching at College, Corsicana, and Winona 38 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION resulted in finding only 30. Of those which were collected at Col- lege 2O pupal records were obtained. The first larva pupated on July 1'7 and the last one on August 11. From these pupae 16 moths emerged, the first emerging July 26 and the last August 21. MAR. APR/L MAY JUNE JULY AUGUST 551377 OCT ‘° °'"° °"’°“’3=o9'£’<7=‘$°">9i‘3§3 119.2835 ">2 i18£811>QE13§°11>92§ \m~ ”7~~1\:N~v 12111111111111 11111111 1 E0 ' 1 110:1 EMERGENC 1 1 WK) 111111 1 1 1 1 11111509111611 11 1 1, 2 1111111 111 Q 11111111 1. 1 1: HATCH/NC 1 1 11 1 1 <1: 11111111 1 1 1 1 E LAFPl/AE .1 1 a‘ FNTEP/NQA/ufi 1 1 1» 111>11O~ 11111111111111 '61 1 ~1 r 511111111111 11 1111 1 21 521151112 11 1 9 ' 1111111” 1 1 1:. HATCH/NO l2 111111111 m‘ 1LARVAE11 S‘ ENVY-Pew? New ° 1 BJAATUON g, 11111111 N 1 11111111111 1 fiM-Erefiwfif. 1 2‘ 1 11111111 1 1L, 1 1 DEPOS/T/O/V b 111111111 1 g‘ 1 1 VWTH/Avk‘ 1 ’ n 111111111 .... _--- 1 Fig. 12. Diagram of the life history of the pecan nut case bearer at College Station, 1920. The seasonal history of the pecan nut case bearer for 1920 is per- haps the most interesting of any of the years in which studies were made. A heavy crop‘ of nuts was set at both College and Corsicana. In connection with some spraying tests, all the nuts which dropped from 50 trees at Corsicana and from 41 trees _at College were collected. A tabulation of these data shows that the crop set in 1920 compared favorably with the crop which matured in 1919. At the end of the first generation there were very few nuts on unsprayed trees at Cor- sicana and none at College. While there were a few larvae of the second generation which completed their transformation, the number was so small that it scarcely can be said that there Was a second gen- LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 39 eration. It has already been stated that there was a large number of spring-brood larvae and also a large number of parasites of the spring-brood larvae. The number of larvae in the first generation were numerous enough to destroy practically the whole nut crop and quite a large number transformed to pupae and moths. There were only a few nuts at the time the first-generation moths were ovipositing and except for the few larvae of the second, generation which trans- formed to pupae and moths, the activity of the insect ceased for the remainder of the season. Whether the absence of food accounts en- tirely for the lack of a second, third, and fourth generation is not known but the information obtained appears to show that this was the reason. 1921 There were four generations in 1921.. Warm weather during the early part of March started tree growth and the larvae became active. The first larva pupated on ‘March 27.‘ On March 28, the minimum temperature dropped to 38 degrees Fahren- heit and the mean temperature continued low during most of the month of April. Pupation occurred over a period of 41 days, from March 28 to April 25, with no very great number of larvae pupating on any one day. The date of pupation was obtained on 228 individ- uals, moths emerged from 186, and 42 died as pupae. The minimum duration of the pupal period was 14 days, the maximum 24 days, and the average 18.5 days. a - Larvae were collected at Olarksville in addition to those collected at College; and 133 pupal records were obtained from these larvae; moths emerged from 108, and 25 died as pupae. The minimum dura- tion of the pupal period was 14 days, the maximum 20, and the aver- age 17.3 days. Emergence began on April 15, and continued until May 20. There was no large‘ emergence on any single day as was the case in 1920 and 1922. The largest number emerged on May 13. Emergence records were obtained on 202 moths; 116 of which were males and 86 were females. From the larvae and pupae collected at Olarksville, emer- gence records were obtained on 108 moths, of which 41 were males and 67 were females. Although a search of several days was made for spring-brood larvae at Corsicana only a few were collected; from these larvae 23 moths emerged. Emergence records were obtained on 333 moths; 202 from larvae collected at_(lollege;-108 from Clarksville; and 23 from Oorsicana. Length of life records were obtained on 133 moths, of which 64 were males and 69 were females. The average length of life was 3.69 days, the average life of the males was 4.2 days and that of the females 3.2 days. The maximum length of life of the males was 8 days and the females 9 days. The number of first-generation larvae at College was considerably 40 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION smaller than that of the spring brood. Larvae of the first generation were also collected at Corsicana and Winona, but while they were more plentiful at Winona than at College, they were not abundant at any of the three places. The first larvae at College pupated on June 6 and the last on June 28. The date of pupation was obtained on 58 individuals, of which 47 emerged as moths and 11 died as pupae. The minimum duration of the pupal period was 7 days, the maximum 12 days, and the average 9.5 days. In addition to the pupal records for College, records were obtained on 230 pupae from larvae collected at Winona. Moths emerged from 161, and 69 died as pupae. The minimum duration of the pupal period from larvae collected at Winona was 7 days, the maximum 13 days, and the average 10.6 days. Emergence records were obtained on 152 moths, 56 males and 96 females from larvae and pupae collect-ed at College; and also on 304 moths, 153 males and 151 females, from larvae and pupae collected at Winona. Length of life records were obtained on 91 moths, of which 35 were males and 56 were females. The average length of life was 3 days, the average life of the males was 3.2 days, the average life of the female 2.9 days. The maximum length of life of both sexes was 6 days. The first pupal record of the second generation was made July 13, a considerable number of larvae pupated daily from July 17 to August 5, and the last pupal record was made August 11. The minimum dura- tion of the pupal period was 6 days, the maximum 11 days, and the average 9 days. The date of pupation was obtained on 369 individuals, moths emerged from 311, and 58 died as pupae. Larvae were also collected at Winona and the date of pupation was recorded on 127; moths emerged from 85 of these, and 42 died as pupae. The minimum length of the pupal periodiwas 6 days, the maxi- mum 17 days, and the average 9.3 days. The first moth of the second generation at College emerged July 22; maximum emergence occurred August 5 and 6 and the last moth emerged August 17. Emergence records were obtained on 784 moths, of which 369 were males and 415 females. In addition, the time of emergence was. obtained on 6 males and 14 females from larvae and pupae collected at Corsicana, and 98 males and 76 females from larvae and pupae collected at Winona. A total number of 978 emergence records was obtained for the second gen- eration; of these 473 were males and 505 were females. Length of life was obtained for 271 moths, 137 males and 134 females. The average length of life of both sexes was 2.6 days; the maximum length of life was 4 days for both sexes. The records for the first part of the third generation are not rep- resentative of field conditions. Due to the absence of the, author from College, the collection of larvae was not kept up. In addition to this on the 10th of September and for several days afterward the valleys of the Brazos and Navasota rivers were flooded. This prevented the LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 41 IVIAFKAPRIL MAY JUNE JULY Auc. 65px 007. In u) QM’) Qvv PUP 5 m; as TC LA A RING wv EMERGENCE ' POSITION TC H/N ARVAE E ON RC1:- NC‘ P05! Tl ON ' HATCH/NC AR VA EN NUT PUPAT l, EMERGE £ DEPO SIT/O TCH/NG RW P/N ARV ' . 5PR/N6 4735OEN. 35° GE NE RAT/ ON Z 5° CE NE RAT/ON 1 '37 GENERA T/ON BROO Fig. 13. Diagram of the life history of the pecan nut case bearer at College Station, 1921, 42 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION collection of larvae for nearly two weeks and made a break in the con- tinuity of the field observations. The first pupae were recorded on September 12, and the last on September 28. Records were made on 263 pupae; moths emerged from 207, and 56 died as pupae. The mini- mum duration of the pupal period was 6 days and the maximum 13 days, and the average 9.5 days. The first moths in the cages began to emerge on September 16, and a considerable number emerged daily from September 1'7 to October 3, with the maximum number“ emerging on September 24, and the last moth on October 11. The date of emergence was recorded for 562 moths, of Which 234 were males and 328 were females. From March 2'7, when the first spring-brood larvae pupated to October 11, when the last moth of the third generation emerged, was 199 days. The entire active period of the insect for 1921 was esti- mated to be 240 to 250 days. 1,922 There were two generations in 1922. There was an abundance of spring-brood larvae and climatic con- ditions were favorable to rapid larval development. The first larva pupated in the laboratory on April 16. A considerable number pupated daily from April 1'7 to May 8; the largest number pupating on any one day was 112—on April 25. The date of pupation was recorded on 663 individuals; 547 moths emerged, and 116 died as pupae. The minimum duration of the pupal period was 9 days; the maximum was [21 days; the average 13.8 days. Larvae were abundant at both Oorsicana and Winona. From larvae collected at Winona the pupal date was recorded for 231 individuals; moths emerged from 181, and 50 died as pupae. The minimum dura- tion of the pupal period was 11 days, the maximum 19 days, the aver- age 14.9 days. _ . Emergence began on May 3, and continued until May 24, the maxi- mum emergence occurring on May 9 at College Station. Emergence was recorded on 639 moths, 298 of which were males and 341 were females. In addition to these, emergence records were obtained on 97 males and 84 females from the larvae and pupae collected at Winona. The total number of moths recorded was 820. Oviposition records were obtained in the cages from 64 females. The maximum number of eggs laid by a female was 163. The length of life of the females which oviposited was 7.1 days. The average time from emergence to first oviposition was 4.1 days and the period over which oviposition occurred was 1.4"days. The length of life of 229 moths was determined; 108 of these were males and 121 were females. The average length of life was 6.35 days, the average life of the males was 6.2 days, the average life of the females was 6.47 days, the maximum length of life of both sexes was 15 days. LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 43 The length of the incubation period for 861 eggs Was 5.6 days. The larvae of the first generation were less abundant than those of the spring brood, although larger numbers of spring-brood moths emerged. The first pupation was recorded on June 6, and the last one June 28. The date of pupation was recorded for 196 individuals; moths emerged from 142, and 54 died as pupae. The minimum duration of the pupal period was 6 days, the maximum 13 days, the average being 9 days. From larvae collected at Corsicana, '78 pupae were recorded; moths emerged from 61, and 17 died as pupae. The minimum duration of the pupal period was 8 days, the maximum l2 days, the average 9.8 days. " MARCH APRIL MAY JUNE JULY ‘o93838oQQSIKIQwQQ8Q°QQQ8SRYIQQISQr% eI/PIIIIQ I I I ' II §§l I I I I I lv I E ERGENCE Om.‘ /l"I'IIII;III f I I I I I I I I I_ DEPOSITION- g I I I I I I I I o I l l l l l I l P HI/‘ITFIHVI? ! . . . . all LARVAE ll ‘$1 F/v TER/NG I /_v_u_-r_s I I I I, t‘; PUPAT/ON ..,_ _ I I I I I I I a I I I I I I I N EMERGENCZ? a t - l l I I I I 2 , I ITI I I a Drfos/IT/o/y I I I g, l II I I I I I N HATCH/Not I I I I I I I I I Fig. 14. Diagram of the life history of the pecan nut case bearer at College Station, 1922. From larvae collected at Winona, 240 pupae were recorded; moths emerged from 1'77, and 63 died as pupae. The minimum duration of the pupal period was 6 days, the maximum 13 days, the average 9.7 da ys. 44 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION Emergence began at College on June 13 ; the maximum number emerged on June 19, and the last moth emerged on July 9. Emer- gence records were obtained on 245 moths; 106 were males and 139 were females. Emergence was recorded from 88 males and 108 females from larvae and pupae collected at Corsicana, and 284 males and 383 females from larvae and pupae collected at Winona. The total number of moths emerging in the laboratory was 1108. The length of life was determined on 457 moths, of which 186 were males and 271 were females. The average length of life was 6 days, the average life of the males was 5.6 days, the average life of the females was 6.2 days. The maximum life of the males was 14 days and that of the females 17 days. Egg deposition in the cages was unsatisfactory. Although 90 moths oviposited, the maximum number of eggs deposited by a single female was 66. The average length of life of the females which oviposited was 7.5 days. The average time from emergence to first oviposition was 4.9 days. Oviposition occurred over an average period of 1.5 days. There was a large number of larvae of the spring brood, also a large emergence of spring-brood moths. The first-generation larvae were fewer in number and by the time those which transformed to pupae had completed their growth, there were very few or no nuts left on trees. Although a considerable number of first-generation moths emerged and deposited eggs, as far as could be determined, the activity of the insect ceased with the larval stage of the second gen- eration. Whether the majority perished for lack of food or for some other cause was not determined; the fact remains that there were scarcely any spring-brood larvae in 1923. 1923 There were four generations in 1923. Spring-brood larvae were difficult to find and only limited numbers were collected, although one person spent several weeks in searching for them. The date of pupation was recorded for 123 individuals; moths emerged from 96, and 27 died as pupae. The first larvae pupated in the laboratory on April 27, and the last on May 16; the maximum pupation occurred on April 28. The minimum duration of the pupal period was 10 days, the maximum 18 days, and the average 14.4 days. The spring-brood moths began to emerge on May '7. Maximum emergence took place on May 13, and the last moths in the cages emerged on May 28. A total emergence of 196 moths was recorded. Of these '71 were males and 125 were females. Oviposition records in cages were secured on 36 females. The average time from emer- gence to first oviposition was 3.9 days and the maximum number of eggs deposited by a single female was 142. The average time over which ovi- LIFE HISTORY AND CONTROL OF‘ THE PECAN NUT CASE BEARER 45 iposition occurred was 2.7 days. The average time from emergence 5to last oviposition was 6.5 days. The averagelength of life of the females which oviposited was 8.5 days and the average time from the last oviposition to the death of the female was 2 days. a g1 Length of life records were obtained on 76 moths in addition to l ithe females which laid eggs. The average length of life was 7.13 ldays, the average life of 26 males was 6.15 days, and the average life 50 females was 7.6 days. The maximum life of the males was 13 days and the maximum life of the females was 20 days. The minimum Y ngth of both sexes was 2 days. The time from April 27, when the est larvae of the spring-brood pupated, until June 5, when the last goth died, was 40 days. Including the active period of the larvae revious t0 the first pupation, the complete duration of the spring- i~ 00d was 55 to 65 days. The larvae of the first generation were more numerous in the spring- ,- ood but not abundant enough to cause any considerable damage. ' l‘ The average duration of the incubation period of 713 eggs was 5 ys. In the cages the largest number of eggs hatched on May 25. The average duration of the larval period for 81 larvae reared in ts on the trees, was 25.6 days. The minimum length of the larval riod was 17 days and the maximum length 40 days. P, The first generation larvae began to pupate on June 12, a considerable if» ber pupated from June 17 to June 29, and the last pupated on TI y 8. The date of pupation was obtained on 206 individuals; moths erged from 176, and 30 died as pupae. The minimum duration A the pupal period was 8 days, the maximum was 16 days, and the erage 9.4 days. i‘ The first-generation moths began to emerge on June 15. A con- pyperable number emerged daily from June 17 to July 7, the maxi- jum number emerging on June 22. Emergence records were obtained u w 519 moths, of which 231 were males and 288 were females. There were 78 females which oviposited in the cages. The maxi- “; u number of eggs laid by one female was 102. The average time ’ a emergence to first oviposition was 4 days; the average time over 'ch oviposition took place was 2 days; the average time from emer- '0 until last oviposition was 5.7 days. The average length of life _,the females which oviposited was 7 days and the average time, after last oviposition to the death of the moth was 1.4 days. gth of life records were obtained on 197 moths, of which 77 e males and 120 were females. The average length of life was =ys, the average life of the males 7 days, and the females 6.9 days. ‘_ maximum length of life of both sexes was 16 days. e duration of the first generation was 65 days, which was the from the first egg deposition by spring-brood moths to the time ,last moths of the first generation died. I the second generation, case bearer larvae were abundant in the V, and exceeded both the numbers in the first and third generations. 46 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION The average duration of the egg stage was 4.6 days. Hatching records were obtained on 1638 eggs; the maximum number of eggs hatched on July 1. The average duration of the larval period for 102 larvae reared in nuts on the trees, was 33 days; the minimum length of the larval period Was 20 days, and the maximum 51 days. In the laboratory the first larvae of the second generation pupated on July 18, a considerable number pupated daily from July 21 to August '7, the last one pupated on August 2'7. The date of pupation was recorded for 508 individ- uals; moths emerged from 424, and 84 died as pupae. The minimum duration of the pupal period was 5 days, the maximum was 12 days, and the average 9 days. The first moths of the second generation began to emerge July 24; the larger number emerged between July 28 and August 16; maximum emergence occurred on August 3, when 103 moths emerged. The last second-generation moth emerged on September '7. Emergence records were obtained on 893 moths, of which 464 were. males and 429 were females. Oviposition records were secured on 64 fertile females in captivity. The maximum number of eggs laid by one female was 190. As was the case in all other generations, a large number of infertile eggs were obtained in the cages. The egg-laying records of unfertilized females have not been included. One moth deposited 62 eggs in a single night. The longest period over which a female oviposited was 12 days and the average time over which oviposition occurred was 2 days. The average time from emergence to first oviposition was 4.4 days. An average of 5.8 days elapsed from the time of emergence to the last oviposition; and an average of 2:2 days elapsed from the last oviposition to the death of the moth. _ Length of life records were obtained on 340 moths; of which 151 were males and 189 were females. The average length of life was '7 days, the average life of the males was 6.9 days, of the females 7.1 days. The maximum length of life of both sexes was 25 days. The duration of the second generation was 49 days, which was the time from first egg deposition by first-brood moths to the death of the last adult of the second generation. There were a large numberiof eggs in the third generation but part of the larvae spun hibernacula and did not transform to pupae; so the number of larval, pupal, and emergence records is less for this generation than for the preceding. The incubation period of 1812 eggs was 4 days. The largest num- ber of eggs W38 laid on August 10, and hatched on August 14. The duration of the larval period was obtained for 44 larvae, the minimum duration was 17 days, the maximum 38 days, and the aver- age 26 days. The larvae were reared in nuts on the trees as in the two preceding generations. The first pupation occurred on August 22, the larger number of LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 47 A NTER/NG ' 7s E PO lT/O/V H/G L v NTf/WA/G Nun PA T/ M A/ J/ / HA TC‘ / LARV E ENTERING /V Ts Pu T/O/V . ’ SPR/NG 3i" efi/vaqm r/o/v 21’ GENEPA r/o/v 1;! CIA/ERA new, B oo EME D POS/ ATC’ /N 4L”GE/V. 0145/? w/A/TER/A/c L‘ RVA E Fig. 15. Diagram of the life history of the pecan nut case bearer at College Station, 1923. 48 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION larvae pupated between September _1 and September 20, and the last on September 29. The date of pupation was obtained on 356 in- dividuals; moths emerged from 291, and 65 died as pupae. The mini- mum duration of the pupal period was 8 days, the maximum 1'7 days, and the average 12.6 days. The moths of the third generation began to emerge on August 29; there was a considerable daily emergence from September 8 to October - 3; maximum emergence occurred on September 1'7, when 50 emerged. The last moth emerged on October 13. The date of emergence was obtained on 662 moths ; of which 290 were males and 3'72 were females. A large number of moths oviposited in the cages; 73 of these moths laid fertile eggs. One moth laid 247 eggs, which was the maximum record on egg laying. The weather was cool and the average time from emergence to first oviposition was -'7 days. The average time the females laid eggs was 2.3 days and the average length of life of the females which oviposited was 11.8 days. The average time from emergence to the last oviposition was 8.6 days and the average length of life after the last oviposition was 3 days. The length of life was obtained on 296 moths; of these 102 were males and 194 were females. The average length of life was 8.8 days, the average life of the males was 8 days, the average life of the females 9.2 days, The maximum length of life of the males was 23 days. The maximum life of the females was 21 days. The duration of the third generation was 49 days, this being the‘ time from the deposition of the first egg by moths of the second gen- eration to the death of the last moths of the third generation. The fourth generation was represented by only the egg and larval stages. The eggs of -this generation were deposited both on nuts and on buds. The duration of the incubation period of 1287 eggs was 5.2 days. The date the last larvae was observed to spin its hiber- naculum was November 11. From April 2'7, when the first pupa was recorded, to November 11, when the last larva ceased feeding, was 199 days. Including the feeding period of the spring-brood larva, the entire active period in 1923 was 214 to 224 days. NATURE AND EXTENT OF INJURY The larva is the only stage of the pecan nut case bearer which is injurious. It damages the tender branches during the spring brood and the nuts in the first, second, and third generation. The spring- brood larvae tunnel the succulent growth (Fig. 8) and cause the ends of the branches to die. From a distance one can locate the spring-brood larvae on a tree by the dead tips of branches. The larvae of the first generation do the greatest amount of damage. They hollow out the young nuts and cause them to drop from the trees just after they have set. One larva may destroy a large number of nuts. When the first-generation larvae are abundant they may de- LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER Fig. 16. A—Size of nuts when attacked by larvae of the first generation. B-Size of nuts when attacked by larvae of the second generation. C—S1ze of nuts when attacked by larvae of the third generation. ~ 49 5O BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION stroy the entire crop as was the case in 1920 and 1922. The larvae of the second generation injure the nuts in the same way as do the larvae of the first generation, ~ but the nuts are much larger by this time and one larva does not do as much damage as a single larva of the first generation. ' . Some of the larvae of the third generation enter the nuts, but many of them tunnel about in the hull or shuck and do not enter thenuts. Many larvaefind locations (Fig. 16) where several nuts touch at their bases and hollow out the shuck at those places. Often the larvae pupate in these hollowed-out places. The third-generation larvae do very little damage. In tunnelling in the hull they cause it to adhere to the nut, which interferes with nutrition to such an extent that, the kernel sometimes does not fill out properly and later becomes rancid. A discoloration appears on the nut at the place Where the tunnel is made and if the larvae are abundant give the nuts a bad appearance. The amount of damage varies a great deal. Some years the insect destroys 90 per cent of the crop; at other times the damage may be as low as 1 to 2 per cent of the crop. Where there were native trees in the vicinity of an orchard, the damage from year to year was . greater than in orchards which were far removed from native trees. Fig. 17.Type of power spraying machine used. LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 51 STUDIES ON CONTROL Experiments 0n control were conducted at Westfield,‘ in the orchard of R. W. Houk, in 1918; at College Station in the orchard belonging to the Horticultural Department of the Agricultural and Mechanical College of Texas in 1917, 1918, 1919, 1920, 1921, and 1922; at Cor- sicana in the orchard of J. M. Blackburn in 1920, 1921, and 1922; and at Winona, Texas, in the orchard of E. C. Butterfield in 1921 and 1922. A careful study of the life history suggests thre'e possible methods of control: - 1. Spraying the trees with a stomach poison to kill the larvae. 2. Spraying the trees with a contact insecticide in, the early spring to kill the larvae while still in the hibernacula. 3. Control by parasites and predacious enemies. The results of the experiments which are tabulated in the following pages have to do with the first method. Contact insecticides have been tried. Lime sulphur has proved to be of little value but oil emulsions give some promise of control. During the six years in which experiments on control were con- ducted arsenate of lead and calcium arsenate were used. All appli- cations were made with a power sprayer at a pressure of 200 t0 300 pounds. Spraying was done both with a spray gun (Fig. 18) and extension rod, but the latter was not satisfactory for spraying large trees and was not used extensively. METHODS OF CONDUCTING THE SPRAYING TESTS In preparing for the spraying tests the ground beneath the trees was made as level as possible. No extra care was necessary where regular cultivation was carried on, but where the ground was not cul- tivated regularly it was made bare by cutting away all the weeds, grass, etc., with a hoe. Since the life history‘ work" was carried on at the same time, it was possible to know when the first larvae were hatching; therefore, the first spraying was done as soon as possible after the first damage by the‘ larvae was noticed. The moths oviposit about 45 days after emerging, and if the weather is warm the eggs hatch in 5 days. About 8 or 10 days after the moths began to emerge in numbers the first spraying was done, if the ground in the orchard was not too Wet to use a power sprayer. After the first spraying, the nuts which fell from the trees were picked up every two or three days. While the nuts were very small it was necessary to pick them up oftener. The nuts were examined for case bearer attack and then placed in two piles, those which fell from the trees on account of case bearer attack and those which dropped from unknown causes. At the end of the season the number of nuts which fell from the trees was added to the number which was 52 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION harvested. This number is given under the heading “Total nuts set.” At Corsicana in 1920 and 1922 it was necessary to count the nuts on the trees before harvesting, because crows were feeding on the nuts and it was not possible to keep them away unless someone constantly watched the trees. In 1920 the count was made on September 2'7. Profiting by the experience of 1920, the nuts were counted on August Fig. 18. Type of spray guns used. s13, in 1922. In 1921 when there was an ample supply of native nuts, the crows did not bother the pecan orchard, but in 1922, due to the illness of the owner at the time the crop was ready to harvest, they took a large part of the nuts on the sprayed trees, which were the only ones having nuts left on them. LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 53 Preliminary Tests—1917-1918 The first tests to control the pecan nut case bearer with arsenate of lead were made in 1917-1918 on but a few trees. A sufficient amount of control was obtained in these tests to Warrant further attempts. IQIQ/Qlollege Station A small orchard of fifteen trees was selected to make more extensive tests than were made in 1917 and 1918. Two plats of four trees each and one plat of three trees were sprayed on April 2'7, and one plat of four trees was left unsprayed as a check. The total number of nuts pharvested was estimated by weighing a few pounds, counting the num- ber and then determining the whole by multiplying the number of nuts in a pound by the number of pounds. Table 11 is a summary of the nuts which were collected from Plat 1, which was not sprayed and was used as a check. Tables 12, 13, and 14 are summaries of the three plats which were sprayed on April 2'7 with 3 pounds of arsenate of lead and 9 pounds of stone lime per '50 gallons of water. The stone lime was slaked with water, passed through a fine-mesh strainer, and then added to the. spray tank, after which the arsenate of lead was added. The nuts which dropped before maturity are tabulated under the heading “Dropped nuts”; those which dropped on account of case bearer attack are tabulated under the heading “Infested”; those which ' dropped from unknown causes are tabulated under the column “Non- infested.” The total number of nuts set was obtained by adding to- gether the dropped nuts and the harvested nuts. This method of * obtaining the total number of nuts set was thought to be more accu- hWlQI-i rate than trying to count them on the trees. As" a' result of this work it was found that the spraying was done too early and might have been more effectual if it had been delayed several days; also that one spraying was not sufficient t0 control the insect. The sprayed plats showed 3 per cent control over the check ‘ plat. PLAT 1. Table 11. Summary of the nuts collected from Plat 1, which was used as a check. Dropped Nuts Harvested Nuts Per Cent Total ~ Tre Variety No. nuts No. Infested Non- No. nuts No. set »Har- Infested Non- infested lbs. per lb. nuts vested infested Bolton. . . . . 663 301 27.2 87 2370 3334 71 2O 80 Bolton. . . . . 797 393 30 .4 87 2640 3830 69 21 79 San Saba. . . 132 143 18 .5 120 2220 2495 89 5 95 Frotscher. . . 32 55 3 52 278 365 76 9 91 Total. . . . 1624 892 79. 1 . . . . . . . 7508 10024 75 16 84 54 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION PLAT 2. Table 12. Summary of the nuts collected from Plat 2, which was sprayed April 27. i Dropped Nuts Harvested Nuts Per Cent Total Tre Variety ' No. nuts No. Infested Non- No. . nuts No. set Har- Infested Non- - infested lbs. per lb. nuts vested infested 1 Pabst . . . . . . 7 20 0 .75 52 39 66 59 11 89 2 Schley. . . . . 35 40 0.5 60 30 105 29 33 67 3 Stuart. . . . . 59 98 2.25 62 139 296 47 20 80 4 Van Deman 74 372 4 67 268 714 38 10 90 Total. . . . 175 530 7 .5 . . . . . . . 476 1181 40 15 85 SPLAT 3 Table 13. Summary of the nuts collected from Plat 3, which was sprayed on April 27. Dropped Nuts Harvested Nuts T t l Per Cent o a Tre Variety No. nuts No. Infested Non- No. nuts No. set Har- Infested Non- _ infested lbs. per lb. nuts vested infested 1 Van Deman 50 380 14. 8 67 788 1218 65 4 96 2 Atwater. . . . 229 675 13.0 72 936 1840 51 12 88 3 Centennial. . 56 663 5 .2 41 220 939 23 6 94 4 Centennial. . 11 254 2 . 0 41 85 350 24 3 97 Total. . . . 346 1972 35.0 . . . . . . . 2029 4347 47 8 92 PLAT 4. Table 14. Summary of the nuts collected from Plat 4, which was sprayed April 27. Dropped nuts. Harvested nuts Per cent Tre Variety ' T0ta1 No. u , No. nuts - In- Non- No nuts No. set Har- In- Non- fested infested lbs. per lb. nuts vested fested infested 1 Mobile ........ .. 72 132 44 53 2330 2534 92 3 97 2 Mobile ........ .. 66 80 30 53 1590 1736 92 4 96 3 Rome .......... .. 1138 2337 3 52 156 3631 4 31 69 Total ...... .. 1276 2549 77 . . . . . . . 4076 7901 52 16 84 1920—College Station In 1920 the case bearer infestation at College was high. The num- ber of nuts remaining on the trees at the end of the first generation was small, the first-generation larvae having destroyed the greater part of them. The orchard was divided into six plats. Three of these plats were sprayed with calcium arsenate at the rate of two pounds per fifty gallons of water, and three plats were left unsprayed as_ checks. The first spraying was done on May '7. There was .33 inches of rain on May 8; 1.7 inches on May 14; LIFE HISTORY AND CONTROL OF THE PEUAN NUT CASE BEARER Fig. 19. NutsIdamaged by first-generation larvae. 55 56 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION and 3.9 inches on May 16. The first application of calcium arsenate was made too soon to be of any value and the rains on May 14 and May 16 prevented further spraying until May 21. Practically all the nuts fell from the trees on the sprayed as well as the unsprayed plats. This may have been due to the fact that calcium arsenate is not efiective over a long period of time, or the spraying of May 21 may have been too late to‘ do much good. Calcium arsenate has not been as efiective a remedy as arsenate of lead in the tests which have been made. PLAT 1 Tab'e 15. Summary of the nuts collected from Plat 1, which was sprayed with Calcium Arsenate at the rate of two pounds per 50 gallons of water. Dropped Nuts l Per Cent Tre Variety ~i——i——— Har- Total No. Non- vested nuts Har- Non- Infested infested nuts set vested Infested infested 1 San Saba . . . . . . . . . . . 44 8 0 52 0 85 15 2 Delmas . . . . . . . . . . . . 32 4 14 5O 28 64 36 3 Rome . . . . . . . . . . . . . . 433 1 19 2 554 0 . 4 78 22 4 Rome . . . . . . . . . . . . . . 298 81 0 379 0 79 21 5 Rome . . . . . . . . . . . . . . 57 32 2 91 2 63 37 6 Rome . . . . . . . . . . . . . . 106 33 1 140 0.7 76 24 Total . . . . . . . . . . . . 970 277 19 1266 2 77 23 PLAT 2. Table 16. Summary of the nuts collected from Plat 2, which was used as a check. Dropped Nuts Per Cent Tre Variety ——————-—— Har- Total No. a Non- vested nuts Har- Non- Infested infested nuts set vested Infested infested 1 Delmas . . . . . . . . . . . . 331 54 0 385 0 86 14 2 Seedling . . . . . . . . . . . . 19 2 5 26 19 73 27 3 Delmas . . . . . . . . . . . . 343 80 2 423 0.4 81 19 4 San Saba . . . . . . . . . . . 105 113 4 222 2 47 53 Total . . . . . . . . . . . . 798 249 11 1056 1 76 24 PLAT a. Table 17.} Summary of the nuts collected from Plat 3, which was sprayed with Calcium Arsenate at the rate of two pounds per 50 gallons of water. _ Dropped Nuts Per Cent Tre Variety i——-—-———-—-— Har- Total N o. Non- vested nuts Har- _Non- Infested infested nuts set vested Infested infested 1 San Saba . . . . . . . . . . . 231 99 30 360 8 64 36 2 Bolton . . . . . . . . . . . . . 10 4 24 38 63 26 74 3 Kincaid . . . . . . . . . . . . 89 46 74 209 35 43 57 4 San Saba . . . . . . . . . . . 28 146 0 174 0 16 5 Rome . . . . . . . . . . . . . . 512 131 1 644 0.2 80 20 6 Rome . . . . . . . . . . . . . . 337 ' 62 0 399 0 84 16 7 Bolton . . . . . . . . . . . .. 372 52 8 » 432 2 86 14 8 Bolton . . . . . . . . . . . . . 167 46 11 224 5 75 25 Total . . . . . . . . . . . . 1746 586 148 2480 6 70 30 LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 57 PLAT 4. Table 18. Summary of the nuts collected from Plat 4, which was used as a check. _ Dropped Nuts Per Cent Tree Varlety i———i—— Har- Total No. Non- vested nuts Har- Non- ’ Infested infested nuts set vested Infested i infested 1 San Saba . . . . . . . . . . . 523 176 20 719 3 73 27 2 Bolton . . . . . . . . . . . . . 385 52 3 440 0.4 88 12 3 Bolton . . . . . . . . . . . . . 273 28 47 348 14 79 21 4 Kincaid . . . . . . . . . . . . 215 15 0 230 0 93 7 5 San Saba . . . . . . . . . . . 38 76 1 115 0.9 33 67 6 Rome . . . . . . . . . . . . . . 744 157 0 901 0 83 17 7 Rome . . . . . . . . . . . . . . 537 93 0 630 0 85 15 8 Bolton . . . . . . . . . . . . . 449 66 2 517 0.4 87 13 9 Money Maker . . . . . . 113 12 0 125 0 90 10 Total, . . . . . . . . . . . 3277 675 73 4025 2 i 81 19 PLAT 5. Table 19. Summary of the nuts collected from Plat 5, which was sprayed with Calcium Arsenate at the rate of two pounds per 50 gallons of water. in the next, plat. Dropped Nuts Per Cent Tre Variety -—i——-—-—— Har- Total No. _ Non- vested nuts Har- Non- Infested infested nuts set vested Infested infested 1 Delmas . . . . . . . . . . . . 63 33 0 96 0 66 34 2 Rome . . . . . . . . . . . . . . 68 69 0 137 0 50 50 3 Rome . . . . . . . . . . . . . . 717 166 0 883 0 81 19 4 Rome . . . . . . . . . . . , . . 360 74 37 471 8 76 24 5 Rome . . . . . . . . . . . . . . 796 174 10, 980 1 81 19 6 Rome . . . . . . . . . . . . . . 534 269 2 805 0 .25 66 34 7 Home . . . . . . . . . . . . . . 1 187 238 0 1425 0 83 17 Total . . . . . . . . . . . . 3725 1023 49 4797 1 78 22 PLAT v6. Table 20 Summary of the nuts collected from Plat 6, which was used as a c_heck. p Dropped Nuts Per Cent Tree Variety Har- Total N o. _ N on- vested nuts Har- N on- Infested infested nuts set vested Infested infested 1 Rome....' . . . . . . . . .. 3 3 0 6 0 50 50 2 Rome . . . . . . . . . . . . . . 15 12 2 29 7 50 50 3 Rome . . . . . . . . . . . . . . 53 7 0 60 0 88 12 4 Texas Prolific . . . . . . . 718 144 O 862 0 83 17 5 Rome . . . . . . . . . . . . . . 965 186 0 1 151 0 84 16 6 Rome . . . . . . . . . . . . . . 88 53 3 144 2 61 39 7 Rome . . . . . . . . . . . . . . 126 - 31 5 162 3 78 22 Total . . . . . . . . . . . . 1968 436 10 2414 0.4 82 18 1920—C0rsicana Fifty trees were selected in J. M. Blackburnis orchard at Corsicana in 1920. Fourteen plats were arranged so that a plat could be sprayed and these trees checked with an equal number which were not sprayed Plats 2, 4, 6, 8, 10, 12, and 14 were sprayed and 58 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION plats 1, 3, 5, 7, 9, 11, and 13 were used as checks. The trees were selected with the aid of the owner, who knew their bearing capacity and could compare them in that regard. The ground was well cleaned by hoeing all Weeds and grass from beneath the trees. Although the orchard had been cultivated early in the spring, that part in which the spraying test was conducted was not cultivated for the remainder of the season. The ground underneath the trees was solid and afforded the best conditions for collecting the nuts as they fell from the trees. There was no rain from the time the first spraying was done until the nuts were of a good size; so there was little difficulty in finding those which dropped to the ground. The nuts were collected every three days until they had attained a good size, when a longer interval was allowed between the making of collections. If they were not col- lected as often as every three days when the nuts were small some of them dried up so completely that they were overlooked. It was necessary to get on one’s hands and knees to do the collecting thoroughly. The trees were sprayed with arsenate of lead at the rate of three pounds per fifty gallons of water. A power sprayer and a spray gun were used to do the work. Two sprayings were made to control the first- generation larvae, the first on May 8 and the second on May 22. A‘ third spraying was made on June 26 to control the larvae of the second generation. From subsequent observations it is thought that better control could have been obtained by varying the spraying dates. The spraying which did the most good was that of May 22, and if it had been followed by another application about eight days later it is thought that better control could have been obtained. As far as could be'determined the spraying done on June 26 was of very little value as far as the case bearer was concerned. It did control the fall web worm. The following figures and tables will serve to illustrate the degree of infestation, the amount of control, and the dates when the nuts dropped from the trees. For those who are interested in the details of this work it should be stated that there was a very high degree of infestation, the nuts were picked up and counted carefully, and the weather conditions were most favorable for the spraying work and the collection of dropped nuts. On the whole, the details of this experiment were carefully carried out and were least interrupted by rain of any of the series that are presented in this Bulletin. LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 59 Table 21 is a detailed record of the nuts which were collected and the dates theyfwerefcollected from the sprayed Plats 2, 4, 6, 8, 10, 12 and 14. Flrst Generatlon Totfi Ggiggiltfiion Tot?! t t 1] t 11111.11 I‘ H1111! 81' PM Tree Da e nu s were c0 ec ed collected qfillllecfid collected No. No. May 29,31 'June a, 4 June 1, s June 14, 1s t June 29 Y Inf. Non. Inf. Non. Inf. Non. Inf. Non. Inf. Non. Inf. Non. Inf. Non. Inf. Non. r 5 3 4 8 38 6 29 45 46 53 65 115 1 82 18 40 133 222 2 6 3 0 13 15 1 1 4O 6O 14 2O 71 96 4 9 75 105 7 2 6 13 43 1 16 13 44 31 46 60 155 9 20 69 175 8 14 2 15 40 5 15 38 52 41 63 113 172 6 21 119 193 11 10 11 34 58 14 50 59 44 133 128 250 291 5 16 255 307 4 12 2 11 16 28 9 25 51 54 39 65 117 183 9 8 126 191 13 0 0 11 38 8 23 24 62 33 76 199 5 14 81 213 14 1 3 10 59 1 3O 16 39 3O 83 58 214 7 36 65 250 17 2 O 11 20 7 23 4O 37 19 36 79 116 8 17 87 133 6 19 13 13 33 105 5 3O 93 76 38 104 182 328 4 31 186 359 22 1 0 8 22 2 6 44 16 19 35 74 79 12 18 86 97 23 4 1 0 2 3 3 1 29 12 4 1 39 17 0 0 39 17 8 24 O 0 3 6 0 3 5 27 15 48 23 84 10 28 33 112 25 4 5 18 43 11 16 6O 38 48 92 141 194 24 36 165 230 26 1 0 19 23 7 14 152 15 41 77 220 129 17 47 237 176 32 10 3 15 9 15 27 28 40 46 133 114 212 6 50 120 262 10 33 2 0 3 5 5 7 22 34 31 71 63 117 6 20 137 37 0 0 1 3 O 11 18 18 10 52 29 84 7 8 ' 92 38 4 1 7 7 8 25 33 50 102 105 154 188 10 34 164 222 42 5 6 2 5 17 29 19 111 43 151 1 22 44 173 12 43 12 10 1O 25 45 85 68 120 135 240 4 28 139 268 45 3 4 0 11 . 7 18 5 22 15 55 9 13 68 48 5 1 3 1 3 1O 3 18 14 30 0 5 14 V '35 14 50 7 6 10 23 30 36 21 41 68 106 2 1O 7O , 116 52 1 3 2 6 14 16 15 21 32 46 O 12 32 58 106 89 267 636 108 352 926 958 878 1633 2285 3668 183 543 2468 4211 60 Table 22 is a detailed record of the nuts which were collected and from the unsprayed Plats 1, 3, 5, 7, 9, 11, BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION til; dates they were collected Fxrst Generation Total Ggfiggixgon Tots] num er num Plat Tree Date nuts were collected collected (‘ggllecfid couectgfi No. No. May 29,31 June s, 4 June 7, s June 14,15 June 29 y Inf. Non. Inf. Non. Inf. Non. Inf. Non. Inf. Non. Inf. Non. Inf. Non. Inf. Non. 1 73 12 79 10 105 23 322 20 222 3 801 68 16 0 817 68 2 30 2 126 27 70 19 441 57 326 12 993 118 11 1 1004 119 1 3 195 46 332 55 166 38 750 74 518 4 1961 217 29 10 1990 227 4 31 7 59 18 39 6 119 3 56 .3 304 37 5 1 309 38 9 47 16 128 64 63 14 275 46 214 19 727 159 6 3 733 162 10 41 25 212 56 143 24 463 62 274 58 1133 225 16 1 1149 226 3 15 5 3 23 13 14 3 153 13 21 4 216 36 9 0 225 36 16 61 28 175 64 123 27 445 A58 351 57 1155 234 10 1 1165 235 18 30 13 95 39 71 17 239 11 155 25 590 105 ’1 2 591 107 5 20 62 20 318 66 99 32 371 32 114 24 964 174 35 18 999 192 21 9 13 63 33 50 6 231 17 108 22 461 91 8 4 469 95 27 53 12 284 88 170 30 860 73 283 28 1650 231 20 10 1670 241 7 28 26 2 96 28 96 16 230 28 100 28 548 102 20 10 568 112 29 c 11 7 37 7 53 16 286 31 316 74 703 135 20 10 723 145 30 5 1 15 5 17 4 142 9 A 38 4 217 23 5 5 222 28 31 26 _ 10 111 20 142 30 510 45 261 34 1050 139 44 16 1094 155 9 34 30 12 139 18 109 16 304 5 89 3 671 54 12 0 683 54 35 29 6 83 19 98 7 187 16 276 11 673 59 8 3 681 62 39 " 39 3 122 12 58 7 282 19 139 3 640 44 13 1 653 45 11 40 20 6 30 11 15 6 63 13 59 4 187 40 0 0 187 40 41 21 3 70 10 Nuts 10st 203 11 157 7 451 31 0 0 451 31 44 67 21 179 18 Nuts lost 473 33 223 15 942 87 25 6 967 93 46 4 3 20 6 Nuts 10st 41 4 7 1 72 14 0 0 72 14 13 47 5 5 8 4 Nuts 10st 96 4 22 8 131 21 2 3 133 24 49 18 8 40 11 Nuts lost 212 12 35 5 305 36 0 0 305 36 938 284 2844 702 1701 341 7698 696 4364 456 17545 2480 315 105 17860 2585 LIFE HISTORY QXND CONTROL OF THE PECAN NUT CASE BEARER 61 ‘ A“ e Bmpzwd Eat? ea9% Zufastéé _ flux: izzfaatafi ] ~ e;}:»a§§a iqnkgl Infested fiéavn infested $2: _Ha§2 Breppéd Nuts sea ~ gee. Infaisiad ' 191,122’ iuiesteigi‘ _ . Fig; 20. Nuts collectedhfrom Plats 2, 4, and 6, which were arsenate o_f lead per 50 gallons of wa sprayed with three pounds of ter. 62 B,ULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION E E fiixx-izzi? %§§§‘ *. T%%§ Fig. 21. Nuts collected from Plats l, 3 ,and 5, which were not sprayed. LIFE HISTORY AND CONTROL OF THE PEOAN NUT CASE BEARER 63 Fig. 22. Photograph of the nuts collected from Plats 8, 10, and 12, which were sprayed with three pounds of arsenate of lead per 50 gallons of water. 64 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION Fig. 23. Photograph of the nuts collected from Plats 7, 9, and 1'1, which. were not sprayed . LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 65 Table 22 gives the number of nuts and the time at which they dropped from the trees in plats 1, 3, 5, '7, 9, 11, and 13. These plats were used as checks and selected and alternated with the sprayed plats 2, 4, 6, 8, 10, 12, and 14. The first nuts were collected on May 29 when they began to fall in large numbers. The peak of the damage was reached just before June 14, as on that date 7698 infested nuts were collected from the 25 trees used as checks. From June 15 to June 29, 4364 nuts were collected from the same trees, which shows that the major damage was done prior to June 15. There were very few nuts on any of the unsprayed trees on June 29; although 315 infested nuts were collected at the time the larvae of the second gen- eration were feeding. That was a small number, considering the num- ber of trees from which they were collected. It will be seen that the larger number of nuts fell from the trees between June 3 and June 15. Very few larvae hatched before May 22. From the life history studies it was learned that when the climatic factors were favorable the moths emerged over a limited period of time, and hence the dam- age would result in a comparatively short period. This was the case in 1920.- The trees which were used as checks gave a better oppor- tunity for a study of the time the major damage occurred, as the larvae destroyed practically all the nuts on the trees. The period from May 22, when very few larvae had hatched, until June 15, when the most of the damage had been done, was 24 days. It will be seen that if the nuts are protected during that period of time only the minimum amount of damage will result. The amount of control ob- tained will depend on the thoroughness of the spraying just previous to the hatching of the greater number of larvae. One or two well timed sprayings should control the insect if there is no rain during this period of three weeks. A study of the nuts which dropped from plats 2, 4, 6, 8, 10, 12, and 14 shows that there was a gradual increase in the infestation on the sprayed plats as well as the unsprayed plats. and that nearly an equal protection was afiorded during most of the time on the sprayed plats. Table 23. Comparative summary of the infested nuts on the sprayed and unsprayed plats . Date infested nuts were collected Plat Total Ma3y129, June 3,4 June 7,8 Junlca5l4, June 29 July 17 Sprayed . . . . . . . . . . 106 267 108 926 878 183 2468 Unsprayed . . . . . . . 938 2844 1 791 7698 4364 315 1 7860 Total . . . . . . . . 1044 3111 1 899 8624 5242 498 2O , 328 On May 29 and 31, the number of infested nuts collected from the check plats was about nine times the number collected ~from the sprayed plats; on June 3 and 4, about eleven times as many were collected from the check plats as from the sprayed; the count on June 7 and 8 was seventeen times as great, but this is not absolutely correct, 66 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION as some of the nuts were lost through an accident and the whole number could not be tabulated; on June 14 and 15 about eight times as many were collected from the unsprayed as from the sprayed plats. Since there were few eggs hatching before May 22, it is not believed that the spraying of May 8 did much good. If that be true, then the application of May 22 afforded protection throughout the greater part of the period during which the major damage occurred. Table 24. Summary of the number of nuts which were collected from Plats 2, 4, 6, 8, 10, 12, and 14 at Corsicana in 1920. Per Cent No. Dropped Nuts Nuts Plat trees Amount of Date ————————— on Nuts on No. in material used sprayed In- Non- trees In- Non- trees Plat fested infested Sept. 27 fested infested Sept. 27 3 lbs. of arsenate of May 8 lead per 50 gals. May 27 2 4 of water . . . . . . . June 26 396 695 3181 9 90 74 3 lbs. of arsenate of May 8 4 4 lead per 50 gals. May 27 of water . . . . . .. June 26 527 961 3531 11 89 70 3 lbs. of arsenate of May 8 6 3 lead per 50 gals. May 27 of water . . . . . . . June 26 359 589 2059 12 88 68 3 lbs. of arsenate of May 8 8 4 lead per 50 gals. May 27 ' of water . . . . . .. June 26 474 535 1901 16 84 65 3 lbs. of arsenate of May 8 10 4 lead per 50 gals. May 27 . of water . . . . . . . June 26 389 713 2645 10 90 71 3 lbs. of arsenate of May 8 . 12 3 lead per 50 gals. May 27 of water . . . . . . . June 26 207 509 1865 8 92 72 3 lbs. of arsenate of May 8 14 3 lead per 50 gals. May 27 of water . . . . . . . June 26 116 209 511 14 85 61 Total . . . . . . . . . . . . . . . . . 2468 4211 15693 11 89 70 . Table 25. Summary of the number of nuts which were collected from Plats 1, 3, 5, 7, 9, 11f and 13, at Corsicana in 19 0. N0. of l i Per Cent trees Dropped Nuts Nuts on Plat in Amount of trees Nuts N0. Plat material used I n- Non- Sept. 27 Infested _ Non- on trees fested. infested infested Sept. 27 1 4 Check (Unsprayed) . . . . 4120 452 65 89 11 2 3 4 Check (Unsprayed) . . .. 3272 659 151 80 20 4 5 3 Check (Unsprayed). . . . 2059 394 156 79 21 6 7 4 Check (Unsprayed) . . . . 3183 526 156 82 18 4 9 3 Check (Unsprayed) . . . . 2458 271 85 87 l3 3 11 4 Check (Unsprayed) . . . . 2258 209 37 90 17 1 13 3 Check (Unsprayed) . . . . 510 74 18 85 15 3 Total . . . . . . . . . . . . . . 17860 2585 668 85 15 3 LIFE HISTORY AND CONTROL OF THE PECAN NUTCASE BEARER I_ 67 . hirsts has: Dressed liars " y Infmed i Nssiafeatad * o igfifi gs???» g? are as 1% 4IIIh* firewsé films Q fiiiiilg w infested Nsreiaifaaiaa a a was gsifeii» i??? 1re ass . arr Fig. 24. Photograph of the nuts collected from Plat 13, which was not sprayed, and from Plat 14, which was sprayed with three pounds of arsenate of lead per 50 gallons of water 1921—College Station A series» of tests Was made at College Station in 1921 to find some material that would increase the sticking power of arsenate of lead and calcium arsenate. The pecan orchard was divided into 11 plats. Plat 5, which was sprayed with arsenate of lead with glue and potas- sium dichromate added as a sticker, was so severely burned that the nuts fell from thetrees a few days after spraying. A shower just after the application was evidently a factor in causing burning, for several plats at Oorsicana were sprayed with thesame materials and no burning resulted. ' A The amount of case bearer infestation was not great enough to give any decisive results. The heaviest infestation of 5 per cent was on Plat 1, which was sprayed with calcium arsenate. The infestation on the unsprayed or check plat was 4 per cent or less than that on the plat sprayed with calcium arsenate. Arsenate of lead to which one pound of gelatin was added gave slightly the best results. There was very little difference between the plats sprayed with arsenate of lead with no sticker; arsenate of lead to which gelatin was added; and arsenate of lead to which calcium caseinate had been added. Plat 2, which 68 ‘BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION Spmpmen DLATs DxzomvsoNurs NuTs 0N TDEF: lNFfizéTEzD NQN-INF-Ezsflzo 8am". 27 4 2466 42.12 15695. UNSPQAYED PLATé DRQPPBD NUTS NUTS 9N Tner; Iwresrrao Nou-Iurzsrzo 5am‘. 27 17sec zses 66a. Fig. 25. Graphical representation of the “Dropged Nuts” and the “Nuts on the trees Sep- A tember 27" at Corsicana in 1920 on t e sprayed and unsprayed plats. LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 69 was sprayed with arsenate of lead, had an infestation of .7 per cent, while Plat 1 next to it sprayed with calcium arsenate had an infes- tation of 5 per cent. Rain stopped the spraying operations on May 14, which probably accounts for the difierence in control by calcium ar- senate and arsenate of lead. _On the whole, these results gave Very little indication of the effectiveness of stickers because of the light infestation. Table 26. Summary of the result of a series of tests_made at College Station in-1921 to determine the value of stickers in combination with arsenate . of lead and calcium arsenate. No. Dropped Nuts Per Cent Plat trees Amount of Date -——————— Har- No. in material used sprayed In- _ Non- vested ln- _ Non- Har- Plat v fested infested nuts fested infested vested Calcium arsenate 3 . 1 7 lbs. per 50 gals. May 14 of water . . . . . . . May 29 83 657 787 5 95 52 Arsenate of lead 3 2 6 lbs. per 50 gals. May 14 of water . . . . . . . May 29 11 483 1144 0.7 99 72 Arsenate of lead 3 3 5 lbs. per 35 gals. of water plus May 14 4._8 oz. Moore’s May 29 82 921 2354 2 98 70 mixture . . . . . . . . Arsenate of lead 3 lbs. 1-2 lb. glue May 14 per 50 gals. water May 29 97 1684 3027 2 98 63 Arsenate of lead 3} 6 6 lbs. 17 pz. cal- cium caseinate per 50 gals. water. . . May 16 ' May 29 24 973 1924 0.8 99 66 May 16 7 5 lbs. 1 oz. cal- May 29 129 1112 2819 3 97 69 Calcium arsenate 3 cium caseinate per 0 gals. water . . 7 Arsenate of lead 3 8 6 lbs. 1. lb. gelatin 50 gals. of water Calcium arsenate 3} May 16 May 29 21 1373 4648 0 .3 99 -77 9 4 lbs. 1-2 lb. ela- tin per 50 ga s. of water . . . . . . . . . . May 16 . May 29 72 1171 1501 3 97 55 Calcium arsenate 3 10 3 lbs. 1-2 lb. glue May 16 per 5O gals. of May 29 5 479 453 0.5 99 48 water . . . . . . . . . . 11 7 Check . . . . . . . . . . . . . . . . . . . .. 117 1477 3406 2 98 68 1921—Corsicana A series of tests was carried out at Corsicana in 1921, but the in- festation was so light that the results are not presented. 1921—Winona A A series of tests was also conducted at Winona in Mr. Butterfield’s orchard in 1921 to "determine the value of stickers in connection with 70 BULLETIN NO. 328, TEXAS ‘AGRICULTURAL EXPERIMENT STATION arsenate of lead and calcium arsenate. Fifty trees were divided into eight plats which w.ere sprayed, an as a check. The infestation was ve results are not indicative of the value of the sticker. plats were sprayed with of glue and potassium mate were added. Plats 3 an and arsenate of lead. d one plat of ten trees was used ry light and for that reason the All of the arsenate of lead, to which varying amounts dichromate or gelatin and potassium dicho- d 4 were sprayed with Moore’s mixture The check plat showed an infestation of 2 per cent. The infestations in the other plats were also small. Table 27. Summary of the result of a series of tests to determine the value of stickers in combination with arsenate of lead and calcium arsenate at Winona, 1921. No. of Dropped Nuts Per Cent Plat trees Amount of Date —-—-————- Har- No. in Variety material used sprayed Non- vested Non- Har- Plat Infested infested nuts Infested infested vested 1 6 Delmas ........ .. 1 lb. gelatin, 2 lbs. arsenate of lea_, 2 May 21 oz potasium dich- June 7 25 528 2350 0..9 99 81 romate per 50 gals. water ...................... .. 2 8 Teehe ............ .. 1 lb. gelatin, 2 lbs. arsenate of lead, 2 oz. potassium dich- May 21 romate per 50 gals. June 2 39 1254 2426 1 99 65 of water ................ .. 3 4 Delmas ........ .. 3 lbs. Moore's mix- ture and arsenate of May 21 lead per 50 gals. of June 8 15 191 451 2 98 69 water ...................... .. 4 10 Teche.............. 3 lbs. Moore's mix- ture and arsenate of lead per 50 gals. of May 21 water ...................... .. June 8 17 1342 2571 0..4 99 66 5 6 Delmas ........ .. 1. lb arsenate of lead; 1-2 lb. glue; _1 oz. May 21 potassium dichro- June 8 8 145 1370 0..5 99 90 mate per 25 gals. of I water ...................... .. 6 4 Teche ...... 1 lb. arsenate of lead; 1-2 lb. glue; 1 oz. potassium dichro- May 21 mate; 25 gals. 0f June 8 1 55 631 0..1 99 92 water ...................... .. 7 4 Delmas ........ .. 1 lb. arsenate of lead; 1-2 lb. glue; _2 oz. potassium dichro- May 21 mate; 25 gals. of June 7' 5 57 538 0..6 99 90 water ...................... .. 3 8 Teche ............ .. 1 lb. arsenate of lead; 1-2 lb. glue; 2 oz. potassium dichro- May 21 mate; 25 gals. of June 7 27 475 1817 1 99 78 water ...................... .. 9 10 Teche.............. 1 1-2 lbs. arsenate of lead; 3 lbs stone May 17 lime; 25 gals. water June 7 18 276 1806 0..9 99 85 l0 1O Delmas ........ .. Check ............................................ .. 7 143 235 2 98 61 LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE‘ BEARER 71 1922—Corsicana Tests on control were conducted in 1922 on the same trees that were used in 1920 and 1921 in the orchard of J. M. Blackburn at Corsicana. Plats 5 and 6 of eight trees each were not sprayed but used as checks. Plat 4, which consisted of eight trees, was sprayed with calcium arsenate at the rate of three pounds per fifty gallons of water. Plats 1, 2, and 3 were sprayed with arsenate of lead at the rate of three pounds per fifty gallons of water; there were eight trees in Plat 3, seven in Plat 2, and eight in Plat 1. All the trees were Halberts and were sprayed twice, the first time on May 8 and the second time May 19. Table 28 is a summary of results of a series of spraying tests made at Corsicana in 1922. No. of Dropped Nuts Per Cent Plat trees Amount of ————————— Nuts . No. in material used on trees Nuts Plat Infested Non- Aug. 13 Infested Non on trees infested infested Aug. 13 1 8 Arsenate of lead 3 lbs. per 50 gals. of water. . 1212 1975 1708 25 75 35 2 7 Arsenate of lead 3 lbs. . per 50 gals. of water. . 1047 2342 1619 21 79 32 3 8 Arsenate of lead 3 lbs. per50gals.ofwater. . 1494 2485 1129 29 71 22 4 8 Calcium arsenate 3 lbs. per 50 gals. of water. 1629 1833 872 38 62 2O Check (Unsprayed) . . . . 2807 1138 61 7O 30 6 8_ Check (Unsprayed) . . . . 1048 459 43 67 33 3 In the check plats, 69 per cent of the nuts dropped from the trees on account of case bearer attack; 29 per cent dropped from unknown causes; 2 per cent remaining on the trees on August 13. The nuts were counted on the trees instead of waiting until time to harvest them. There were very few nuts on trees which were not sprayed and scarcely any on the native trees. Great numbers of crows collect in this vicinity in the fall of the year and the nuts had to be counted on the trees instead of waiting until they matured, as the crows could not be kept out of the orchard except by constant watching. causes; and 2O per cent were on the trees August 13. Plats 1, 2, and 3 were sprayed with arsenate of lead; 25 per cent of the nuts fell from the trees on account of case bearer attack; 45 per cent from unknown causes; and '30 per cent were on the trees August 13. The case bearer infestation was as serious in this orchard in 1922 72 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION as it was in 1920, but a smaller degree of control was secured. This was probably due to the fact that the date of spraying was not as carefully determined as in 1920; also to the fact that there was more rain during the spraying period in 1922 than in 1920. The orchard at Corsicana is situated near several creeks, where there is an abundance of native trees, and there was always a supply of moths from larvae on these trees to reinfest the sprayed trees. 1922—Winona In 1922 aspraying test was conducted in Mr. E. C. Butterfield’s orchard at Winona on six varieties, viz: Schley, Stewart, Moore, Pabst, Teche, and Success, to determine the relative amount of control it might be possible to obtain and the comparative infestation on these varieties. A row of ten consecutive trees was selected for each variety and five trees were sprayed and five were left as checks. The results are tabulated in Tables 28 and 29. Plats 1, 3, 5, 7, 9, and 11 were sprayed with arsenate of lead at the rate of 11} pounds per 50 gallons of water, to which 3 pounds of stone lime was added. Plats 2, 4, 6, 8, 10, and 12 were not sprayed. Table 29. Summary of series of spraying tests on six varieties of pecans at Winona in 1922 No. of Dropped Nuts Per Cent Plat trees Amount of Date ——i——- Har- No in Variety material used sprayed Non- vested Non- Har- Plat Infested infested nuts Infested infested vested lead; 3 lbs stone May 13 391 2604 2032 8 92 40 1 5 Schley............'.... 1.5 lbs. arsenate of } lime; 25 gals. water lead; 3 lbs. stone lime per 50 gals. of water ...................... .. May 16 3 5 Stuart .............. .. 1.5 lbs. arsenate of May 26 65 517 4600 1 99 89 lead; 3 lbs. stone lime per 50 gals. of water ...................... .. 5 5 Moore .............. .. 1.5 lbs. arsenate of . May 13 519 5057 27600 2 98 83 7 5 Pabst ................ .. 1.5 lbs. arsenate of lead; 3 lbs. stone lime per 50 gals. of May 17 626 2471 1055 15 85 25 water ...................... .. _ ' 9 5 Teche ................ .. 1-2 lbs. arsenate of _ lead; 3 lbs. stone ‘ lime per 50 gals. of May 18 118 1491 7400 -1 99 82 water ..... .L ............... .. 11 5 Success................ 1.5 lbs. arsenate of } lead; 3 lbs. stone lime per 50 gals. of water ...................... .. May 17 288 1774 574 11 89 22 Total ............................................................ .. 2007 13914 43261 3..39 97 73.7 LIFE HISTORY AND CONTROL OF THE PEGAN NUT CASE BEARER 73 Table 30. Summary of the check p_lats used in the variety spraying tests made at Winona in 1922. ‘ No. _ Dropped Nuts Per Cent Plat trees a Variety Date sprayed ——————————— Har- No. in In- Non- vested In- Non- Har~ Plat fested infested fested infested vested 2 5 Schley . . . . Check (Unsprayed) 482 2873 1103 11 89 * 25 4 5 Stuart. . . . Check (Unsprayed) 113 794 3300 3 97 78 6 5 Moore. . . . Check (Unsprayed) 485 4006 25100 2 98 85 8 5 Pabst. . . . . Check (Unsprayed) 513 2086 952 14 86 27 10 5 Teche. . . . . Check (Unsprayed) 199 1248 5753 3 97 80 12 5 Success.. . . Check (Unsprayed) 535 1668 504 20 8O 19 Total. . . . . . . . . . . . . . . . . . . 2327 12675 _ 36712 4.49 96 70.9 It will be seen that the extent of infestation was similar for allt varieties on both the sprayed and the unsprayed plats. In the Pabst variety the infestation was 1 per cent greater on the sprayed than on the check plats. The infestation in the two plats of Moore was about thesame on the sprayed as in the unsprayed plats. In the Stuarts and Teche there was a 2 per cent greater infestation on the check plat than on the sprayed plat; in the plat of Schleys there was a 3 per cent greater infestation on the check than on the sprayed plat; and on the plat of Success there was 9 per cent greater infestation on the check plat than on the sprayed one. The amount of control on the sprayed trees in the whole series was 1 per cent over the unsprayed ones. Table 31. Summary of a comparison of the amount of infestation onfthe sprayed and unsprayed plats at Winona 1n 1922. _ Per Cent of Infestation Variety Sprayed [ Unsprayed Schley . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 11 Stuart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3 ‘ Moore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 Pabst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 14 Teche . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3 Success . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 20 74 BULLETIN NO.’ 328, TEXAS AGRICULTURAL EXPERIMENT STATION ACKNOWLEDGMENT Several people have assisted in the work set forth by this Bulletin, and the Writer wishes to acknowledge the assistance rendered. Dean E. J. Kyle of the College of Agriculture of the A. and M. College of Texas first suggested the problem and gave helpful sug- gestions in the course of investigation. A Mr. E. C. Butterfield of Winona, Mr. B. W. Houk of Westfield, and Mr. J. M. Blackburn of Corsicana not only gave the auther per- mission to carry on control experiments in their orchards, but also gave their own personal assistance in picking up fallen nuts and col- lecting larvae. Messrs. W. W. Derrick, B. K. Fletcher, T. P. Remy, and V. A. Little assisted the author in conducting the life history work. Mrs. Bilsing not only assisted the author in the life history studies, but also helped in compiling the data for the Bulletin. SUMMARY OF THE LIFE HISTORY The pecan nut case bearer passes the winter in the larval stage in a tough silken hibernaculum. As soon as the trees begin to grow, the larvae begin feeding on the buds to which the hibernacula are attached. After feeding in the. hibernacula for some time they emerge from their winter quarters angd enter the new tender growth at the axils of the leaves. The larvae will be found feeding in these burrows during the latter part of March and the month of April. The point of entrance may be determined by the frass and excrement which the larva throws out. After complet- ing their development, the larvae stop up the entrances to their bur- rows with silk and excrement and then pupate. The length of the pupal period depends a great deal on temperature and ranges from 9 to 24 days. The average length of the pupal period of the spring- brood varies from 12 to 18 days. The moths which emerge from these pupae are known as the spring-brood moths. The greater number emerge the last half of April and the first half of May; the maximum emergence occurring between May 5 and May 13. The eggs which are deposited by these moths are the beginning of the first generation. The eggs are usually deposited in the center of the pistil or on the upper or lower surface of the calyx lobes. Ovi- position usually begins on the third or fourth night after emergence. The eggs hatch in about 5 days. Shortly after they have hatched the young larvae wander about until they have found a protected place and begin feeding. In most cases the larvae feed upon buds for two or three days, after which they enter, the small nuts at their bases. The larvae enter by cutting out small circular holes and. feed on the interior of the nuts, which at this time are about the size of an English ea. A larva goes from one nut to another until it is fully developed. The length of the larval period is about 25 days. When full grown, LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 75 the larva selects a dry nut and stops up the point of entrance with silk and pellets of excrement, after which it spins a flimsy cocoon and pupates within the nut. The pupal period of the first generation is approximately 9 days and there is but little variation. The moths of this generation begin emerging the latter part of May or the first of June. They live only a short time and begin ovipositing shortly after emergence. The eggs of these moths are the beginning of the second generation. The nuts are nearly half grown at this time and there is little op- portunity for ovipositing in the pistil. Hence the eggs are usually deposited in grooves near the tip and base of the nuts or on buds below the nut clusters. The eggs hatch in about 5 days and the larvae feed on the buds below the nuts for a short time. Then they enter the base of the nuts and hollow out the interior as in the first generation. A single larva destroys fewer nuts because of the increased size" of the nuts. The length of the larval period is about 33 days. After completing its growth the larva closes up the entrance, spins ' a cocoon, and pupates within. The pupal period is about 9 days. The moths of the second generation emerge over a longer period than the moths of the first generation. The moths of the second generation begin emerging July 22, and continue to emerge until about Sep- tember 7. The eggs which are deposited are the first stage of the third gen- eration. The eggs hatch in 5 days. At this time the nuts are about full grown. Most of the larvae feed within the shucks or in an en- closure formed where three or four nuts touch. The larval period of the third generation lasts about 26 days. After becoming full grown the larva spins a cocoon and pupates in the larval burrow. The pupal period lasts 9 to 13 days. The moths of this generation begin emerg- ing about August 29, and continue to emerge until October 25. They oviposit in a short time after they emerge and the eggs which they deposit are the beginning of the fourth generation. If the weather is cool, oviposition may be delayed for a considerable number of days. The eggs of the fourth generation are deposited on nuts. If there are no nuts at hand the moths oviposit on buds. The length of the egg stage varies with the temperature and may be 4 to 9 days. The young lavrae feed at the base of leaf stems for a time and then spin their overwintering hibernacula. GENERAL CONCLUSIONS ON SPRAYING 1.. Spraying to control the case bearer is not practicable when the infestation is less than 8 to 10 per cent. 2. Spraying must be done thoroughly and at the proper time to obtain good results. " 3. The time to spray should be determined if possible by collect- ing one hundred or more spring-brood larvae and pupae and rearing 76 BULLETIN NO. 328, TEXAS AGRICULTURAL EXPERIMENT STATION the moths. Spray 8 or 10 days after numbers of moths began to emerge daily. Usually this is shortly after the nuts have set. Spray a second time '7 to 10 days after the first. If the infestation is heavy, spray athird time 7 to 10 days after the second. 41. _ If it is not practicable to rear moths t0 determine the spraying date, watch for the first signs of damage when the larvae begin to feed on the buds below the nut clusters and spray at that time. The first spraying date in the years during which the insect was observed was between May 10 and May 22. Anyone, by a little observation can learn the important points about the life" history. 5. The use of arsenate of lead at the rate of three pounds per fifty gallons of water has been found most efiective. When water contain- ing sulphur is used or when the humidity is high, three pounds of slaked ‘stone lime or four pounds of hydrated lime should be used per each fifty gallons of water. If, upon adding the arsenate of lead to water, the mixture turns black, lime should always be added. 6. Use only a good power spraying machine which will maintain a pressure of at least two hundred and fifty to three hundred pounds, and a standard spray gun. Efficient work cannot be done with any other kind of equipment. 7. Thoroughly drench the trees, as the degree of control is de- termined in a great measure by the amount of spray remaining on the buds as Well as on the nuts. 8. It has not been found practicable to spray for any but the first- generation larvae, but further studies may show that other sprayings are practicable. 9. Heavyrains have been one of the most serious hindrances to effective spraying because of the fact that they wash off the poison and make it impossible to spray again in the immediate future on account of soft ground. When this occurs at the critical spraying time as in 1920 at College the crop may be lost before it is possible to spray again. ' 10. Under the most favorable climatic conditions 85 per cent of control has been secured, but under unfavorable, conditions an equal per cent of the nuts have been lost. 11. Study Tables 1 and 2, which show a correlation between the amount of damage and the number of generations and adapt your spraying program accordingly to it. It will require observations for a longer period of years to fully substantiate this fact, but at the present time it seems important. 12. Spraying with contact insecticides to kill the larvae in their hibernacula would be a more desirable method of control than the use -of arsenate of lead, but at present no contact insecticide has been found which is effective. LIFE HISTORY AND CONTROL OF THE PECAN NUT CASE BEARER 77 13. Larvae are not easily killedafter they are several days old, because they do not feed on the outside of the nut. 14. If an orchard is in the vicinity of native trees, control will be more diflicult than when such is not the case, and more applica- tions will be necessary to control the insect.