Historic, archived document Do not assume content reflects current scientific l ^ r R U 4 < s s 1 A N ; M — 1|^ P 1 n ^ \ , ° /v' 1 % ■^ A D A % P V Jp '"^S ^^ ?. ^ - "A ^ :^ t '^^ 1% • • • Is tVs" ^ ^ ^ •i^ ^r ^ ^ k1 |f* ^ J- ^ r _^s; 1 C I f \ • %1 • • • • 0 p r 1 A N TIC ^ ^E^ O^Sfff? p ^ X ^ c? 1^ 5e: e: Wl P 1 R E *^ g o C 1 F C E A / c V i^ E A !f ^»^ " h- V/»/?/« _E3Y ^.^^ ^ 1 z^\ |ORMOBA _^_ .^_ fe""~ 'uls7' or cANcea L...5^ •®' ^ ^^5 -^""in -f JsCNEOAL ►" 7 N • ^L fr-^ \f" rit ? ^ S % 2 ^3 ^^ ^T- I" .^s.^ ^ ^/ \ ]=;&g f ^ »- 1 ECUADOR/ V f St' .. B 1 / , 0 c ^^^M ^ 1^ ^a,^ec^ ^S Z 1 L L #\H y 1^4 ■'^^n • ^^ ^^ 1 r ^ '1 ^,£> i^% — - --- --- U T H --- .__ __. -- — -| ^ ^- 1^ SOUTH — J# - — --- -- c * U S T R A L - P A C 0 C t'/; c 1 ^ ^ ; E A <• I c V ^ r ^^ ^ ^^ r % r; i r/ % i f •1 1 C ^ p 1 1 . 1 s (%, -— 0'' — ir^ P O'' 7^" o" 0" ■^V' «• 40» 60» 0° 80- ^^ .^o| = = °^ " i •■-■^ " ,....-....--«-.- U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY— BULLETIN No. 50o L. O. HOWARD, Entomologist. THE COTTON BOLLWORM. 4u fac PREPARED UNDER THE DIRECTION OF THE ENTOMOLOGIST BY A. L. QUAINTANCE and C. T. BRUES. WASHINGTON: GOVERNMENT PRINTING OFFICE, 1905. LETTER OF TRANSMITTAL. United States Departi^ient of Agriculture, Bureau of Ektomology, Washington^ D. C.^ Fehruary 6^ 1905. Sir: I have the honor to transmit herewith for publication a full account of the bollworm, prepared under my direction by Messrs. A. L. Quaintance and C. T. Brues, special field agents of this Bureau. Mr. Quaintance has been engaged for two years in in^ '^stigating the work of this very important and injurious insect, hib ork having been done mostly in the State of Texas. Mr. Brues as ced him for the larger part of the year 1901. The report is a very careful and complete account of the bollworm, which, although it has previoush' been written about by many entomologists, has never before received such a full consideration, and I recommend its publication as Bulletin No. 50 of this Bureau. The illustrations submitted are an essential part of the report. Respectfully, : L. O. Howard, Entuniologist. Hon. James Wilson, Secretary of Agriculture. (2) PREFACE. Until the advent of the Mexican cotton boll weevil the bollworm was easily the most serious of the numerous insect pests of the cotton plant. The coming of the weevil has in no way lessened the destruc- tiveness of the bollworm, though its injuries have been overshadowed by the more serious depredations of the former species. The extent of bollworm ravages in recent years, notably in portions of Texas, was the occasion of an investigation su^jplementary to those previously made by the Bureau of Entomology. Under the provision of Congress for investigations concerning the cotton boll weevil, the senior author was detailed to the bollworm work in Texas in March, 1903. Headquarters were established at Victoria, where office and laboratory facilities were available in the building occupied by the force engaged in boll weevil investigations. During that year special attention was given to field work, though such laboratory investigations as were possible were conducted. The principal results of field work in 1903 have been reported in Farmers' Bulletin No. 191 of this Department. By reason of an increased appropriation the bollworm. investigation was considerably enlarged in 1901. Headquarters were established at Paris, Tex., and a field laboratory was fitted up with necessary appa ratus for thorough life-history studies. Field experiments were also greatl}^ extended, the area under experiment amounting to about 600 acres. Three additional entomologists were employed in the work, and a fifth was engaged from July 1 to October 31. In addition to the authors, these were Messrs. F. C. Bishopp, A. A. Girault, and C. R. Jones. The senior author, under the direction of the Entomolo- gist, has been directly in charge of the investigation in the laboratory and field. Laboratory details were supervised by the junior author, assisted b}^ Mr. Girault. Messrs. Bishopp and Jones were occupied in making field observations and with work connected with the several experimental farms. Original observations by these gentlemen are credited to them in the pages of this bulletin. Thanks are due many citizens of Texas and of other States, both planters and business men, for courtesies extended during the course (3) , of the investigation. The several gentlemen on whose plantations the Department's experimental farms have been located have greatly facilitated the work b}' careful attention to instructions given as to the growing of the crop. The principal results of field experiments in 1904 have been pub- lished in Farmers' Bulletin No. 212 of this Department. The present work deals more especially with results of laboratory investigations and other points of interest concerning the insect as a pest to cotton and other crops throughout its extended range. CONTENTS. Page. Classification and synonomy 11 Varieties - 12 Common names 12 Geographical distribution 13 Original home 14 Food plants 17 Status of boll worm in foreign countries ... 19 Economic status in the United States 21 Injury to corn 21 Injury to cotton , 23 Injury to tomatoes ■ 25 Distribution and destructiveness in relation to life zones 25 Transition zone 26 Upper Austral zone 27 Carolinian area 27 Upper Sonoran area 28 Lower Austral zone 28 Austroriparian area 28 Lower Sonoran area 28 ; The bollworm in the western United States 29 Farm methods in relation to bollworm injury 29 Relation of weather to bollworm injury '. 32 Injury to cotton from other causes than the bollworm 35 Earlier investigations of the Department of Agriculture 37 Life history 40 Summary 40 The egg 41 Description- 41 Oviposition 42 Oviposition on corn 42 Time and manner of oviposition 44 Oviposition on cotton 45 Time and manner of oviposition 45 Distribution of eggs on cotton 46 Oviposition on other plants 47 Number of eggs laid by a single moth 48 Deposition of infertile eggs 49 Eggs remaining in the ovaries at death 49 Effect of fertilization on egg laying 49 Changes in external appearance 50 Embryonic development 50 Hatching 50 (5) 6 Life history — Continued. Page. The egg — Continued. Shrinking of infertile eggs 51 Eating of shells and eggs by newly hatched larvae 51 Percentage of eggs that hatch 52 Length of the egg stage .• 52 Effect of reduced temperatures 53 Effect of atmospheric conditions 54 Effect of submergence on eggs 54 Eggs destroyed by storms 55 Effect of sun on eggs 55 The larva _. 55 Descriptions of instars 57 Possible causes of color variation 62 Duration of larval instars 63 Growth during the larval instars 64 Influence of external conditions on growth 66 Number of molts 67 Process of molting 67 Habits of neWly hatched larvae on cotton 68 Effect of external conditions -on newly hatched larvae 68 Character of injury 68 Character of injury to corn .' 69 Character of injury to cotton 69 Character of injury to other plants 70 Choice of food by larva^ 71 Relative attractiveness of Upland and Egyptian cottons 71 Comparative inj ury to early and late cotton 72 Amount of damage done by a single larva 74 Damage to young corn 74 Damage to ears of corn 75 Damage to cotton 76 Number of larvae on a single plant 78 Relation to the number of eggs laid 78 Percentage of corn plants infested - 78 Cannibalism 79 Leaving the plant and entering the ground for pupation 80 Formation of the pupal cell 81 Variations in the form of the pupal cell 82 Pupation in other situations 83 Changes undergone in the formation of the pupa 83 The pupa 84 Description of pupa - 84 Length of the pupal stage 84 Effect of external conditions - 86 Heat : --.. 87 Soil 87 Mortality during the pupal stage 88 The adult 89 Emergence 89 Description of moth 89 Size of moths - - 90 Variation and possible causes - 90 Anatomv and sexual differences 91 Life history— Continued. Page. The aduh — Continued. Proportions of the sexes 92 Length of hfe 92 Day habits 93 Night habits 94 Attraction by Hghts 95 Attraction by poisoned sweets 96 Length of life cycle 97 Generations of the bollworm 98 Laboratory experiments 99 Seasonal history 102 Appearance of spring moths 102 Progress of infestation by generations 103 Increase in numbers during the season 104 Do the adults hibernate? 104 Insects sometimes mistaken for the bollworm 105 Predaceous enemies 107 Predaceous enemies of the eggs and young larvse 107 Predaceous enemies of the larger larv?e and moths 109 Parasites. 115 Parasites of the egg 115 Description of TricJiogramma pretiosa Riley li 8 Description of Telenomus heliothidis Ashmead 119 Parasites of the larva 119 Hymenopterous parasites 121 Description of Microplitis nigripeanis Ashmead 122 Dipterous parasites — Tachinidse 123 Diseases /- 124 Bacterial disease - '. 124 Scavengers following the bollworm 126 Methods of bollworm control 127 Cultural methods 127 Trap crops 130 Arsenical poisons 131 Ineffective methods of combating the bollworm 132 Mechanical destruction 133 Methods of bollworm control on corn, tomatoes, and tobacco 133 Bibliography 135 Index 151 ILLUSTRATIONS PLATES. Page. Plate I. Map showing distribution of boll worm in world Frontispiece II. Life zones of the United States 24 III. Fig. 1.— Egg of the bollworm 40 Figs. 2-7. — Respective larval instars 40 Fig. 8.— Pupa 40 Fig. 9.— Moth 40 IV. Fig. 1.— Field of corn of age to attract moths for oviposition 44 Fig. 2. — Bollworm eggs, enlarged, seen from above 44 V. Tip of ear of corn showing bollworm eggs on silks 44 VI. Fig. 1. — Bollworm on leaf stalk of cotton plant 56 Fig. 2. — Variation in markings of larv?e, lateral view 56 Fig. 3. — Variation in markings of larvse, dorsal view 56 Fig. 4. — Dorsal pattern of markings of dark-brown larva 56 VII. Fig. ]. — Young corn plant, showing injury to "bud" by bollworm. 68 Fig. 2. — Bollworm and its work in corn tassel 68 ^ VIII. Fig. 1. — Bollworm and its injury in ear of field corn 68 Fig. 2. — Bollworm and its injury in ear of sweet corn 68 IX. Fig. 1. — Bollworm and its injury in cotton flower 68 Fig. 2. — Cotton flower destroyed by bollworm 68 Fig. 3. — Injury of very young larva to cotton square 68 Fig. 4. — On the right, "flared" cotton square due to bollworm injury ; on left, normal square 68 Fig. 5. — Bollworm destroying young cotton boll 68 X. Fig. 1. — Bollworm eating into a half-grown cotton boll 68 Fig. 2. — ^Bollworm boring into full-sized cotton boll _ 68 Fig. '3. — Work of bollworm in interior of cotton boll 68 Fig. 4. — Cotton boll only partially destroyed by bollworm, two "locks" open 68 XI. Fig. 1. — Bollworm injury to tobacco 68 Fig. 2. — Bollworm and its injm-y to tomato 68 Fig. 3. — Bollworm boring into green peach 68 Fig. 4. — Bollworm attacking okra 68 Fig. 5.— Bollworm boring into cowpea pod 68 XII. Fig. 1. — Larva entering soil for pupation 80 Fig. 2. — Shrunken appearance of larvce just before molting into pupa stage - 80 Fig. 3. — Larva in its "cocoon, " as made in sandy soil 80 Fig. 4. — Bollworm pupae 80 XIII. Fig. 1. — Pupal cell of bollworm in soil 80 Fig. 2. — Plaster of Paris casts of pupal cells 80 (8) 1 Plate XIV. Fig. Fig. Fig. Fig. Fig. XV. Vari XVI. Fig. XVII. XVIII. XIX. XX. XXI. XXII. XXIII. XXIV. XXV. 1. — Exit holes of moths from pupal cells in ground 2. — Condition of moth immediately after emergence 3.— BoUworm moth with wings expanded 4. — Bollworm moth on the alert 5. — Moth at rest on cotton leaf Variation in markings of bollworm moths Fig. 1. — Cotton square attacked by caterpillar of Ccdycopls cecrops. Figs. 2 and 3. — Larva of Prodenia ornithogaUi on cotton square and boll Fig. 4. — Moths of Prodenia ornithogaUi Fig. 1. — Breeding cage used in determining generations of boll- worm ; planted to corn Fig. 2. — Same, planted to cotton later in the season Fig. 1. — PoUstes annularis and nest 2. — Lycosa riparia, with captured bollworm moth 3. — A robber fly, Beromyia anguslipennis 4. — Malloplwra orcina Fig. 5. — Metapodius femoratus, male and female Fig. l.—Microplitis nigripennis, adults, cocoons, and parasitized bollworm , Fig. 2. — Archytas piUventris, parasitic on bollworm Fig. 3. — Bollworm killed by bacterial disease : Fig. 4. — Bollworm killed by fungus Fig. 1. — Bollworm experimental farm at Willspoint, Tex Fig. 2. — Fertilized and unfertilized cotton plats at Willspoint, Tex Comparative maturity of King and Myers cottons grown under identical conditions Fig. Fig. Fig. Page. 88 88 88 88 88 88 104 104 104 104 104 104 104 104 104 104 124 124 124 124 124 124 128 128 128 128 128 128 128 128 128 Fig. 1. — Proper use of corn as a trap crop Fig. 2. — Improper use of corn as a trap crop Fig. 1. — Method of poisoning cotton for leafworm and bollworm . Fig. 2. — View of spraying work in poison experiments Fig. 1. — Geared poison ''blower" for poisoning cotton Fig. 2. — Machine used in jarring and collecting boll worms from cotton Fig. l.-r-Cyanide light trap Fig. 2. — Pans with poisoned sweets TEXT FIGURES. Fig. 1. Map of area infested by bollworm 2. Egg of bollworm ; side and top views S. Diagram showing "regular" and "irregular" oviposition curves 4. Diagram showing relative length of egg stage '. 5. Head of bollworm larva 6. Diagrammatic representation of comparative rate of growth of larvae during different instars 7. Diagram illustrating relative width and variation in width of the head casts of larvie in third and fourth instars 8. Diagram of different types of pupal cells 9. Enlarged caudal end of pupa 10. Chart showing relative length of pupal stage 11 . (Tcnitalia of male bollworm moth 12. ' ' Sharpshooter, ' ' Homalodisca triquetra 106 24 41 49 53 65 66 81 84 85 92 10 Page. Fig. 13. Triphleps insidiosus: adult and nymph 107 14. Hippodamia convergens: adult, larva, and pupa 108 15. Solenopsis geminata 108 16. Chrysopa oculata: adults, eggs, larv?e, and cocoon 109 17. Calosoma scrutator: beetle ill 18. Calosoma calidum: beetle and larva 112 19. Podisus spinosus: adult, egg, and nymphs 112 20. Trichogramma jrretiosa 115 21. Boll worm egg parasitized by Trichogram ma, preiiosa 118 22. Telenomus heliothidis 119 23. Microplitis nigripennis: adult, larva, and cocoon 121 24. Ferilampus hyalinus: adult and cocoon 122 25. Archytas piliventris: adult fly 123 26. Winihemia 4-pustulata: adult and parasitized moth pupa 124 27. Diagram showing comparative earliness and quantity of cotton crop from fertilized and unfertilized plats 129 THE COTTON BOLLWORM {Heliothis obsoleta Fabricius. ) CLASSIFICATION AND SYNONOMY. The adult of the bollworm is a moth belonging- to the family Noc tuiclai, division Trilid^. Sir G. F. Hampson, in his Catalogue of Lepidoptera Phala3na3 in the British Museum (1903), places the species in the subfamily Agrotinse. Doctor Dyar, however, in his List of North American Lepidoptera,^' follows Dr. J. B. Smith in assigning this species to the subfamily Noctuin^. The genus Heliothis was founded by Ochsenheimer in 1810 in his Schmetterlinge von Europa, while the species had been described in 1793 by Fabricius in his Entomologia Systematica under the name BoiTibyx obsoleta. Hiibner in 1796 designated the insect in his Samm- lung Europaischer Schmetterlinge as Noctua armigera. Owing to its great variation in color and markings, Heliothis ohsoleta has at various subsequent times been described as new, and it has therefore a some- what extended synonomy, as follows: Bomhyx obsoleta Fab., Ent. Syst., 3, I, p. 456, 1793. Noctua armigera Hlibn., Samm. Eur. Schmett., p. 370, 1796. PhaUvna zea Boddie, Am. Cotton Planter, July (?) 1850. Heliothis pulverosa Walk., Brit. Mus. Cat., XI, p. 688, 1857. Heliothis conferta Walk., Brit. Mus. Cat., XI, p. 690, 1857. Thalpophila rubrescens Walk., Brit. Mus. Cat., XV, p. 1681, 1858. Heliothis uniformis Wllgrn., Wien. Ent. Monatsschr., IV, p. 171, 1860. UeliotJiis punctigera Wllgrn., Wien. Ent. Monatsschr., IV, p. 171, I860. Heliothis umbrosus Grote, Proc. Ent. Soc. Phila., I, p. 219, 1863. Hdiothis sucdnea Moore, Proc. Zool. Soc. London, p. 443, 1881. Heliothis interjacens Grote, Bui. Brooklyn Ent. Soc, III, p. 30, 1882. The original description of Bomhyx obsoleta by Fabricius^ is as follows: B. alls defl»xisflavescentibus: macula media strigaquepostica obsoleta obscurioribus. Habitat in Vmericse meridionalis Insulis Dom. Smidt. «Bul. 52, U. S. National Museum, p. 185, 190^ ^'Ent. Syst., 3, I, p. 456, 1793. 12 Media. Antennae simplices. Corpus flavescens. A]?f? flavescentes macula media, obsciiriore, postice striga obsoleta punctis minutissimis fuscis notata. Margo posticus fuscescens. Posticse flavescentes margine postico, fusco.« VARIETIES. Two varieties and a subvariet}^ of the bollworm moth have been des- ignated from the United States; one varietv from Hawaii, one from Europe, and one from Australia, with two subvarieties. With the forms occurring in the United States, at least, there is almost every intergradation in color and markings, and it is doubtful if these ma}^ be referred to in a more definite waj^ than as the more abundant types. In a collection of 65 moths, bred during the present investigation from larvae taken on corn, cotton, and other phmts in Texas, 35 may be classed as variet}^ ochracea^ with some of them approaching y?^^<:?«, and 30 as variet}^ innhrosa. The forms which have thus far been indi- cated are given in the table below^ with their essential points of dif- ference, as taken from the British ]\Iuseum Catalogue (1. c), and Tutt's British Nocture and Their Varieties.* Heliothis obsoleta Fab. Table of varieties and subvarieties. (1) orhracea Ckll. Ordinary tawny colored form figured in Fourth Rept. U. S. Ent. Comm., 1885, pi. 3, fig. 7. (2) fusca Ckll. Dark brown (European). (3) umbrosa Grote. Usually rather large, paler, and more olivaceous than the Euro- pean type (Southern United States esjjecially ) , the larva, the common boll- worm. (a) sub-var. eumacnlata Ckll. Stigmata margined with ferruginous (Colorado). (4) haicaiiensis, n. var. Fore-wing with prominent angled dark brown median band , diffused on outer side ( Hawaii ) . (5) rubescens, hind- wings with the groimd color orange yellow (Australia). («) Head, thorax, and fore-wing suffused with rufous. (6) Head, thorax, and fore-wing suffused with dark pink. COMMON NAMES. Owing to the fact that the boUworm attacks a great variety of plants, and to the further fact that it occurs in most parts of the civilized s\'orld, it has become known under numerous common names. In the United States it is very generally known under the name of bollworm'or corn-ear worm. In the States of the cotton belt the former name is ver}^ generalh^ used in referring to this specie^, or it is "A bombyx, with wings deflexed and j^ellowish; with a middle spot and posterior obsolete streak, rather obscure. Habitat, islands of South America [W^st Indies?]. Collector, Father Smith. Of medium size. The antennas simple. The body yellow- ish, with wings yellowish, with a more obscure middle spot. Posteriorly with an obsolete streak which is spotted with very small j)unctures. Hind ma'gins brownish. Hind wings yellowish, with posterior margin fuscous [smoky?].— e. a. s. ft British Noctuee and Their Varieties, III, p. 128, 1892. 13 simply designated the "worm," in distinction to the so-called "cater- pillar" or "army worm," the larva of Alctbama (Aletia) argillacea Hbn. In certain portions of the cotton belt, as southern Louisiana and Missis- sippi, the insect is commonly called the "sharpshooter" or "sharp- shooter-fly." It should be stated in this connection that the name sharpshooter is properly applicable only to certain homopterous in- sects of the genus Homalodisca, especially Homalodisca triquetra Fab. , a very different insect from the cotton bollworm. The almost universal injuries of the insect to corn have resulted in the use of three names for the bollworm, descriptive of the parts ^ attacked. Thus, in the spring, when infesting the "buds" of young |- field corn, it is known as the bud worm, and later, when the unfold- I ing tassels are attacked, it is called the tassel worm. But the larva is I most frequently met with infesting roasting ears and has thus become I well known under the name of corn-ear worm. It has been desig- nated in Minnesota by Lugger as the sweet-corn moth. On tomatoes the frequent considerable injury by the larvae to the green and ripening fruit has given rise to the name of tomato fruit- worm, or simply tomato worm. In southern New Jersey, according to Dr. J. B. Smith, the larvae are known to tomato growers as heart worms. v;, Tobacco growers know the bollworm under the name of bud worm, though two species of Heliothis are concerned in injury to the tender buds of the tobacco plant. In New South Wales our bollworm is known as the maize moth; in Cape Colon}^, South Africa, as the peach under-wing, from its depredations on this fruit, and also as "risper," signifying caterpillar. Throughout this bulletin the name "bollworm" is adopted, as its present consideration refers more especially to its depredations on cotton. GEOGRAPHICAL DISTRIBUTION. But few, if any, species of insects are more widely distributed throughout the world than is our cotton bollworm. Within the paral- lels of about 50° north and south latitude, the localities of its occur- rence form an almost complete girdle around the world. The most southerly recorded point of its occurrence is Dunedin, New Zealand (South Island), south latitude about 46°, and the most northerly is Sjf^lland, Denmark, north latitude about 55° 30'. In its vertical dis- tribution it is known to occur at sea level at man}^ places, and it is recorded from Milpas, Durango, Mexico, by Druce at an altitude of 5,900 feet. In Natal, according to Mr. Claude Fuller (in lit.), it has v,r been noted from sea level to 5,000 feet above. ^ In the accompanying outline map of the world (PI. I) the principal f points of its occurrence are indicated by dots. In the United States 14 it occurs practical]}' throughout. The map is ])ased on inforuiation gathered from different sources, but principally from the British Museum Catalogue of Lepidoptera (1. c), and from letters from for- eign entomologists to Dr. L. O. Howard. The following classified list will indicate more exactly the localities, States, provinces, etc., where the species is known to occur. It is ver}' probable that it occurs in greater or less abundance throughout the various countries from which it is recorded, and it may perhaps now be said that the prophec}' of Grote, made some years ago, ''We shall soon write after its habitat, 'The World,'" has been practically fulfilled: Canada: Ontario (Ottawa); Toronto; Manitoba (Beulah). United States: Throughout, except possibly in 3Iontana and Washington. Mexico: Morelos (Cuernavaca); Jalapa; Durango (Milpas); St. Maria; Mexico City. Central America: Guatemala (San Geronimo, Topote); Costa Rica. Panama: Volcan de Chiriqui. South America: Venezuela; Rio Grande do Sul (Porto Alegre); Brazil (Rio); Peru (Callao); Chile (Coquimbo). West Indies: Jauiaica; Barbados; St. Vincent; Porto Rico (San Juan, Mayaguez) ; Cuba (Habana); Dominica. Europe: Britain; France (Nice); Germany; Spain (Gibraltar); Russia ( Sarepta) ; Sicily; Italj^ (Piedmont, Lombardy, central and southern Italy); Denmark: Zealand (SJEelland); Austria-Hungary: Budapest (vicinity); Transylvania (Heing truly indigenous over this vast territory, it may be worth while o consider some facts bearing on the subject of its original home. As has been noted in the original description of this species by Fabri- cius under the name Boiribyx obsoleta^ its habitat is given as Americse Meridionalis Insulis. Accepting the identity of Bomhyx ohsoleta with our bollworm moth, as held by Sir G. F. Hampson and others, the species was first described from a specimen or specimens probably from the West Indies. Apparently the earliest reference to the bollworm as depredating on crops comes from the United States. B}^ 1820 its ravages on cotton were the occasion of a short note in the American Farmer b}" a correspondent writing under date of September 20, 1820, to the efi'ect that the pods of his cotton had been attacked by a large green worm from 1 to 1^ inches long, which ate its way into the pod and did not leave it until it had completed the destruction. Some of the worms were smaller; some were brown and red. The injury seemed to be severe, with the prospect of one-fourth of the crop being destroyed. y 1811 the bollworm had become prominent as an enemy to cot- ton and corn in the Southern United States, and it is recorded as attacking corn in Illinois in 1812. 22051— No. 50—05 2 16 As early as 1853 its distribution, according to Guenee," was "Central Europe, North America, South America, East Indies, New Holland, and probabl}^ in other countries of the globe." At the March meeting of the London Entomological Society in 1869 specimens of the bollworm moth were exhibited by a Mr. Bond from the Isle of Wight, Java, and Australia. Mr. Grote, a well-known student of the Noctuidse, to w^hich family our insect belongs, has expressed the opinion that it is native to , America, especially because it feeds here on some peculiarl}^ American gene'ra of plants. Its rare occurrence in Europe as compared with its abundance and destructiveness in America is also cited, and from I its occurrence in Australia and Java the query is raised: Has it not reached Europe from America by a westward route ? As bearing on this point it is to be noted, as has previously been mentioned, that usually species introduced into a new country become much greater pests than in their original home, and on this basis the bollworm should be added to our already long list of imported pests. Mr. J. G. O. Tepper, of the Public Museum of South Australia (in lit.), sa3"s: The species [Heliothis ohsoJeta] appears to be indigenous throughout the continent [Austraha]; a specimen was brought by the Elder exploring expedition in 1892 from a till then uninhabited region in Central Australia, and t>f the pale variety, ^g^ Mr. E. E. Green, the well-known student of scale insects, says: ^ The very fact of extensive damage by any insect may of itself almost be accepted as proof of its foreign origin. Looking over the list of the different scale insects occurring in Ceylon, I find that all of the more troublesome species have been pre- viously described from some other country and are, therefore, presumably imported insects. In America, however, we have numerous native insect species that are first class pests, as the Colorado potato beetle, the plum curculio, and others, so that the argument as applied to our conditions loses much of its force. More data of this character could be presented, but w^ould serve no useful purpose in clearing up the question of the native home of the bollworm. Hardl}^ an3^thing can be inferred from a consideration of the food plants of the insect, for it is practically omnivorous. Its pre- ferred food plant in the United States is corn, and probabl}^ also throughout its range in other countries where this crop is grown. Its second choice in this countr}" is cotton, a plant which has for centuries been grown in many parts of the world. Its third choice is probably tomatoes, a plant held to be native to Peru. . , Except in the United States but little has been recorded concerning its parasites, and these are all native to America. «Lep. Noc, II, p. 181. 17 FOOD PLANTS. Throughout its range a great variety of plants belonging to many different natural orders are known to furnish subsistence to the boll- worm. On some of these, as various weeds, its occurrence is more or less accidental, due to the indiscriminate habits of the moth in egg lay- ing, the food being plainly not suitable for the best growth and devel- opment of the larva. In the case of many vegetables and ornamental and fruit plants, however, these are fed upon with evident relish, and the larvae are able to develop normally. Reports of occasional severe injury to plants of this character may be held to indicate the capabili- ties of the species, under favorable conditions, for depredations in the future. With a species of such general feeding habits severe local injury, in the absence of its preferred food plants, might reasonably be expected to occur to some of the numerous other crops which it is known to attack. Manj^ of the plants mentioned in the subjoined table are, in foreign countries, seriously ravaged b}^ this pest. Important injury in the United States is confined principally to cotton, corn, tomatoes, and tobacco, concerning which a more detailed account will be given on another page. Table I. — Food plants of Heliothis obsoleta. Food plants. Parts injured. Reported from. Convolvulacege: Morning glory {Ipomcea comrau- tata). Bind weed {Ipomosa sp.). . .. United States. Foliage Do. Chenopodiacese: Pigweed ( Chenopodium sp. ) Amarantacese: Amaranth { Amarantus spp. ) Labiatse: Do. Green seeds Do. do United States (south Texas). United States. Do. Cucurbitacese: Squash {Cucurbita pepo, var. con- densa). Pumpkin ( Cucurbita pepo) Vines, flowers, young fruit Cucumber ( Cticumis sativa) Muskmelon ( Cucumis rnelo) Vines fruit. •Do. Do. do Do. Composita?: Cocklebur (Xcmthium struviariam) Foliage stems Do Sunflower (Helianthus sp. ) United States, India. do United States. Dahlia {Dahlia sp. ) (•?) Cape Colony. United States. Cannacese: Ganna ( Canna indica) Tender central bud; seed cap- sules. Squares, bolls, flowers, stems, foliage. Malvaceae: Cotton ( Gossypium spp. ) Okra {Hibiscus esculentus) Southern United States, India (?). United States. Do Sida spp do Do Hibiscus sp . . . Cape Colony. United States, Porto Kico. Graminse: Indian c )rn {Zea mays) Tender "bud," tassel, ears Tender central "bud," green seeds. Sorghum ' ''iu}t vulgaris, var. sacchar. Brazil, Australia, Europe, Cape Colony. United States, Natal. 18 Tarle I. — Food plants of Heliothis obsoleta — Continued. If Food plants. Parts injured. Reported from. Graminse— Continued. Millet ( Chsetochloa italica) Crab grass (Fanicum sanguinale) .. Colorado grass {Panicum texanum). Sugar cane (?) {Saccharum offici- nale). Wheat ( Triticum sp. ) Oats {Avena sativa) Barley {Hordeum spp. ) Kafir corn Rice ( Oryza sativa) Solanacese: Tomato {Ly coper sicum esculentum) . Jimson {Datura strainonmm) , Ground cherry (Physalis spp. ) Cape gooseberry {Physalis peru- viana) . Pepper ( Capsicum annuum) Tobacco {Nicotiana tabacum) , Nicotiana repanda , Egg plant {Solanum melongena) — Solanum spp , Potato {Solanum tuberosum) Vitacese: Grape ( Vitis var. ?) Urticacese: Fig {Ficiis carica) Hemp ( Cannabis sativa) Iridiacese: Gladiolus ( Gladiolus var. ?) Geraniacese: Geranium ( Geranium var. ?) Pelargonium {Pelargonium sp. ?) . Cruciferse: Cabbage {Brassica oleracea) Collards {Brassica oleracea) Liliacese: Asparagus {Asparagus officinale) . Rosacese: Peach {Prunus persica) Plum {Prunus sp. ?) Prune {Prunus sp. ?) Pear {Pyrus communis) Strawberry {Fragarla chiloensis) . . . Rose ( Rosa spp. ) Papaveraceae: Opium poppy {Papaver somniferum) Leguminosse: Alfalfa; Lucern {Medicago sativa).. Chick-pea, gram ( Cicer arietinum) . Acacia sp Beans, Lima and string ( Phaseolus vulgaris) . Peas { Pisum sativum) Sweet peas {Lathyrus odorams) "Khesari" {Lathyrus sativus) Pulse {Dolichos lablab) Cowpea ( Vigna catjang) Erythrina herbacea Milk vetch {Astragalus caryocarpus) Resedacese:. Mignonette {Reseda sp.) Caryophyllacese: Carnation {Dianthus caryophyllus) Green seeds Foliage ....do Tender central ' ' bud ' Young plants. do .-..do (?) (?) Green and ripening fruit, stems, foliage. Green seed capsules Green and ripening berries (?) Pods.. Foliage, tender "buds," green seed-capsules. ..-.do Green and ripe fruit Green berries (?) Foliage . Stems, flower buds (?) (?) Foliage Stems Berries (?) Green and ripening fruit, flower buds. Green fruit, flower buds do Foliage ' ' Crown " Flower buds Seed capsules Foliage, tender stems Foliage, pods (?) Pods ..--do.. Pods (?) Pods (?) Pods (?) Pods.... do.- ...-do-. United States. Do. United States (Texas). Southern United States. Australia. Do. Do. Cape Colony, Natal. India. United States, Europe, Cape Colony, Natal. United States. Do. Cej^on, India. United States. United States, Japan, Aus- tralia, Italv. United States (Texas). United States. Do. India. United States (California). Europe, United States. United States (?; India. United States. Do. Australia. United States, Cape Colony. United States. Do. United States, Cape Town, South Africa. Cape Town. Do. United States (California). United States. United States, Ceylon. India. United States, Europe, Cape Colony. Europe,'lndia. Cape Colony. United States, Cape Colony. Do. Cape Colony. India. Do. United States. Do. Do. Europe. Cape Colony. 19 In the laboratory at Paris bollworms were fed on the following- plants, which were eaten with (Evident relish: Corn. Gourd. Rose. Bindweed. Cotton. Cucumber. Amarantus spp. Stachys agraria. Tomato. Nasturtium. Tobacco. Physalis angulata. Apple. Castor bean. Catalpa. , Solidago sp. Peach. Millet. Blackberries. Canna indica. Irish potato. Alfalfa. Bermuda grass. Datura stramQnium. Sweet potato. Taraxacum vulgare. Rudbeckia sp. Chenopodium sp. Cowpeas. Helianthus tuberosum . Poke weed. Sida sp. Garden peas. Green peppers. Solanum spp. Squash. Okra. Erigeron spp. The food plants of the bollworm, as at present known, are thus seen to number 70, distributed in 21 natural orders. If to these be added the plants on which the larvae have been fed in confinement, the list becomes somewhat increased. STATUS OF BOLLWORM IN FOREIGN COUNTRIES. Throughout its extended range the bollworm is nowhere so well known as in the southern United States in connection with its injuries to the cotton crop. Its injuries in foreign countries are, however, in some sections not inconsiderable, and attention may appropriately be called to its status as a pest in other countries than our own. Throughout the countries of Europe its injuries are, on the whole, comparatively insignificant. In Great Britain and Ireland, according to Mr. E. A. Shipley (in lit.), well-authenticated British specimens of the moth are so rare as to sell at from |2.50 to 14 each. Dr. Paul Marchal writes that bollworms were observed by him injuring tomatoes in middle France in 1900 and 1901, and also injuring corn in north Spain. In Hungary, according to Dr. Josef Jablo- nowski, moths are ver}^ rare and larvae are unknown. A related species, HeliotMs dipsaceus Linn., is at times troublesome, feeding on corn, flax, peas, potatoes, and other crops. Dr. Antonio Berlese, of the Royal High School, Portici, Italy, advises (in lit.) that the bollworm in Italy attacks principally tobacco and Indian corn. Its injuries are not ordinarily important, and gath- ering the larv8e bj^ hand and destroying them is the method followed in its control. Three generations annually are considered probable. Concerning the status of the bollworm in Cape Colon}^, South Africa, Mr. Charles P. Lounsbury, Government entomologist, wi'ites that it is one of the most common of the lepidopterous insects of the Cape, its larva being well known to farmers, fruit growers, and gardeners alike. In feeding habits the larva is almost omnivorous, attacking pear, prune, plum, peach, lucern (alfalfa), cabbage, tomatoes, corn, 20 various flowers, and pine. Often serious injury is done to early toma- toes and peas, and much complaint is made of injur}^ to buds of flowers and 3^oung fruit of peaches, plums, prunes, etc., of which 50 or more per cent are quite often scarred. Corn is generalh^ infested. Hand picking is largely practiced to protect orchard trees, and thorough cleaning up for protecting vineyards. In Natal the pest is apparently less destructive. Mr. Claude Fuller, formerh" Government entomologist, has noted its injuries to corn, Kafir corn, and tomatoes, but generally the damage is slight. In Australia the insect is very generally distributed over the cen- tral parts, according to Mr. J. G. O. Tepper, of Adelaide, it being one of the most common of the larger moths. The larvae feed almost indiscriminately, attacking wheat, barle}", and oats while these crops are young, and most other herbaceous plants in all stages, the former crops being attacked at or near the ground, much after the manner of cutworms. Native crows and magpies feed on the larvee, rendering- much service in this way. It is noted that native grasses are not attacked. Several generations annually probably occur. Mr. Arthur M. Lea, writing concerning this same insec^t in Austra- lia, mentions an instance where the larvae, leaving the flowers of ''everlasting," on which they were feeding, appeared to migrate simul- taneousl}^ in true arm^^-woi^ fashion, attacking a near-by paddock of oats, which was completel}" destroj^ed. The same gentleman states that the bollworm is very rare in Tasmania, only two specimens hav- ing been obtained during a period of four years. In Ceylon, Mr. E. Ernest Green, of the Royal Botanic Gardens, writes that the bollworm does not there rank as a serious pest. The larv^ are principally injurious to flowers, as rose buds, and to vege- tables, as the fruit of Phy sails j)eruvia7ia^ the Cape gooseberry. Hand picking is the onl}^ method employed in its control. In Japan, according to Mr. Yasuchi Nawa, of Gifu, the bollworm is most injurious to tobacco, cotton not being especially injured. Other plants attacked are flax, corn, cucurbits, and hemp {Cannabis saiiva). The insect is controlled by destroying the eggs by the use of kerosene emulsion. Three or four generations occur annually. Attention should here be called to the occurrence in the cotton fields of Egypt, of an insect there known as the bollworm, which is, however, a species quite different from the bollworm of the United States. The Egyptian bollworm resembles our own mostly in its habit of feeding on cotton bolls. Its life histor}" presents numerous points of differ- ence. Mr. George P. Foaden, in the Journal of the Khedival Agri- cultural Societ}" for May and June of 1899, page 940, gives an account of this species under the name of Earias insulana. 21 ECONOMIC STATUS IN THE UNITED STATES. As shown on page 17, the food plants of the boll worm in the United States comprise a veiy long list. It is best known, however, as a pest of corn, cotton, tomatoes, and tobacco, its injuries to the other men- tioned food plants being as yet of comparatively little importance. INJURY TO CORN. Corn is without doubt the preferred food of the boUworm, and it is subject to attack from the time the plants are 12 to 18 inches high in the spring until late in the summer and fall, when the yellowing leaves and stalks and ripening ears are no longer attractive. Of the different types, sweet corn is most generally infested, which may be taken as evidence of its partiality for the sweet varieties. In the South gen- erally, the culture of sweet corn for market or home use is usually very unsatisfactory by reason of the depredations of this insect; and it is not attempted so generally as farther north. Early-planted sweet corn is just coming into tassel and silk as moths from hibernating pupae make their appearance. The plants are thus stocked with eggs, the leaves, stalk, tassel, ears, and silks often being literally covered with them, numV)ering, for a single plant, not infrequently from 300 to 500. The tender central roll of leaves, or ''bud," the unfolding tassel, and the milky kernels of the ear are attacked by the larvae, and the plant soon presents a sorry sight. Scarcely an uninfested ear may be found. The injury may be confined to the destruction of the terminal portion, or large irregular cavities may be eaten quite the length of the ear. This injury, together with the quantities of filthy excrement voided by the larvae in their rapid growth, practically renders the product unfit for market purposes, though more or less injured ears are often found for sale. The citizens of the South are, therefore, largely deprived of this favorite vegetable on account of the presence of this pest. The species has much the same character in the more northern States, but the severity of attack and the completeness of destruction are much less pronounced, except during occasional years. In New Jersey, Delaware, Maryland, Ohio, Indiana, Illinois, and bordering States, where the cultivation of sweet corn for market and for can- ning purposes has attained considerable proportions, the ravages of the insect one year with another bring about a considerable financial loss. Frequent mention is made in the literature of economic ento- mology of the depredations of the bollworm on sweet corn, the loss being variously estimated at from 10 to 50 per cent of the crop. Extreme cases have been recorded where the injury has been so severe that no attempt was made to even utilize the crop. , Actual losses suf- fered by growers of sweet corn for commercial purposes may be only approximately indicated. Statistics are not at hand bearing on the 24 pronounced in 1903 than in 1904. This was due not onl}^ to the more favorable weather conditions for bollworms durino- late Juh^ and August, but to the general lateness of crops, due to an unusuall}" wet spring, which everywhere dela3^ed planting from three to five weeks. The following estimates of bollworm injur}^ to cotton in several counties of Texas during 1903 have been made from all obtainable data, including personal investigations, and will illustrate the possibilities of injury of this species under exceptionally favorable conditions: Table II. — Estimated hollworm injury in certain counties of Texas in 1903. County. Percentage of crop destroyed. County. Percentage of crop destroyed. 20 to 25 15 to 20 20 to 25 8 to 10 8 to 10 15 to 20 50 to 60 40 to 50 Henderson Delta . 50 to 60 Limestone Hunt 30 to 35 Falls 25 to 30 Bell Kaufman 25 to 30 Van Zandt 20 to 25 Fannin . It should not be understood that injury was confined to these coun- ties. The injury, in fact, was quite ge «ral over the principal cotton- producing counties of the State. Likewise in Louisiana, Mississippi, Fig. 1— Map of area infested by bollworm (from Quaintance and Bishopp). Indian Territory, and Arkansas bollworm injury was ver}^ severe. The area most seriously injured in 1904 is shown by the shading in the accompanying illustration (tig-. 1). From evidence collected and from personal investigation it is believed that an average annual injury of 4 per cent to the cotton cror>s of the Ue(iyj}Ourts»fthe Zon&s ewe knoM^n^ cusr ihje. Trcun.s7;tiijony,r SonoTXUv ajTjd Lower SoTtor'art . ::=t- Corrected to Dece: BuL. 50, Bureau of Entomology, U. S. Dept. of Agriculture. Gorrecter] to I)..-cernber, 1897 LIFE ZONES or THE UNITED STATES BY C. liAllT MERRIAM. 25 above-mentioned States would be a most conservative estimate. For the purposes of the present computation, bollworm injury in the States of Alabama, Georgia, Florida, the Carolinas, and the other cotton-growing- States not mentioned may be ignored as of little importance. The total value of cotton fiber and seed for the States of Texas, Louisiana, Mississippi, Indian Territory, Oklahoma, and Arkansas for 1899 is given by the Twelfth Census as 1213,695,256. Four per cent of this amount is $8,547,810, the approximate annual tax of the boll- worm on the cotton planters of these States. INJURY TO TOMATOES. Bollworm injury to tomatoes is variable and hard to more than approximatel}^ estimate. Injury by the first and second generations of larvae is probably most severe, but reports of depredations in the late summer and fall are not wanting. The destruction of the early fruit augments the loss. In the commercial tomato-growing regions of the South, especially in Florida, Mississippi, and eastern Texas, complaints of severe injury are frequent; likewise in Maryland, New Jersey, Delaware, and other States, where large quantities of tomatoes are grown for canning purposes, the average annual injur}^ is doubtless quite important. A possible basis for an estimate of loss to tomato growers by the bollworm is to be found in the statistics of the pack of this vegetable in the United States for 1900, which are given by the Twelfth Census as 5,495,093 cases of twenty -four 3-pound cans each. At the minimum valuation of $1.46 per case, the crop in 1900 was worth $8,022,835. Placing the average annual loss to this crop by the boll- worm in the United States at 2 per cent, which is undoubtedly a very conservative estimate, the amount is 1160,456. Bringing together the losses to the afore-mentioned crops, there is shown a total of $27,129,119 as the 3^ early tax of this species on growers of corn, cotton, and tomatoes in the United States. The extent of losses to various other crops, such as tobacco, alfalfa; cowpeas, various garden vegetables, and others, would increase this amount somewhat, and the sum total of losses from its depredations in this and foreign countries would be an amount sufficient to easily place the bollworm amongst the foremost injurious species of the world. DISTRIBUTION AND DESTRUCTIVENESS IN RELATION TO LIFE ZONES. With the probable exception of the Boreal, the cotton bollworm is known to occur in all of the life zones of North America, as mapped out b}^ Doctor Merriam (PI. II), namel}^, the Transition, Upper Aus- tral, Lower Austral, and Tropical. 26 TRANSITION ZONE. The species occurs well up in the Transition zone, if not indeed overlapping on the southern limits of the Boreal zone, though in this northern latitude it is apparently not ver}^ destructive. It is here recorded as injurious to late sweet corn and also tomatoes. Rather severe injury was reported in the vicinit}^ of London, Ontario, in 1898, by Dr. James Fletcher,^' and also by Mr. J. Dearness.* Several fields of corn were infested, varying in extent from about 20 to 95, or in one case nearh^ 100 per cent, with from one to several larva? in each ear. In a letter concerning this species Doctor Fletcher states: Heliothis armiger \_obsoleta'] is sometimes abundant and destructive to late sweet corn, the larvae at that time being of all sizes to full grown. * * * Moths are out at Toronto and here [Ottawa] by the end of September and sooner. * * ^ We have also received specimens from Beulah, Manitoba, but the species is decidedly not common. Injmy to sweet corn in 1892 is reported^ from Farmington, Me., a town on the border line of the Boreal and Transition zones in that State. The identity and character of the insect seem to have been quite unknown to those suffering from its ravages, which ma^^ be taken as evidence of its infrequent occurrence. No records have been found to indicate its occurrence in the numerous patches of the Boreal zone along the Alleghen}^ and the mountain chains of the AVest, although it is known to occur in numbers in adjacent areas of the Transition zone. It may, therefore, perhaps be safely inferred that the insect is not able to extend itself permanenth^ into the Boreal zone, by reason of temperature and other conditions. It is pertinent to mention that in New Mexico Prof. T. D. A. Cockerell, who has given considerable attention to the life zones of insects, records^' the species onh" from the area designated by him Upper (including middle) Sonoran. The restraining influence of low and sudden changes in temperature on the successful- existence and increase of species of more southern occurrence, in their northward spread, has been recentlv commented upon ^ b}^ Doctor Chittenden, of this Bureau. According to this gen- tleman's observations the bollworm was comparatively rare on corn and other crops, which it commonly infests in the vicinity of Washing- ton during the season following the severe freezes of February and March, in 1899. The severe character of the winters .of the more northern States, coupled with the relativeh^ low sum of effecMve tem- perature, no doubt has an important bearing on the comparative immunity of this territor}^ from serious injury. "Eept. Ent. Soc. Ont., 1898, p. 82. &Ibid., p. 62. cAnn. Kept. Maine Agric. Exp. Sta., Pt. IV, 1892, p. 119. ^Bul. 24, N. Mex. Agric. Exp. Sta., p. 35. eBul. 22, U.S., Div. Ent., U. S. Dept. Agric, p. 56. 27 In the more southern part of the Transition zone the insect is nota- bly more successful, though nowhere in this zone is it a pest of regular occurrence or of any considerable importance. In Massachusetts it was reported as quite abundant in 1894, and its presence had been noted in sweet corn several years previously in certain of the smaller towns in the neighborhood of Boston. It would appear, however, that the bollworm becomes thus numerous at rather long intervals. Accord- ing to Doctor Fernald (in lit.) only three examples were received by him at the Massachusetts Experiment Station from 1899 to 1904. In Michigan, which is largely within the Boreal and Transition zones, the bollworm is also of comparatively rare occurrence in inju- rious numbers. Thus Mr. Tyler Townsend states ^^ that the species came under his observation only once during a period of fourteen years, namel}^, in 1881, when the larvae were frequently found in ears of green corn. In Minnesota, according to Doctor Lugger,^ the insect does not winter, all individuals being killed in late fall, thus necessitating their reintroduction each year. In commenting upon this statement Doctor Fletcher remarks that it is his opinion that some of the insects, at least, hibernate in Canada as pupae. The almost total absence of references to this species in experiment station and other literature from the Dakotas, Montana, Wyoming, and Washington indicates its comparative scarcit}^, at least as a pest. In a recent letter Prof. Avon Nelson states it as his belief that the bollworm does not occur in Wyoming^; Professor Cooley does not know of its presence in Montana; while Prof. W. H. Lawrence advises that according to his information it does not occur in Wash- ington. It is, however, reported from Idaho and Oregon. The absence of sufficient data will, however, preclude the consideration of the zonal distribution and destructiveness of the bollworm throughout this region. UPPER AUSTRAL ZONE. By reference "to the map (PI. II) it will be seen that the Upper Austral zone covers a large part of the more central territory, east and west, of the United States. This zone is divided into two sub- divisions, namel}^, the Carolinian area and the Upper Sonoran area. In the present discussion it is necessary to consider them separately. CAROLINIAN AREA. The Carolinian area is distinguished from the Upper Sonoran by reason of its greater humidity. It finds its western limits along the one-hundredth meridian. Throughout practically all of this area the « Insect Life, II, p. 42. ^Bul. 43, Minn. Agrc. Exp. Sta., p. 198. c Mr. E. S. G. Titus, of this Bureau, however, reports that he has taken the boll- worm in Wyoming. 28 bollworm is well established, appearing in considerable numbers almost every year and attacking y weet corn, tomatoes, lield corn, garden vegetables, ornamentals, and various other plants. Numerous reports are made of its injuries to these plants. In New Jersey, Delaware,, Mar^^aud. Ohio. Indiana, Illinois, and other States of this area, where sweet corn and tomatoes are largely grown for canning purposes, the insect is considered a pest of prime importance to these crops. Injury to tield corn occurs in varying degree almost ever}' \qb.i\ often attain- ing considerable proportions. The character and regularity of injuries by this insect fix it as a permanent pest in this area, and it is unnec- essar}' in this connection to cite specific examples of injury. UPPER SON OR AX AREA. In the western or more arid portion of the Upper Austral zone east of the Rocky Mountains the bollworm, from the data in hand, appears to lose much of its importance as a pest. Sufincient data are not avail- able to discuss the extent and character of its injuries, but the few reports indicate that during certain years it is moderatel}^ abundant and destructive to sweet and field corn. LOWER AUSTRAL ZONE. In the Lower Austral zone, especially the area eastward of, approxi- mately, the one-hundredth meridian, and known as the Austroriparian, the bollworm attains its maximum abundance. AUSTRORIPARIAN AREA. The Austroriparian area marks, approximately, the principal cotton- growing territory of the South. While the bollworm varies much in destructiveness throughout this territory — a fact due largely to local conditions, such as difierences in methods of farm practice — yet it is eveiy where present, and usualh' in injurious numbers, on some of its numerous food plants, as corn, cotton, tomatoes, tolmcco, alfalfa, and various garden vegetables. Throughout the greater part of the area the commercial culture of sweet corn is attended with the greatest difficulty by reason of the attacks of this species. In Florida and other sections of the South, where the growing of early tomatoes for north- ' ern markets is an important industry, the bollworm is yearly the source of much loss from its ravages to the early fruit. Probably nowhere in the world does the cotton bollworm become the soiu'ce of more complaint than in the Austroriparian area of the United States. LOWER SONORAN AREA. The western and arid portion of the Lower Austral zone is desig- nated the Lower Sonoran area. In Texas, from about the ninetv-eighth 29 meridian westward, the bollworm rapidly becomes of less and less importance along with the diminishing- annual rainfall. The further consideration of this area will be included in the next topic. THE BOLLWORM IN THE WESTERN UNITED STATES. Owing to the incompleteness of data on the distribution and destruc- tivcness of the bollworm in the more Western States traversed by the Rock}^ and other ranges of mountains, and the consequent breaking up of the zones into small and more or less poorly defined areas, it will not be possible to indicate the relative destructiveness of the insect in this territor}^ except in a ver}- general way. No records have been found of the occurrence of the bollworm in the States of Montana and Washington, In Oregon, however, it was reported b}^ Professor Washburn " as destructive to sweet corn at Corvallis, in 1889, and elsewhere in the State. It was not con- sidered a newcomer, as it had been reported by farmers four, or even eight, 3"ears previously. These reports appear very probable, in view of the records of this Bureau of two specimens from Oregon prior to 1885, as mentioned by Riley in the Fourth Report of the United States Entomological Commission . The bollworm was to be found in California as early as 1879, accord- ing to a note in the Pacific Rural Press of September of that year. More recenth' ^ the insect has been mentioned b}^ Mr. Coquillett as feeding on various plants in that State, though no data are furnished to indicate serious injury from the pest. In Nevada, according to Prof. F. H. Hillman,^' the bollworm is commonly injurious to sweet corn, and less frequently to tomatoes, in the western part of the State. Injury is reported '^ from Buckeye, Ariz., to corn in 1899, and its occur- rence in portions of New Mexico, injuring corn and tomatoes, has been occasionally mentioned by Professor Cockerell. In Utah, according to Prof. E. D. Ball, the bollworm is a pest of considerable importance, injuring corn and other crops. FARM METHODS IN RELATION TO BOLLWORM INJURY. As has been elsewhere mentioned, present injury to cotton by the cotton bollworm assumes its greatest proportions in Texas, Louisi- ana, Indian Territory, Oklahoma, Mississippi, and Arkansas, with more or less injur}' in Alabama. The fact that the western part of the cotton belt should be thus afflicted, while the Carolinas, Georgia, and Florida enjoy practical immunity, is somewhat remarkable, and this «Bul. 3, Oreg. Agric. Exp. Sta., p. 6. & Insect Life, I, p. 331. cBiil. 36, Nev. Agric. Exp. Sta., p. 19. rfBul. 32, Ariz. Agric. Exp. Sta., p. 288. 80 condition of affairs is apparent!}^ attributable to certain definite causes, susceptible of explanation. It is almost an axiom in economic entomology that greath^ increased planting' of a crop, to the practical exclusion of all others, is followed by a corresponding increase in insect depredations on the crop thus grown. Those who have followed the development of the cotton- growing industry in the States west of the Mississippi River during the past two or three decades need not be told how extensive this has been. Quoting from the Twelfth Census: Of the entire crop, 34.05 per cent was grown west of the Mississippi River in 1879; 38.44 per cent in 1889, and 43.80 per cent in 1899. * * * Of the total increase of 4,099,831 acres in the decade 1890 to 1900, 3,637,398 acres, or 88.7 per cent, were con- tributed by Texas, Indian Territory, and Oklahoma. The increase in Texas was 3,025,824 acres; in Indian Territory, 371,987 acres; in Oklahoma, 239,569 acres. This leaves an increase of only 462,433 acres for all the other States, which was nearly reached by the increase of 440,970 acres in Alabama. The tide of immigration which in 1850 began to move westward from the more eastern cotton States peopled this newer country largely with cotton farmers, and until recently but little attention has been given to diversified farming, corn and cotton being the principal crops grown. As transportation facilities have improved, the tendenc}" has been to increase the farm acreage in cotton and to depend more and more on the North and West for the food supply. This extension of the cotton area and neglect of crop diversification have resulted partly from the belief that climate and soil were not adapted to the cultiva- tion of those crops grown successfully farther north, but more largely on account of labor and economic considerations. Landowners have for the most part come to consider cotton as the onh^ crop which might be grown on a large scale with reasonable convenience and safetv to themselves, and there has thus been developed a condition of finances which has necessitated the planting, by tenants and small landowners in need of credit, of cotton as collateral for the amounts advanced. Plantations -and farms of large size are the rule, and the tenant system, therefore, finds its maximum development in the area under consideration. This fact, in connection with the large areas in cotton as compared with other crops, and the natural fertilitj^ of the soil, pro- ducing a rank, succulent plant growth, have been important factors in bringing about the present importance of bollworm ravages. The cotton crop requires the occupancy of the ground from earl v in the spring until late in the fall, the growth of the plant being checked only by frost. If the fall be unfavorable, the picking may be greath^ delayed, often extending through the winter and well into the following spring. Under such circumstances thorough plowing of the ground in the fall or winter, with its consequent beneficial influence in destroying hibernating pup?e, is not possible, and land is planted to cotton, often during several successive years without a thorough breaking up. 31 As a rule cotton crops have not received the attention necessary for their best g-rowth and fruitf ulness. This lack of necessar}^ cultivation is more particularly noticeable with tenant farmers. The plant is thus least able to overcome insect ravages and put on additional fruit in place of that destroyed. The natural perennial habit of the cotton plant tends to make its growing season later and later for a given locality. The continued use of seed of local and often unknown origin, frequently secured from public gins, has been instrumental in produc- ing a rank, late fruiting and maturing strain of cotton on which boll- worm ravages are generally admitted to be much more severe than on earlier maturing varieties. The principal crops grown, namely, cotton and corn, are the two preferred food plants of the bollworm, and in the absence of fall and winter plowing the insect finds conditions most favorable for its development. In the more eastern cotton belt States conditions affecting the status of the bollworm present important differences and readily account for the unimportant character of the insect as a cotton pest in these States. The smaller size of farms does not permit of the cultivation of cotton in such large and unbroken areas; while the ''weed" is smaller and less succulent by reason of a lesser fertility of the soil. The general use of fertilizers hastens the formation of fruit, so that it is more quickly out of danger of insect attack. The rotation of crops also is much more generall}^ practiced. The three-year rotation of corn, cot- ton, and oats, or other crops, insures thorough plowing of the lands. Cowpeas are very generally planted in corn as it is being laid by, and often after oats, thus furnishing the bollworm moth with an abun- dance of food from the nectaries of the flower stalk, and they are thus not forced to the cotton fields for food. In Georgia the senior author has seen bollworm moths literally in swarms feeding in cowpeas, to the complete neglect of adjacent fields of cotton. It would appear that there is some relation between the relative acreage in cotton and peas in the different States and the injury suffered by these States from bollworms. The following table, com- piled from the Twelfth Census, of the plantings of cotton and peas for the year 1899, is of interest in this connection: Table III. — Comparative acreage in cotton and cowpeas, 1899. state. Acreage in cotton. Acreage in peas. Ratio of acreage in cotton and peas. 1, 007, 020 221,825 2, 074, 081 3, 513, 839 3, 202, 135 2, 897, 920 1,641,855 1, 376, 254 6, 960, 367 88, 407 17, 875 143, 070 167, 032 91,126 64, 490 31,414 15, 190 33,947 11 tol Florida 12t0l South Carolina 13 tol Georgia 21 to 1 35 tol Mississippi .' 41 to 1 Arkansas 52 to 1 Louisiana . .... 91 tol Texas , 205 to 1 ^051— No. 50—05- 32 It will be noted that the acreage in peas, as compared with the acre- age in cotton, decreases almost in proportion to the increase in sever- ity of bollworm injury in the respective States. In Texas, where there is but 1 acre in peas to every 205 acres in cotton, bollworm injuries are of greatest severity. The very general practice of planting late corn for forage, silage, and other purposes is, in effect, the application of the trap-crop idea. By this practice, which has come about simply as a farm expedient, the farmers of the Carolinas, Georgia, and portions of Alabama have unconscioush" greatly lessened the danger of bollworm injurv to cot- ton by providing the insect with a succession of its favorite food plant. RELATION OF WEATHER TO BOLLWORM INJURY. The belief is firmly established in the minds of many cotton planters that rain}^ weather, especially during late July and earh^ August, is largeh^ responsible for severe bollworm injury to cotton. Further, the opinion is occasionally expressed that the "'worm" is the direct result of such weather conditions. The fact that it is just at this time that the hardening of field corn forces the moths to the cotton fields appears to be lost sight of, and the sudden and destructive appearance of the larvae on cotton has often been attributed to the occasional showers Avhich may occur at this time of year. However, a belief so well established, resulting from many years of observation and expe- rience, should have some foundation in fact, and such appears to be the case. The accurate explanation of the factors involved, however, is by no means easy, owing to the difficulty of obtaining data on a question of this kind. As the reader will learn in the following pages of this bulletin, the bollworms, upon completing, during July, their growth in the ears of field corn, enter the soil and, after constructing a cell, become pup^e, from which, in_the normal course of events, the moths or parent insects issue about two weeks later. Observations have shown that many of these pupal cells are not made with sufficient care b}^ the larvae to permit of the ready escape of the moth from the soil. The most common defect is that the cell is not extended upward sufficienth^ near the surface of the ground so that there will be but a thin crust of earth for the moth to break through in making its escape. The occur- rence of a soaking rain and the consequent softening of the soil would permit the escape in perfect condition of many moths which under conditions of hard-baked soil must have perished in their pupal bur- rows. It has often beeii observed in the course of this investigation that moths were noticeably more al^undant shorth^ after a soaking rain. This fact probably has its explanation, as above intimated, in 33 the increased number of moths which are able to escape in perfect con- dition from a moist, wet soil, as compared with a dry and harder one. Abundance of suitable food appears to be a vital necessity for the normal longevit}^ of the moths. Thus, during July and August moths kept without food in the laboratory lived for about six days, which was about half the length of life of females supplied with food. Fur- ther, laboratory records show that oviposition does not reall}^ begin until after the female has been able to partake of food. The food of boll- worm moths during the months of July and August, under outdoor conditions, consists partly of such nectar as may be obtained from flowers, but principally of nectar from the nectaries of cotton flowers and squares, and it would appear reasonable that during periods of drought this nectar supply would be far less copious than during rain}^ weather. Occasional showers would at least furnish an abun- dance of water collected at the base of flowers and elsewhere, which the moths have been frequentl}^ observed to feed upon. So far as the adult stage of the insect is concerned, there would appear to be some foundation for the belief that the insects are more successful during rainy than dry weather. There is but little information bearing on the influence of climatic conditions on the pupal stage of the insect except that pertaining to the effect of low temperatures, which will not be discussed here. During the larval or bollworm stage it is most exposed to the attack of parasitic and predaceous insect and other enemies which, on the whole, are much more active during dry than rainy weather. Various species of wasps, principally of the genus Polistes, are very effective predatory enemies of the bollworm. From early in the morning until late in the evening, during fair weather, these insects may be seen busily searching the cotton plants for larv^, and the sum total of boll- worms destroyed by these hunters in the course of a single day must result in considerable pecuniary gain to the planter. Rainy weather keeps the large majority of these wasps from the fields, and the boll- worms are thus permitted to develop to that extent unmolested. Other predatory enemies, as tiger and ground beetles and their larvse, robber flies, etc., are also noticeably more active in fair than rainy weather, and the cessation of the attacks of these species during such weather is doubtless an important reason for the more serious depre- dations of the bollworm. An important hymenopterous parasite of the smaller bollworms, when on cotton or other plants where they feed more or less exposed, namely, 2flcroplitis nigripennis Ashm., appears, from general observa- tions made during the season of 1904, to be out in greatest abundance during clear weather; and this is probabh^ true of other parasitic insects, such as Tachinid and other flies. 34 Trelease" observed more than tliirt}^ years ag'o that during dry weather, and on the drier situations of the field, ants were much more abundant and hostile to bollworms than during- rain^^ weather, or on the lower and more moist parts of the field. Several observers have advanced the theorv that the absence, during- dr}^ seasons, of both the boll and cotton worm is largeh^ due to the effectiveness of several species of ants in keeping them in check. The importance of this theory, in its bearing on the subject under discussion, rests on the assumption of the predator}' habits of the ants. From our own obser- vations we are not inclined to attach much importance to the work of ants, for the reason that frequent and close observations of these insects in cotton fields and elsewhere have failed to verify previous statements of their habit of voluntarily preying' upon bollworm larvae. Under certain conditions, as when provoked, several species of ants have been observed to attack and kill small bollworms, but the few instances when ants have been observed feeding on larv^ in the fields have not been free from the suspicion that the worms had been pre- viously injured and more or less disabled, as by one of their fellows. At no time during the past two ^ears have any of the native cotton- field ants been observed, under natural conditions, to voluntarily attack bollworms. It remains to mention a fact doubtless of considerable importance, namely, that rains produce in the cotton plant a rapid and more succu- lent growth, which, by furnishing the larva? an abundance of tender food, great!}' favors their development. This and the increased food suppl}' for the moths under these conditions, as well as the increased percentage which are able to escape from the soil, are reasons which in themselves are almost sufficient to account for the greater destructive- ness. An illustration of this is to be seen almost every year in the known greater destructiveness of bollworms on ^'bottom-land'' cotton where the soil is moist and more fertile and the weed growth stronger, as compared with the injur}- on the more stunted growth on uplands. It is probable that the moths are primarily attracted to the ranker cot- ton by reason of the greater nectar supply, and eggs are deposited on these plants during the course of their feeding. The influence of shade, as during cloudy and rainy weather or by reason of the luxuriant growth of cotton in closely planted rows, is also apparently favorable to the larv^, but it is to be noted that these feed readily without seeming discomfort on the exposed portions of the plants, often in the direct rays of the sun. In the egg stage the bollworm is subject to parasitism by a minute chalcidid fly {Trichogramma jpretiosa Riley), the importance of which in destroying bollworm eggs doubtless varies much with the character f'Comstock's Kept, on Cotton Insects, Washington (1879), p. 378. 35 of the weather. It is almost certain that these minute "insects are not active during rainy Aveather, as they could scarcely live under such conditions. It is further probable that the}^ are actually destroyed in large numbers b}^ the rain, despite their efforts to secure safe retreat. As opposed to the favorable influence of rain}^ weather on the boll- worm b}^ interference with the work of its natural checks must be mentioned the considerable destruction of eggs under the same condi- tions which are favorable to its increase in other stages. A heavy rain has the effect of washing from the plants to which they are attached man}^ of the eggs, the great majority of which are destroyed by the combined mechanical effects of the rain and particles of soil. Fre- quent observations before and immediately after heavy rains leave no doubt that many eggs are thus destroyed. The foregoing remarks have been confined to an explanation of some of the factors involved in the greater destructiveness of boll- worms to cotton following rain}^ weather in late July and in August. The month of August, including during some seasons the last week or ten days of July, marks the period of danger from bollworms. The tendency on the part of the planters has been therefore to limit the influence of weather conditions to about this period. The insect, how- ever, is subject to these same conditions in its several generations from early in the spring until late in the fall, and during the winter the pupae in the ground are probably much influenced by climatic con- ditions. The possibilit}^ of severe injury to cotton in July and August therefore depends also on how they have been able to maintain their numbers during the balance of the year. Owing to their rate of mul- tiplying in geometrical progression, the destruction of a pupa during the winter, or of a larva in young field corn in the spring, would diminish the possible number of bollworms ready to attack cotton in August by many thousands. Their abundance or scarcity on cotton is therefore seen to depend on other conditions than those existing during the immediate period of injury. INJURY TO COTTON FROM OTHER CAUSES THAN THE BOLLWORM. The known capabilities of the boll worm to injure cotton has led to its being charged with practically all forms of injury affecting the squares and bolls, aside from that done by the boll weevil, and the seriousness of its ravages has thus often been greatly exaggerated, especially by those not accustomed to examine closely into matters of this kind. As is shown on a later jmge, there are a few insects affect- ing both corn and cotton which might, from the character of their work, be mistaken for bollworms. These are, however, relatively unimportant in the extent of damage. Certain hemipterous insects, as Calcoris rapidus Say, HornalocUsca trtquetra Fah., and Largus cinctus 36 H. -Sch. , are known to occur on cotton plants and puncture the squares and bolls uaore or less, but ordinarily, according to our observations, these species are not the occasion of much injury. Much more important, however, is the shedding of squares and young bolls, or their drying up on the plant, which is in no way the result of insect attack, but is a physiological trouble. Injury of this character has often been pointed out as due to boll worms, and, on the whole, it is not ordinarily distinguished by planters from the work of this insect. Interesting observations on this trouble were made b}' Dr. (Jr. F. Atkinson when biologist of the Alabama Agricultural Experiment Station, and reported in Bulletin Xo. 41 of that station. The impor- tance of the subject warrants the presentation from that publication of certain remarks which throw light on the character of the malady: The shedding of bolls or "forms," or then- death and drying while still attached to the plant, is very frequently a source of great loss to the cotton crop. The trouble has been long known, but one widely prevalent and disastrous form has been mis- understood. It is often confused with the work of the bollworm, with punctures made by some hemipterous insect, etc. That some of the shedding is due to the work of the bollworm is true, but the shedding referred to here is a purely physio- logical trouble. During three years' observation in Alabama the author found this physiological form of shedding to be very serious. It occurs most frequently in extremes of either dry or wet weather, or during the change from one extreme to another. It may occur to some extent under normal climatic conditions, especially if the cotton plants are too thick, or the variety of cotton is one which develops a very large amount of fruit forms in proportion to the leaf surface. During a normal period of growth the j^lants put out as many fruit forms as could be matured should the conditions favorable to growth continue. If a very dry period succeeds this, interfering with the supply of nutriment and moisture, there will occur a partial withholding of tissue-forming material and moisture at a very critical period in the life of the young "forms," and the tissues of the young fi'ujt are forced into an unnaturally matured condition. The fruit, including the pedun- cle and often more or less of the surface tissue of the stem at its point of attachment, becomes first of a paler green color than the adjacent parts of the plant, so that a well-marked color line delimits the healthy fi'om the unhealthy portion. In many cases the tissue is separated at this line, so that the fruit falls off completely or hangs by a few fibers to the stem. The early growing season may be exceptionally favor- able for the development of a large plant with an abundance of young fruit, and if followed by even ordinarily normal conditions will result in a partial loss of this fruit. A long rainy season may also cause the young bolls or forms to fall, the soil being so saturated with water as to interfere with root absorption, and the assimila- tive activity of the leaves will also be disturbed. Observations have been made at different times bearing on the amount of injury from the bollworm as compared with that from other causes. The following table made up from observations by Mr. C. R. Jones indicates the character of results in general. Squares were picked at random from the cotton plants in passing through the fields, and afterward examined and classified. Five hundred squares were picked from each field. Bui. 50, Bureau of Entomology, U. S. Dept. of Agricultur Plate IV. A^im^'^^^^am^: pmw';ivm, Fig. 1.— Field of Young Corn at Paris, Tex., at About the Age in the Spring WHEN it Becomes Attractive to Moths for Oviposition (Original). Fig. 2.— a Number of Bollworm Eggs on a Piece of Black Paper, Enlarged About Seven Times (Original). Bui. 50, Bureau of Entomology, U. S. Dept. of Agriculture. Plate V. Tip of Ear of Corn, Showing Bollworm Eggs on the Silks. In the upper right-hand corner are a few eggs, on silks, enlarged about four times (original; 37 Table IA''. — Injury to cotton by hollworm and other causes. Date. Place. Number of good squares. Number of squares injured by boll- worm. Number of squares injured from all other causes. Remarks. July 14 Julv 16 Wharton, Tex 168 472 483 411 454 489 446 444 342 1 3 331 25 17 52 20 5 31 35 67 Largely injured by boll Morgan Tex weevil. July 20 July 24 July 25 July 27 Aug. 4 Aug. 5 Aug. 6 Comanche Tex Groesbeck, Tex., field No. 1 .... Groesbeck, Tex., field No. 2 ... . Gilmer Tex 37 26 6 23 21 91 Some injured by weevil. Mineola, Tex., field No. 1 Mineola, Tex., field No. 2 Providence, Tex Total 3,709 208 583 Average per cent injured by boll worm 4. Average per cent injured from other causes 12. EARLIER INVESTIGATIONS OF THE DEPARTMENT OF AGRICULTURE. The investigation of the cotton boll worm was one of the first ento- mological problems undertaken b}^ the Federal Government. With the appointment of Townend Glover as entomologist to the division of agriculture of the Patent Office on June 14, 1854, an investigation of the insects injurious to the cotton plant was immediately begun. In September of that year Mr. Glover visited plantations near Columbia, S. C, and made many interesting and important observations on the bollworm, as well as on other cotton insects. Many points in the life history and habits of this insect were determined, and at this early date the striking similarity between the bollworm and corn-ear worm was pointed out. But it should be here noted that their identity had been practically accepted by Mr. J. W. Boddie, of Jackson, Miss., in July , 1850, as a result of his own observations. A brief report on the bollworm was made by Mr. Glover in the Patent Office Report for 1854, pages 60 and 64.- The same insect is also treated under the caption of "The Corn Worm," on page 69 of this report, many of the essen- tial points in regard to its habits and injuries to this plant being set forth. As bearing on the control of the bollworm on cotton at this time, Mr. Glover states that, according to Mr. B. A. Sorsby, of Columbia, S. C, when the corn on two or three plantations was carefully "wormed," the bollworms did not make their appearance that season on cotton, although on neighboring plantations great injury was inflicted. Mention is made of a recommendation to light fires in vari- ous parts of the plantation at the time when the first moths make their appearance, and the statement is made that the moths are attracted to lights and will be killed in great numbers. Successful experiments in killing moths by attracting them to a mixture of vinegar and molasses are reported as made by Colonel Sorsby a year or two previous. 38 Concerning the control of this insect on corn, Mr. Glover states: The method to extirpate these insects would be to devise some method of destroy- ing the first brood of the perfect moths before the eggs are deposited, either by means of hghts or the vinegar and molasses on plates, as suggested by Colonel Sorsby. In the Patent Office Report for 1855 Mr. Glover gives further observations on the bollworm and again refers to the remedial meas- ures previoush^ mentioned. The possibilit}^ of poisoning the vinegar and molasses solution to kill the moths is suggested. Mention is made of the dissection of a single bollworm moth b}" Dr. John Gamble, of Tallahassee, Fla., which contained at least 500 eggs. In the Monthly Report of the Department of Agriculture for 1866, page 282, Mr. Glover, under the title ''Insects Injurious to the Cotton Plant," again presents previously determined facts concerning the bollworm without adding sluj points of importance. Three genera- tions at least are said to occur annually in Georgia. Nothing is added to the remedial measures previously indicated. Aside from frequent notice of injury from the bollworm in various parts of the cotton belt in the Monthh^ Reports from 1867 to 1876, Mr. Glover's work on this species seems to have closed in 1865. Mention should, however, be made of his "Manuscript Notes from my Journal, Cotton and the Principal Insects, etc.. Frequenting or Injuring the Plant in the United States," a collection of illustrations of this class of insects bearing date of 1878 and issued for private distribution. Although Mr. Glover determined man}^ valuable points concerning the life and habits of the bollworm, but little progress was made in the wav of determining effective means of control. His recommenda- tions for the use of sweets and fires to attract moths to their destruc- tion have subsequenth" been shown to be of no practical value. The next important work of the Department pertaining to the boll- worm was begun July 1, 1878, in connection with an investigation of the insects injurious to the cotton plant, ordered by Congress. This work was in charge of Prof. C. V. Riley until the date of his resigna- tion as Entomologist of the Department of Agriculture, May 1, 1879, when the continuance of the investigation fell to Prof. J. H. Comstock, appointed to the vacancy. A special report was ordered by Congress from the Department of Agriculture on insects affecting the cotton plant, and this was submitted by Professor Comstock November 11, 1879, entitled "Report on Cotton Insects," a work of 511 pages, deal- ing with the cotton-leaf worm (AJahama argiUacea Hbn.) and the cot- ton bollworm, 28 pages being devoted to a consideration of the latter insect. At this time, also, an investigation of the bollworm was in progress in connection with a stud}^ of cotton insects by the United States Ento- mological Commission, working independent!}^ of the Department of 39 . Agriculture. The results of the investigation of the United States Entomological Commission on cotton insects are contained in the Fourth Keport of this Commission, by Prof. C. V. Riley, a volume of about 600 pages, of which 29 are devoted to the bollworm. While the report referred to was issued in 1885, the work of the Commission was prac- ticall}^ completed in 1881. From these reports much was gained in knowledge of the injuries, life history, and habits of this pest, and sound remedial measures are suggested. The character and scope of the work may be best indi- cated by the presentation of the topics discussed in the report of Pro- fessor Comstock: The bollworm: Importance of the subject; Natural history; Nomenclature; Geo- graphical distribution; Food plants; The egg; The larva; The chrysalis; The moth; The number of eggs; Influence of weather. Remedies: Natural remedies; Artificial remedies; Topping; Poisoning; Handpicking; Destruction of the chrysalids; Destruc- tion of the moth. The principal points presented in this report are the wide geograph- ical distribution of the bollworm moth; the practically omnivorous habits of the larvae; the determination of the fact that the eggs of the bollworm are distributed quite generally over the plant, as foliage, stalk, square, and flower, and the feeding of the young larvae on more or less exposed portions of the plant near the place of their birth; the hibernation of the pupae in the soil; habits of the parent moth; the determination of five annual generations for central Alabama; the fact of more serious injury during wet seasons; the possibility of killing bollworms by poisoning; the possible utility of corn as a trap crop, and the usefulness of fall plowing in more northern latitudes for the destruction of hibernating pupae. Many of these points were not original with this investigation, as, for instance, the recommendation of the possible utility of corn as a trap crop in protecting cotton. This idea appears first to have been suggested by Mr. E. Sanderson in 1858, as a result of his belief in the identity of the corn worm and bollworm, and his recommendations are set forth in the American Cotton Planter of 1858. Professors Riley, French, and others had also previously determined many of the points here presented. The report of the United States Entomological Com- mission on the bollworm, by Professor Riley, adds but little to our knowledge of the pest as presented in the report of Comstock, and need not be considered in detail. A special investigation of the bollworm was provided for by Con- gress in 1890, and this work was begun July 1 of that year, by Mr. F. W. Mally, working under the direction of the Entomologist, Professor Riley. The chief object of this investigation was to con. duct further experiments with remedies, as well as to verify the value of those already employed, and incidentally to ascertain new facts 40 concerning the life history and habits of the insect, and to verify or disprove what had been previousl}^ written concerning these points. The results of this investigation b}^ Professor Mally are presented in Bulletins 24 and 29, old series, of the Division of Entomology, and were issued in 1891 and 1893, respectively. Many detailed observations on the injuries to corn, cotton, and other plants were made, and a S3^stematic series of experiments was con- ducted with various insecticidal substances in order to determine their possible value in bollworm control. The value of corn as a trap crop is demonstrated and a definite plan is presented for its utilization by planters. Experiments with bacterial diseases were conducted, and the uselessness of attempts to attract moths to lights and poisoned sweets, as previously recommended, is pointed out. The reports together cover 123 pages, and bring together the important facts then known concerning the cotton bollworm and present for the first time results of any considerable experimental work. Frequent mention has been made of the bollworm as injuring cotton, corn, tomatoes, or other crops in the bulletins and reports from the office of the Entomologist of this Department, and recently (1896) a full account of this species, by Dr. L. O. Howard, has been distributed in Bulletin 33 of the Office of Experiment Stations,^ which was issued in revised form in 1897 as Farmers' Bulletin 47, "Insects affecting the cotton plant.'' In spite of the work of the Department on the bollworm, but little progress had been made by the planters in its control. The recent increase of the ravages of the pest in certain parts of the cotton belt, notably in Texas, led to provision by Congress for another investiga- tion, and the present paper is a final report on this the fourth specific investigation of the species. The present investigation was begun in the spring of 1903, and continued to December 31, 1904. Reports of field work have already been published in Farmers' Bulletins 191 and 212 of this Department. LIFE HISTORY. SUMMARY. The eggs of the bollworm (PI. Ill, fig. 1) are deposited by the boll- worm moth upon the food plants of the larva?, which are preferably corn and cotton, or less commonly tomato or tobacco. Each female ma}^ lay from 500 to 3,000 eggs, which she deposits singly in a more or less promiscuous manner over the plants, more especially on the silks of corn and the squares of cotton. During the warmer parts of summer the eggs hatch after two or three days and the larvae begin feeding. On corn they attack the tender bud in the spring and the «The Cotton Plant, pp. 328-333. il. 50, Bureau of Entomology, U. S, Dept. of Agriculture. Plate III. Stages in the Life History of the Bollworm. Fig. 1, Eggs on corn silks; figs. 2-7, larvae, first to sixth instars, respectively; fig. 8, pupa- fig. 9, adult female moth— all figures enlarged one-fourth (original). 41 tassel and milky ear later in the season; while on cotton, during August and September, the squares and the bolls are eaten. The larvae bore directly into the squares and bolls through a small orifice which they make, and eat oat a varying portion of the contents. This causes the squares to flare and drop from the plants, and partially or entirely destroys the bolls. The larvae (PI. Ill, figs. 2-7) have molted five times and are completely grown in about two weeks during hot weather, at the end of which time they leave the food plant and burrow into the soil to pupate. In this stage (PL III, fig. 8) another two weeks is passed before the adults (PI. Ill, fig. 9) of the next generation emerge. After the latter have been out for several days egg laying again begins. The larvae and moths are extremely variable in color and markings, the former var3dng from a pale green through pinkish to dark brown. During the course of the summer in the cotton belt there are from four to six generations, while to the north the number decreases to two or three in the Central States and probably to a single one in Canada. The bollworm passes the winter in its earthen cell beneath the surface of the soil, emerging as a moth early in the spring. During the mid- dle of the summer in the cotton belt the entire life cycle occupies from 30 to 35 days only, while in the spring and fall, and also in northern localities, it may extend over as much as two months. THE EGG. DESCRIPTION. The eggs of the bollworm are small white objects, scarcely one- fiftieth of an inch in diameter. On account of their rather pale color they are not very difiicult to detect when deposited on green foliage or on dark- ,,.,^i;-. ^^', colored corn silks, but on the paler silks ^^\^vf^\ 0^^^^ one must look verv closely before they can f'-^ 1 1 \\\S llfC'^^E.^ be seen. A number of eggs are repre- '"''•( I'M^ ^^H^P' sented considerably enlarged on Plate lY, -. ^, 1. jn c. t:^ M ' ' Fig. 2.— Egg of bollworm; side figure 2; also see text figure 2. Followmg is and top views (original). a more minute description : Width, 0.48 mm.; height, 0.50 mm. Shining, waxy white, faintly tinged with yellowish. The form is almost dome-shaped, except that it is slightly narrower at the extreme bottom and widest about the basal third. Base flat and apex obtusely round.ed. Micropyle elevated, somewhat conical; its sides finely longitudinally grooved; the margin circularly roughened. The sculpture is rough and consists of fourteen primary polar ribs which converge toward the apex, where they become obsolete. Between these is a series of second- ary ribs which are more irregular, often bifurcate at the apex or joining the primary ri})s. Spaces between the ribs transversely furrowed by a series of oval depressions, b-tween which are fine transverse carinse. These latter do not rise as high above the surface as the polar ribs and are much more delicate. The shell is rather tough, and, although the eggs are quite delicate, they are not very easily crushed. 42 OVIPOSITION. The eg'gs are laid usuall}^ in the earl}^ part of the evening, between sundown and dark. During the summer months the moths are not infrequently seen fl^'ing and ovipositing on cloudy or dark days, or very rarely even on bright ones, but this is the exception. Egg laying begins some two or three days after emergence from the ground if the female has been fertilized by the male; otherwise it may be delayed for some days longer. Quite often solitary females kept in confine- ment in the laboratorj- deposited large numbers of infertile eggs, but this probably rarel}^ happens in nature. On account of the different circumstances surrounding oviposition on corn and cotton, the process on these respective plants will be con- sidered separately. OVIPOSITION ON CORN. Although the moths which appear in early spring from hibernating pupae lay a few scattering eggs on other plants, such as various garden vegetables, by far the greater number of them confine their oviposition to young field corn. As soon as the corn has attained a height of from 10 to 16 inches oviposition begins, but it does not become general until the plants are somewhat more advanced, like those shown on Plate IV, figure 1. The earliest records in Texas for 1901 are: Victoria, March 26; Beevill^, March 28; Austin, March 31; Calvert, April 2; Terrell, April 22; Paris, April 20. After these dates the eggs become gradually more abundant, although variable in number, scarcely ever being entirely absent in corn fields until the ripening plants later in the season become no longer attractive to the moths. The following table, compiled by Mr. F. C. Bishopp from counts made on 3^oung corn during the spring of 1904, shows the average deposition at that time: Table V. — Oviposition on early corn. Date. Locality. Height of plant. Num- ber of plants ex- amined. Total number of eggs. Approxi- mate number eggs per plant. 1904. Apr. 23 Apr. 24 Apr. 25 Apr. 26 Apr. 27 Apr. 28 Apr. 29 May 3 Corsicana, Tex . . . Hempstead, Tex.. Houston, Tex Victoria, Tex San Antonio, Tex Waco, Tex Arlington, Tex ... Paris, Tex li to 2 feet 1 to 4 feet lifeet 1 to 3 feet 2 to 3 feet 8 inches to 2 feet 1 to U feet lto2feet 200 150 10 150 125 125 125 150 66 383 0 22 40 40 32 150 0.33 2.5 0 0.14 0.32 0.32 0.25 1 These records are practicall}^ the first which show any considerable number of eggs present. Deposition throughout the remainder of the season is shown in the two following tables, one from Calvert, Tex. , 43 from counts made by Mr. G. H. Harris, and the other from Pomona, Ga., from counts made by Mr. Mark Riegel. In each case twenty plants were examined at an observation, and, as the corn had been planted at regular intervals, plants in fresh silk could be chosen in most cases. Table VI. — Comparative oviposition on corn throughout the season. CALVERT, TEX. Date. 1903. Mav4.... May 26... May 29... June 3... June 5... June 10.. 1903. May 30... June 6 ... June 13.. June 20.. June 27.. Number eggs per plant. 0.66 .00 .00 .00 1.40 .40 Date. 1903. June 17. June 24. Julvl... July 15.. July 18.. July 22.. Number eggs per plant. 0.25 .65 1.25 10.30 .75 7.00 Date. 1903. July 29... Aug. 5 . . . Aug. 12.. Aug. 19 - . Aug. m . . Sept. 2... Number eggs per plant. 23.50 1.80 42.00 15.60 2.75 25.25 Date. 1903 Sept. 9 . . Sept. 16 . Sept. 23 . Oct. 3... Oct. 7... Oct. 14., 1903. Sept. 12. Sept. 19. Sept. 26 . Oct. 10.. Oct. 24.. Number eggs per plant. 11.80 4.90 2.20 1.10 .55 .50 POMONA, GA. 1.15 2.90 .35 .55 2.45 1903. I July 4... , July 11.. July 18.. j July 25.. I Aug. 1 . . 20.40 7.60 5.50 2.30 1.65 1903. Aug. 8 . . Aug. 15 . Aug. 22 . Aug. 29 . Sept. 5. . 1.45 2.60 18. 20 14.30 16.90 9.35 8.85 6.60 5.10 .60 These tables are quite irregular and do not show the dates of maxi- mum oviposition for each generation as well as might be hoped, but the data therefrom will be referred to later, in their bearing on the number of generations during the season. No doubt a great propor- tion of these discrepancies are due to local weather conditions and to the variable maturity of the corn plants at the time the eggs were counted. For comparison with Table V another one, compiled from records made by Mr. C. R. Jones in the season of 1904, is given herewith: Table VII. — Oviposition on corn in silk, Texas, 1904. Date. i904. July 15 July 24 July 26 July 30 Aug. 11 Aug. 16 Aug. 19 Locality. Wharton, Tex Grossbeck, Tex,... Gilmer, Tex Quinlan, Tex Ben Franklin, Tex Paris, Tex Quinlan, Tex Condition. Silking 5 feet; no silks... Silking Tasseling Silking do do Eggs on— 259 16 5 14 77 36 11 1,053 '""85" 456 338 265 14 0 0 22 137 148 60 2,249 113 105 547 1,256 989 678 89.9 4.52 4.2 10.94 62.8 98.9 23.1 44 These records are in sharp contrast with those of Table V, show- ' ing a general average of 37 eggs to the plant instead of a little less than 1 egg to each plant. The largest number of eggs observed dur- ing 1904 was 989 on 10 plants, or nearly 100 per plant. Some counts made during 1903 exceed by far those for 1904, and are also given for comparison. Table YIII. — Oviposition on corn in silk, Texas, 1903. Locality. Ill 5- = Condition. Eggs on— 1 Date. i 3 1 a> 02 1 §^5 oft > < 1903. :Mav 3 1 Silking 210 830 553 1,106 511 633 284 122 241 121 1 T'l 344 Aus- 21 Willsnnint Tpx 3 do 660 ! •> l'^3 707 Sept. 4 Calvert, Tex 5 .....do 307 1 - 734 347 From this great number of eggs most likely only two or three larvae would succeed in attaining full groAvth and pupating. From these same tables a comparison can be made as to the proportion of eggs laid on different parts of the plants. In every case where silks were present, these bore the largest number of eggs in the following ratio to the other parts of the plant: Table IX. — Distribution of eggs on different parts of corn plant. Upper ! side of leaf. Lower side of leaf. Silks. Sheath. Tassel. Stalk. 1904:^ • 1,694 32.3 ! 1,593 27.1 ; 388 7.3 2,197 40.8 2,250 40.3 138 2.6 647 1L2 359 6.S - 1,088 19.5 501 9.5 1903: "Vumber («) (I Not counted. This proportion varies greatly under different conditions, but the above is quite reliable. Larvee from the immense number of eggs laid upon the stalk, sheath, and leaves must inevitably perish, as do also the greater proportion of those laid upon the silks. The significance of this fact will be dwelt upon in the consideration of corn as a trap crop. Time and manner of ovipositiGn. — Oviposition takes j^lace usuall}^ between sunset and dark, often continuing much later, and f requenth" moths have been observed to lay on corn and cotton at other times of the day. In the case of corn, the silks are usually chosen first if these are present on the plant; the moth momentarily alights upon the tip end of an ear, bends the abdomen sickle-shaped beneath her and moving the tip about among the silks, deposits several eggs. (See PI. V.) After this process, which requires only a few moments, she will usuall}^ fly away 45 often returning after several seconds to repeat the operation on the same ear. Then %ing from ear to ear the oviposition continues, with an occasional visit to other parts of the plant to lay on the tassel, leaf, or stalk. Some moths show much less steadiness of purpose and fly about much more irregularly^, ovipositing promiscuously on all parts of the plant. When cowpeas are present between the rows of corn, especially in fields of June corn in Texas, and very generally in field corn in other Southern States, they receive a number of the eggs, the moths feeding on the peas at intervals between the periods of oviposition. The advantage of planting cowpeas in corn is thus evident, for the moths do not leave the corn fields as they would if food were scarce, and oviposition is confined largely to the corn. If food is not to be had in the corn fields the moths are compelled to move about in search of it, many of them flying to cotton fields, where food is always to be found if the plants are " squaring" or blooming. OVIPOSITION ON COTTON. As ma}^ be gathered from the foregoing, oviposition on cotton does not begin until the season is well advanced. Owing to the very suit- able condition of field corn for oviposition early in July, when the maximum number of moths of the second generation are laying eggs, but few of these moths oviposit on cotton. The resulting larvae from the small percentage of eggs which are thus laid may, however, cause the destruction of a few of the earliest squares. By the time the third generation of moths has begun to emerge, which is about the first of August in northern Texas, the field corn has begun to dry and the ears to harden, so that it is no longer attractive either for food or for oviposition. The moths are now attracted by the food offered by the nectaries of the cotton plants in the adjacent fields and desert the ripening corn almost entirely. Time and manner of oviposition. — ^The process of oviposition is not continuous, but is varied by alternate periods of feeding and resting. As soon as twilight begins, the moths commence to leave their hiding places and fly about. At first their principal desire seems to be for food, and they fly from plant to plant feeding on the drops of moisture on the flowers and at the nectaries on the squares. Soon periods of egg-laying and resting are interpolated and later oviposition goes on rather steadih\ The moths seem to fly about almost without purpose and to lay eggs wherever the}^ happen to alight if they can obtain a firm foothold. This last seems to be rather important, for most of the failures to lay were noticed on the upper sides of the leaves, where it is difiicult for the moths to catch hold with their tarsi. The abdomen is bent sickle-shaped beneath the thorax and the eggs pressed against the desired spot with the ovipositor. Quite often several hasty 46 attempts are made before an egg is laid. A strong, healthy moth, however, does not often fail to lay. From one to two seconds are usualh^ required for each deposition. When possible the body is held either with the head up or horizontal when ovipositing, although when feeding the body may be turned at almost any angle without apparent inconvenience to the moth. In order to obtain the foregoing data regarding oviposition on cot- ton some 34: moths were followed in the field at dusk, and the portion of the plants upon which eggs Avere laid was carefully noted at each deposition. Most of these records were made between 7.15 and 8 o'clock in the evenings during the first week of August. At that time the moths were so common that the greatest dilBculty in following them was to avoid confusion of the observed moth with others in close proximity. The appended table gives the individual records of a few of the moths, together with the totals for the entire lot of 34 moths. Table X. — Distribution of eggs on the different j^arts of the cotton plant. Part of plant. Lower surface of leaves Upper surface of leaves 7 14 Squares 9 12 Growingtips 8 4 Flowers 2 i 11 Stems 2 1 Petioles 0 ! 4 Bolls 7 I 1 Weeds 0 I 0 Objects on ground 0 0 Dead leaves 0 0 Individual records of 11 moths. Total eggs laid Time observed, in minutes. Number of plants visited . . . 42 i 55 8 I 8 60 50 19 84 31 149 94 , 139 23 65 80 i 120 Total of 34 moths. 191 194 326 46 110 64 29 120 20 21 20 1,141 474 1,175 Per cent. 16.7 17.0 28.5 4.0 9.7 5.6 2.5 10.5 1.7 1.8 1.7 In all, the deposition of 1,141 eggs is recorded upon 1,175 plants. The very close^correspondence in numbers might suggest that one egg is usually laid to a plant by each moth, but this is not true, as many receive none at all and others a considerable number. A total time of 28,440 seconds was occupied, which gives a probable average of twenty- five seconds between two successive depositions, and allows for the ovi- position of some 280 eggs each evening during a period of two hours. This is not far from the average obtained from observations on moths la3dngin confinement. While this may be a good general average, it is inapplicable to any special case* on account of the great individual variation among different moths. Distribution of eggs on cotton. — More eggs are laid upon the squares than upon any other part of the plant except the leaves, although only 28.5 per cent of the entire number are so placed. The fact that 47 71.5 per cent are deposited elsewhere than on the squares has a very important bearing on the question of poisoning the young larva^, and will be referred to again in the following pages of this bulletin. It is quite possible that the large number of eggs laid upon the squares is accidental and due to the attraction offered b}^ them on account of the nectaries at which the moths feed. At any rate, they appear to ovi- I posit indiscriminately wherever they happen to alight on the plant. It is by no means unusual for a moth to oviposit occasionally on dried leaves or sticks beneath the plants, or even on the bare surface of the ground itself. It appears that old and worn females do this I more often than strong and healthy ones. OVIPOSITION ON OTHER PLANTS. The remarks on oviposition would not be complete without some reference to the great variety of plants on which the eggs are laid. ' The following table contains the records of the eggs found on miscel- laneous plants during the seasons of 1908 and 1904: Table XI. — Record of eggs found on miscellaneous plants, 1903-4. Date. Locality. Plant. Remarks. Apr. 15 Apr. 20 Apr. 20 Apr. 30 May 1-2 May 28 May 28 July 20 July 21 July 15 July 15 July 16 July 18 July 24 July 24 July 29 Aug. 1 Aug. 1 Aug. 3 Aug. 3 Aug. Aug. Aug. Aug. Aug. Aug. Aug. Aug. Aug. Aug. Aug. Aug. 10 Oct. 6 Ladonia, Tex... Victoria, Tex... Greenyille, Tex Hetty, Tex ....do Paris, Tex Victoria, Tex... Paris, Tex do do do do do do do do do do Calvert, Tex. Paris, Tex . . . do do Calvert, Tex. do do Paris, Tex . . . do do Calvert, Tex. do do Paris, Tex . . . do Rosebuds. Rosebud.. ....do.... Allium canadeiise do Tomato Siitasp.? Tobacco (buds) Okra Cowpeas Amarantus sphiosus Solanum maviviosum. . . Amarantus sp.? Asclepias tuber osa EuphorMa coroUata Amarantus sp.? Johnson grass Asclepias tuber osa Millet Crab grass Osage orange Carpet weed Datura stramonium, Seedling bindweed Cocklebur Grass Okra pods Asclepias tuberosa Virginia creeper .* . Ipojncea sp.? Sedge grass Peach tree Rosebud Several eggs (in cemetery). A single egg. Do. Numerous, 3 to 4 on each head. A few. 8 eggs on 15 plants. A single egg. A few. 1 on a dead flower. Very scarce on the plants. 1 to a plant. 2 or 3 to a plant. A single egg. Scarce, 2 on 20 plants. A single egg. Do. Do. A few. 17 eggs on 14 heads. A few. A few on leaves of small bush. Quite numerous. Rare. Neglects cotton to find it. A few. 3 eggs on many plants. Rather abundant. 3 seen. A single egg. Lays freely. 1 egg on a blade. A single egg. Do. In addition to the above, the following plants were noted bearing boUworm eggs, the dates of observations not being recorded: Canna indica^ NlcofAanarepanda^ alfalfa, beans, sorghum, Milo maize, Stachys agraria^ and Panicmn texanum. 22051— No. 50—05 4 48 Some 32 plants on which eggs have been found, or upon which moths have been observed to oviposit, are included in this list. A number of these are present as weeds in corn and cotton fields and the eggs deposited are more likely laid on account of proximity than otherwise. In the case of the wild-onion flowers and rosebuds it is probable that the scarcity of food at such times (April and October) attracts them to these plants. Indeed, roses in gardens and cemeteries seem to be the ' first plants chosen for oviposition early in the spring. Oviposition on alfalfa, tobacco, etc., is by no means accidental, as the larv^ thrive well on these plants. The number of miscellaneous plants is sufficient to show, however, that under certain conditions no ver}^ careful selec- tion is exercised by the female in ovipositing. It must be mentioned that garden vegetables were at all times very free from bollworm eggs, especially in the spring and fall. This is at • variance with the records of a number of observers, who have found larvae common on such plants. The occurrence of larvae on miscellaneous plants will be considered on a later page. XUMBEE OF EGGS LAID BY A SIXGLE MOTH. Numerous moths were kept under observation at various times during the season to determine the number of eggs which would be deposited under different conditions. Observations on early spring moths in the northern part of Texas seem to indicate that the number of eggs laid b}^ them is rather small, averaging only ttlo for each moth of a series of ten which were kept in the laboratory. At Victoria, however, in the southern part of the State, moths developing from overwintered pupte averaged over 1,200 each for a series of five moths. Table XII. — Daily oriposition records of moths. Locality. Began to lay. Died. ' Egg-laying record on consecutive days. Total. Paris, Tex May 13 May 12 Mav 12 Apr. 25 :SIay 10 Mav 9 Mav 7 May 7 Julv 16 Julv 18 July 23 May 18 36 Mav 19 I 10 Mav 20 48 Mav 4 147 May 14 i 556 Mav 16 1 671 Mav 19 404 May 13 74 Julv 17 j 548 Julv 27 3 Aug. 1 1,780 260 42 157 140 245 441 107 ^85 777 11 542 50 19 159 165 184 405 0 148 66 100 141 189 193 130 78 38 246 92 113 148 115 486 Do ^70 23 152 10 32 64 437 Do 62 6 585 Victoria, Tex.. 105 1,125 1,218 2 159 Do Do 148 50 117 76 45 98 116 26 Do ........ Do 26 8 50 9 905 830 Paris Tex 1, 325 Do 23 404 15 337 29 251 60 221 33 71 53 95 20 12 50 5 297 Do 2, 718 General average for each moth, 1,098. __ It will be noticed that there is nearly always a gradual decline in the number of eggs laid during each succeeding da}". In the case of a few moths, more than one day shows a considerablv greater oviposi- tion than the others, the number of eggs rising to one maximum, decreasing, and then rising again, thus resulting in an irregular curve, 49 like the one shown in figure 3, A. In others the egg laying gradually rises to a maximum and then declines, as shown by B, of the same figure. DEPOSITION OF INFERTILE EGGS. All of the data given above are records of deposition of fertilized eggs. In the case of one female which had not mated and was hence laying infertile eggs, 1,723 were deposited, showing that the growth of eggs in the ovaries must apparently go on without any reference to fertilization. EGGS REMAINING IN THE OVARIES AT DEATH. In nearly all female moths at death there are in the egg tubules of the ovaries a number of full}^ formed eggs. This number varies from a very few to over 300 in different individuals. About 70 may be 375- 350- 325- 300- 275- 250- 225- 200- 175- 150 - - .^75 1 ■^cin / -325 - "^00 / / - 275 / 250 / \ 99^ / \ S 200 / / \ \, y \ \ ^^ y 150 1?"^ - / I \ ^ \ lOc 100 - / / 1 \ "^^.^ \ ^ \ 100 75 - A / \ \^ \ 75 50 25 50 - B \ 25 - \ f EGGS - 2 3.4 i i 6 7 f £ 10 II 12 EGGS DAYS Fig. 3.— Diagram showing, A, regular and, B, irregular oviposition curves (original). considered a fair average. Besides, there are in the ovaries a number of much smaller eggs, in which the 3^olk has not yet been formed. These "potential" eggs are much more numerous in females which have, laid comparatively few eggs during life, and fewer in others which have deposited the full number, varying thus from 2,000 to only 50 or less. EFFECT OF FERTILIZATION ON EGG LAYING, Some interesting facts bearing on this matter were observed by Mr. Girault in the laboratory. Several females which had been deposit- ing infertile eggs were allowed to mate with males, and an accelera- 50 tion in oviposition was at once apparent. Following are the ovi posi- tion records for each night, the time of fertilization being marked b^^ the separating vertical line. Table XIII. — Effect of fertilization on egg laying. Infertile eggs. Fertile eggs. Moth No. 1 41 50 'si' 45 3 209 35 4 180 23 293 894 337 1,570 71 122 619 227 27 200 150 26 40 36 20 33 34 17 3 Moth No. 2 Moth No 3 CHANGES IX EXTEENAL APPEARANCE. The original uniform white color of the egg persists for a period of about fifteen hours. At the end of this time the upper third has usually acquired a tint which is noticeably more yellowish than the rest of the egg. The lower part of this 3'ellowish portion gradually darkens until, about thirty hours after the egg is laid, it has become reddish or brownish. This brownish color deepens until, at the end of thirty-six hours, it is quite distinct, even to the naked eye. The outlines of the band are often broken or irregular and an additional reddish spot, much less evident than the band, can now usually be seen near the micropyle. When about forty hours have elapsed, the whole egg has acquired a dull appearance, and the pigmentation of the brownish band is also a little deeper. After this the whole egg rapidly becomes dusk}" four or five hours before hatching and the brown zone is obscured. E3IBEYONIC DEVELOPMENT. In order to connect the real development of the egg with the series of external changes indicating its growth, it may be well to summarize briefly the embr3"onic development. The egg is fertilized shorth" before it is laid and development begins immediately. After about twelve hours the blastoderm is completely formed and the beginning of the germ band several hours later causes the appearance of the pale brownish ring when the egg is from fifteen to eighteen hours old. The development of the embryo and the for- mation of the appendages during the next twent3'-four hours are indi- cated by the deepening of the color. Finallv, the disposition of- the pigment in the chitinous skin and tubercles causes the blackening of the egg just previous to hatching. HATCHING. The head of the fully developed embryo larva is quite plainly to be seen through the eggshell, as is also more or less of the coiled body. The head is now directly under the microp^'le, and the body of the larva extends backward with its dorsal surface pressed against the egg- 51 shell. It follows the shell thus down the side, across the bottom and up the other side, until the anal prolegs at the posterior end of the body are just beneath the head. The embryo, in making its escape, bites viciously with its mandibles at the hard, tough membranes of the egg^ and gradually the spot weakens and the head of the larva sud- denly bursts through. It can now easily enlarge the hole until it is of sufficient size to crawl through. Once this is done, the larva is free from the egg in about two minutes. The whole process, from the first attempt to pierce the egg membrane until the larva is excluded, requires but a few minutes. In two cases where the exact time was noted it was thirteen and sixteen minutes, respectivel3^ The exit hole is usually large, with very ragged edges, situated on one side of the egg between the base and apex. The empty shell is of a translucent white, with a distinct purplish iridescence seen in cer- tain lights, more especially when viewed against a dark background. It retains its original shape. SHRINKING OF INFERTILE EGGS. The changes in external appearance undergone b}^ infertile eggs are sufficient!}^ different from those of normal fertilized ones to merit sep- arate mention. One fact is important. From thousands of infertile eggs laid b}^ moths in the laboratory not a single one ever hatchf d or showed the slightest external signs of embryonic development. Almost as soon as they are laid infertile eggs acquire a distinctly yellowish color, and wdthin a few hours begin to shrivel up. After twenty-four or thirty -six hours they are always greatly shrunken and are acquir- ing a dusk}^ color. From the very first they are higher and more conical than the normal eggs, this shape being accentuated by the shrinking, which occurs principally in an equatorial direction. EATING OF SHELLS AND EGGS BY NEWLY HATCHED LARV^. In the great majority of cases the newly hatched ]i)ollworms do not go immediately in search of food, but turn their attention to the deserted eggshell. Not content with the portion already gnawed out in their attempts to escape, they start anew to eat the shell. This may last only for a few^ minutes, or, again, may continue for nearly an hour. Frequently the entire shell is consumed, although often only one-half or three-fourths of it is eaten. What may be the benefit derived from eating the tough chitinous shell is rather uncertain. The idea that the larva derives any nourishment therefrom, or that it destroys the shell to remove traces of its own presence on the plant, can hardly be accepted. Nevertheless,' the eating is a very constant habit. After this is done the larva begins wandering about in its search for food. Quite often in captivit}^, when large numbers of eggs are close 52 tooether and plant food is scarce, thej' may develop cannibalistic pro- pensities and begin feeding on adjacent nnhatched eggs. Owing to the wa}" the eggs are scattered about in nature, such an occurrence must be rather rare under normal conditions. PERCENTAGE OF EGGS THAT HATCH. In all lots of eggs laid by fertile females, the percentage that fail to hatch is so small that it was disregarded except in a few cases where careful counts were made. These show that of 493 eggs 6 did not develop, giving an average of 1.22 per cent, or about 1 in a hundred. This is doubtless the approximately correct percentage for the hatch- ing of eggs laid out of doors. LENGTH OF THE EGG STAGE. During the summer of 1904 a long series of observations was made in the laboratory b}" Mr. A. A. Girault to determine the length of the egg stage at different dates during the entire season and at varying tem- peratures. In all, the developmental period for over 1,300 eggs was recorded. These results may be tabulated as follows: Table XIV. — Length of the egg stage at different dates throughout the season at Paris, Tex., 1904. ■ Date of hatching. Length. Date of hatching. Length. Date of hatching. Length. April 14 Days. June 23 - Days. f 3 if 2i August 31 Days. 21 2i April 15 April 21 R ! June 26 September 1-^ 91 April 28 ' ! 5i June 27 Septenil)er ''o 3^ Mavis 4i 11 ■' JulvlO ol Mav '^0 Jul V 12 October 9 October 12 li Mav28 Julvl3 ii 4 May 29. Julvl.S 03 October 14.. December 1 4* Mav 30 Julvl9 2I 9i 17 Julv25 Aug. 5 3 A clearer conception of the vaiying length during the season may be had from the following curve (figure 1), which is based on the data given in the table: In general it is seen that during the warmer parts of the season the egg period is much shorter than in the spring and fall. Although the embryonic period is thus inversely proportionate to the temperature, it is not so in any constant ratio. A number of calculations regarding the sum of effective temperatures^' to which different lots of eggs have « Following the theory of Merriam (Nat. Geog. Mag., VI, 229-238, 1894), the sum of mean daily temperatures above 43° to which the eggs had been exposed during development was calculated with the following result: Lot 1, April 14-22, 189°; Lot 2, June 22-25, 111°; July 15-18, 105°; November 1-17, 203°. Assuming 45° to mark the inception of embryonic development, the figures agree somewhat more closely: 173, 105, 100, 169. The summer sums are lower than the spring ones in either case. 53 been subjected fails to show an}^ very constant ratio between the two. Under normal conditions the longest egg period recorded in the spring was eight da}' s, and in the fall seventeen days. EFFECT OF REDUCED TEMPERATURES. Aside from the numerous records of the length of the egg period at different temperatures under normal conditions, a few experiments were made to ascertain the effect of much reduced temperatures on 18 17 16 15 14 13 12 II 10 7 6 5 /I APR. MAY JUNE JULY AUG. SEFT OCT NOV 18 \7 16 15 14 13 12 II 10 8^ 7 6 5 4 3 2 1 0 / / / / / / ' 1 / ^\ / \ / V / ^ — ^ J 3 2 1 0 X --^s^^ ^_^^ /^ ^ ^.^.y ^^''^ APR. MAY JUNE JULY AUG. SEPT. OCT NOV. Fig. 4. — Diagram showing relative length of o.'g^ stage during season of 1904, Paris, Tex. (original). embryonic development. The first series consisted of six lots which were placed in an ice-box where the temperature varied irregularly, between 50° and 60° F. The appended table summarizes the results: Table XV. — Effect of low temperatures on embryonic development. Num- ber of eggs. Age of egg. Time in ice-box. Remarks. 4 1 428 Brown ring present . . About to hatch Newlv laid Days. 13 2 lOi 10 33 13 Eggs showed no development until removed, then hatched after 48 hours. Egg showed no development until removed, then hatched after 3 hours. A very few developed the brownish band, a few shriveled, and the greater portion remained white until removed, when they hatched after 2\ days. Were dark at the end of 10 days and hatched on being taken out. Eggs developed a wide brown band and became orange yellow; 12 hours after removal they darkened as if to hatch, but shriveled instead. After 13 days many were hatching, while about 50 were hardly developed. Many. do 600 do 382 do The effect of much lower temperatures was tested at the Paris ice factory, where the maiaagement very kindly placed at our disposal their 54 cold-storage vaults for these and other experiments. The folloTving- temperatures were tried on two lots of eggs, some freshly laid and others partly developed. After the periods mentioned the respective lots of eggs were removed and the percentages hatching noted, as shown in the table: . Table XYI. — Effeci ofloirer temperatures on eggs. Treatment. First series — eggs with trace Second series — brown ring of brown ring. well formed. 34° F. for 48 hours i About 90 per cent hatched.. Practically all hatched. 34° F. for 24 hours, then 27° F. for 72 hours.! AboutnOper cent hatched..! Do. 34° F. for 24 hours, then 27° F. for 24 hours. About 25 per cent hatched..! About 33 per cent hatched, then 18° F. for 72 hours. It is evident from the figures in the table that eggs which are further developed are less susceptible to the effects of cold, and that the eggs are able to withstand short periods of cold better than longer ones. Althouo'h there was onlv about twelve to eighteen hours differ- ence in the age of the eggs in the two series, the proportion hatching from the older one was from 10 to 50 per cent greater. Some of the larv^ hatching from these eggs were kept to see if they had been weakened in any way by the cold, but all seemed as healthy as larva? hatched under normal conditions. The shock to the egg in the experi- ments must have greatly exceeded that caused by any sudden cold spell to wliich they might be subjected in the early spring. EFFECT OF ATMOSPHERIC COXDITIOXS. Moisture and dryness seem to have no effect on the time required for development. A number of eggs submerged under water shortly after they were laid and others placed in a desiccator dried by sul- phuric acid, hatched in practically the same length of time as a check lot under normal conditions. This resistance to atmospheric conditions is no doubt du^ to the thick. imperA'ious. chitinous eggshell which prevents the transpiration of water vapor to any extent. EFFECT OF SrBMERGEXCE OX EGGS. In the spring a good proportion of the eggs are deposited on young corn plants: they are often subjected to wetting by heavy rains which occur during this season of the year, and at times are washed down into the "bud" where the rain water accumulates. To ascertain how much submergence under water the eggs are able to withstand, a number of experiments were tried in the laboratory. On June 4. Si freshly laid eggs were submerged in six lots for periods varying from twenty-five minutes to four hours. Of these only 2 failed to hatch, and these were not in the lot which was under water longest. At another time a card with 8.5 eggs attached was placed in a vial of 55 water. The eggs had been laid about eighteen hours and were left under the water for three days. At the end of this time 8, or 23 per cent, had hatched and 3 larvie remained, drowned in the water, while the other 5 had crawled up into the air and escaped. From this it is evident that the short periods during which eggs are exposed to extreme moisture in nature can have but little influence on them. EGGS DESTROYED BY STORMS. A very important factor, however, and one which undoubtedly causes the destruction of immense numbers of eggs, is the mechanical force of the rain during violent storms. Although they are rather firmly attached, the combined effects of rain, wind, and sandy parti- cles washed against the plants removes many eggs. On two occasions during the spring. May 16 and May 29, plants in the laboratory gar- den known to have had eggs on them were examined after the rains and most of the eggs were found to be missing. Regarding field con- ditions, no positive data are at hand, but the unusual scarcity of eggs on corn after hard rains was evident on several occasions. EFFECT OF SUN ON EGGS. There is an opinion held among many planters that a large number of eggs, when laid on exposed portions of tlie plant, are destroyed by the rays of the hot midsummer sun. This led us to try the experi- ment of subjecting eggs to the direct rays of the sun. On August 30 a lot of 20 eggs which had been laid on a dried cotton leaf were pinned high up on a cotton plant, where they were in continuous sunshine during the day. All hatched after the normal period. Again, a few days later a moth was caged over a few leaves of a growing cotton plant, and some 50 eggs were laid on the upper sides of the leaves. After this the cage was removed and the leaves slanted so as to receive the perpendicular rays of the sun. The eggs were in no way injured, however, and practically all of them hatched normally. THE LARVA. When the young larva hatches from the e^g it is scarcely over a millimeter in length, and during growth it molts or sheds the skin six times before becoming a pupa or chrysalis. Very exceptionally one of these molts may be omitted, the bollworm pupating after only five molts. Each successive instar is larger, and the larva grows more and more rapidly as it nears maturity. The larvse were carefully studied by Mr. Girault during the course of his breeding work, and the technical descriptions included in the following account have been prepared by him from notes made at that time. 56 The larva is of the usual noctuid type, resembling in general aspect some of the cutworms, with no peculiar characters which will readily identify it. (See PI. VI, tigs. 1 and 2.) It varies so much in color that considerable study was necessary before a good detailed descrip- tion could be drawn up. It was found convenient to choose one of the predominating forms as a type and refer other varieties to it. The following is a description of this especially common form: Body dark, the ground color pale ocher-yellow; the upper side brownish, marked with nine (or seven) fine interrupted longitudinal lines of yellowish white, includ- ing the median line. The latter bordered with broader lines, which are slightly darker than the ground color. The upper side stripes dull orange or brown, as wide as the lower or stigmatal stripes, which are pale yellow and con- spicuous. Thoracic segments paler. Head reddish-yellow or brownish, spotted; the cervical shield varying from red- dish-yellow to shining black, more or less marked with whitish or with a pale dash along each side. Anal shield obsolete. Body beneath pale, with glaucous median and Fig. 5.— Head of boll- lateral stripes (absent in the first three stages). Tubercles v^e^forrkiTlT''^'^''^ shining black, i and ii « on first and second abdominal seg- ments and i on the eighth abdominal segment more con- spicuous, those behind the ninth segment concolorous with the body. Thoracic legs black, prolegs pale. This color type is very constant in all larvae through the first two instars, fairly so in stages three and four and in man}^ larvse until maturity. During the first three instars a midventral row of orange spots is invariably present, becoming faint in IV^ and disappearing in V. In the first three instars the anal shield is dusky and complete. In the first instar (and sometimes in the second, in spring and fall) the head is black. The simplest variations from this type consist in a change in the ground color, in the color of the fine lines on the dorsum, or in that of the lateral stripe. A very slight change in depth of color to rust- red or orange-yellow is common. A change to pinkish or greenish leads to the two other color types next to be considered (PI. VI, figs. 2 and 3). These begin to appear in stages IV and V, usually at the time of molting or, more rarely, suddenl}^ during an instar. The first of these is characterized by a greenish ground color and general absence of darker or lighter markings. Occasionally this type shows dark stria- tions and thus passes over somewhat to the brown type. In other specimens rose-colored side spots are developed which serve more or « These numbers refer to the classification of , larval tubercles as given by Doctor Dyar. ^The Eoman numerals refer to the respective stages, thus: I, II, III, IV, V, VI. r 57 less as a transition to the third type, which is pink or rose colored. The dorsal color pattern in a dark type of larva is shown in Plate VI, figure 4. DESCRIPTIONS OF INSTARS. Following are the detailed descriptions of the different stages of a generalized larva. ^ No reference is made to the color variations or to slight individual differences shown in the specimen at hand: Stage I. At exclusion from the egg the tubercle areas are pale and the cervical shield characteristically crescent-shaped, its posterior margin regularly convex, the anterior margin concave on each side and acutely produced medially. Shortly afterwards both become normal for instar I. Millimeters. Average length at hatching 1.5 Average length before ecdysis 3. 8 Average width of head ca^t 3 '*Semi-looper." Body slender; pale translucent, yellowish in certain lights; greenish after feeding. Surface minutely hairy. Head much larger than the follow- ing segments, cordate; shining black, bearing many setae. Mouth parts, ocellar spots, and antennae pale. Cervical shield shining black, sometimes paler, bearing eight small tubercles arranged in two rows of four each; shape broad, peltate, the anterior and posterior margins emarginate or sinuate, the sides oblique. Anal shield dilute black, quadrate, emarginate behind; bearing eight small tubercles. Legs dusky, furnished with many stiff setae. Prolegs pale, their shields quadrate, dilute black, the latter being in reality the blackened area surrounding tubercle vii; the anal pair with an inverted V-shaped dusky marking on the lateral aspect; the two anterior pairs shorter than the others, first one-half as long as third and fourth and the second slightly shorter than the third and fourth. Spiracles inconspicuous, black. Body beneath pale, the ventral nerve ganglia showing through as single round orange spots on segments I to X. Tubercles minute, situated in large irregularly circular dusky areas which are absent in the larva directly after exclusion from the egg. Tubercles arranged as follows: Segment I : i-viii placed in two rows of four each above and in front of the spiracle. Segment II: Ten tubercles in a transverse row across the segment, the line curv- ing forward; i smallest, ii largest, twice the size of the next smaller and equal to v. A single tubercle aboye and behind the leg. Segment III: Arrangement the same; i smaller than i of preceding segment and vi farther back. Segment IV: i, ii, iii, and iv, circular, equal; seen from above i and ii form a trape- zoid; i slightly larger than ii; seen from the side iii, iv, and v form a triangle surrounding the spiracle, iv in the stigmatal stripe; vi absent; vii and viii minute, in a transverse row. Segment V: Arrangement the same; vii and viii in a triangular group on the venter, the first or outer of vii largest. « Combined from a series of twelve boll worms hatching from eggs laid by the same moth and reared under identical conditions. 58 Segment VI: Arrangement the same; vii consisting of two, yiii normal, at the iaterior base of the proleg. Segment YII: Arrangement the same; vii and viii the same. Segment VIII: Arrangement the same; i and ii equal; vii and viii the same. Segment IX: Arrangement the same; i and ii equal, smaller; vii and viii the same. Segment X. Arrangement the same; i smaller than ii; iv farther back and below the spiracle; vii consisting of but a single tubercle, forming with viii a transverse row on the venter. Segment XI: Arrangement the same; i and ii equal, larger, forming a square when seen from above; vii and viii as in segment X. Segment XII: Arrangement the same; i and ii forming an inverted trapezoid, iii nearer to ii, iv opposite v of preceding segment; v and vi absent, viii apparently- consisting of two contiguous tubercles. Segment XIII: Eight minute tubercles in two transverse rows of four each on the anal shield, the posterior row following the outline of the margin; vii minute in a triangular group outside of the anal proleg; viii single, at inner base of proleg. Stage II. Millimeters. Average length after ecdysis 3. 85 Average length before ecdysis 6. 50 Average width of head cast 49 Body stout, tapering slightly before and behind, head smaller than the following segments. Head shining, black or paler with mottled markings, bearing scattered setse. Ocellar spots brownish red. Cervical shield shining black or paler, trapezoidal when seen from in front, bearing eight setc^e. Anal shield dark, paler at base and tip. Legs slfining black, paler at the joints. Body marked as follows: Ground color pale greenish, with comparatively broad median and dorso-lateral lines of orange or brown, which are interrupted at the inci- sions and are less distinct on the thorax. The dorso-laterals branched at the middle of each segment, giving out dorsal and ventral arms. The former forms another interior parallel line and the latter embraces tubercles iii and iv. On the sides of the body irregular paired lines of orange or brown define incompletely a faint creamy stigmatal stripe. Body beneath pale greenish with a median row of orange spots ■which fade out behind. Anal prolegs marked at the base behind with a looped dusky line. Spiracles larger, black, and resembling the tubercles. Tubercles shining black or dusky, their setge black. Arranged as follows: Segment I: Eight on cervical shield, as in i; two contiguous ones above and in front of the spiracle in an oblong kidney-shaped area; two other contiguous ones in front and below the spiracle; one in the center of their large black area and the other at the edge; also two contiguous tubercles at the base of the leg. Segment II: Twelve tubercles in a transverse row across the segment, the lower (vi) inconspicuous, its area absent; i and iv equal, one-half as large as iii and v; ii slightly smaller than iii; vii situated behind iv and v, forming with them a triangle; the tubercle above the base of the leg single, equal to iii. Segment III: Arrangement the same; ii, iii, and iv equal; posterior tubercle a little smaller. Segment IV: i, ii, and iii equal, iv and v equal and smaller, all in circular areas; i and ii forming a trapezoid when seen from above; iii above the spiracle, iv behind the spiracle, and v below; vi present, in a line with the thoracic leg tubercles; vii and viii in a transverse row of three on the venter, the outer of vii minute or absent and the inner much larger. 59 Segment V: Arrangement the same; v much farther below the spiracle; vii and viii in a parallelogram on the venter, the outer of vii minute or absent, the inner equal to viii. Segment A^I: Arrangement the same; vii in an inverted triangular group of three exterior to the proleg; viii minute, on venter at inner basal angle of proleg. Segment VII: Arrangement the same; i and ii slightly smaller. Segment VIII: Arrangement the same. Segment IX: Arrangement the same. Segment X: Arrangement the same; iii irregular; iv below. and behind the spir- acle; vi smaller; vii and viii in transverse row of two on the venter, vii much larger than viii. Segment XI: Arrangement the same; i and ii forming a square when seen from above; iii, iv, and v equal, closer to the spiracle; vi smaller, closer to v; vii and viii in a row of two, equal. Segment XII: Arrangement the same; i, ii, and iii equal and smaller than iv; i and ii forming an inverted trapezoid seen from above and i, ii, and iii forming a tri- angle seen from the sides; vii and viii in a transverse row of two tubercles, of which vii is the larger. Segment XIII: Arrangement the same; viii double, situated at inner basal angle of anal prolegs. Stage III. Millimeters. Average length after ecdysis 8. 96 Average length before ecdysis 10. 92 Average width of head cast 80 Body slightly narrower on the three anterior segments and suddenly sloping behind on the eleventh segment. Ground color pale, translucent, marked as follows on each side of the pale yellowish median line: First, a line of reddish; second, an equal line of yellowish white; third, a broader line of reddish; fourth, a narrower line of yellowish white; fifth, a stripe of reddish; sixth, the pale yellowish stig- matal stripe, more or less interrupted in the center of each segment. Following these below the spiracles is an irregular brownish stripe. Under side of body pale, except for brownish marks descending from above. Orange spots generally visible except posteriorly. Head reddish yellow or darker, spotted with dusky markings which leave a more or less distinct inverted V-shaped mark on the front. Ocellar spots pale with dark margins, placed in a curved line. Mouth parts pale. Mandibles fine toothed, darker at the tips. Cervical shield dark, or pale with the margins darker; broad, with the front margin straight and the posterior edge concave, sides curved, pos- ' terior angles truncate or obtuse; sometimes with paired line of spots near the median line; its disk transversely impressed behind. Anal shield much smaller, dusky, three or four sided, emarginate in front, its disk roughened. Legs black, bearing many stiff setee. Prolegs pale, their shields shining black, sometimes paler. The anal proleg with an inverted V-shaped marking on its shield. Prolegs about equal in size, first pair slightly larger. Crotchets or claws consisting of at least twelve pieces. In locomotion, larva humps segments I and II of abdomen. Tubercles nearly the same as in Stage II, much larger and their setse larger and stiffer. The margins of the tubercular areas quite irregular and the smaller tubercles circularly roughened. On the cervical shield the two middle tubercles of the pos- terior line are nearer the median line and a little farther forward. On segments I to III, vi is larger and circularly roughened. On segments IV and V, iii is largest, iv and the second of vii each a little smaller and each fully five times larger and some- what blacker than the others in groups vii and viii. On segment X, ii is closer to the median line, so that i and ii form a square when seen from above. 60 Stage IV. Millimeters. Average length after ecdysis 15. 65 Average length before ecdysis 17. 85 Average width of head cast 1 . 33 Body slightly narrower behind. Pale translucent, minutely hairy; marked as follows: Dorsal surface reddish, the median line pale yellowish, as are also three more pale lines on each side of it. Of these the lateral ones are broken behind segment X. The dorso-lateral stripe is a deeper rust-red and the stigmatal stripe which lies imme- diately below is broad and pale yellow, sometimes tinged with brown above. Below this is a stripe of reddish brown which is waved along the lower margin, embracing tubercle vi, narrowing gradually beyond the sixth abdominal segment and embracing the bases of the thoracic legs anteriorly. Underside of body pale, with indistinct brownish marking on the basal abdominal segments; median line of orange spots sometimes to be seen, as is also a pair of grayish side lines. Head equal to following segments; brownish yellow or brown, with darker oval spots, and an oblique dash on each epicranial lobe, which forms an inverted V-shaped marking on the front; surface furnished with many pale setae. Mouth parts darker and gular surfaces pale, the ocellar spots in a strongly curved line. (Cervical shield shining, blackish, with a conspicuous pale dash along each side, a faint pale median line and four pale spots which form a square on the disk. Shield broad with obtuse angles, the front margin sometimes notched, the sides and posterior margin sinuate. Anal shield inverted, crescent-shaped, triangular, or four-sided, dusky or concolorous with the body. Legs shining black. Prolegs pale, except anal ones, which are black with whitish markings externally behind, the area of tubercle viii dusky. Prolegs about equal in size, first and second pairs more slender. In locomotion the hump at the base of the abdomen is less noticeable. Spiracles black, inconspicuous, more noticeable before and behind. Tubercles about the same as in Stage III, but more conspicuous and with black setae. On segment I the two contiguous pairs are directly above and behind the spiracle, respectively. On segments II and III, tubercles i, ii, and iii gradually increase in size by about one-half, respectively; tubercle iv often as in the next instar; vi adjacent to v on segment II. On segment IV, i and iii are equal and the largest, and ii, iv, and v equal, each about half as large as i; i, ii, iii, and iv are con- spicuously conical and the second of viii sometimes marked with paler dots. On segment V, iv is closer to the spiracle, and iii and iv are adjacent, the latter irregular. On segment VI, rand ii are equal and iii is the largest. On segment VII, vi is slightly larger and more depressed; still more so on segment VIII, while on segment IX it becomes very large and quite flat. On segment X it is again much smaller and nearly the size of iv; on this segment iv is below and behind the sj^iracle almost in a line with v. On segment XI, iv and vi are again equal. On segment XIIj i is the largest, and iii one-half smaller. On XIII, the anal segment, vii consists of five tubercles on the outer side of the anal proleg, and viii is the same. Stage V. Millimeters. Average length after ecdysis 24. 27 Average length before ecdysis 28. 32 Average width of head cast : 2. 03 Body tapering slightly behind; translucent, the ground color ocher-yellow or paler, marked as follows: Median line pale yellowish, bordered on each side by alternating lines of brown and pale yellowish; of the former there are three on each side, and of the latter four, the inner brown line being widest and the outermost pale one 61 indistinct. All of these lines were broken behind the eleventh segment. Following these markings is the broad darker brown dorso-lateral stripe, which is faintly streaked with pale. Below this is the pale stigmatal stripe which is bordered below and sometimes above with yellow. Subspiracular stripe poorly defined, followed by the gray stripes on the sides of the venter. Venter with a median gray or pale line, the nerve ganglia not to be seen externally. General color of thorax above paler than the abdomen. Head brown or reddish, marked much as in Stage V, front with an imperfect X -shaped pale marking. Mandibles brown, five-toothed, the two inner teeth minute. Cervical shield brownish yellow, with irregular pale markings and black margins. Shield broad, almost covering the dorsum of the segment, its surface microscopically sculptured into five-sided areas and bearing at the center a shallow transverse impres- sion. Anal shield colored like the body, the sides darker; shape triangular, with sinuate or notched margins. Legs and prolegs pale, the anal prolegs spreading. Tubercles inconspicuous; i spotted with dusky, ii spotted with shining black; i and ii are the largest on segments IV, V, and XI, where they are conical, shining black and conspicuous; iii and iv shining black, the latter inconspicuous; vii and viii con- colorous, their setse pale. Arrangement differing from that of Stage IV as follows: On segment I, the area of the first pair is oblong and the additional tubercles at the base of the legs are minute. On segments II and III, iv is flat, depressed, and circu- larl)^ roughened. On the lower side, in front of the base of the legs, are two widely separated pairs of minute tubercles and a third pair at the outer bases of the legs. These tubercles first appear as a single pair in stage III. On segments V, VI, and VII, i, ii, and iii are equal and iv is much smaller, v is below the spiracle and further from it than iii and iv. On the succeeding segments vi increases in size, equaling iii on segment VII, exceeding it on segment VIII, and equaling it on segment IX; after- wards, as in stage IV. On the last segment the two tubercles of viii form an oblique line. Stage VI. Millimeters. Average length after ecdysis 34. 95 Average length when full grown 42. 25 Average width of head cast 3. 95 Body somewhat stouter than in Stage V, the first and second abdominal segments distinctly widened and the tip of the abdomen narrowed. Ground color opaque yel- lowish, body marked as follows: Median line pale, interrupted, bordered by a broader stripe of velvety black, which is finely lined with a jiale streak. Aside from these the dorsal region is' greenish-yellow, marked on each side by fine narrow yellow lines, the inner and outer ones broadest and the others often interrupted. Beyond the eleventh segment all are irregular, and the median black lines are fused together. Dorso-lateral stripe dusky, broad, and conspicuous, indistinctly marked by three fine broken pale lines. It extends from the head to segment XII, where it suddenly fades out. Stigmatal stripe broad and conspicuous, pale yellow, bordered below with whitish. It extends back from the head, gradually tapering to the base of the anal proleg. Below this the' surface is irregularly marked with whitish. Under side of body greenish-gray, the middle and side stripes whitish, narrow, and quite conspicu- ous, except on the thorax and apex of the abdomen. Sides of the body below more or less tinged with pink. Thorax not paler. Head brownish red, tinged with green, its sculpture and spots irregularly polygo- nal. Paraclypeus paler, transversely grooved. Clypeus densely grooved. Mandi- bles dark at tips, with an indistinct sixth tooth. The cheeks paler. Cervical shield brownish red, margined with black behind and along the sides, marked irregularly with white; the edge curved in front and straight or emarginate behind, and the disk with a median and two transverse impressions, its tubercles placed in minute 62 depressions. Anal shield triangular, irregularly marked with paler, its margins con- vex. First and second pairs of prolegs one-third shorter than the third and fourth; anal prolegs clasper-like. In locomotion the hump at the base of the abdomen is scarcely noticeable. Tubercles much as in Stage Y ; i and ii on segment IV and iii and iv on all segments shining black, the others inconspicuous. On segment I the second pair are separated, the posterior one much smaller, and the pair at the base of the legs are separate and of equal si7e. The additional ventral tubercles present in stage Y are absent. On segments II and III, tubercle iii is three times as large as i and ii; iv is minute and the ventral tubercles are absent. On segments lY to IX, iii is largest, i and ii are equal, and iv is farther forward. On segment lY, vi is closer to vii, and v and vi are equal. On segment Y, v is smaller than vi, while iii and vii are equal. In the group, i is smallest, iii a third larger, iv twice as large, and ii four times as large. On segment YI, iii is just above and in front of the spiracle, and v and vi are subequal. On seg- ment IX, iv is smaller and less distinct, v is farther down, near the base of the proleg, and vi is just above the base of the proleg. On segment X, i, ii, v, and vi are equal, iii is smaller and closer to the spiracle, iv is distant from the spiracle, and vii is four times as large as viii. On segment XI, i, ii, and iii are equal, as are also iv, v, and vi; iv is just behind the spiracle, with vi beneath it, and viii far down on the side of the segment. On segment XII, iii is minute and more depressed, directly below i, and iv is in the stigmatal stripe at the posterior edge of the segment. On segment XIII, vii consists of 8 inconspicuous tubercles on the outer side of the anal proleg, viii midway between the base and apex of the proleg on the inner side. POSSIBLE CAUSES OF COLOK. TAEIATION. In connection with the color variation above referred to, Mr. Girault has prepared a table showing- the growth and color differentiation of three larvae which proved to represent the three well-marked color varieties; all hatched from eggs laid by the same female (var. ochracea), and were reared during September under similar conditions, on cotton. Table XYII. — Variation in three Jarrx reared unJer similar conditions. In star. I. II. III. IV. VI. Dark variety. Rose varietv. Green varietv. Normal, marked distinctly with deep orange. Dark, marked with dull orange. Like the type, hut lighter and greenish. Dark, greenish, marked with dull orange. The usual brown type: oliva- ceous above with olivaceous side stripes and yellow stig- matals. Twenty-four hours later, dorsal region lighter and stripes very conspicuous. Just before ecdysis. larva green. Grayish; gray above with whit- ish and yellow lines; dark, the side stripes dark and the stigmatals yellow. Normal, lemon yellow, marked with dull orange. Pale, marked Avith dull orange. Olivaceous, marked with dull orange, becomingpaler later. Ground color pale ochreous marked with rust red; later with greenish lines above and conspicuous side stripes. The usual brown type dorsal region greenish with yel- lowish lines; side stripes with crimson spots, stig- matals pale, margined. La- ter with the crimson spots more distinct. Normal, yellowish, marked with deep orange. Marked with dull orange. Grayish, marked with dull orange. Typical at first, but after 24 hours changed to green with dusky side stripes and whitisii stigmatals. Typical; side stripes brown; "later pale green with pale yellow lines above and darker green stripes. Stigmatals pale yellow. The Tisual pink type; pink Theu.sualgreen type; body above the pale lines; side greenish, the stripes stripes broad, velvety black; j darker green and the stigmatals reddish yellow. " lines above pale yellow. 63 Such facts as these show that the various color t3^pes may develop among- bollworms grown as nearly as possible under similar conditions, and sugg-est that the matter is entirely an hereditar}^ one. Neverthe- less the apparent predominance of certain types on various plants and under different conditions led us to undertake some experiments along this line. Six lots of ten larvae and one of three were fed on cotton, tobacco buds, tomato buds, Irish potatoes, flowers and buds of cow- peas, corn silk, and the leaves and spikes of Amarantiis spinosits^ respectively, but variations peculiar to each lot did not appear. The experiment was later repeated with twent}^ larvae from eggs of a single moth, fed on cotton, tomato, potato, and tobacco, but afforded no fur- ther results. Other experiments were tried b}^ rearing larv^ in moist and dry atmosphere, and in light or dark situations, but no evidence was secured. Cold weather influences to some extent the color of the head. Normally this is black in the first stage and pale in the others, but in the spring and fall and in the ice box, the black color persisted through the second stage. In the field numerous variations, presumably due to environment were noted. Among larvae feeding on cotton, the pale pink or green tj\)Q is apt to predominate, except when feeding on the foliage, when bright greens and yellow make their appearance. On corn all three types occur at nearly all times, although green individuals with crim- son spots are rather scarce in midsummer. On alfalfa a uniform green type is most common. These dark greens, noticed in specimens feed- ing on foliage, may be due in great part to the bright-green color of the blood under such conditions. DURATION OF LARVAL IN STARS. This question was worked out very thoroughl}^ by Mr. Girault in the laboratory at Paris during the season of 1904. Some thirt}^ lots were reared with this object in view and the molts recorded as accu- rately as possible down to hours. The number is too large to represent consecutive generations, and the life cycles of the different lots overlap one another more or less. The following table summarizes the entire number: 22051— No. 50—05 5 64 Table XVIII. — Duration of larral instars. ;tage I. Period of growth. Stage Stage 11. III. Stage Stage Stage ' ^ . , is IV. V. VI. j ^^^^^- ^Si g-^ Corn stems do do Rosebuds Corn silk do 7 I do 8 Cotton 9 ' do ....do Tobacco ! Cotton I ....do ....do Miscellaneous . . Cotton Araarantus Tobacco Cowpeas i Cotton Tobacco Tomatoes | Cotton I ..-.do ...-do i ....do Cowpeas Cotton Apr. 1-Mav9 Apr. 10-Mav9... Apr.l9-Mayl6.. May 1.5-June 3. . June 29-Julv 17. Julv9-Julv'25.. Julvl9-Aug.2 .. Julv 19-Aug. 3 - . Julv29-Aug.l3. July 30-Aug. 16 . Aug. 4-Aug. 19 - Aug. 7-Aug. 22 . , Aug. 8-Aug. 24 - , Aug. 8-Aug. 23 . Aug.8-Sept. 6.. Aug.20-Sept.8. do Aug. 20-Sept. 9 . Aug. 20-Sept. 1 . Aug. 31-Sept. 18 Aug.31-Sept.l6 Aug. 31-Sept. 20 Aug. 31-Sept. 17 , Sept.8-Sept.25-, Sept.l6-Oct.5.. Sept.20-Oct. 20. Sept.28-Oct.21. Oct. 13-Dec. 20 . . Average . 11 2 2 2 3 ! 2 15 2 4 4 19 21 i(«) 7 6 5 5 23 3 2 i 2 18 23 S 13 20 ' 4 2 14 21 2 15 18 17 2 22 3 23 5 1 37 ; 12 24 : 6 27 : 11 16 , 13 16 22 14 21 14 17 26 10 17 23 19 17 20 15 11 j 22 20 i 23 21 6 18 16 17 0 19 1 29 1 21 19 70 3 °F. 810 440 677 871 668 656 532 657 682 632 547 566 525 520 1,033 681 737 802 478 735 656 702 646 429 687 960 637 c-643 a Omitted. b Not recorded. In this average Nos. 15 and 28 are omitted. In the last column are given the sums of effective temperature (above 43^) to which the larvas were subjected. While the range ^' (429^-871°) is great, an average of 617^ does not fall far from most of the records. The following table shows the average length of the different instars for larvae feeding on corn and cotton: Table XIX. — Average length of larval instars for larva; fed on corn and cotton. Instar. Days? 1 Hours. I . II . III. IV . V . VI . 3 3 3 I 13 6 17 0 19 11 Total 20 18 GROWTH DITRIXG THE LARVAL IXSTARS. The comparative rate of growth during the respective larval instars is of interest as indicating the periods of most vigorous feeding, and, a Only rearings on corn and cotton are here considered. 65 consequently, the periods during which greatest injury is done. Deter- niinatiojis of this character were made in connection with the previ- ously mentioned breeding work. Measurements made of the length of the body are of but little use, since the}^ may be varied so much by the movements of the larva. There is a rather constant and gradual increase, however, from birth to maturity, as shown b}^ the measurements given below, which are averages of twenty-live larvae. Table XX. — Showing amount of growth, during, and length, at end of, each instar. Instar. Amount of growth during each in- star. Lengtli at end of each in- star. I 7nm. 2.02 2.65 7nm. 3. 52 fi 17 II III 4 53 1 10. 70 1 IV V VI 7.68 10.51 13.35 18.58 29.39 42. 74 Thus it will be noticed that a larva shows a greater amount of growth during each succeeding larval instar. This is shown graphically in the accompanving curve (fig. 6). More accurate measurements are those based upon the size of the head, which does not change between the molts, and thus serves b}^ its almost constant size to identify the instar of any given larva. By meas- uring large numbers of head casts thrown off at the molts, it was found that they are fairly constant for each instar, sufficiently so to enable one to tell the stage of any larva positivel3^ The following table is compiled from measurements of over one hundred specimens: II III IV V VI Fig. 6.— Diagrammatic represen- tation of comparative rate of growth of larvse daring dif- ferent instars (original;. Table XXI. — Showing average width of head casts for respective larval instars. Width and range. Stage I. Stage II. Stage III. Stage IV. Stage V. Stage VI. Width mm. 0.30 («) mm. 0.48 0. 42-0. 54 mm. 0.78 0.67-1.00 mm. 1.33 1.21-1.50 mm. 2,05 1.73-2.28 vim. ' 3 95 Range 2 85-5 00 a Practically constant. 66 It will be noticed that not in a single case do any measurements of the ditferent stages overlap. In abnormal individuals, or in rare cases where the larva undergoes onh^ four molts before it pupates, the meas- urements are of course irregular and are here disregarded. The variation in head width, in Stages III and IV, in a lot of five larv83 reared from eggs of a single moth and on the same food, is shown graphicalh^ in figure 7. INFLUENCE OF EXTERNAL CONDITIONS ON GROWTL. The effect of seasonal variation in temperature on the development of the bollworm is easily noted by glancing down the right-hand column of figures in Table XVIII, page 64:. The length of the larval stage is thus seen to decrease from 37i da3^s, recorded in April, to 14 da3'S during the warmer parts of the summer, and to increase again in the fall. Experiments were, tried to ascertain if atmospheric conditions had any effect on growth, but they III. ^^^^^^^^^L_ gave onh^ negative results. The ■ — effect of different diet on growth IV. I has been watched, but there Fig. 7.— Diagram illustrating relative width and vari- SCCmS tO bc but little relation ation ill width of the head casts of larvae in third between the twO, CXCept pOSsi- and fourth instars (original). i i • i • bly m one case, where it was found that larvee grew much faster on g-reen cowpea pods than on either corn or cotton. The effect of temperature on growth was also investigated by rear- ing larvae simultaneously at three different temperatures. This was done by means of a commercial chicken-egg incubator, which could be kept at a temperature of from 80° to 90° F. ; an ordinar}^ ice box, maintaining a temperature of from 50° to 60° F., and the laboratory breeding room, which w^as subject to the usual daily fluctuations in temperature. - During the latter half of April a lot of larv^ reared in the incubator at an average temperature of about 85° attained full growth in four- teen days, and the moth emerged twelve days later, making in all twenty-eight days, as compared with forty-five days required in the laboratory, where the average temperature was about 71°. In the ice box, where the temperature was below 60° most of the time, it proved difficult to raise any larvae be^^ond the third molt. The following- table gives a comparison of the three lots: 67 Table XXII. — Rate of groivth of larvx at different temperatures. Location. Average tempera- ture. Larval stage. Sums of ef- fective tem- peratures. Incubator ° F. 85.4 71 57 Days. 14 2.8 a 41 ° F. 425 Luboratorv 677 o516 « Three molts. The effect of severe cold on larvse was also tried in a number of cases. All subjected to temperatures somewhat below freezing were killed outright by an exposure of from twenty-four to forty-eight hours, but of those kept at 34° F. for forty-eight hours a small per- centage survived and matured successfully. The ability to live for any length of time without food is not very great. Newly hatched larviB live about twenty-four hours in the laborator3% ])ut it is probaVjle that in nature the drying effect of the sun and other untoward conditions would shorten this period consid- erabl} . Larger larvae usually live several days, and occasionally three-fourths or nearly grown ones will pupate successfully if deprived of food. NUMBER OF MOLTS. The number of molts has already been stated. Of 100 larvae reared in the laboratory at Paris, Tex., in 1904, 90 per cent molted 5 times, 8 per cent 4 times, and 2 per cent 6 and 7 times, respectively. . The cause of this variation in the number of molts in regard to the 10 per cent thus varying could always be traced to abnormal condi- tions. Highly nutritious food and excessive care in breeding appar- ently caused less than the normal number of molts. Seven out of eight larvae reared on cowpeas molted thus. Molts in excess of the normal were paused by neglect and insufficient or disagreeable food. PROCESS OP MOLTING. The process of molting is normal. A fews hours after ecdysis the larva stops feeding and remains in an extended, slightl}^ arched posi- tion. In this condition it is very helpless, especially when nearly full grown. At the time of molting the body contracts spasmodically, the skin splits back of the head, and the head is thrust out. Three or four minutes more pass before the larva has shed the skin entirely, and after three or four hours feeding begins again. In midsummer the stages preparatory to molting are very short (15 to 18 hours), and in the fall longer (3 to 4 days). After the earlier molts the larva? sometimes devour their own shed skins, as do also the older ones, but more rarely. 68 HABITS OF NEWLY HATCHED LARY^ ON COTTON. The feeding habits of the newly hatched larv^ have a very impor- tant bearing on the question of poisoning and have for this reason been rather careful!}^ studied. The habit of eating the deserted eggshell has already been described. After this follows a period of very pre- carious existence for the young larvae. They begin to wander about in search of suitable food, here and there rasping the epidermis of the leaf or involucre where they happen to be, and passing on to repeat the process. They are not satisfied to remain on the leaves, and very often reach some tender growing tip soon after hatching. This is usually to their liking, and the}^ remain and feed for some time upon the tender foliage. The}" do not sta}" long, however, and are soon again on the move after a short interA^al. If a square is next .found they at once crawl Vjeneath the involucre and begin feeding. Other- wise they may feed to a slight extent on a leaf, or another growing tip, until a square is finalty found. During the search for proper food many of the larvae perish; in fact the great majorit}" of them do. A number of times during the summer from 100 to 150 eggs or newly hatched larvae placed on a cotton plant have yielded only four or five larvae after a few days. This is much in excess of the number of eggs usually laid on a plant, and serves to show what an enormous number of the larv^ die in the presence of food in plenty. One thing which is important and should be borne in mind is that the larvae almost always feed to some extent on large leaves or tender foliage before the}" begin feeding inside the squares. If the}- are to be poisoned it must be largel}^ during this period of external feeding. EFFECT OF EXTERNAL CONDITIONS ON NEWLY HATCHED LARV.E. The 5"oung larvae feeding on corn early in the spring are often washed down by rain and submerged for considerable periods. To test their ability to withstand such conditions a number were experi- mented upon in the laboratory. Twent}^ newly hatched larvte were entangled in a bit of cotton and submerged for seventeen hours. All but four survived the immersion. Larger larvae can not stand such long periods, but when dropped into water make feeble attempts to escape, becoming stupefied after a few minutes. CHARACTER OF INJURY. The characteristic habits of the larger bollworms, like those of the newly hatched larvae, are utterly difi'erent on corn and cotton and must be considered separately. 69 CHARACTER OF INJURY TO CORN. In 3^oang corn still in the bud the larv?e seek out the tender uncurling leaves near the base of the opening portion (see PI. VII, fig. 1). Here they bore through the curled mass, making burrows which show as transverse rows of holes after the leaf has fully opened. Occasionally the plant grows too quickly for the boUworm and the sepa ration of la3^ers by unequal growth may squeeze it to death. As soon as the tassels are beginning to form, and while they are still well sur- rounded by leaves, they are attacked (see PL VII, fig. 2). The larvae now feed on the tassel proper, scarcelj^ ever eating into the leaves or stem. As soon as the ears begin to form the remainder of the plant is no longer disturbed. The damage to corn ears will be considered at greater length elsewhere. CHARACTER OP INJURY TO COTTON. The method of attack on cotton before the squares have formed is of little importance, since it is very rare for such cotton to be injured by the boll worm. It is interesting, however, as it shows that the spring generation can feed on cotton if forced to do so. Under such conditions they seem to prefer, when small, to bore into the cotyledon leaves or buds, and later to feed promiscuously on any part of the leaves. The squares are without doubt the part of the plant preferred by the majority of the larva?. After the newh^ hatched larva? have gained enough strength to get about readily they almost invariably enter a square and begin feeding on it near the base. As a rule the first square attacked is eaten hardly at all, and only a small black puncture is to be seen when the square ''flares" some twent3^-four hours later. The flaring of a square is a very characteristic process, the bracjts of the involucre folding back and exposing the inner portion (PI. IX, figs. 3 and 4). Almost invariably squares which have flared drop from the plant some hoars later, breaking off at the juncture of the petiole and stem. Very rarely the}^ may dry up and remain upon the plant. A very slight injur^^ made by a newly hatched bollworm will cause a square to flare, but the}- can often withstand a considerable needle prick without harmful effects. The second square to be attacked by the growing larva shows a larger scar and generally a trace of excrement and a few silken threads spun by the larva, which has left it before the flaring begins. Such injur}'- to squares is quite generally known as the work of "sharpshooters;" improperly so, however, since the real sharpshooter belongs to another order of insects. After the larva has fed upon two or three squares it may either turn its attention to bolls or continue its depredations on othei* sq uares or flowers. It has now increased considerably in size and is about one-third grown. If it continues to feed on squares a large hole is 70 gnawed in one side near the base and the contents eaten out, leaving onl\' a hollow shell still retaining its original shape (see PL IX, lig. 4). Subsequent injmy to squares is done in the same wa}^ except that the hole eaten by the full-grown larva is considerably larger. Bolls are scarcely ever attacked by newly hatched larvae, although the latter can subsist on them without difficulty in the absence of other food. Larvfe one-third grown or larger may bore into the bolls at a point not far from the base or farther up on the side, as shown in figures 1 and 2, Plate X. If the boll is small, like -the one shown on Plate IX. figure 5, the entire contents are appropriated, as in the case of a square, but if it is large usuallv only one or two '•locks'' are badly eaten (see PI. X, figs. 3 and 4z). When the larva leaves the boll its exit is most generally made through the entrance hole, although a second opening is sometimes made. The excrement left in the boll l)y the departing larva usually stains what fiber may be left in that lock to a dark brown, and often favors fermentation and the development of mold, which quite often ruins the boll entirelv. If two or three locks have been destroyed the boll may open more or less imperfectly, as shown on Plate X. figure 4, or fail to open at all. In such bolls the large hole made by the bollworm is always plainly to be seen. The flowers are often attacked soon after they have opened and before the petals have become pinkish. Usually the pistil, stamens. and ovary are destroyed and the flower ruined (see PL IX, fig. 2). The stamens especially seem to be very well liked and injury may be confined to the destruction of these (see PL IX, fig. 1). The leaves of the cotton plant are not fed upon by the bollworm unless squares and bolls are very scarce. Under such conditions they take very readily to leaves, eating them in a' way similar to the cotton worm {Alabama [AJeiia] argillacea). In the large field cage in the laboratory garden at Paris a method of feeding not noticed elsewhere was observed. Tiie squares and bolls had practically all been destroyed and the large larvae, boring through the axillary buds into the stem, caused it to break at that point and wither and die. CHARACTER OF INJURY TO OTHER PLANTS. The feeding habits of the bollworm on other plants than corn and cotton are rather beyond the scope of the present bulletin and can only be briefly referred to. On tomatoes the green fruit is usually the part chosen, the young larva boring through the skin at almost any place, while the older ones prefer to enter near the insertion of the stem (see PL XI, fig. 2). Tobacco is injured at the growing tips or "bud '' early in the season (see PL XI, fig. 1), but later, if the plants are not topped, the green seed pods are preferred. 71 Injury to ripe peaches still attached to the trees is recorded by Webster" in Ohio. BoUworms attack peaches about as they do tomatoes (see PI. XI, fig. 3). Peas, beans, and okra are all bored into and the green seeds eaten, the bollworms often being very destructive to these plants (see PI. XI, figs. 4 and 5). From eggs laid on rosebuds early in the spring a lot of larvae feed- ing upon the unopened buds were reared. CHOICE OF FOOD BY LARV^ Aside from field observations, a series of experiments were made in the laboratory to determine the choice of food by larvae when plenti- fully supplied with several kinds. When given corn, cotton squares, green tomatoes, and tobacco buds, the corn is almost always chosen, often after first tasting the others; but with difi'erent parts of the corn plant selection is not always so uniform. Apparently the tender bud and ear are about equally attractive. In the case of cotton the flowers and squares were liked best, as is shown in the appended table. Table XXIII. — Choice of differeiit parts of King cotton bij holhwrms. Number of larvae. First series. Second series. Total. Part of plant. >> >. >. ol >> >> >i Remarks. a >> cj ^• !>. . 'C cd 'O •^ r^ ^ >. -o aj ^3 r? rrt ^ -C "C w 03 -a -d -a -a t3 -d A Tli t3 A a> xi 2 i 5 X > £ O o 2 1 ^ .^3 c > .^3 o o ^ & H ;=H U^ ID w ^ OQ H 1^ t^ m CO W p!H m Leaves f> 8 ?, 1 0 n 0 ^ 0 n 0 1 0 0 0 8 9 Fifth choice. Tender growth 2 2 1 4 2 0 0 1 4 2 0 1 0 0 0 n 8 Fourth choice. Flowers (a] (n) ('-') (a) (a) King. Black-waxy, wooded. Hall. Black-waxy, wooded. King. Post-oak. King. Gray, prairie. Big Boll. Black, prairie. King. Red River bottom. •Sui^U^ld JO 91T3a Apr. 1 Mar. 29 Apr 1 ....do... Mar. 30 Mar. 23 •iijnCui JO ^uao i3d sSbjgav cDCDLOOil^cD CO lO "O Tl? o> iC •iUBid uo :}injj pjjoj. issps co' -d '.s "S 1 •p;ox 446 584 257 1,211 183 753 " •snoq uMoiS-nnj gg^gg^l s ■snoq uA\.ojS-8q;jnoj-99jqj, g?§?3gS| CO •snoq UA\.ojS-Ji'Bq-9UO ss^^gss s •snuq uAVOjS-q^inoj-9UO |28^gSS 8 CO •snoq [[-Buis Xj9A s^^i^^ ^ •S9JBnbg S|^'|;^S o 3 1 S3 is" 1 •Wox |SS2^!5 i •sxioq uAvojS-nnj[ loo^ooo OS 00 •snoq UAvoiS-sqiinoj-99jqx C^OI^OrHCO 00 CO tN - •siioq UAVoaS-j[i3q-9uo t^TtlrHOOCO - " •snoq uA\ojS-qiJnoj-9uo t^ iM CO 03 a> GO - ^ •snoq n'Bnis j?J9A S^^^^?^S5 •s9J'Bnbs 1-HCOOiOCO^ CO 1—1 1-H 03 OOOOiOO •p9utun?x9 siuBid JO jaqninjs[ 1 ^'-'^oi i-i CO Locality. c c II a; :: c 1 ^ c > c Date of observa- tion. a- bj < jbibj -<< < < CO CbX) D King. Black-waxy, wooded. Hall. Black-waxy, wooded. Big Boll. Post-oak. Rowden. Gray, prairie. Peterkin. Black, prairie. Fleming. Red River bottom. May 2 Apr. 15 Apr. 25 May 2 May 1 June 2 COmOOCDCO UO CO O O oi CO CO (N 1-H i-H rH ^ S OlCOQOi-lOO ^3^C^2?5 ss ^ggJSSS C<1 CD lO CD TfH 00 CD 03 00 o> CO t-^ OOOOiOO S _2 'E c c c C 1 < 5 o h > o b < 1-HC^ Obcbi Ob < )b < )bj < ' 1 74 Table XXVI. — Comparative injury by holhvorm to early-planted and late-planted cotton. Early-planted. Late-planted. Per cent of in- jury. Per cent in favor of early plant- ing. Locality. Date of planting. cent Seed P^ Date of planting. Seed used. Kind of soil. Ladonia, Tex Ben Franklin, Tex. Quinlan.Tex Willspoint, Tex ... Paris, Tex Almont, Tex Apr. 1 Mar. 19 Apr. 1 Mar. 30 ....do... Mar. 23 King .1 23.6 1 Hall..i 5.6 King. 5.5 ...do.. 4.9 Gin... 19.7 King .( 5.6 i 9.3 May 2 Apr. 15 Apr. 25 May 2 May 1 June 2 King Hall Gin Rowden . . Gin Fleming.. 35.3 23.5 10.0 10.0 29.6 23.6 11.7 17.9 4.5 4.1 9.9 18.0 Black-waxy, wood- ed. Do. Post-oak. Gray prairie. Black prairie. Red River bottom. Average of all ob- 20.7 11.4 servations. : . It will be noted that in determining the percentage of injuiy obser- vations were made on earl}^ and late cotton in the same locality and on the same date, as shown in Tables XXV and XXVI, so that the com- parisons are quite fair. The average total injury to early cotton was 9.3 per cent, as compared with an averaoe total of 20. 7 per cent to late cotton. This difference is undoubtedly less than would be the case during seasons of more severe bollworm injur^^ than occurred in 1901:. The decided preference of the bollworm for squares and young bolls is shown in the figures of average percentages of injury given in both tables. Thus, the sum of the percentages of injury, as shown in the tables, to squares and bolls one-half grown or less is 119.9, while on bolls from three-fourths to full grown the injury amounts to only 11.5 per cent. The fact of the comparativelj" less injur}^ to early cotton indicates the desirability not only of planting as earl^^ in the spring as possible, but of adopting all other practicable measures that will further th-e production of an early crop, such as the use of seed of earh^ fruiting varieties, the use of fertilizers to hasten and increase the production of fruit, and eai'ly and thorough cultivation. This subject will be more fully discussed under the consideration of remedial measures. AMOUNT OF DAMAGE DONE BY A SINGLE LARVA. Owing to the very different method of attack on corn and cotton, the damage done b}^ a single larva is of an entirel}' different nature in the two cases and will be considered separateh^. DAMAGE TO YOUNG CORX. When the larva feeds on 3'oung corn b}" eating into the bud, consid- erable injur}' is done to the unfolding leaves and the plant presents a very ragged appearance. (See PL VII, fig. 1.) From general obser- vation it would seem that the small percentage of plants which are injured when 3^oung must be less productive later in the season. 75 Such is apparently not the case, however, as two experiments made on corn plants show. Two average young phmts of field corn grow- ing in the laboratoiy garden were chosen and watched until maturity, with the result shown below: Table XXVII. — Effect of hollivorm injury to young corn. Experiment 1. Experiment 2. Date. Observation. Date. Observation. May 14 May 15 May 19 May 20 June 2 June 11 June 21 Placed a one-fourth grown larva in bud of corn plant 2^ feet high. Larva has eaten from one of the partially uncurled leaves in the bud; damage slight. Bud is now badly damaged. Damage is greater, but growth is not im- paired. Plant now 7^ feet high; shows serious damage, but is still healthy. Now in tassel and silk; is one of the healthiest plants in the garden. Is bearing two fine ears. May 17 May 18 May 19 May 20 June 11 June 21 Placed three larvse (one-fourth, ohe- fourth, and one-half grown) on corn plant. Some damage down in bud is notice- able Much injury is now noticeable. Damage increased; one larva visible in the bud. In tassel and silk; quite healthy. Is bearing a large, healthy ear. In these two cases, at least, the plants, although much disfigured when young, were fully up to the average in productivity^ later in the season. At times the feeding of the larvae in corn buds produces a deformity resulting in the failure of the developing leaves to unroll normally, but such instances are too rare to have any bearing on the question of bollworm injury by this brood. The injuiy to tassels (PL VII, fig. 2), which occurs later in the sea- son, is of small economic importance also, since the few which may be partially destroj^ed must have but small effect on the pollen produc- tion of the field. DAMAGE TO EARS OF CORN. It is in the ears that the real damage and loss occurs, but this injury is frequently overestimated. In ears of early sweet corn it is not exceptional for the larva to bore directly down the ear, as shown in Plate VIII, figure 2. In this case the actual number of grains destroyed may be considerable, and the filthy excrement distributed over so large a space favors decay and subsequent molding of the ears, thus mak- ing the corn unfit for the market or table use. Feeding normally about the apical portion of the ear, the part affected scarcely ever amounts to more than one-fourth or one-fifth of the ear. But the extent to which sweet corn is infested, as compared with field corn, makes the loss to this crop proportionally heavy. In feeding on the larger and more rapidly hardening ears of field corn, injury is usually confined to the silk and apical portion, as shown on Plate VIII, figure 1. The exact quantity consumed by each larva is not readily determined, since it is quite variable. xVf ter the eggs have hatched the silks may furnish the food until the larva is from one- 76 eighth to one-half grown, or sometimes even much larger, so that a corresponding!}' large or small portion of the kernels beneath is consumed during later development. Experiments made in the labo- ratory show that a bollworm ma}' consume from 30 to 50 kernels of corn durino- its entire life. AUowino- 900 kernels to an averao-e ear. this would mean an injury of from 3 to 6 per cent. Often more than one larva may mature in a single ear, and again the silk may supply the greater part of the food. Taking into consideration, also, that the apical portion of the ear, which is least valuable, is the first destroyed, the injury to field corn will probably not often exceed the estimate given above, and will, of course, fall lower wheie the percentage of infestation is less than 100. Although the eggs are laid in the fresh silks, the larv» scarcely ever hatch in time to destroy the silks before pollination has occurred, so that the fertilization of the infested ear is not interfered with. DAMAGE TO COTTOX. The extent of the injury caused by a single larva to cotton bears directly on many questions of bollworm control, and has been investi- gated carefully by a series of experiments and observations made upon cotton growing in the laboratory garden at Paris. The first series relates to very young cotton, and was made during late May and early June. At this time the plants were from T inches to 1 foot high. On May 31 two quarter-grown lafv^ were placed on one of the largest plants and covered by a wire-screen cage. Both entered the soil to pupate on the 10th of June, leaving the plant almost completely defoliated, after the fashion in which the cotton caterpillar injures the plants later in the season. Although the plant was in bad condition when the larvfc left it, later in the summer it was practically as well developed as its fellows in the immediate vicinity. This and other plants similarly treated had not yet formed any squares. The other plants treated gave, on the whole, about the same results as the one described, thoug'h the average extent of injury wa.> somewhat less. A second and more important series of observations was made during the latter part of July and the first half of August. The plants exper- imented on were about two weeks earlier than the general planting, and hence were at that time in the same stage as the field crop during August, when the third generation of bollworms is most destructive: that is, when full of squares, flowers, and bolls. Six of the more com- plete records are given in the succeeding paragraphs: E'.cper'iment 1. — A newly hatched larva placed on a plant \L\ feet high July 13. By the 25th it had entered the soil, after destroying twelve squares, one one-fourth grown boll, and one flower. Krperiment 2. — Small larva placed on a plant 3 feet high on July 15. It entered the soil on the 2Tth. after destroyiiig one square, one small boll, and two large bolls. 77 Experiment S. — A*newl_y hatched larva was placed on a plant 3 feet high July 15. It entered the soil July 28, after destroying one square, one flower, and two full-grown bolls. Experiment ^. — Larva one-eighth inch long was placed on plant 3 feet high July 26. It entered the soil August 4, after destroying nineteen squares. No bolls or flowers were injured, although two large bolls bore evident marks where the larva had tasted them and passed on. The daily injury done by this larva ma}^ be of interest: First and second day, one square; third day, two small squares; fourth day, one small square; fifth da}^, one square; sixth day, two squares; seventh day, five squares; eighth day, six squares. Experiment S. — A one-eighth inch larva was placed on a plant 3 feet high Jul}^ 27. It entered the soil August 7, after destroying four squares, two flowers, and two bolls (one-fourth and three-fourths grown, respectivel}^). Experiment 6. — A one-sixteenth inch larva was placed on a plant 3 feet high August 10. By August 2(» it had destro3^ed thirteen squares and one flower. A summary of these six cases shows a total injury of fifty squares, eight bolls, and five flowers. This gives an average of eight squares, one and two-thirds bolls, and one flower for each developing larva. A great individual difference in tastes is at once evident, some larvfe preferring squares entirely and others feeding more or less on bolls when both are present in sufficient quantities, as they were in all these experiments. Squares are invariably chosen by the youngest larvae, some of them continuing when older to search out the squares and others turning their attention to the bolls. In one case a boll was attacked by a rather young larva, which afterward consumed only squares and flowers, but this is unusual. On account of their large size, a much smaller number of bolls are destroyed than squares. In fact, it was seen in one case that two large bolls and one flower served to mature a larva, while another, which fed only on squares, required nineteen. During the experiments each individual plant was covered by a large wire-screen cage, 3 feet square at the base and 4 feet high. This prevented in great measure the escape of larvae, and kept out any .other insects which might interfere with the accuracy of the results. The cotton plants each bore from 40 to 60 squares and from 8 to 12 well-developed bolls, in addition to a varying number of flowers and small bolls. Hence it is apparent that it would require only seven or eight larvae, feeding at the rate of those observed, to destroy nearly all of the fruit on one large plant. 78 NUMBER OF LARViE ON A SINGLE PLANT. As before mentioned, a large number of young larvae may be present in a single ear of corn, but of these never more than one, two, or less frequently three mature. On cotton the number present on each plant is so variable that records of this sort can have no permanent value. The injury corresponds closely to the number of larv«, and estimates are best made b}^ noting the extent of the injury. EELATION TO THE NUMBER OF EGGS LAID. The most important fact to be noted is the wholesale destruction which takes place among the young larvae. At times when nearly one hundred eggs are present on a single ear of corn, and but two larvae can mature, the elimination reaches 98 per cent. On cotton the num- ber of eggs laid per plant is considerably less, and the proportion of larvae to mature so much the greater. PERCENTAGE OF CORN PLANTS INFESTED. In the early part of the season, as has already been pointed out, injury to corn b}" the first generation of larvae is not great, but increases later with the appearance of the second brood. This is shown in the following table, compiled from observations of over 6,500 corn plants made at Paris, Tex. : Table XXVIII. — Percentage of infestation in early corn. Date. May 1 May 18 May 24 May 24 May 24 May 24 May 81 May 81 June 16 July 18 July 20 July 20 July 20 July 21 Sept 28 Age of corn. 18 to 24 inches . 2itp3ifeet 8 feet do 4 to 6 feet, tassellng 3 to 4 feet, tasseling 3 to 5 feet, tasseling Silk and tassel Roasting ears do do Number of Number Number obserya- of of tions. laryse. injuries. 1,000 1 1 650 2 6 1,200 9 16 170 2 2 200 2 2 650 20 20 1,000 35 54 1,000 12 14 100 38 27 80 19 46 100 56 157 98 110 180 116 176 75 75 Per cent of injury. 0.1 0.9 1.25 1.2 LO 3.0 5.4 1.4 27.0 98.0 57.5 56.0 70.0 97.2 100.0 A second table shows the percentage of infestation at a number of other localities during the latter part of the season. It includes data for localities representing practicall}^ the entire cotton belt, showing an average percentage of infestation of Y8.3. The difference between the early and late corn is plainly seen, averaging only 78 per cent for a number of cases of the former and 98 per cent for the latter. Table XXIX. 79 -Percentage of infestation of corn plants at different localities in the cotton belt. Locality. Date of exami- nation. Age of corn. ai o 3 3 It op Locality. Date of exami- nation. 3 1 er 3, 1903, but two survived the winter, while of twenty- five larvae left to pupate at the same time, ten had pupated and sur- vived. The results shown all point to a much greater mortality for this generation, although much seems to depend on local conditions. Bui. 50. Bureau of Entomology, U. S. Dept. of Agriculture. Plate XIV. The Bollworm Moth. Fig. 1, Exit holes of moths, made in escaping from pupal cells in ground; fig. 2, condition of moth immediately after its emergence from soil; tig. 3, bollworm moth with wings expanded; i\g. 4, moth, showing alert position when disturbed; tig. 5, moth at rest on cotton leaf— all figures about twice natural size (original). 50, Bureau of Entomology, U. S. Dept of Agricultu'e. Plate XV. 89 THE ADULT. EMERGENCE. The method of emergence of the moth has been already referred to under the discussion of the pupa. Under normal conditions the pupa, resting at the lower end of its subterranean burrow, splits the pupa case along the median dorsal line of the thorax, and the moth, escap- ing, with still unexpanded wings crawls up to the top of the burrow. Here it must break through the thin wall of earth before reaching the surface of the soil. The moths are very strong and have no trouble in loosening a piece of the thin crust, making an aperture through which the}^ accomplish their exit. The openings through which two moths have emerged are shown on Plate XIV, figure 1. Once out, the moth is perfect, with the exception that the wings are unexpanded (see PI. XIV, tig. 2). After a few minutes the wings have become extended to their full size, and several hours later the moth is able to fly (PI. XIV, figs, tt and 5). If disturbed before the wings are strong enough for flight, the moths are very active and can run about with surprising agility. There is a well-marked tendency among moths toward emerging daring the night and very early morning. About twent\" appear dur- ing these parts of the day, compared to six which come out later. DESCRIPTION OF MOTH. As has been already mentioned in the earlier pages of this bulletin, the boUworm moth is extremely variable in color and markings (see PI. XV). Of the five varieties there enumerated, but two, or possi- bly thre'e, have been met with in Texas. The commonest variety is ochracea Ckll., thirt3^-five in a lot of sixty-five being referable to it, some of them very dark in color and apparently approaching the European fusca kll. The remaining thirty are variety umhrosa Grote. Individuals belonging to these difierent forms have been reared from eggs deposited b}^ the same female, and there can be no doubt that they interbreed with perfect freedom. In ochracea the wings have an ochraceous or reddish tinge which is often quite coppery in very dark moths. The hind wings are always rather strongly marked, the apical band very distinct, and the wing veins usually lined with black. The front wings have in the darker specimens a very distinct transverse dark band, but in lighter indi- viduals this is often scarcely at all evident. The stigmal spot is often absent and never strongly marked. Beneath, the wings have a subapical cross-band, less distinct on the hind wings, and a very distinct sub- lunate spot. 90 The specimens referable to variety umhrosa have a more olivaceous cast and are generally lighter in color. The stigmal spot is nearly always A^er}^ plainly marked and the cross-band of the front wings more or less obsolete. The black apical band of the hind wings is not so pronounced as in oclvracea. Beneath, the markings are about the same, except that the band on the front wing is weaker and the one on the hind wing nearly alwa^'S obsolete. ^lore of the females fall in the ochracea group and more of the males under umhrosa. SIZE OF MOTHS. Measurements of a series of 100 moths gave the following sizes: Table XKXV. — Comparative sizes of boll worm moths. Sex. Wing expanse. Length. 1 Largest. Smallest. Average. Largest. Smallest. Average. Male Millimeters. 47 46 Millimeters. 30 34 MiUimcters. 40.42 Millimeters. 21.9 Millimeters. 13 Millimeters. 18 5 Female 40.86 20.5 14.5 17.89 From this it can be seen that the males are considerably more vari- able in size than the females. In wing expanse they average a little smaller, but in length greater, probably on account of their longer and more slender abdomen. VARIATION AND POSSIBLE CAUSES. In spite of the very apparent variation of the moths, the causes which govern this variation are veiy obscure. Riley" thought that those moths feeding on corn in the Western States were darker and more brightly colored than those of the cotton belt. In our experi- ence in breeding no constant difference was noticed between moths bred from larv^ raised on corn and on cotton under the sanie climatic conditions. - On several occasions it was noticed that moths emerging from pup» which had been placed in cold storage and kept at a low temperature for several days proved to be much darker than any specimens we had seen elsewhere. On the other hand, no especially dark individuals are to be noticed among the moths of the spring brood whose pupiv have been subjected to the gradually lowering temperature of the win- ter months. This shows plainly that the moths may be influenced by temperature, but it is evident that there are other factors concerned also. To ascertain whether there was any relation between the extremely variable color of the larvae and the color of the moths, the color of a "Fourth Report, p. 371. 91 number of ])ollworms was noted and. they were then allowed to pupate separatel}^ After emergence a comparison was made, but it failed to show even the slightest relation. ANATOMY AND SEXUAL DIFFERENCES. It is bej^ond the scope of the present bulletin to consider in detail the anatoni}^ of the boUworm moth. Most important in relation to the economic position of the insect are the organs concerned in feeding and reproduction. In common with other lepidopterous insects, the bollworm moth feeds only on liquids, which are sucked up through the long, flexible proboscis. The latter is about three-fourths as long as the body and when not in use is coiled tightl}^ beneath the head. When feeding it is held out nearly straight, a little curved near the tip, which is applied to the nectaries on the squares when feeding on cotton. Owing to the considerable length of the proboscis it can also reach well within the cotton flowers. The food is drawn into the pro- boscis by means of the large muscular pharynx which acts as a pump. The pharynx connects with the food reservoir, or stomach, by a slender oesophagus. If overfed, as is often the case when food is plenty, the stomach becomes greatly swollen. In the female almost the entire cavity of the abdomen is filled by the ovaries. These organs consist of eight long tubules, four to each side of the bod}^, although owing to their great length they are coiled and folded upon one another many times. Near the tip of the abdo- men they unite to form a single tube through which the eggs pass one by one, as they are laid. The more mature eggs are near the end of ^ach tubule and those still in the process of formation near the farther and more slender tip. The distal portion of the oviduct is hard and chitinized, forming the ovipositor, by means of which the eggs are placed on the plants. When the moth emerges the eggs in the ovaries are small, but develop rapidly during the first day or two, at the end of which time oviposition may begin. From counts made of the eggs present in newly hatched moths, it seems probable that there is a con- tinual formation of new eggs during life. In the male the abdomen is usually narrower than in the female and the sides are more nearly parallel instead of bulging. The tip is also less pointed and more squarely cut off'. The amount of food in the abdomen, however, very often conceals these characters, and others must be relied upon for the separation of the sexes. A second charac- ter which is sometimes available is the presence of certain spines on the front margin of the wing near the base. In the male there is a single long curved spine and in the female two equal smaller ones on each hind wing. They are not always easy to see, however, and are easily broken off. When such is the case it is necessary to resort to dissection to be positive. 92 In the male the o-enitalia are quite peculiar and consist of two fan- like lamellae, thickly fringed with long pale ochraceous hairs, which partiall}^ inclose the claspers (fig. 11). AYhen everted the tufts of yellow hairs are very noticeable, but at rest they are almost completel}^ retracted within the abdomen. Copulation was observ^ed only once, in a small bottle and under ver^^ abnormal condi- tions. The moths were united end to end, as is the usual habit among moths. Many Fig. ii.-Genitaiia of male boihvorm other individuals havc coDulated in the breed- moth (original). . . • . i i i ^ i ^ i mg ]ars m the laboratory, but never when under direct observation. PROPORTIONS OF THE SEXES. A number of observations were made aq^ixiata concerning over 300 moths were collected which bear evidenc^^n the proportions of the sexes. These include records of moths collected in the field and of those bred out in the laboratory. In practically all cases there is a slight preponderance of females in the ratio of 168 females to 120 males. Since the sexes are not readily distinguished externally, that of each specimen was determined by dissection. It might be suggested that the small number of males may be due to their greater agility in eluding capture in the field, but the records from the laborator}^ breeding do not bear out such a conclusion. LENGTH OF LIFE. The life of the moths seems to be determinexi almost entirely by the external conditions after emergence, especially by the supply of available food. During the season some eighty specimens were kept in breeding jars in the laboratoiy and subjected to variable conditions in order to ascertain the length of life. A short summarj^ of the results is given in the table below. Table X^^XYl.-— Average length of life of moths in laboratori/, 1904. Month. Males. Females. With food. Without food. With food. Without food. Mav Days. 7J Days. Si Days. 9i- 16 12 13 18 Hi Days. 5i 3 6 6 12 4i 10 i 4 July August September 14i 11 lOi 4 October Longest life of males, 19 days 12 hours, during September. Longest life of females, 38 days, during September-October. 93 From this it is apparent that the first generation is distinguished by its much shorter life, but with regard to any other generation it is not safe to generalize, except possibly to mention that the longest indi- vidual records were made during the month of September. During September Mr. Girault experimented on a series of twenty moths, each of which was subjected to different conditions of food supply. His results are given below. Table XXXVII. — Effect of food conditions on length of life of moths. Number and sex of moths. Food given. Length of life. Range. Eggs de- posited. Lot. Males. Females. General average. 1 1 female, 3 males All females None Days. 6 Days. 44 64 H 104 30 23f Days. 3 to 6f 44 to 94 64 to 84 7 to 12i 17 to 38 23 2 Water for one day 91 3 4 5 2 males, 2 females 2 males, 2 females 2 males, 2 females Sirup one day Water every day . . Sirup every day . . . 64 94 174 160 10 866 It is at once seen that the length of life increases as we pass down the columns, but that oviposition is not really begun until food is obtained, for it will be noticed that moths given only water laid prac- tically no eggs, although they lived longer than those fed once on sirup. This one feeding, however, sufficed to induce considerable oviposition. The apparent necessity for a continuous food supply is a factor which is very important in relation to the feeding habits of the moths in nature, and will be referred to again in connection with the use of June corn and cowpeas as a trap crop. One point which may be mentioned in passing is the gluttony of the moths when given abundant food. The sirup or sugar solution used in the laboratory had to be given very sparingly, otherwise the moths would gorge themselves, and the subsequent fermentation of the sugar which could not be digested would invariably cause premature death. DAY HABITS. During the daytime the boll worm moth is usuall}^ very quiet, rest- ing immovable in more or less concealed places. During the early part of the summer, corn, which is still in the ''bud," furnishes the favorite hiding place. Here the moths remain well down in the cen- tral cavity or between the still closely curled leaves. The insects rest with the head up and the wings tightly folded down over the back. In this position they often remain during the entire day unless molested or frightened. A jarring of the plant, or any unusual disturbance, however, quickly awakens the resting moth, and hastily leaving 'the plant it flies wildl}^ until it chances upon another, where it quickly insinuates itself into the bud by a series of zigzag backward move- 94 ments. For a few moments afterward, until it has regained its com- posure, the wings are held somewhat apart and vibrate rapidly (see PL XIY, fig. 4). If again disturbed while thus on the alert, the sec- ond flight is usually longer, and the moth will iiy for a hundred feet or more before alighting. When the corn plants grow larger and the tassels and silks are formed, the moths are usually concealed at the base of the leaves close to the stalk. Later in the season the moths most frequently hide during the daytime in cotton fields, patches of cowpeas, or weeds in fence rows. In cotton or cowpeas the leaves afford abundant shelter and the moths are usually to be found resting on the upper side of one leaf in the shadow of another. (See PI. XIV, fig. 5.) More rarely they may be observed hanging to the flowers or squares. When disturbed, they dart down along the rows or between the plants, losing no time in choosing a second hiding place. They are so quick in getting concealed that they sometimes disappear as if b}- magic, especialh' where the foliage is dense. It is only rarely that moths are to be seen feeding or ovipositing in bright daylight. But at periods when food is scarce a number of moths are usualh' active during the day. The}' have been seen feed- ing on the following plants in the daytime: Alfalfa flowers; cotton: cowpeas; Eupatoriuin serotinurn^ a common roadside weed; wild sun- flowers; and Solanum rostratum^ another roadside weed. On corn they have been observed to feed on the sweet secretion of Aphis maid is Fitch and Dicranoptropis {Deljyha.j^ ma id is Ashm.. and on drops of rain and dewdrops upon grass. Cockerell records them feeding on plum blossoms at Mesilla Park, N. Mex., early in April. NIGHT HABITS. At about 4 o'clock in the afternoon, when the heat of the day has passed, the period of activity for the moths begins, and continues until well into the night. Sometimes, however, activity does not begin until much latei*. often not until half-past 6 or T oVlock. It is quite noticeable that during periods when food is scarce, owing to drought or other causes, the moths are out earlier than at other times. In fact, their entire attention is given to feeding at first, after which the females begin to alternate this with periods of oviposition, as has been described in the preceding pages. The males no doubt continue to feed until the females are well started on their work of egg-laying, but after oviposition has become quite general males on the wing become scarce. During the process of feeding the moths fly in much the same way as when ovipositing. On cotton only the squares and flowers are visited, no notice being taken of the nectaries on the uuder surface of the leaves. Alighting on a square, the moths seek out the nectaries, and if nectar is present each bract is usually visited in succession. If 95 the nocmiy is dry, however, no time is wasted before seeking another. In feeding on the flowers, the proboscis is inserted into the corolla, usually near the base between the petals. In such situations the moths are no doubt searching for moisture rather than hone3^ It is rnrefor tlie moth to visit more than three or four parts of one plant before flj'ing awa}^, although quite often it will return to a plant previously fed upon. During the course of an hour a moderately active moth, alternately feeding, resting, and ovipositing, will cover several acres of ground, visiting anywhere from one hundred to one hundred and fift}^ plants. Early in the evening, when the moths are first on the wing their flight is ver}^ swift, but gradually slows down. As a general rule they are quicker and shyer on the clear evenings following hot, dry days, and less active in cloudy or rainy weather. This does not indicate a decrease in ovi position in rainy weather, as might appear at first sight, for rapid flight does not determine active oviposition. Night feeding is confined almost entirely to corn and cowpeas early in the season and to cotton and cowpeas later. Corn offers no primary attraction in the way of food, but they feed upon the moisture present and upon the honey dew of aphids. The honey secreted by the glands on the fruit stalks of the cowpea draws them to the plants, although, as before noted, oviposition is not common on them. Cotton must also offer a great attraction by supplying food, aside from any other con- sideration. At the time cotton is squaring and blooming extensively other food is scarce, and for this reason alone the moths may be induced to turn their attention to it. ATTRACTION BY LIGHTS. Although the uselessness of trying to capture the mcths b}^ means of trap lanterns has been pointed out again and again, the method was tested very thoroughly during the year. Several tin traps were con- structed like the one shown on Plate XXV, figure 1, somewhat similar to a model described by Gillette, with the addition of a patent oil -torch lamp and a series of tin reffectors above. The lower portion was well stocked with cyanide, and the lamps put in operation in corn and cotton fields at various dates during the season. The first night, Ma}^ 2, a single male Heliothis was captured, but the traps yielded no further moths in fifteen future settings, and were abandoned until later in the season. During the early part of September the traps were again resorted to with less discouraging results, 8 males and 2 females being caught in four settings. At this time, however, moths were present in countless numbers in the patches of corn and cowpeas where the traps were placed. .Aside from these captures, 3 single female speci- mens were collected at different times flying to the lights in windows 22051— No. 50—05 7 96 of dwellings. All observations serve to show that the attractino- of the moths to ordinary oil lights is an utterl}^ hopeless task. Brilliant arc lights are an attraction, however, and during the early part of August, at Paris, along the business street, within a space of four blocks, sometimes as man}^ as fort}" or fift}" of the moths could be counted near the lights. Saloons and fruit stands offered especial inducements, no doubt on account of the odors of fermenting fruit, etc. Professor Morgan^ mentions a similar instance: Last season, in collecting by an electric light on the university campus, under which the crab grass had been permitted to grow and go to seed, great numbers of a hght- colored moth were seen to be perched upon the heads and stems of the crab grass, from 20 to 50 feet from the arc light. Upon collecting a few they were found to be specimens of the bollworm moth. * * * During the entire evening not a single specimen was seen to fly up to the light, but all remained at some distance from it. Chittenden^ also states that during the latter part of September, 1900, bollworm moths formed about 16 per cent of the total number of moths attracted to the electric street lights at AVashington, D. C We have had experiences similar to the one noted by Professor Morgan. During early September it was observed that the corn plants for a distance of 50 feet surrounding the lantern traps were well supplied with hiding moths the day after the traps had been in opera- tion, although hardl}" any moths had been caught in the trap itself. ATTKACTIOX BY POISONED, SWEETS. All attempts to trap the bollworm moths in this way have yielded absolutely negative results. During the latter part of the summer quite a number of experiments were tried with different combinations in varying proportions of New Orleans molasses, sorghum, vinegar, and beer; some of them poisoned by potassium cj^anide or cobalt, and others not. The solutions were placed in flat pans elevated on pedes- tals from li to 1^ feet high (see PL XXV, fig. 2). None of them attracted more_than an occasional stray moth, although they were placed in fields of corn and cowpeas where the moths were extremely abundant. At other times during August and September a number of water- melons were cut open in the fields and left to ferment and deca}'. At no time did these attract any bollworm moths, although the cotton moth Alalama (AJetia) argillacta was observed to feed on them to a slight extent. Experiments were also tried bv spraying the cowpea vines with a mixture of sorghum, vinegar, and beer poisoned with cobalt. This "Bnl. La. Expt. Sta., 2 ser., 48, p. 155. & Bui. Xo. 30, n. s. , Div. Ent. , U. S. Dept. Agric. , p. 86. 97 injured the vines to a slight extent, but no moths could be seen feeding on it, nor could dead ones be discovered in the vicinity. From these tests it is safe to conclude that the use of poisoned sweets can never be a success in trapping the moths. LENGTH OF LIFE CYCLE. The duration of the embr3^onic, larval, and pupal instars has already been discussed, and the length of the life cycle is easily had by com- bining these records made on the same individuals. This has been done in the following table, which gives the duration of a series of life C3^cles during the different parts of the season of 1904, at Paris, Tex. Table XXXVIII.— Lm^^/Zi of life cycle at Paris, Tex., 1904- Eggs laid. Eggs hatched. Larvae pupated. Moth emerged. Life cycle. Sum of effective tempera- tures. April 2 April 10 Mays May 31 Days. 59 52 53 41 32 30 36 48 35 63 ° F. 1,485 1,420 1,601 April 12 \pril 19 May 16 June 3 April 29 Mays June 3 June 20 July 6 July 9 July 27 August 16 1,597 July 16 July 19 August 2 August 17 1 237 Augusts Do Augusts do August 22. 1,186 August 25 Septem^ber 11 1,573 August 28 August 31 September 8 September 16 . . . October 15 1,319 September 5 September V6 October 10 1,138 October 10 November 15 1,417 At Victoria, the previous season, some life-cycle records were made early in the year, averaging as follows: Table XXXIX. — Length of life cycle at Victoria, Tex., 1903. Eggs laid. Eggs hatched. Larvae pupated. Moth emerged. Life cycle. April 14 April 18 Mav 16 June 2 Days. 49 May 3 Mav 6 May 28 June 14 42 The influence of the seasonal variation in temperature is very plainly to be seen, the length of the life cj^cle decreasing from fifty-nine days earh^ in the spring to only thirty da3^s during the hottest part of the summer. It will be noted that the sums of effective temperatures for the dif- ferent records vary from 1,186^ to 1,601°, with an average of 1,417° F. This latter may, no doubt, be accepted as very near the normal at moderate summer temperatures. 98 GENERATIONS OF THE BOLLWORM. It has long been stated that the number of generations annually of the bollworm in the cotton belt varies from about four in the more north- ern part to six or even seven in the extreme southern part. It does not appear, however, that this statement is based on actual breeding- experiments, but rather on the result of field observations. Conclu- sions regarding this matter based solely on field observations are some- what unsatisfactory, as they are apt to be spread over a wide terri- tory and to be complicated by variations in climate and environment, as well as by the fact that the broods are confused on account of the long period of emergence of the moths in the spring. This causes the period of spring oviposition to be lengthened, so that long after the majority of bollworms are well grown others are still in the egg stage. These supplementary generations persist thi'oughout the sea- son, and, although numerically unimportant, are apt to lead to con- fusion regarding the principal ones. As the question of the number of generations is one of importance, effort has been made to secure as much data on the subject, confirma- tory or otherwise, as possible. In 1903 attempt was made to secure information on this point by ascertaining, for different localities of the cotton belt, the periods of maximum oviposition of the moths during the season. It was thought that these egg records for the season, when plotted, would indicate approximately the periods of greatest abundance of the moths, thus marking the respective genera- tions. Theoretically such data would undoubtedly furnish the infor- mation desired, but in practice many factors were found to enter into the making of trustworthy records, such as variations in the age of the corn used in making counts, the character of the weather, etc. , so that little may be safely inferred from the egg records obtained. It is proper, however, that acknowledgment be here made of the assist- ance received in_this work from Dr. W. E. Shaw and Mr. A. C. Lewis, of the Oklahoma Agricultural Experiment Station: Mr. Mark Eiegel. Pomona. Ga.: Prof. H. A. Gossard, of the Florida Agricultural Experiment Station, and the late Mr. G. H. Harris, of this Department. The records made by Mr. Eiegel and by Mr. Harris are presented under the caption •'Oviposition on corn" (p. 42), to which the reader is referred. At the beginning of the season of 1904 it was decided to carry a series of consecutive generations through the entire summer under natural field conditions. This work was conducted in a large field cage placed in a lot adjoining the laboratory at Paris. Tex. The cage consisted of a solid framework 15 feet long. 12 feet wide, and 8 feet high, covered with ordinary black window screen and provided with a small door on the side. (See PL XVII.) In it were planted two lots 99 of corn, March 2 and May 5, and two lots of cotton, April 29 and Jal}^ 20. With this arrangement the corn could be cut when it was no longer needed and the entire space given up to cotton later in the season. The screen prevented the escape of any moths or larv«, but left them subjected to very nearly normal weather conditions. It also served to keep out predaceous enemies and many of the larger para- sites, thus providing against possible depletion from these sources, and at the same time preventing accesa to the plants by moths outside of the cage. The cage was stocked with a large number of eggs on May 9, and the forthcoming generation of bollworms was traced in its develop- ment. The following table, compiled from dail}^ records, summarizes veiy briefly the average growth of each generation: Table XL. — Generations of bollworms, Paris, Tex., 1904. [Dates are for Paris, Tex., latitude about 33° 45'.] Brood. Moths out. Eggs de- posited. Larvae hatched. Larvae one- fourth grown. Larvae one-half grown. Larvae three- fourths grown. Larvae full grown. Pupae. 1 (50 days) - 2 (35 days). 3 (31 days). 4 (48 days). 5 May 6 June 25 Aug. 3 Sept. 3 Oct. 22 May 9 June 27 Aug. 5 Sept. 10 May 14 June 30 Aug. 7 Sept. 13 May 21 July 7 Aug. 10 Sept. 18 May 26 July 11 Aug. 14 Sept. 23 June 1 July 14 Aug. 17 Sept. 25 June 5 July 16 Aug. 20 Sept. 27 June 8. Julv 18. Aug. 22. Oct. 2; in hiberna- tion. The first record of injury to cotton was on July 6, due to young larvae of the second brood. The damage rapidly increased until, on July 12, some sixty squares and a few yoang bolls had been destroj^ed. A few da3^s later, after the larvae from corn had pupated, the corn was removed and late cotton planted in its place. The injury of the two following generations was confined entirely to the early planted cotton, as the late cotton was not squaring in time to be subject to attack. The fourth brood was represented by but few individuals, due possibly to the fact that the greater number of the pupae from the third genera- tion had remained in the soil to hibernate. This conclusion was strengthened by the appearance of a moth on September 22, evidently a belated specimen of the generation due to emerge on September 3. The few larvae pupating early in October also passed into hibernation with the pupae of the previous generation still in the soil. LABORATORY EXPERIMENTS. In working out the life cycle of the bollworm in the laboratory at ditferent times during the summer it was found by Mr. Girault that the growth and transformations undergone by individuals indoors closely coincided with the data obtained from the field work. The two sets of experiments were run along together, and the agreement 100 between the two was most gratifvino-. His laboratory records are presented in connection with the lengths of the life cycle on page 97. From observations and breeding experiments there can be no doubt that there are four principal generations each season in northern Texas. Besides these there is a fifth, which is of very small extent, and appears too late to damage cotton to an appreciable extent. At Victoria, Tex., about 3'20 miles south of Paris and in about the latitude of Leesburg, Fla. , the number of annual generations, from all available data, appears to be about six. On the basis of four broods at Paris, six broods at Victoria could reasonably be expected by reason of its more southern location and consequent longer breeding season. In 1903. and also in 1904, moths were out and ovipositing freely by the 1st of April, and in the fall of the former year, essentially normal, larva? had largely entered the soil for hibernation as pupa? by the middle of November. There would thus be a breeding period of 234 dsLvs, time sufficient for six broods at the average time of 37 days for each generation and a few days over, indicating a partial seventh gen eration. which actually occurs by the emergence of a few moths from late fall pup^e. It is considered very probable that in the vicmity of Brownsville, Tex., and extreme southern Florida there may be seven full genera- tions each year. In the vicinit}' of Miami, Fla:, according to Prof. P. H. Rolfs, complete hibernation probably does not occur, as he has observed bollworm larv^ during the winter months feeding on toma- toes, naturally necessitating more or less activity on the part of the moths during this period. However, according to the gentleman men- tioned, the larva? do not appear in force until along toward May, so it would appear that the bulk of the insects hibernate as pup^e. It is therefore seen that there may be from four to six annual gen- erations of the bollworm for the cotton belt. It will be remembered that this number ao-rees exactlv with the estimated numbers of gen- erations by other workers. For the extreme southern parts of the United Stated complete hibernation may or may not occur, depending on local conditions and the character of the season. The number of annual generations of the bollworm has been indi- cated with more or less certaintv for several localities in the central and more northern States. For northern Delaware. Professor Sanderson states:" In this latitude the moths appear during May and deposit their eggs on com and other food plants, such as beans. * * * The second brood of moths appears in northern Delaware about the middle of July, and a third brood during the first two weeks of September. This would indiciite three generations of larv^, the third pupating for the winter. (I Ins :eets injurious to staple crops, 1902, p. 153! 1 101 In New eTersey, according to Dr. J. B. Smith/*^ moths appear early in May and long before there is any corn for them to oviposit on. Eggs are therefore deposited on a great variety of plants, peas and tomatoes being favorites. Toward the end of May early corn is well up, and some eggs are deposited on these plants, the larvae eating in the buds and often boring into the stems. B}^ the middle and toward the end of June the earliest larva? are full-grown on peas and are ready for pupation. By the middle of July most of the larvse on tomatoes in the southern part of the State are full grown and before the end of the month have disappeared. At this time, before the middle of July, moths from the earliest larvae have appeared and have laid their eggs on corn. Young larvae are found on the small ears before July 20, and by the middle of August have attained their growth and have changed to pupae. The pupal stage at this time lasts only about a week and young larvae of a third brood appear before the 1st of September. There may thus be three broods of this insect in the southern part of the State. North of the Sandy Plain two broods are normal and a third is very exceptional. Concerning the number of generations in Ohio, Webster and Mally state :^ While there may be three broods in southern Ohio, in the northern part of the State there are probably but two. These broods appear to be interminably mixed before fall, and so late as November partly grown larvae may be found in the ears of corn. Three generations are indicated for Illinois by Mr. C. A. Hart,^ in spring boring into tomatoes, in summer eating unfolding corn, and later feeding in the cavity near the tip of the growing ear. According to Professor Osborn/^ in Iowa — There are probably two broods in this latitude. The larvpe of the first brood appear in the early part of the season and feed on various infants, so that they do not attract attention, while the second brood of larvae attacks the corn at the time the ears are forming or soon after in the manner already described. The second brood of larvae pupate and produce moths in the latter part of the summer, and farther south at least it is stated that a third brood of larvae occurs from which pupae are produced to pass the winter. A statement by Professor Riley ^ in the Fourth Report is of interest in this connection: If, as we have stated, there are 3 normal broods a year as far north as New Jersey, Ohio, and northern Illinois, then in South Carolina, north Georgia, Tennessee, and Arkansas there are probably 4 broods, and as many as 6 in south Texas and Florida. «Ann. Eep. N. J. Exp. Station, 1892, p. 442. &Bull. 96, Ohio Agric. Exp. Sta., p. 17. cSyn. Ins. Coll. for 111. High Schools, 1903, p. 38. ^Bull. 24, Iowa Agric. Exp. Sta., p. 1004. ^Fourth Kept. U. S. Ent. Com., p. 373. 102 In Massachusetts, according to Lounsbuiy^ — The caterpillars pupate beneath the surface of the ground, and those of the second brood pass the winter in the pupal stage. Concerning the generations of this insect in Ontario, Prof. ^y. Lochhead states:^ Observations point to the view that the corn worm is single-brooded with us, but it may be double-brooded in some of the southern localities. In order to ascertain, if possible, what relation the total effective temperature during the breeding season has to the number of genera- tions of the bollworm in dift'erent localities, the following table was constructed. It is based on Weather Bureau temperature records for various localities and the effective temperature determinations derived from laboratory experiments at Paris, Tex. In each case it is assumed that the average effective temperature required for a single life cycle is l,^!!'^ F. and that activit}^ in the spring does not begin until the monthly mean has reached from 62^ to 65°, ceasing in the fall at the same temperature. Such assumptions seem justified b}- the observa- tions presented in the earlier part of this bulletin. Table XLI. — Effective temperatures, calculated and reported member of generations of bollworm for different parts of United States. Locality, Season of activity. Total ef- fective tempera- ture during season of activity. Calculated number of genera- tions. Reported number of generations. Jupiter, Fla Victoria, Tex Paris, Tex Baltimore, Md . . . Indianapolis, Ind Boston, Mass Oswego, N.Y All vear Mar. 1-Nov. SO . Apr. 1-Oct. 31 . . May 1-Sept. 30 . do Junel-Sept.30. Junel-Aug.30. 11,058 8,876 6,802 4,362 4,178 2,967 2, 217 7.9 6.2 4.2 3.0 2.9 2.1 1.5 4. 3 (Delaware). 2-3 (Ohio>. 2 (Mass). ' 1-2 (Ontario). SEASONAL HISTORY. APPEARANCE OF SPRING MOTHS. The earliest records of moths in various parts of Texas during the spring of 1904 have been already referred to in connection with ovipo- sition, where the dates of finding the first eggs are given. While these dates probably represent very nearl}^ the first emergence of moths, they do not show the general appearance, which is much later. Thus, the first moth to emerge at Victoria from a lot of overwintered pupte appeared March 20, and the last April 18, nearl}^ a month later, while at Paris the moths first appeared during April, the greater portion not until the middle of Ma}^, and the last not until well on toward the «Bul. 28, Mass. Agric. Exp. Sta. (Hatch), p. 16. &Eept. Ent. Soc. Ontario, 1901, p. 75. 103 beginning of elune. The later broods also showed long periods of emergence, as indicated below. Table XLII. — Dates of emergence of moths. Generation. Paris, 1904. Calvert, 1903. April 3 to May 30 April 5 to June 5. Second June 20 to Jiilv 10 June 20 to July 5. Third July 18 to August 22 . . . . July 20 to August 20. Fourth August 25 to September 25 October 1 to October 5 August 25 to September 20. Fifth (?) It must be anderstood that these dates are the result of general impressions and observations made on oviposition, larvse, etc., and can not be put forth as exact data. It was thought at first that there might be some ver}^ definite relation between the sum of effective temperatures to which the pupae had been subjected during the winter and spring, and the dates of spring emer- gence; but calculations based on Weather Bureau temperature records do not show this. The dates of appearance in the different parts of the State are much closer together than such figures would indicate. It seems, rather, that spring emergence must be determined by the temperature of the soil during a smaller number of consecutive warm days. Our Texas records tend to show that moths begin to come out in the spring about the time that the mean monthly temperature reaches 63° to 65° F. PROGRESS OF INFESTATION BY GENERATIONS. Once the spring moths are out they soon begin to oviposit, princi- pally on young field corn, it being the most general food plant for the first generation of larvae. These larvae mature in the corn, pupate, and the moths of the second generation emerge in time to oviposit upon the tassels and young ears of the corn in the same fields which supplied food for the first generation. The resulting larvae mature, most of them pupating just as the ears commence to harden. Two weeks later, when the third generation of moths appears, the early corn is well hardened and unfit for oviposition. On this account the near-by cotton fields are chosen by the moths and the eggs of this generation are placed on the cotton plants. The larvae of this gen- eration also attack late corn if it is accessible, much preferring it to cotton. This is the generation of boll worms which does the greater part of the injury to cotton. Alfalfa is also considerably attacked by this generation, even if it is growing close to corn and cotton. The fourth generation, appearing early in September, attacks espe- cially late cotton, which is still green and bearing squares and 3^oung bolls. Late corn and alfalfa also suffer to a considerable extent from this generation. 104 INCREASE IN NUMBERS DURING THE SEASON. The comparative difference in numbers between the moths of the tirst and second generations can be determined in a general wa}" from the tables on oviposition already given, since corn receives practically all the eggs of these generations. It is seen that the second genera- tion la3\s about forty times as man}" eggs as the first, and assuming, as seems to be the case, that these moths la}^ individually many more than the spring moths, it ma}^ be said that for every spring moth there are thirt}" moths in the second generation. This agrees well with observations made in the field. Fifteen, or one-half of these moths being females, lay pj'obabh^ about 1,100 eggs each. Of these onl}^ about one larva in fifteen matures, or about fifteen times as man}" as there were moths in the second gener- ation. This number is about 1,100. Half of these, emerging as female moths of the next generation, will lay in all some 605,000 eggs. Observations show that about one in ten of these eggs, or 60,500, will give rise to destructive larvte. Allowing for the probable decimation of 65 per cent by the para- sites and predaceous enemies of the growing bollworms, there still remain some 21,175 larvse of the third generation to mature on cotton for every moth emerging the previous spring. This shows the great importance of destroying the larvae of the first generation, as every one of them will average 683 descendants in the late summer capable of completely ruining 78 large cotton plants. DO THE ADULTS HIBERNATE? The hibernation of the adult bollworm moth has always been an open question, and in order to obtain all possible data bearing evi- dence on this point, Mr. Girault made a trip into southern Texas dur- ing the early part of February, 1901, with the especial purpose of searching for hibernating individuals. At Corpus Christi and Victoria a number of days were spent in examining places where hibernating- moths would be apt to hide. These included w^oodlands surrounding fields, rubbish in corn and cotton fields, barns, outhouses, etc., but not a single bollworm moth was discovered. Fresh growing plants and garden vegetables were searched also and sugaring tried, but with the same result. Mr. J. D. Mitchell, of Victoria, believed that he had frequently seen hibernating specimens, but in two cases at least it was found that he had been misled by the close resemblance in color and general appear- ance of Helhpkila {Leuccmia) unipivncta Haw. and Bemigia repanda Fab., to the bollworm moth. All laboratory experiments bearing on this point, also tend to show that while life may be prolonged by subjection to low temperatures, no Bui. 50, Bureau of En-tornolop'y, U. S. Dept. of Agriculture. Plate XVI. Insects Sometimes Mistaken for the Bollworm. Fig. 1, Cotton square attacked by caterpillar of Cnli/cnpls cccrops; fig. 2, larva of Prodaua ornitho- galli, injurious to cotton square; fig. 3, larger larva of same species, boring into a large boll; fig. 4, adult moths of tlie same— all figures enlarged about one-lialf (original). !ul. 50, Bureau of Entomology, U. S. Dept. of Agriculture. Plate XVII. Fig. 1.— Large Breeding Cage. Used at the Paris laboratory iu deterniiiiiiig gent-rations of tlie bollworm. Planted to corn (original ). Fig. 2.— Same, Planted to Cotton Later in the Season (Original). Bui. 50, Bureau of Entomology, U. S. Dept. of Agriculture. Plate XVIII, Predaceous Enemies of the Bollworm. Fig. 1, Polistes anmdaris, a wasp predator^' on the bollworm, and its nest, two-thirds natural size; tig. 2, Lycosa riparia with captured bollworm moth, natural size; fig. 3, iJcrmin/in (nn/iistipeimis, a robber fly predatory on the bollworm moth, enlarged one-half; fig. 4, jilnllniiliom orcina, another robber fly which destroys moths, enlarged one-half; fig. 5, Metapudi/is j'< moratus, cf $, known to attack bollworms, enlarged one-half (original). 105 moths live long enough thus to enable them to pass the entire winter in hibernation. With regard to the moths in the large field breeding cages some evi- dence was secured. Although scattering moths continued to emerge during September and October, all died within a short time, and none showed the slightest inclination to hibernate. This is, of course, negative evidence, but enough to permit of the conclusion that hibernation of the moths in Texas is most unlikely, and that if it does occur an extremel}^ small number must hibernate in this way compared with the numbers of the insect which pass the win- ter in the pupal stage. On the other hand, it is quite probable that in southern Florida the moths remain more or less active throughout the entire year, since the temperature there ordinaril^^ does not fall below 65^^ F. in the winter. This is not true hibernation, however. INSECTS SOMETIMES MISTAKEN FOR THE BOLLWORM. Unlike the Mexican boll weevil, the bollworm has been for so long a well known cotton pest that it is rather unusual for planters to con- fuse it with any other insect affecting cotton. There are, however, two other caterpillars which injure cotton in exactly the same manner as the bollworm, so that unless the insects themselves are in evidence it is not possible to tell their work from that of the genuine bollworm. . Fortunately neither of them is ever present in large numbers, and the damage which they cause is imma- terial compared to that done by the bollworm. The first of these is the cotton cutworm, Prodenia ornitJiogalli Guen. (see PI. XVI, figs. 2, 3, 4), which sometimes feeds on the squares, flowers, and bolls. It bores into them in exactly the same way as the bollworm. It is also a very general feeder, frequently occurring on the spiny pigweed growing adjacent to cotton. Larv« were seen on cotton only during July and the early part of August, disappearing after that date. The second is the larva of a butterfly, Calycopis cecrops Fab., bet- ter known under the name of Thecla poeas Hbn. The adult oviposits on the involucre surrounding the squares, and the resulting larvte eat out the contents of the squares, making a large hole in the side similar to that left b}^ a good-sized bollworm (see PI. XVI, fig. 1). This caterpillar also is most abundant early in the season, generally during the latter half of June and the first two weeks in July. No doubt it would be much more destructive were it not for the frequency with which parasites prey upon it. Out of eight or ten larvie brought into the laboratory at various times every one proved to be parasitized. 106 As has been mentioned alread}^ the work of the young bollworni is often termed ''sharpshooter work," and tlie ver}^ young larva? referred to as sharpshooters, thus confusing them with the true sharpshooter, Hamalodisca trlguetra Fab., which feeds b}^ puncturing the stems of the cotton plant (see fig. 12). When greatly pressed for food, the cotton-leaf caterpillar, AJalama {Aletia) argiUacea^ sometimes injures small bolls in a way which might possibly be mistaken for bollworm injury. Bolls thus injured alwaN^s have the involucre eaten away first, and then large irregular cavities are eaten out along the sides. Often several caterpillars take part in injuring the same boll. In the identification of the bollworm moth by planters frequent mis- takes are made. The moths most usuallv confused are the arm}' worm, Heliophila {Leuccmia) uni- jmncta, and the cotton moth, Alabama, just referred to above. It is very unfortunate that such confusion exists, since on account of it the moths of the third brood are not noticed when they begin to oviposit on cotton. To know the dates of maximum oviposition is impor- tant, since all attempts at poi- soning the 3'oung larva? must be made with a knowledge of the time when they will be hatching from the eggs. On corn, however, several species injure the plant in a way somewhat similar to the bollworm, both by feeding in the tender "bud'' and in the ear. In the South the larva of the fall army worm, Laj)lnjgma fTiigijJerda S. & A., is often found during the spring of the ^^ear eating out the bud of field corn, and from its resemblance to the lighter- colored bollworms is usually mistaken for that insect. During the summer late-planted June or other corn is usuall}' badly infested by the fall army worm, and the offender is almost universally considered to be the bollworm. The former insect occasionally bores into the soft milky ears of corn, either from the tip end, or from the base or side. In the more northern States, and occasionally south, the larva of Papaipeina nitela Guen. eats into the bud of young field corn, boring- Fig. 12.— "Sharpshooter," HomaJodisca triquetra (after Rilev and Howard). 107 down into the wtem, and its work is thus likely to be confused with that of the bollworm. Various cutworms at times attack corn in a way which, in the absence of the culprit, would suggest bollworm injury. PREDACEOUS ENEMIES. PREDACEOUS ENEMIES OF THE EGGS AND YOUNG LARV^. The exposed position in which the eggs are placed lays them open to attack by numerous insect enemies, although the fact that the}^ are scattered promiscuously about on the plants no doubt prevents much wholesale destruction which might otherwise take place. The nymphs and adults of Trijpldejys insidiosus Say (see fig. 13) have been repeatedly observed feeding on bollworm eggs and on very small larvae. This little heteropteron is especially abundant in fresh corn silk, and is often seen fre- quenting cotton plants also. Although in a number of instances noticed in the laboratory they seem loath to attack living larvae, they are sometimes to be fig. is.—Triphieps insicuosus: aduit seen in the field with newly hatched and nymph (original). larvae impaled on their slender beaks. Their principal value lies, however, in the large number of eggs which they destroy. A special count was made at Sulphur Springs, Tex., on August 16, 1901, to determine the probable proportion of eggs destroyed b}^ this agency. The eggs on ten different silking ears were examined, and on an aver- age 55 per cent of the eggs were found to be shriveled. It is probable that most of these shriveled eggs had been punctured and their con- tents sucked out by the Triphleps, which were numerous on the silks at that time. This is no doubt an exceptional case, but it serves to show of what great value the Triphleps may be under favorable conditions. Larvae of the coccinellid beetle Megilla maculata DeG. , were observed on several occasions feeding upon bollworm eggs, and they probably do so ver}^ generally, especially on corn, where Megilla is quite abun- dant. In feeding they often tear the Qgg from its support, eat out the contents, and cast aside the empty shell. The ladybird larvae can not cope with bollworms which are their equal in size, but no doubt often feed upon those newly hatched if eggs are scarce. While no other species were observed to feed on bollworm eggs or larvae, it is not improbable that others do. Figure 11 illustrates a common form in cotton fields, feeding on^plant lice and possibly on other insects. 108 Ashmead" records an ant, Monomorkun carhonariurn Smith, as feed- ing on the l^oll worm, and the same ant was again seen at Victoria feeding on emlnyo bollworms extracted from their shells. The same observer found Sole)iopsis geminata Fab. eating boUworm eggs, and we have seen A^:/" Fig. 14. — Hippodaniia convergcns: adult, larva, and pupa (from Chittenden). a second, smaller species of the genus {Solenopsis texcma Em.) very common on young cotton plants and apparently destro3nng newly hatched larvae which had been placed there pur- poselv. Other ants have been observed under more or less suspicious circumstances which point to them as possible bollworm destroyers, although, on the whole, their value in an economic way is very doubtful. Following is a list of the ants in the probable order of their importance: 1. Solenopsis geminata Fab. 2. Cremastog aster lineolata Say. 3. Solenopsis texana Emery. 4. Monomorium carhonariurn Smith. 5. Dorymyrmex pyramicus Smith. 6. ForeUus maccooki Emery. A worker belonging to the first of these species is shown in figure 15. The larvee of certain species of Chr3^sopa (fig. 16) are often abun- dant on corn and cotton plants, feeding on both the young larvae and the egg^. The eggs of the chrysopa are laid on the cotton plants quite frequently and are sometimes mistaken for the eggs of the boll- worm. They are deposited in an entirel}^ different manner, however (see fig. 16, (/), being attached by a long flexible stalk and not laid fiat upon the plant, as is the case with those of the bollworm. On two occasions, once at Clarksville, Tex. , and again at Victoria, during May, 1903, a small reddish mite was seen feeding on freshly laid bollworm eggs. Fig. 15.— Soleiiopsis gemi- nata (after McCook)^ « In Insect Life, 1894. 109 PREDACEOUS ENEMIES OF THE LARGER LARV^ AND MOTHS. Foremost amon^ the predaceous enemies of the bollworm are several species of Polistes. There are three species which frequent the cotton fields: P. annidarw Linn., a large black form with black wings and a single black cross band of yellow near the base of the abdomen; P. ruhiginosus Lepel., a large, slightl}^ stouter, rust-red species, with dark wings; and P. texanus Cress., a smaller, more slender, and variably striped form with paler wings. Polistes annularis builds large nests, often nearly a foot in diameter (see PI. XVIII, fig. 1), and sometimes containing upward of a thousand cells; the others construct smaller nests, generall}^ from 3 to 6 inches in diameter, and containing a pro- portionatel}^ smaller number of cells. Fig. 16.—Chrysopa ocidata: adults, eggs, larvse, and cocoon (from Marlatt). The adults of Polistes pass the winter hibernating in protected places near the cotton fields, and early in the spring each female starts a new nest. The larvse of the wasps are fed upon chewed-up bits of caterpillars captured by the wasps. By the middle of the summer, when the bollworm is attacking cotton, their colonies are well grown and vast numbers ' of the wasps are circulating through the cotton fields in their tireless search for caterpillars. Once a bollworm is discovered, the Polistes seizes it just back of the head with her mandibles and in the case of a large worm usually stings it to death. Then, after a preliminary chewing, she carries it off to the nest, where it is distributed and fed to the wasp grubs. All cotton fields are well supplied with the wasps. 110 which build their nests in nearby trees or sheds close to their foraging ground. The prickly branches of the osage orange trees, which often grow along the roadsides, are favorite locations for them. It is difficult to estimate the amount of good done b}^ the wasps, but there can be no doubt that it is ver}^ considerable, probably exceed- ing that done by an}^ other of the predaceous enemies. They are at work from daylight until dark, constantl}^ in search of larvae, and the vast numbers foraging in the cotton fields must necessarily destroy the bollworm almost exclusively. The most abundant and undoubt- edly the most beneficial form is Polistes anmdaris. On one occasion a nest of P. annularis at Pittsburg, Tex., was watched by Mr. Bishopp to ascertain the number of bollworms brought in b}" the wasps. The nest was of medium size, consisting of about twenty-five or thirty cells, with pupae, 200 to 250 larvae, and 30 adults present at one time on the nest. During a period of half an hour eight bollworms and one Geometrid caterpillar were brought in by the wasps and fed to their larvae and to other adults. From these facts it is apparent that the present custom of wantonly destroying the nests of these wasps where they occur in or about cot- ton fields is a bad practice and should be disparaged strongly, so that the wasps may have full swaj" in their beneficial work. The wasps also frequent corn fields, and we have often watched them searching for bollworms w^here we have passed along the rows stripping the shucks from the ears and removing the larvae. Several times they were seen to pounce upon larvae left intentionally upon the ears. In cotton fields, where the larvae are most exposed, the wasps are continually in search for them, feeding by turns on the honey secreted by the nectaries on the squares. Forming another group of predaceous enemies are a few large species of robber flies (Asilidae) which frequent the fields. These flies do not destroy the larvae, but confine their attacks solely to the moths. The only species actually seen with a bollworm moth was the large brown . Deromyia angustipennis Loew, but judging from their observed habits the numerous Erax and Mallophora (PI. XVIII, figs. 3 and tt) must undoubtedh^ catch the moths also. On one occasion a specimen of Deromyia was brought into the laboratory and tested as to its feeding- habits. A bollworm moth was introduced into the jar with the fl}-, and although the latter was much hampered by lack of freedom, scarcely two seconds elapsed before it had secured the fluttering moth firml}^ between its legs and was inserting its sword-like proboscis into the moth's hodij. The following is a list of the more common robber flies which were observed in the cotton fields: Erax lateralis Macq. Deromyia umbrinus Loew. Erax bastardii Macq. Dizonias bicinctus Loew. Mallophora orcina Wied. Sderopogon latipennis Loew, Deromyia angustipennis Loew. Ill Another enemy of some interest, although probably of small impor- tance, is the wasp Eumenes hollii Cress. On one occasion a nest of this species was found by Mr. Bishopp on a cotton leaf at Ladonia, Tex. The nests are constructed of mud and stored with caterpillars as food for the young wasp grub, which matures inside the clay nest. There can hardly be any reasonable doubt that the wasp building in this situation made use of bollworms for storing its nest. Quite a number of spiders were observed at various times destroying the bollworm in its different stages. In three of these cases moths had been captured, once at Victoria by a large specimen of Lycosa riparia Hentz (PL XYIII, fig. 2), and again at Paris, Tex., and also at Ladonia b}^ a jumping spider (Attus fasciolatus Hentz). A specimen of the same species of Lycosa^ which was kept in captivity during the sum- mer, proved to be very fond of bollworm larvae and moths, devouring several during the course of a day. A small striped Attid spider (Dendryphantes imibilis Hentz) was not infrequently seen nesting beneath the involucres of the cotton squares at Paris, and on three different occasions they were observed with one- eighth to one-fourth grown larvae which they had captured in these situations. Another form (Attus cardi- ncdis Hentz) was seen at Calvert, Tex., during August, 1903, with a half -grown bollworm in its jaws. No Texas ants have been observed in the act of capturing any large larvae or moths, and it is probable that none of them do so, except under very excep- tional conditions. Several times larvae which had most probably been previ- ously injured were being devoured by ants, and once a moth which had emerged under a jar in the garden was found dead soon afterward, literall}^ covered with the little yellow "thief ant," Solenopsis texana Em. That they were the cause of its death is, however, exceedingly doubtful. Among the beetles there are two groups which probabl}^ destroy a fair number of bollworms. Certain ground beetles, notably Oalosoma anguIatumChev.^ O. scrutator Fab. (fig. 17), O. calidum Fab. (fig. 18), and Ilarpcdus caligiiiosus Fab., all known to have a fondness for cater- pillars, are not infrequent in cotton fields and are probably of some 22051— No. 50—05 8 Fig. 1' -Calosoma scrutator: beetle (after Com stock). 112 service. Several species of tiger beetles are also common. Their larvae nest in burrows in the soil about the plants, no doubt destroy- ing an occasional larva, which for some reason or another finds itself upon the g-round. The most abundant of these are Tetracha Carolina Linn, and Cicin- dela vulgaris Say. Several large predaceous Hemiptera known to destro}^ caterpillars are often seen in cotton fields, but none of them have actually been seen by us in the act of devouring a bollworm. The follow - ing list includes the more important members of this group: Fig. 18. — Calosoma calidum: beetle and larva (from Riley). Metapod'ms femoratus Fab. (PI. XVIII, %5). Sinea diadema Fab. Mdanolestes picipes H.-Sch. Apiomerus crassipes Fab. Arilus cristatiis Linn. Podimis spinosus Dsill. (fig. 19), CEhalus pugnax Fab. In addition to the aforementioned enemies, the "devil's horse" (Stag mom ant is Carolina Burm.) may be mentioned as an activel}^ pre- daceous insect frequenting the fields. Among the A^ertebrate enemies, the common toad {Bicfo lentiginosns and B. valiceps) stands out as rather important. Although feeding upon almost any living insects which it can capture, sometimes at least bollworms form a considerable portion of its diet. On September 14, 1904, Mr. C. R. Jones collected at German- town, Ark., a number of toads from a field of late cotton badh^ infested b}^ the bollworm. The toads in the field at that time were exceed- * z - / a, \to inHv numerous, and nine were sent in for ^^^- i9— Pod?s»s ^innosus-. J- X- -i-i, Ir. i! 11 - 1^ ^^^^^' ^^^' ^"^ nymphs dissection, witn the lollowmg results: (fromRiiev) Table XLIII. — Stomach contents of toads from cotton field at Germantown, Ark., September 14, 1904. Toad. Number of bollworms. No.l None No. 2... No. 3... No 4 do Two: |-inch and i-inch None No. 5... do No. 6... No. 7... Four: Full grown, If-inch, f-lnch, piece of large worm. No. 8... No. 9 Two: ^-incb and i-inch One: ^-inch . Miscellaneous insects. Small ant; Aletia larva, :J-inch. Aletia larva, 1-inch; two ladybirds; a Sciara; a small Chryi melid beetle. Chrysopa larva, Scydmsenid, and Chrysomelid. Aletia larva, i-incli, and a small Carabid. Aletia larva, full grown; a few small Coleoptera. None. Do. Miscellaneous bits. Several small Coleoptera. 113 The toads examined were from 1^ to 2 inches in length, and no douht larger specimens would have had even larger caYJacities for bollworras. Another lot of toads, collected at Calvert, Tex., on the night of August 13, 1903, gave the following large number of bollworms, besides some other caterpillars and a few beetles: Table XLIV. — Stomach contents of toads from cotton field at Calvert, Tex., August 13, 1903. Toad. No.l.. No. 2.. No. 3.. Bollworms in stomach. 23, mostly large, 21, all rather large. 3, all large. On another occasion a large toad was brought into the laboratory and fed on bollworms. It devoured six large bollworms within half an hour, two moths within the next ten minutes, and was apparently not yet satisfied when the supply was exhausted. A feeding experiment was tried on the common Texas horned toad {Phrynosoma coniutum)^ or horned frog, as it is sometimes called. The specimen in question was in a cornfield badl}^ infested by the boUworm, and seemingly on the alert in search for food. A large boUworm was thrown upon the ground a foot or two away from him, and it had scarcely un(;urled itself to crawl away before he perceived and quickly devoured it. The same action was repeated in rapid suc- cession until seven had been eaten and the animal was gorged with food. The worms were just of the size which the toad might encoun- ter in nature wandering about in search of a suitable place to pupate. From this it would seem quite likely that when the more conventional diet of the animal (consisting almost entirely of the large red "agri- cultural ant") is scarce, it may turn its attention to the bollworm. It is very generally believed that birds exert an important influence in insect control". During their nesting period particularly, large numbers of insects are fed to the young, and in normal food habit many species of our commoner birds are largely insectivorous. It is commonly stated that various birds frequenting cot on and corn fields destroy a greater or less number of bollworms along with other insects. The number of species which have been actually observed feeding on bollworms, however, or in which the insect has been found in stomachs, is very limited. During the present investi- gation but one wild bird was observed to actually catch a bollworm. This was a red-bellied woodpecker {Centuries carolinus)^ which Mr. Jones observed extracting a bollworm larva from an ear of field corn. The red-headed woodpecker {Melanerpes erythrocephalus) may often be seen working at the ends of roasting ears in a way to suggest that 114 bollworms are hein^' sought. Probably in most instances it is simply feeding on the soft, milky kernels, and the destruction of bollworms is more or less accidental. According to Dr. C. Hart ^Nlerriam, of this Department, bollworms were found in the stomach of the great- tailed grackle {Jfegcujuiscalus major macrourus). Mr. Glover ^' records an instance of the common kingbird or bee Yim.Yt\i\{Ti/mnnus tyranniis) catching a bollworm moth, and also mentions that bollworm moths formed part of the daily diet of some 3'oung mockingbirds, as evi- denced by the dismembered wings on the ground beneath the nest. ]\Ir. L. N, Bonham^ records '"blackbirds" as feeding on bollworms in Ohio during a period of drought. While the birds were not actualh^ observed with the insects, the evidence presented is strong that the larv^ were being extracted from the ears of corn in the field in which the birds had settled. Although direct evidence of the usefulness of birds in destroying bollworms is meager, 3 et it is practically certain that many common farm birds destro}^ these among other injurious farm and orchard insects. For practical as well as aesthetic reasons, therefore, they should be protected and encouraged as much as possible. Reference may here be made to the considerable service rendered by barnyard fowls in destroying insects. Chickens and turke3^s have at different times been observed feeding on bollworms. In one case an individual turkev of a large flock in an alfalfa field was observed to pick up twenty larv^ in one mmute b}^ the watch, and the distended crops of the turkeys of the entire flock gave evidence of the destruc- tion of a large number of bollworms. The following list of birds occurring in and about cotton fields in Texas was kindly furnished by Doctor Merriam. Those species likely to feed on bollworms, as indicated b}^ Professor Beal, are marked with an asterisk. ^ Bobwhite- ( CoZmits virginianus and CoUnus v. texanus). Mourning dove [Zenaidura macroura). * Mississippi kite {Iciinia mississippiensis). * Sparrow hawk [Falco sparvenus). * Yellow-billed cuckoo {Coccyzus aniericanus). Eed -headed woodpecker {Melanerpes erytlivocephaJus). Red-bellied woodpecker {Centunis caroUnus). Flicker {Colaptes auratus luteins). Scissor-tailed flycatcher ( 3Iuscivom forficata ) . Kingbird {Tyrannus tyrannus). Crested ^y catcher {Myiarchus crinitus). * Blue jay ( Cyanocitta cristata). * Crow ( Corvus hracliyrhynchos) . *Cowbird {Molothrus ater). * Eed- winged blackbird ( Agelaius phoeniceus) . "Monthly Report, 1866, p. 285. i' Insect Life, II, p. 47. 115 *Meadowlark {Sturnelta magna). Orchard oriole {Icterus spurius) . Baltimore oriole {Icterus galbula). *Crow blackbird {Quiscalus quiscula seneus). ^ Great-tailed grackle ( Megaquiscalus major viacrourus) . Western lark sparrow {Chondestes grammacus strigatus). Chipping sparrow {Spizella socialis). Field sparrow {Spizella pusilla) . *Towhee {Pipilo erythrophthalmus) . "^Cardinal {Cardinalis cardinalis). Blue grosbeak {Guiraca cxrulea). Indigo bunting ( Cyanospiza cyanea ) . Painted 'bunting ( Cyanospiza ciris ) . Summer tanager {Piranga rubra). Northern yellow-throat {Geothylpis trichas hrachidactyla) . Yellow-breasted chat ( Icteria virens) . * Mockingbird {Mhnus polyglottos). * Catbird {Galeoscoptes carolinensis) . * Brown thrasher {Toxostoma rufum). Carolina wren {Thryothorus ludovicianus) . Texas wren ( Thryomanes bewichii cryptus). Tufted titmouse {Bseolophus bicolor). Blue-gray gnatcatcher {Polioptila cserulea). * Robin {Merula migratoria) (in early spring and late fall). * Bluebird ( Sia lia si a lis ) . PARASITES. Under this head we have to consider a very important factor in the natural control of the bollworm. There are two stages in the life his- tory of the bollworm when the destructive work of parasites is most effective. These are the egg and the young larva, two stages which are passed before the bollworm has done the greater part of its dam- age. As the method of at- tack is so different in each case it will be well to consider them separately. PARASITES OF THE EGG. There are two small spe- cies of Hymenoptera which are parasitic on bollworm eggs, but one of them is of very rare occurrence and has but little economic significance. The second, Tricliogramma pretiosa Riley, is extremely abundant and of great vakie (fig. 20). The eggs of the Fig. 20.— Trichogramma pretiosa (from Riley). 116 parasite are deposited inside the boll worm eggs hj the female, which is provided with a sharp ovipositor capable of piercing the hard chiti- nous shell of the egg. The young parasitic grubs eat out the contents of the egg^ thus preventing hatching. The following tables, compiled from a large number of records, show verv graphically the large percentage of eggs which fail to hatch on account of these parasites: Table XLY. — rercentages of jnrras-itized eggs on corn, 1903. ' Date of exami- nation. Number of eggs ex- amined. Locality. Eggs on— Per cent para- sitized. Mavol 194 100 144 283 747 100 Victoria, Tex. do... do do do Calvert, Tex Corn silks 84 "TO Do Corn silks Corn leaves do do 83 June 3 70 Do 44.8 Augusts S Table XLVI. — Percentages of eggs parasitized, 1904. , Number Date of exami- I of eggf' nation. I ex- amined. Locality. Per cent para- sitized. May 16 June 3 June 10 August 1 August 12 Do Do August 14 August 16 August 20 Do August 29 September 3 September 7 September 24 - - . October 19 150 10 '. 20 . 40 . 31 j. 32 I. 10 '. 40 |, 40 40 I 40 I 40 : 34 44 ' 40 ■ 28 Paris, Tex. ....do ...-do .--.do.-... .-..do--... .---do -..-do --..do -...do ...-do --..do --.-do .--.do .-.-do ...-do ....do Corn. do do do Corn silks Corn leaves Tobacco leaves Corn leaves . . . Cotton Corn leaves . . . Corn silks Corn leaves . . . Cotton Tomato leaves. Corn leaves . . . do 59.3 70 80 50 • 30 100 22.5 92.5 62.5 75 35.5 86.5 82.5 43 Observed average parasitized during 1903. Observed average parasitized during 1904. General average, all observations Per cent. .... 63.3 .... 63.4 .... 63.35 Glancing down the table, it will be noted that the maximum parasi- tization is on corn leaves, with corn silks next in susceptibility, and parts of the cotton plant considerably in the rear. This may pos- sibly be due to the hindrance oii'ered to the locomotion of the Tricho- gramma during the process of oviposition by plant hairs, since the leaves of corn are more nearly free from these than the other objects mentioned. The first appearance of Trichogramma in the spring corresponds approximately with the first general occurrence of boll worm eggs on 117 corn, which in 1904 was about the middle of May in northern Texas. After this time there is always a continual supply of eggs, owing to the laying by belated moths of the spring generation; and through- out the season the smaller number of eggs between the more marked generations serve to furnish a continuous supply of food for the parasites. Experiments were conducted in the laboratory by Mr.* Girault to ascertain the length of the life cycle of Trichogramma and the number of broods during the season. The first generation, started on May 26, required eleven days, but the time for the succeeding generations graduall}^ decreased to eight days during Jul}^ and August, and length- ened to eleven again by the beginning of October. During the whole summer some fifteen consecutive generations were under observation. Some of the adults of the fifteenth generation apparently do not emerge from the pupa state, although a large proportion of them do. These ma}^, under favorable conditions, produce other scattering broods, but it is probable that most of them must die before finding eggs which they can parasitize. Those remaining in the pupa stage no doubt hibernate in this condition, not emerging until the beginning of the following summer. When a boUworm egg is discovered by the nervous little Tricho- gramma, as she darts about in search for one, she will quickly examine it by crawling over the surface and tapping it with her sensitive anten- nae. If it seems suitable to her, she quickly sets about inserting her thin, flexible ovipositor at the desired spot. After about half a min- ute this has pierced the thick shell and is well within the egg^ allowing the parasite to deposit her egg near the center of the bollworm egg. The ovipositor is then withdrawn and the parasite is ready to repeat the process. The laying of each egg requires about two minutes. On several occasions we have seen Trichogramma ovipositing in the field. The procedure seems to be essentially the same as that observed in the laboratory, but necessarily rather hard to observe without the aid of a rather powerful lens. Ap])arently the insect has no means of ascertaining whether a bollworm egg has alread}^ been parasitized, since eggs known to contain Trichogramma eggs are often selected by a second female for oviposition. This second parasitization, however, seems to occur onh^ before the egg begins to turn black, which would suggest that the Trichogramma detects an egg already parasitized by its dark color. It the laboratory it was found that the Trichogramma could be raised on infertile bollworm eggs, although the latter normally shrivel up shortly after they are laid. As infertile eggs are laid very rarel}^ in nature, this discovery is of more scientific than practical value. Mr. Girault's observations tend to show also that Trichogramma may. 118 under certain conditions, reproduce parthenog-enetically. Observa tions on breeding such minute insects are difficult to make, however, and must alwaj'S be attended with some uncertainty. The sex of the parthenogenetically produced individuals was not determined. From a parasitized egg there emerge, on an average, about two parasites, although often as many as four, and sometimes onh^ one, have been bred. The adults live at most only about four da^^s, and their average life is but one and one-half days. During this stage it is probable that they feed but little, although they have been observed to feed on fruit juices in the lab- orator}^ and might easily find food in nature at the nectaries on the cotton squares or leaves. ^'v^l^^zfa^j'-^ich!- For some two days after the eggs are stung by the g r a m ma pretiosa parasite they sbow DO Bxtemal sign of parasitism, but (ongina ). ^ generally on the third day they rapidly become dusky and translucent, which color changes to an opaque bluish black soon after. This color persists ver^^ distinctly, even after the parasites have emerged, and alwaj^s serves to distinguish a parasitized egg. Their exit is accomplished by cutting a rounded, often jagged, hole in the shell of the host egg (see fig. 21). Although several parasites ma}^ come from a single egg, generally but one exit hole is present, it being in most cases on one side. Copulation usually takes place within a few hours after emergence and oviposition follows almost immediately. DESCRIPTION OF TRICHOGRAMMA PRETIOSA RILEY. Trichogramma is an extremely minute Chalcis-fly, scarcely visible to the unaided eye, and resembling closely the numerous other species belonging to this group. It can be recognized readily, however, b}^ the characteristic arrangement of the hairs on the front wings, i. e., in regular rows, and by the presence of only three tarsal joints. Length 0.3 to 0.43 mm., the males being usually the smaller. Color pale yellow, as a rule, although some specimens are almost black. Eyes dark red and wings hyaline. Head wider than the thorax; antennse eight-jointed, pedicel about two thirds the length of the scape, one small ring joint, the two joints of the funicle equal, together shorter than the pedicel, club conic ovate, a little longer than the scape; funicle and club beset with many long hairs in the male and with short ones in the female. Hairs of the front wings arranged in about fifteen lines. Abdomen not so wide as the thorax, but as long as the head and thorax together. Eggs attacked b}^ this little parasite have been obtained at various localities in South Carolina, Georgia, Florida, Alabama, Texas, and Arkansas, so that there can be no doubt of its very general distribu- tion throughout the cotton-growing States. It is also a very useful parasite of the eggs of the cotton caterpillar. 119 Of the hundreds of specimens bred out during the past summer from eggs kept in the laborator^^ ]>y Mr. Girault the proportion of the sexes seems to be about eciual. Both sexes frequently emerge from the same bollworm egg. The eggs of the bollworm are attacked by a second parasite belong- ing to a second group, the Proctotrypoidea, Telenoimts heliothidis Ashm. (see fig. 22). This species was first discovered by Mally and described from a single specimen bred by him from an egg of the bollworm. Two females and a single male speci- men issued on May 30, 1904, from bollworm eggs kept in the laboratory at Paris, Tex. These eggs had been collected on cornsilks in a field and were laid by moths of the first gener- ,. -VT • £ i.\ ' FiG.22.— Teleno7nus heliothidis— much ation. No more specimens of this ^^i^^^^^ (original). parasite were obtained during the year, although hundreds of eggs were under observation. It seems probable, therefore, that it is very rare, or possibly that it attacks the eggs of some other insect also. DESCRIPTION OF TELENOMUS HELIOTHIDIS ASHMEAD. Female. — Length 0.6 mm. Black, smooth, impunctured, head large, much wider than the thorax; eyes pubescent. Antennje dark brown, the flagellum twice as long as the scape, the pedicel stout and as long as the first and second funicular joints together, the third and fourth about equal, not longer than thick, the fifth larger, monil- iform, club four-jointed, the second and third joints quadrate, the last conic. Thorax ovoid, faintly pubescent, almost bare, mesonotum without furrows, metathorax short, rounded, unarmed. Wings hyaline, with a long fringe; submarginal vein joining the marginal at about one-fourth the length of the wing. Abdomen not longer than the thorax, broadly truncate behind, the first segment exceedingly short, striate, second segment not, or very little, longer than wide. Legs dark brown, the coxse black, and the tarsi whitish- Male. — Differs from the female as follows: Length 0.65 mm., mandibles brownish yellow, antennae longer, filiform, about as long as the body; flagellum three times as long as the scape, pedicel and first flagellar joint about equal and rounded monili- form, following joints a little smaller, last one-half longer and obtusely conic. Bases of the tibise yellowish. PARASITES OF THE LARVA. Owing to the cannibalistic habits of the bollworm, the breeding of parasites is a rather tedious process, since each larva must be confined in a separate breeding jar. This is most easily accomplished by con fining the desired number of larvae under a series of inverted tumblers, each provided with a small boll or bit of other suitable food. In prac tice we have found that pieces of green cowpea pods are most avail- 120 able, as the}^ are easih' handled and the larv^ee thrive on them. With such an arrangement the food can readil}^ be changed and the bollworm examined whenever desired. B}^ using this method large numbers of parasites were bred out at the laboratory. The habits of the bollworms in feeding on corn are such that they are well protected from parasites after the first few days of their life, during which time the}^ have been boring down through the silk into the ear. When once well inside the ear it is practical!}^ impossible for parasites to reach the larva, unless it should leave the ear, which is ver}^ rarely the case. These conditions explain the small percentage of parasites shown in the following table: Table XLYII. — Percentages of lanw parasitized on corn, 1904. Date col lected. May 15 May 30 June 1 June 14 June 26 July 14 Aug. 18 Sept. 10 Sept. 10 Sept. 12 Sept. 30 Locality. Hempstead, Tex. . Dallas, Tex Ladonia, Tex Paris, Tex Corsicana, Tex . . . Paris, Tex do Batesburg, S. C. . . Pine Bluff: Ark... Montgomery, Ala . Paris, Tex Average . Size of larvse. Miscellaneous , FuD -grown Miscellaneous Large •. . . Miscellaneous . do Large do Miscellaneous Large Miscellaneous collected. V^;^ Number 18 45 19 75 35 25 105 34 22 34 30 Number para- Per cent para- sitized. 0 0 0 0 0 0 0 0 4.5 3.0 3.0 Feeding on cotton, larvae are much more exposed to the attack of parasites, as they must move about in search of fresh squares or bolls; and even when partiall}^ hidden within a square or boll a larva is not completely immune. The following table shows very clearl}^ the greater proportion of parasites on cotton as compared with corn: Table XLYIII. — Percentages of larvx parasitized on cotton, 1904- Date col- lected. Locality. ' Size of larv?e. Number collected. Number parasi- tized. Per cent parasi- tized. Aug. 20 Paris, Tex 184 40 104 13 31 27 53 9 16.75 Aug. 25 Aug. 31 do 67.50 do Miscellaneous 51.00 Sept. 16 Tupelo, Miss Small 69.00 51.00 From these data it is evident that practically one-half of the larvae of the August brood are destroyed b}" parasites. This is especially important when Ave recall that it is this brood which causes the greatest damage to cotton. The insect responsible for this wholesale elimina- tion is a small hymenopteron belonging to the family Braconidse. It is more fully treated in the following pages. 121 It will be noticed by referrino- to the table that the greater percent- aiie of parasites come from the smaller larvae; or, in other words, that the larvfe are destroyed before the}^ are half grown and consequently before they have done the greater part of their injury to the plants. HYMENOPTEBOUS PARASITES. Practically all the parasites bred from the young larvae belong to th(^ same species^ JficropI it is n ig7'ij)en7his Ashm.^ of the family Bra- conidje. This species was first bred in the laboratory from a larva collected on tobacco at Paris July 5, 1904, but it was not observed in any numbers until the middle of August, when a large percentage of the boUworms feeding on alfalfa were found to be parasitized b}^ it. Its frequent occurrence on cotton after that time has been referred to. The eggs of the parasite are deposited in larvae which are about 10 or 12 mm. in length, or much more rarely in larger specimens. After it has been stung by the Braconid, the larva continues to feed, but at a much diminished rate, for two or three days. It now becomes very slug- gish and eats the involucre of the square or boll in''>^ rather desultory manner,^, chewing it into small bits, many of which it fails to swallow. These small pieces usually remain webbed to- gether loosely by delicate strands of silk spun by the boll worm, and present quite a characteristic appearance. By the time the parasitic grub is full- grown, the larva lias ceased feeding entirely and is scarcely larger than when first attacked. The Microplitis now bores its way out through the skin of the quiescent bollworm, leaving a large black scar (see PI. XIX, fig. 1) to mark the point of its emergence, which is gen- erally on one side of the bod}^, near the first pair of prolegs. In one case the grub was watched during the act of emerging from the boll- worm. It had protruded the pointed head and was gradually working its fleshy body through the small hole in the larva's skin. In doing this the body had to be constricted dumb-bell shape in order to pass through the small orifice. Once free from the larva, it spins its pupal cocoon (see PI. XIX, fig. 1, and text fig. 23) on some surrounding object, gen- erally a stem or a leaf, spending several hours in this work. The cocoon is about 5 or 6 mm. in length, oval in shape, pale dingy yellow in color, and furnished with a few coarse longitudinal ribs. When first spun it is almost white and rather delicate. After a few hours, however, it acquires its mature color and its consistency becomes verj" tough. LLH Fig. 23.- Micropliti^ nigripennis: adult, larva, and cocoon (original). 122 After the parasite has left it the boll worm usually lives for several days, but does not feed at all during that time. Before death it grad- ualty shrinks and dries up. Larvt^ which are parasitized almost always acquire a pale yellowish color and shriveled appearance, which is quite characteristic, even before any other external sign of the parasite is evident. Some of the specimens bred out in the laboratory were confined over night with several bollworms in a breeding jar, and from one of these an adult parasite was reared. The life cjxle is about three weeks, some nine da3^s of which are spent in the pupal stage. At no tinae have we obtained more than a single specimen of Micro- plitis from one bollworm. DESCRIPTION OF MICEOPLITIS NIGRIPENNIS ASHMEAD. Length, 4 to 5 mm. Black, except the abdomen and legs, which are usually red- dish yellow. Wings very strongly infuscated. Antennae 17-jointed. Head and thorax shining black, metathorax coarsely reticulated, with a me- dian carina. Abdominal petiole black at base and remainder of abdomen sometimes much dark- ened. Legs reddish, the coxae more or less black at base. Wings very dark, veins blackish, second cubital cell about as high as long, subtriangular. We have bred over fifty specimens of this species, mostly from larvBe collected in northern Texas, although the following localities are also represented: Montgomery, Ala.; Tupelo, Miss., and Pine Bluff, Ark. It was bred from larv« collected on the following plants: Cotton, corn, alfalfa, and tobacco. The Microplitis is attacked by two species of secondary parasites, but fortunately neither of them has been bred in large numbers. The first, Perilampiis hyalimts Say, a brilliant metallic blue chalcidid fly (see fig. 24), was bred out on two occasions. The first specimen came from Pine Bluff, Ark., September 13, 1904, and the second from Ladonia, Tex., October 11, 1901. The Perilampus issues by' gnawing an irregular hole through the end of the Microplitis cocoon. The second, Mesochorus americanus Cress, is a well-known secondary parasite, infesting various species of Braconidse. It was bred on only one occasion, during August, 1901. The little chalcidid fly Euplectriis comstocki Howard, which usually preys upon the cotton caterpillar, also attacks the bollworm, according to Prof. H. A. Morgan, who has bred the species, « but we have never met with it in Texas. Fig. 24. — Perilampus hyalinus: adult and cocoon (original). « Bul. La. Exp. Sta. No. 48, p. 159. 123 DIPTEROUS PARASITES — TACHINID^. There are a number of species belonging to this family of flies which are parasitic on the bollworm. The female fly deposits her eggs on the surface of the body of the larva, generally toward the anterior end. Sometimes but a single egg is laid, although a parasi- tized larva frequently bears several eggs attached to it. The eggs are of a pearly white color when first laid, but often turn darker when the embryo begins to develop in them. They are somewhat less than a millimeter in length, elongate in shape, with rounded ends and paral- lel sides. As soon as the egg hatches, the parasitic grub bores into the bollworm through the skin and begins feeding upon its fatty tissue, undergoing a very rapid growth. Even when a number of eggs are attached to a single larva, it is rare for more than one parasitic grub to mature in the bollworm. The species of the family resemble each other so closely that it is almost impossible for anyone not familiar with them to recognize the different forms. The table below gives a summary of the species bred. Table XLIX. — Species of Tachinidx bred from holhvorms during 1903 and 1904. Name. Locality. Date. Food plant of bollworm. Winthcmict It-ptistuldto, Fab Paris Tex Aug. 22,1904 Sept. 4,1903 Aug. 18,1904 Nov. 2,1904 Nov. 7, 1904 May 26,1903 May 29,1903 Alfalfa Calvert, Tex Euphorocera claripennis Macq . . Paris, Tex Ladonia Tex Alfalfa Gonio, ccvpitdid De G Do Do Paris, Tex Do. Archytas piliventris v. d. W Victoria, Tex Com Do do Do Of these it is probable that the first is most valuable in northern Texas, and the last mentioned (see fig. 25) in the southern part of the State. In addition to this list the following species are known to be parasitic on the bollworm, although they were not bred by us during the past two seasons: Frontina arinigera Coq., F. frenchii Will., and F. aletlm Riley. The first was bred b}'- Coquillett^ from boUworms collected at Los Angeles, Cal. ; the second b}' Rile}^^, and the last by Trelease^. Early in November a lot of eighty- seven larva3, mostly full-grown, were ^ „, , , ., . . , ^ ' X P ' YiG. 25.— Archytas pthventris: adult fly collected b}^ Mr. Girault in an alfalfa (original). field at Paris, and forty of them, or nearly 50 per cent, bore tachinid fly eggs on their bodies. One had as many as eleven, but most of « Insect Life, J, p. 331. ^Fourth Missouri Kept. p. 129, footnote. •Fourth Eept. U. S. Ent. Com., p. 377. 124 them onh^ two or three. It proved impossible to rear the parasites from most of these larvae, for the latter were nearly all affected with a bacterial disease and died before the parasites could attain full growth. The records are very meager, but serve to show that Tachinidfe are of but little assistance in controlling the boll worm. During the past season the life history of one parasite, Wlnthemia Ji,~iymtidata Fab. (see fig. 26), was worked out. A female kept in the laboratory deposited ^gg^ on three different bollworms, la^^ng five on one, seventeen on another, and one on a third. The eggs are 0.8 mm. in length, elongate-oval in shape, and pearly white at first, but after twenty-four hours they turn to an orange-3^ellow color. The duration of the life C3^cle is as follows: Egg, two days: larva, three days; pupa, nine to ten days. Summarizing the conclu- sions to be reached from a study of the insect parasites of the boUworm, it is evident that the destructiveness of the third and fourth generations is materialh' lessened h\ them. During September, 1904, when the fourth generation should have been damaoino- much of Fig. 26. — Winthemia U-pustidata: adult and parasitized moth pupa (original). the late cotton in northern Texas, it was almost impossible to find am' bollworms on cotton, and the few to be obtained in the neighboring alfalfa fields were invariably attacked bj^ parasites. At the same time adult specimens_of Microplitis could almost always be collected in these locations by the use of the sweep net. Meanwhile, the late corn nearby, where the parasites could not get at the larv^, was badly damaged. Such evidence plainly suggests that the dearth of larva? on cotton at this time must have been, in a measure at least, due to the good work of parasites. DISEASES. BACTERIAL DISEASE. There is only one disease that plaj^s an important part in the econ- omy of the bellworm. It is one evidently caused b}' bacteria, although its exact nature has not been clearly worked out. Its effects are most clearh' apparent among larva? feeding on corn, more especialh' those of rather large size. 125 The appearance of a larva after the disease is well advanced is char- acteristic. The body loses its firm consistency and becomes quite flabby, while its color fades to a rather uniform greenish yellow. (See PI. XIX, fig. 3.) The larva loses the power of coordinated move- ment, only wriggling or twitching spasmodically when disturbed, and soon beofins to turn darker. Within a few hours after its death it assumes a purplish black color, and the whole internal contents liquefy more or less completely. When the skin is broken this liquid mass is seen to have a distinct reddish tinge. Larvae living in a humid atmosphere seem to be more susceptible to the disease. The following table, containing some of the more com- plete records made during the course of the work, will give a general idea as to the percentage of larvae destroyed b}^ this disease: Table L. — Percentage oflarvx destroyed by bacterial disease. Date of col- lection. Locality. Food plant. Number collected. Per cent diseased. July 1, 1903 Aug. 3,1903 Aug. 4,1903 Aug. 17,1903 May 28,1904 Aug. 20,1904 Aug. 2p,1904 Aug. 30,1904 Sept. 24, 1904 Oct 7 1904 Victoria Tex Corn 2-3 Calvert, Tex do 300 U .do . . do 6 do Alfalfa Corn 81 56 184 40 12 111 17 37 10 Dallas, Tex 10 Paris Tex . Cotton do 49 do 5 do Corn 17 ..do .do 63 do Alfalfa do 12 Oct. 24,1904 do 29 Averages: Corn, 18 per cent; cotton, 27 per cent; alfalfa, 17 per cent. The great discrepancies in the difi'erent lots are in large part due to the fact that some counts were made by examining larvae freshly col- lected, and others from larvae kept in the laboratory for a considerable time, a few dying each day. The large percentages indicated in some of the columns, however, show plainly that under certain conditions a great proportion may succumb to this malady. One unfortunate cir- cumstance is the fact that it is nearly always the larger larvae which are attacked. In the laboratory several cultures were made from a dried larva that had died from bacterial disease. After five days all the cultures had acquired a pinkish tinge, and each, when examined under the micro- scope, yielded a ciliated organism of a bright crimson color, readily visible with a one-twelfth-inch oil-immersion lens, without staining. Four health}^ worms were infected from the cultures by pressing the head and mouth parts against the red gelatine. Of the larvae thus infected, two died within two days with the symptoms of the bacterial disease; one escaped, and the fourth, full-grown when infected, pupated successfull3^ From one of the first cultures, two more were then started and after six days were characteristically red. These 126 experiments were conducted in a crude way, without the use of special bacteriological apparatus, and are, of course, open to question. Thev tend to show, however, the bacterial nature of the disease, the presence of a specific organism, and the possibility of contagion. Another observation serves to show the contagious nature of the disease. It was noticed on August 15, iOOl, that four larvae had died in succession in as many nights in the same breeding jar, the dying bollworms having been daily replaced by new ones. At this time a thorough washing with hot water and soapsuds prevented future mor- tality^ in the jar. We have noted man}^ other similar instances during the breeding work. Quite often the larva has already entered the soil before it is appar- entl}^ attacked, and, again, not infrequently a larva may die while in the act of constructing its burrow. It is very noticeable that larvae which have been injured or bitten by their fellows are much more susceptible than healthy specimens; in fact, a larva which has been but very slightl}^ hurt scarcely ever escapes infection. At present there seems to be no hope of making any practical use of the disease in controlling the bollworm, as has been done with some other species of injurious insects. It is an important factor, however, and helps to keep the pest in check. SCAVENGERS FOLLOWING THE BOLLWORM. In addition to the true parasites of the bollworm there are a num- ber of insects acting as scavengers, some of which are often mistaken for parasites. On numerous occasions we have observed minute flies, belonging to the family Phoridfe, hovering about the breeding jars which contained specimens of larvae, pupee, and adults; in fact, it is almost impossible to keep large numbers of bollworms or pupae together without attract- ing these little scavengers. In one case the Phorida? were allowed to oviposit upon aHead and decaying moth, and after a period of seven- teen days the adults of a second generation appeared. They proved to be AphiocJiBeta fungicola Coq. In other lots of larvae from various localities many speicimens of Phora hicisufrdis Loew were obtained at different times during the summer, and doubtless other species might have been found if special search had been made for them. Aphlochdeta nigriceps Loew {Phora aletise Comst.) has been observed" to feed upon the dead pupae and adults in the same way, and was at first thought b}^ Comstock^ to be a true parasite. This has been abundantly disproved, however, and none of the species have any especial economic significance, since they never attack living boll- worms in any stage. oEiley, Fourth Kept. U. S. Ent. Com., p. 117. &Eept. Cotton Ins., p. 208. 127 The presence about the breeding jars of flies belonging to species of Sarcophagid^e was frequently noticed throughout the summer, but only once were any adults bred from jars containing boll worms. In this case some living pup« had been buried in finely sifted earth in a glass jar covered with cheese cloth to determine the ability of the emerging moths to pass through a stratum of loose soil. One morning after several moths had appeared, three small specimens of Helicobia helicis Town, appeared also. On exhuming the remaining pupae the fly puparia were unearthed close to an empty bollworm pupa case. Whether the eggs of the fly were in the soil, whether they were laid through the cloth, or whether the eggs or young larvae were already on one of the live pupae, would be impossible to say. Hubbard ^^ records an almost exactl}^ similar instance. Whether this is a case of true parasitism remains very doubtful. Larvae of another fly, Exixesta annonae, Fab., were obtained by Mr. Jones at Wharton, Tex., on July 20, 1904, feeding on the juices of a dead bollworm, and from them adults were bred out in the laboratory. The flies are often to be seen about corn plants during the earlier part of the season, and no doubt their larvae also feed on decaying vegeta- ble matter, like the other species of the genus. The other small muscid flies, 3rosojMla j)unGtulaUt Loew and D. ampelophila Loew, were bred from cotton bolls decaying as the result of bollworm injury. Monocrepidius vesjyertinus Fab. and another larger click beetle also act as scavengers after the bollworm. A small nitidulid beetle {Conotelus obscurus Er.) is very common in ears of corn which have been previously injured by the bollworm. In a badly damaged ear often as man}^ as thirty or forty of these little black beetles may be present when the corn is nearly ripened. The}^ do not attack the corn unless it has been already injured by the bollworm. Several other species of Nitidulidae also frequent the damaged ears and bolls. METHODS OF BOLLWORM CONTROL. CULTURAL METHODS. By reason of its feeding habits, the control of the cotton bollworm, as compared with many insects, presents unusual difiiculties. On cot- ton, corn, and tomatoes, particularl}'^, it feeds on the interior plant tissues, and is therefore not amenable to such insecticidal treatment as is efi'ective for many related species. Further, it is much less subject to the attack of parasitic and predaceous enemies than insects feeding « Fourth Rept., p. 110. 22051— No. 50—05 9 128 in more exposed situations, and the bollworm is thus able to develop with comparative freedom from these important natural checks. In the case of many insects affecting staple crops their best control is often to be found in the adoption of some chanoe in farm practice that will take advantage of some peculiarity in the life and habits of the pest. Such changes are usually quite in line with better farming, and involve no extra outla}^ of labor and money not warranted for other reasons than those of insect control. The bollworm falls easily into this class of insects, and the means which are of most importance in avoiding injury consist in certain changes in agricultural practice which are in themselves desirable, aside from their influence on the pest. Attention has elsewhere b'een called to the relation of the farm- ing methods in vogue to bollworm injury to cotton. Experiments dur- ing the past two years indicate that by improved cultural methods much ma}^ be done to insure a crop of cotton, even during years of severe bollworm injury. Detailed results of Held experiments have been given in Farmers' Bulletins Nos. 191 and 212. to which the reader is referred. The value of the so-called cultural method lies in the fact that cotton is not attacked in force until the field corn of the sur- rounding country, the favorite food of the bollworm, has begun to yellow and ripen and is no longer attractive to the moths for egg- laying purposes. The moths, therefore, concentrate in the cotton fields, obtaining their food from the nectaries on the squares and flowers of the cotton plant, and on these latter they deposit the bulk of their eggs. This time of migration to cotton will vary somewhat, depending on the relative earliness of surrounding corn, but will aver- age, one year with another, about the 1st of August, for the central and northern parts of the cotton belt. Another fact to be mentioned in this connection is the comparative immunity of the larger and maturer cotton bolls to attack b}' boll- worms, as compared with the smaller bolls and squares. This is indi- cated on page 72. These two circumstances in the natural histor}^ of the insect permit, by the use of improved cultural methods, of the production of a fair crop of cotton ahead of danger from bollworm injur}' in August. The importance of the early production of a maximum number of advanced bolls is therefore evident, and the cultural method involves the employment of all such means as will contribute to that end. such as — (1) Thorough plowing of land in the fall to destroy as many hiber- nating pupfe as possible. (2) The use of seed of earh^-f ruiting- varieties. (3) The use of fertilizers to hasten and increase fruit production. (1) Early planting in the sp^'ing. (5) Early and thorough cultivation. Bui. 50, Bureau of Entomology, U, S. Dept. of Agriculture. Plate XXI. .= m 7 > Bui. 50. Bureau of Entomology, U. S. Dept of Agriculture. Plate XXII. Bui 50, Bureau of Entomology, U. S Dept. of Agriculture. Plate XXIII. ..<-. , ^. — « 'SSI^mSaEakvM^. Fig. 1.— Poisoning Cotton by Pole and Bag Method (Original). t 4 ji'^BHSB^m^^mI^Bm ^hR iiMiiMIEMBB[^3^SHil^HNHHMar'>><*««Mli^Mli^^^^K Hi Fig. 2.— Poisoning Cotton by Use of Spray Pump (Original). Bui. 50, Bureau of Entomology, U. S. Dept. of Agriculture. Plate XXIV. Fig. 1.— Poison "Blower" Formerly Much Used in Destroying Cotton Caterpillars, Useful Against Bollworms (Original). Fig. 2.— Machine Used in Collecting Bollworms from Cotton Plants ^Original) Bui. 50; Bureau of Entomology, U. S. Dept of Agricultur Plate XXV. Fig. 1 .—Light Trap Used in Experiments to Attract Moths to Light (Original). Fig. 2.— Pans of Bait Used in Experiments to Attract Moths to Poisoned Sweets (Original). 129 The cultural method begins with thorough preparation of land in the fall, winter, or early spring for the succeeding crop, by which means hibernating pupie in the soil are in many cases destroyed. As a female moth appearing in the spring from a hibernated pupa may be the progenitor of many thousands of bollworms by early August, the importance of their destruction by thorough fall and winter plowing is evident. Experiments made with fertilizers during 1904 on several types of soil, including the so-called sandy soils of east Texas, the post oak, ora}^ prairie, river bottom, and black waxy soils of central and north r«^xas indicate that these are very useful in the production of an early ;iiul large crop of cotton (see PL XX for views on one of the Depart- ment's experimental farms in 1904). The accompanying diagram (fig. 27), compares the yield, with respect to earliness and quantity of o/ir£:^ AUG. SEPT OCT. NOV, 30 4 9 14 19 2a 29 a 9 14 (9 24 29 i 8 I3 i8 23 28 7 000 6 500 - ;;;;;;;;::: :: = : ==^=?r;^'" y . 5 500 T t'. ^ 4500 / J 3500 I30OO ^2 500 2 000 1500 1000 500 ;■ ■ I .■■" %■■■ '■'>■" X- \. ■■■■'- ::::::::::: /' / y / ,( i,' ( < "^^o7M'o^%l^;;^°^^ lOli'lO^* .0^* ,0§* .O^W Sfe* 1 Fig. 27— Diagram showing comparative earliness and quantity of cotton crop from fertilized and unfertilized plats (from Quaintance and Bishopp). seed cotton, from two plats of the experiment farm at Pittsburg, Tex. Plat 1 was treated with a fertilizer analyzing phosphoric acid 10 per cent, potash 2 per cent, at the rate of 300 pounds per acre. Plat 4 was unfertilized, the treatment in all other respects being the same. Specific recommendations as to the quantity per acre and kind of fertilizers to be used may not be given as the result of one year's experimentation. Simply the fact of their utility is pointed out. Planters should arrange for a series of tests calculated to answer these respective questions for their own soils. Of equal importance is the use of seed of varieties with an inherent tendenc}^ to begin fruiting earl}^ in the growth of the plant, thus insuring an early crop (see PL XXI, illustrating comparative matur- ity of King and Myers cotton treated the same throughout the 130 season). This habit of early fruiting- is more characteristic of the shorter-jointed sorts than of the longer-jointed varieties. These desirable qualities, viz, early fruiting, prolificacy, good staple, etc., may be perpetuated and improved by seed selection, and , special attention should be given to this work.- The importance of j the use of selected earh^-fruiting varieties, as compared with native "run-down-' gin seed, has been illustrated man^^ times in the course of these investigations. In 1903, on the plantation of Capt. B. D. Wilson, at Hetty, Tex., under conditions of severe boUworm injury, early-planted early-fruiting cotton produced an average of 1,318 pounds of seed cotton per acre, as against 187 pounds of early-planted but later-fruiting gin seed. The importance of planting as early in the spring as practicable has been recognized b}^ planters for many 3'ears, and this has been about the only practice emplo^^ed looking to the avoidance of bollworm injury. Best results from this work have often not been secured, however, because of the use of gin seed of unknown parentage and variety. No fixed dates may be given for the planting of cotton, but the effort should be to plant as earh' as possible, even though danger from frosts may not have entirel}^ passed. The advantage gained in early plant- ing more than compensates for the injury b}^ frost during occasional 3"ears. Early and thorough cultivation is an important factor in the cultural method of producing early cotton. Early chopping out of the plants will permit of free branching and consequent square production. The fertility of the soil, either native or introduced in the way of ferti- lizers, may be used hj plants onh^ in a liquid condition. Hence, for the conservation of moisture and other reasons, timely and frequent cultivation are of the utmost importance. The steps in the production of early cotton, outlined above, include the principal recommendations for the growing of cotton in the pres- ence of the boll weevil. It is therefore seen that injury from the cotton bollworm and the cotton boll weevil may be best avoided by the adoption of one and the same course of improved farm practice. The spread of the latter species will render imperative the adoption of these methods in profitable cotton culture, and along with this change the ravages of the bollworm during normal seasons should become less and less. TRAP CROPS. The preference of the bollworm for corn, as compared with its other food plants, permits of the use of this plant in a way to protect cotton from injury. In general, protection will be needed only from the August generation of larvae, and this ma}^ be secured by planting corn in belts through the cotton fields at a time that will result in its being in 131 tassel and silk b}^ the 1st of August (see PL XXII, fig. 1). Corn in this condition will receive the great majorit}^ of the eggs deposited by the moths which otherwise would be placed on the cotton plants. In planting cotton in the spring leave vacant strips across the field every 2()() or 300 feet sufiiciently wide for planting 10 or 12 rows of corn. Under favorable conditions of rainfall and with good cultivation, Mexican June corn planted by June 1 will be in prime silking condi- tion b}^ August 1. The corn should be allowed to mature and may be harvested in the usual way. Corn should not be planted in belts through the cotton field at the usual time in the spring. With the ripening of the corn the insects simpl}^ turn their attention to the adjacent cotton (see PL XXII, fig. 2). The planting of cowpeas in the trap corn belts is strongly recommended. Peas planted soon after the corn crop is up will ordinarily be in full blossom by early August and will serve to furnish the moths with an abundance of nectar for food, thus obviating the necessity of their visiting the adjacent cotton plants and the consequent deposition there of a certain proportion of their eggs. Much the same protection may be secured b}^ the plant- ing of late corn here and there over the plantation after such early maturing crops, as wheat, oats, etc. In all cases peas should be planted in the corn. The greatest benefit will result from the use of corn as a trap crop, when it is generally adopted b}^ the planters of a neighborhood. On large plantations it is perfectly practicable to grow late corn in such a manner as to attract the bollworms from the plantation generally. ARSENICAL POISONS. It is the general belief among cotton planters that the boll worm may not be successfully poisoned on cotton, from the fact of its bor- ing to the interior of bolls and squares and there feeding out of reach of insecticidal substances. Such belief is true only of the later stages of the larva. A newly hatched boUworm is so small a creature that it does not usuall}^ attract the attention of the average observer (see PL III, fig. 2), and the habits of the insect during this early larval existence are not generally taken into account. This unobserved period in the growth of the larva is about the only time during which poisons may be expected to exert any considei'able influence in its control. As has been elsewhere pointed out, the deposition of the eggs over the cotton plant and the habits of the newly hatched insect have an important bearing on the possibility of poisoning. Larvae hatching from eggs placed on other parts of the plant than the tender growing tips, squares, and flowers, which are ordinarily soon penetrated, must spend some time in crawling around in search of tender food. Dur- ing this aimless wandering of from several hours to a day or more, 132 frequent attempts are made at eating, and the larvae would be readih^ poisoned if poisons were present on the plants. From a series of observations, both in 1903 and lOO^l, it was found that from 62 to 73 per cent of the eggs deposited b}^ the bollworm moth on cotton were placed on the leaves, stems, leaf stalks, etc., or on other parts than the tender tips, squares, and flowers, so that the resulting larvae could be destroyed by timely applications of poison. Ordinarily, : poisons will be profitable only against the August generation of larvee, and results will be much more pronounced during seasons of severe, as compared with moderate, bollworm injur3^ The plants should be kept poisoned from about the last week in July until about the second week in August, and later if the moths are seen to be abundant. During this period the eggs of the destructive August brood will be deposited, and the presence of poisons on the plants as the young larvae are hatching will result in their destruction in large numbers. As between the dusting and spraying methods of applying poison, the former seems more practicable (see PI. XXIII, fig. 1). In dusting with Paris green, this should be used at about the rate of 2 to 3 pounds per acre for each application, the quantity varying somewhat with the size of the plants. In many cases, as with careless labor, it will be more economical to dilute the poison with cheap flour or dry slaked lime. Applications ma}" satisfactorily be made by the usual pole and bag method. The use of geared poison blowers (see PL XXIV. fig. 1) would permit of the work being done more rapidl}", which is ver}" important. Applications of dry poison should be made at night, earl}" in the morning, or late in the evening, when the plants are sufiiciently wet with dew to insure its sticking. Paris green, applied in water, should be used at about the rate of 1 pound to 50 gallons, which amount will cover about 1 acre (see PL XXIII, fig. 2, illus- trating Department's spraying experiments in bollworm control). The effect of a rairrwill be to wash the poison largely from the plants, and the application must necessarily be at once repeated. Applications of poisons, as above indicated, at intervals of a week or ten days, should keep the plants sufiiciently poisoned to accomplish the desired results. INEFFECTIVE METHODS OF COMBATING THE BOLLWORM. During periods of serious bollworm injury planters often resort to various methods in their efforts to prevent the destruction of the crop. The burning of lights in the fields, the use of poisoned sweets, and the burning of sulphur were more or less practiced in 1903. These and similar methods have been shown, by numerous tests (see PL XXV, figs. 1 and 2) during the present investigation, to be of no practical value whatever, and attention is called to their futility that needless expense may be avoided in the future. 133 MECHANICAL DESTBUCTION. Various types of machines for collecting cotton boll weevils from plants have been devised during the past few years. Some of these have been tried for collecting the cotton boUworm (see PL XXIV, iig. 2). In one case it was determined by a series of counts that about 10 per cent of the bollworms were collected by the machine in passing over the plants. It is considered possible that machines of this char- acter may be so perfected as to render their use profitable in collecting bollworms. METHODS OF BOLLWORM CONTROL ON CORN, TOMATOES, AND TOBACCO. It must be acknowledged that thus far no satisfactory method of controlling the boUworm on sweet and field corn has been discovered. In those States where the insects hibernate in corn fields fall or winter plowing would be especially valuable in destroying the pupse in the soil. Indeed, this practice is about all that may be recommended. During the present investigation tests have been made of several plans which have been recommended as of possible value. The plan to crush larvae in the roasting ears, by hand or otherwise, does not, apparently, take account of the often numerous smaller larvae to be found in the ear and which largely escape the eff'ects of pressure fatal to the larger individuals. Tests by Messrs. Bishopp and Jones of various substances placed on corn silks and ears, as black pepper, tar, sulphur, tobacco, crude petroleum, pennyroyal, creolin, pyrethrum, etc., as repellents to the moth in egg laying on these parts, gave negative results. While some substances apparently prevented the moths from ovipositing, their effect was to kill the portions treated. The first brood of larvae infesting ''buds" of corn in the spring could in many instances be profitabl}^ sought for and destro3^ed by children, or plow hands in the course of their work, thus greatly lessening the numbers of the insects in succeeding generations. This practice uniformly followed by the farmers of a neighborhood should serve in the course of a year to so reduce the numbers of the bollworm that its injuries would be of little importance. Such a plan would be perfectly practicable in lessening injury to cotton, and its value would be in proportion to the extent of its adoption by the planters of a neighborhood. No experiments in the control of the bollworm on tomatoes were undertaken during the present investigation. While there are but few data as to the deposition of eggs by the bollworm on tomato plants, it is certain that these are placed quite as promiscuously over the leaves, stems, etc. , as was found to be true in the case of cotton 134 and corn. It would therefore appear that arsenical poisons might profitabl}" be used in bollworm control on tomatoes, either alone or in fungicidal preparations designed to prevent fungous diseases. Appli- cations of poisons should be made as soon as bollworm moths are observed in numbers in tomato fields. Two or three applications at intervals of a week or ten days should suffice to protect from important injury. Early sweet corn may be planted in belts through the tomato field in a way that will afiord much protection to the earliest fruit. A sj^s- tematic effort toward the destruction of all larvae found in these trap belts would contribute much toward lessening future injury. Bollworm injury to tobacco is confined principall}^ to the ^'bud.'' A treatment which has been in practice for many years by the tobacco growers of Florida, and possibh^ elsewhere, is to sprinkle into the "bud" at frequent intervals, b}^ means of a tin can with perforated bottom, a mixture of Paris green and cornmeal. Where tobacco is spraj^ed with arsenites in the control of the "horn worm," this treat- ment will probabl}^ keep the bollworm in subjection. BIBLIOGRAPHY. The following bibliograph}^, prepared largei}^ by Mr. A. A. Girault, includes only the more important S3^stematic and economic references to the literature of Heliothis obsoleta. References marked b}^ an aster- isk have not been seen. 1793. Fabricius, J. C— Ent. Syst., 3, i, pp. 456-457. Original description under the name Bombyx obsoleta. 1796. HtJBNER, J.— Samm. Eur. Schmett., p. 370. Description as a new species under the name of Noctua armigera. 1810. OcHSENHEiMER, F. — Die Schmetterlinge von Europa, Leipzig, IV, p. 91. Heliothis peltigera, var. armiger Hbn. 1810. OcHSENHEiMER, F. — Syst. Lep. Europse., Abth. II, ii, p. 292. Listed, and placed in the genus Heliothis. *1825. Treitschke, F. — Schmetterlinge von Europa (Fortsetz. F. Ochsenheimer) , V, III, p. 230, n. 6. Lists in the genus Heliothis. 1829. Meigen, J. W.— Syst. Beschr. derEurop. Schmett., I, p. 234, Tab. CXX, fig. 15. Description of the adult, with poor colored figure; good note on food-habits and development. 1831. Brulle, Aug. — Coup d'oeil sur 1' Entomologie de la Moree. Annales Sci. Nat., Zodlogy, Paris, Series 1, Tome XXIII, p. 265. Mentioned as Noctua armigera, with note on distribution. *1832. BoisDuvAL, J. A. — Chenilles d' Europe. Heliothides. Coll. icongr., et hist, des chenilles d.Eur., Paris, Heliothides, Tome 2, fig. 3. Larva figured. 1833. BoisDUVAL, J. A. — Faune Entomolog. de Madagascar, Bourbon, et Maurice. Lepidopteres., p. 98. The genus Heliothis; brief synonomy, description, and distribution. 1840. BoisDuvAL, J. A. — Genera et Index Methodicus Europseorum Lepidopterorum, Paris, pp. 162-163. Lists. 1841. Guenee, a. — Noctuarum Europse. Index Methodicus. Annales Soc. Ent. France, X, p. 247. *1842. Anon. — Southern Planter, Richmond, Va., II. Potation of corn with cotton advised. Reference could not be found in the volume cited. 1843. l^DLESTON, R. S. — Note on the capture of Heliothis armigera near Salford. Zoologist, London, I, p. 260. Addition to British fauna; taken in Sept., 1840. . 1845. Herrich-Schaeffer, G. A. W. — Heliothis armigera H. Syst. Bearbeitung der Schmett. Eur., II, p. 367. Description of adult, with distribution; larval food. Reseda lutea. 1846-1874. White, A., and A. G. Butler.— The Zoology of the Voyage of H. M. S. Erebus and Terror, 1839-1843. Insects, p. 35. Listed, with good synonomy. (135) 136 *1850. BoDDiE, J. W.— Amer. Cotton Planter, July (?), 1850. Description of Helio- this obsoleta Fabr. as Phahcna zea. Note on the first and second broods; remedy. 1852. GuENEE, A. — Species general des Lepidopteres. Noctuelites. Paris, YI, ii, p. 181. Localities and references; varieties not constant. 1852. Lucas, Hippolyte. — Note sur V Heliothis armigera, Catocala convert., Megasoma repandum. Annales Soc. Ent. France, serie 2, X, bul., p. 24. Brief notes. 1853. Burnett, W. I. — The Cotton Worm of the Southern States. Proc. Boston Soc. Nat. Hist., IV (March 17, 1853), pp. 317-318. Mentions as accompanying the "caterpillar" [Alabama argillacea'] with brief notes on habits and injury. 1855. Glover, T. — Insects Injurious and Beneficial to Vegetation. Kept. U. S. Commissioner Patents, 1854, pp. 60, 64-65, 69-71. Repr. De Bow's Review, 1855. Good general account; results of investigations. 1855. Stainton, H. T. — Lepidoptera. New British Species Since 1835. Entomolo- gist's Annual, London, 1855, pp. 38-39, 2d Ed. Lists, and gives reference to Edleston (1843). *1855. Zimmermann, J. H. — The Cotton Worm, its Character, Habits, etc. Amer. Cotton Planter, Aug., 1855. ■ De Bow's Review, 1855. Includes notes on the metamorphoses of Heliothis obsoleta, with remedies. 1856. Glover, T.— The Boll Worm. U. S. Patent Oflice Report, 1855, pp. 99-103. Report of further investigations on the bollworm. 1857. Lederer, Jul. — Die Noctuinen Europas, Wien, pp. 42-43, 178-179. 1857. Stainton, H, T. — A Manual of British Butterflies and Moths, London; I, pp. 289, 291, 291-292. . Mentions as very rare; brief description of adult and larva, with food plant of the latter. 1857. Walker, Francis. — List of the Specimens of Lepidopterous Insects in the Col- lection of the British Museum. Brit. Mus. Cat., Pt. XI, p. 688. Description of Heliothis obsoleta as Heliothis pulverosa Wlk. 1857. Walker, Francis. — List of the Specimens of Lepidopterous Insects in the Col- lection of the British Museum. Brit. Mus. Cat., Pt. XI, p. 690. Description of Heliothis obsoleta as Heliothis conferta Wlk. 1858. Sanderson, E. — Boll W^orm, Cotton Miller, etc. The Amer. Cotton Planter, Nov., 1858 (n. series, Vol. II, No. 10), pp. 339-340. Theory concerning the bollworm; believes the corn worm and the bollworm the same. Recommends good remedies: (1) Planting cotton early, corn late; (2) Corn as a trap-crop. 1858. Walker, Francis. — List of the Specimens of Lepidopterous Insects in the Col- lection of the British Museum. Brit. Mus. Cat., Pt. XV, pp. 1681-1682. Description of Heliothis obsoleta as TlialpopJiila rubrescens Wlk. 1859. King, Peyton. — Cotton Culture and the Boll Worm Again. A Review. Amer. Cotton Planter, Feb., 1859 (n. series. III, No. 2), pp. 48-50. A review of E. Sanderson (1858) with interesting remarks and questions. 1860. Stainton, H. T. — Lepidoptera. Rare British species captured in 1859. Ento- mologist's Annual, London, p. 141. Listed, with localities, and references to recorded captures. 1860. Wallengren, H. D. J. — Lepidopterologische Mittheilungen. II. AYien. Ent. Monatsschr., IV, pp. 171-172. Description of Heliothis obsoleta as Heliothis punctigera; states that it approaches obsoleta. 137 I860. Wallengeen, H. D. J. — Lepidopterologische Mittheilungen. II. Wien. Ent. Monatssch., IV, p. 171. Description of Heliothis ohsoleta as Heliothis uniformis; says that it approaches Heliothis scuteligerse. 1862. Grote, a. R. — Additions to the Catalogue of the IT. S. Lepidoptera. Proc. Ent. Soc. Philadelphia, I, p. 219. Description of Heliothis obsoleta as Heliothis umbrosus Grote; observes differences from the European species. 1863. Grote, A. R.— Proc. Ent. Soc. Philadelphia, I, p. 347. Establishes synonymy of Heliothis ohsoleta, Fab., and Heliothis umbrosus Grote. 1865. Glover, T.— Ann. Kept. U. S. Dept. Agric. f. 1864, p. 554. As a corn and cotton enemy; brief note. 1865. Goureau, Ch. — Insects Nuisibles, 2d Sup., p. 132. Records feeding on tobacco, corn, and lucerne. 1866. Dodge, J. R.— Insects. Mon. Rept. U. S. Dept. Agric. f. 1866, pp. 388-389. . Correspondent's report. Injury to Cotton in Alabama and Mississippi. 1866. Glover, T.— Rept. U. S. Commissioner Agric. f. 1865, p. 43. Heliothis ohsoleta eaten by crows. 1866. Glover, T. — Insects Injurious to the Cotton Plant. Mon. Rept. U. S. Dept. Agric. f. July, 1866, pp. 282-285. Habits and ravages, and means against the bollworm. Description and figures of the stages. 1866. Newman, Edw. — The Army Worm. Entomologist, London, III, pp. 166-167. Answer to correspondent, quoting from the Liverpool Mercury (11 Sept., 1866) on the identity of the so-called army worm. Refers it to Heliothis ohsoleta. 1867. Glover, T. — Entomological Extracts from Correspondence. Mon. Rept. U. S. Dept. Agric. f. Oct., 1867, p. 329. Reported by correspondent as injuring corn in low^a. 1867. Hempstead, 0. H., Jr.— The Cotton and Bollworm. Mon. Rept. U. S. Dept. Agric. f. May and June, 1867, pp. 214-215. . Remarks on injuries from the bollworm to cotton in parish of Jefferson, La. Published anonymously in body of report. 1867. MuLLER, A. — Heliothis armiger and the Army Worm. Entomologist, London, III, pp. 213-215. Valuable notes on identity of larva; footnote in regard to the gender of the word Heliothis. References. In answer to Newman (1866). 1867. Newman, Edw. — Description of a caterpillar brought to me by Mr. H. J. Harding, feeding on Hyoscyamus niger, on Oct. 10. Entomologist, London, III, p. 361. General description of a larva, supposedly that of Heliothis pelligera, or H ohsoleta. 1868. Praun, Sigmon von. — Die Europiiischen Eulen. Noctuse. Niirnberg, Gatt. LXV, Taf. 33, Fig. 19. . Notes food plant and distribution. 1868. Riley, C. V. — Report of the Committee on Entomology. Trans. Illinois State Hort. Soc, 1867, p. 115. Observations on ravages and habits. 1869. Bond, W. J.— Proc. Ent. Soc, London, Mar. 1, 1869, p. v. Specimens exhibited from Java, Australia, and the Isle of Wight. 1869. Brodnox, B. H. — Scarcity of the Corn Worms and Boll-worms. Amer. Ent. Nov., 1869, II, p. 53. Scarcity in Mississippi. 138 1869. Fallou, M. J.— L'Insectologie Agricole, 1869, p. 205. Larva feeding on the chick-pea. 1869. LoRiNG, F. W., and C. F. Atkinson. — Cotton Culture and the South. Boston, pp. 63, 65. Mentions injury from bollworm; late planting of corn supposed preventive. 1869. Newman, Edw. — The Scarce-bordered Straw. An Illustrated Natural History of British Moths, London, p. 439, fig. 678. Description of moth and larva; distribution. Figures adult. 1869. Walsh, B. D. and C. V. Kiley.— Cotton Insects. Amer. Ent. I, pp. 212-214. Describes stages, habits, ravages, and mentions food-plants; suggests remedies. 1869. Walsh, B. D., and C. V. Riley.— The BoUworms or Corn Worms. Amer. Ent., II, pp. 42-44. Seasons, food-plants, ravages and remedies. 1869. Weir, J. W.— Proc. Ent. Soc. London, Dec. 1, 1869, p. xxviii. Two specimens bred from tomatoes imported from Spain or Portugal. 1870. Bethune, C. J. S.— Miscellaneous notes. Larva of Heliothis armiger. Cana- dian Ent., II, pp. 66, 67. Brief notes on food-plants; references. 1870. Grote, a. R., and C. T. Robinson. — Descriptions of American Lepidoptera. No. 5. Trans. Amer. Ent. Soc, III, p. 180. Habitat note under Heliothis umbrosus Grote; the latter is mentioned as a probable synonym of the European Heliothis obsoleta, Fab. 1870. Riley, C. V.— The Fall Army Worm. Amer. Ent. and Bot., II, p. 328-329. Compares the larva of Heliothis obsoleta and Laphygma frugiperda. 1871. Fallou, M. J. — Annales Soc. Ent. France, series 5, I, pp. liii-liv. Note on food-plants {Zea mais, Panicum miliaceum, Setaria italica, and common bean) ; method of attack on bean. 1871. Hoffman, E. — Praun's Abbildung und Beschr. europiiischen Schmetterling- raupen, Niirnberg, Noctuse, Vol. 11, fig. 9, a, b. Figure of larva. 1871. Riley, C. V. — The Corn Worm, alias Bollworm; Heliothis armiger. 3rd Ann. Rept. on the Noxious, Beneficial and other Insects of the State of Missouri, pp. 104-109. General account with remedies; figure. 1872. Fereday, R. W. — On the Direct Injury to Vegetation in New Zealand by Various Insects, with reference to larvae of Moths and Beetles feeding upon the field cTops; and the expediency of introducing Insectivorous Birds as a Remedy. Trans. N. Zeal. Inst., pp. 290, 291. Read before the Philosophical Institute, Canterbury, 12 Dec, 1872. Brief note on habit of moth and larval foods. Lists with those insects most injurious. 1872. Glover, T. — Report of the Entomologist and Curator of the Museum. Rept. U. S. Commissioner Agric f. 1871, p. 84. Brief note on rej^orts of injury. 1873. Dodge, L. A.— The Cotton Caterpillar. Amer. NaturaHst, VII, pp. 213-216, fig. 39. Includes brief note, with an erroneous figure of larva and moth. 1874. Glover, T.— Report of the Entomologist and Curator of the Museum. Rept. U. S. Commissioner Agric. f. 1873, p. 162. Comparison of Alabama {Aletia) argillacea and Heliothis obsoleta. 139 1874. Grote, a. E. — On Allied Species of Noctuidge inhabiting Europe and North America. Bui. Buffalo Soc. Nat. Sciences, II (1874-1875), pp. 194, 199-200. Under the heading — Species believed to be common to Europe and North America, exclusive of Labrador or circumpolar forms — hsts Ileliothis obsoleta, Fab. (Europe) and Ileliothis umbrosus (N. A.), thus again establishing their synonomy. cf. Grote, id. 1875. 1875. Anon. — On the Relation between European and American Noctuina. Psyche, I, pp. 65-68. American and European species identical. Vide Speyer (1875). 1875. Berg, Carlos. — Patagonische Lepidopteren, beobachtet auf einer Reise im Jahre 1874. Bui. Soc. Imperiale Naturalistes de Moscou, XLIX, pt. 2, pp. 191, 192-193, 219-220. Separate, Mockba, 1876, pp. 1, 2-3, 29-30. Lists with valuable notes. This article is reviewed by Lintner (1878). 1875. Grote, A. R. — On Allied Species of Noctuidse inhabiting Europe and N. A. Bui. Buffalo Soc. Nat. Sciences, II (1874-1875), pp. 313-314. Fresh observations reduce the number of species held to be common to both continents. Ileliothis obsoleta retained as originally. Vide Grote, ib., 1874. 1875. Speyer, A. — Europilisch-amerikanische Verwandtschaften. II. Ent. Zeit., Stettin, XXXVI, pp. 158-159. Coniparison of American and European specimens of obsoleta; general notes. 1876. Bird, H. M. G. — Ileliothis armiger. Entomologist, London, IX, p. 261. Food-plant and variation of larvae; specimen reared on geranium flowers in the Isle of Wight. 1877. Packard, A. S. —Half-hours with Insects, Boston, p. 224, fig. 172. Brief notes; very poor figure of moth and larva. 1877. Packard, A. S. — Report on the Rocky Mountain Locust, and other insects now injuring or likely to injure field and garden crops in the Western United States and Territories. Rept. U. S. Geol. Surv. f. 1875, pp. 778-780. General considerations. 1877. Tugwell, W. H. — Life History of Ileliothis armigera. Entomologist, London, X, pp. 283-284. Includes account of cannibalism and method of feeding on geraniums; general. 1878. French, G. H. — Economic Entomology of Illinois. II, Lepidoptera. 7th Ann. Rept. State Ent. Illinois, f. 1877, in Trans. Dept. Agric. Illinois, XV, pp. 231-233. The Armed Heliothis. Short account, with descriptive note on stages. Fall plowing and early planting recommended. 1878. French, G. H. — Insects Injurious to the Vegetable Garden. Lepidoptera. Trans. Illinois State Hort. Soc, f. 1877, n. series, XI, pp. 198-199, fig., p. 204. Discussion of habits and injuries. 1878. Glover, T.-^Cotton and the Principal Insects frequenting the plant. Illustra- tions N. A. Entomology, Washington, 1878, pis. 17-18. Original figures of all stages and of the injury to cotton. 1878. Lintner, J. A. — On Some Lepidoptera Common to the United States and Pata- • gonia. Entomological Contribution No. IV, vi, 30th Ann. Rept. N. Y. State Mus. Nat. Hist., 1878, pp. 164-166. A review of Berg (1875). Valuable notes on cause of distribution and habits of larva. 1878. Thomas, C— The Corn-Worm or Bollworm {Heliothis armigera). 7th Ann. Rept. State Ent. Illinois, in Trans. Dept. Agric. Illinois, XV, pp. 4, 102-106, etib., ante, Rept. Mus. Committee, p. 99, -seg., p. 110. General account with remedial measures. 140 1879. Axon.— Canadian Ent., XI, p. 202. Mentions carnivorous habits. 1879. CoMSTOCK, J. H. — Report on Cotton Insects. U. S. Dept. Agric. 1879, pp. 287-315, pi. II, text-figs., 76, 77. Very complete, covering natural history and remedies. 1879. French, G. H. — Corn AVorm. Pacific Rural Press, Sept. 13. Tall varieties of corn perhaps attacked less than short varieties. 1880. BuTLEE, A. G. — On a second Collection of Lepidoptera made in Formosa by H. E. Hobson, Esq. Proc. Zool. Soc. London, 1880, p. 676. Listed with the synonymic Hdiotliis succinea Moore, 1880. Claypole, E. W. — Heliotlils armiger feeding on Hard Corn. Amer. Ent., Ill (n. series, I), p. 278 Abundance, habits, and ravages on corn in Ohio; injury by second brood; percentage of corn infested. 1880. CoMSTOCK, J. H. — The Bollworm. Ann. Rept. V. S. Commissioner Agric. f. 1879, pp. 332-347. Condensed accomit of the bollworm from Comstock (1879). 1880. Jones, R. W. — Effect of Pyrethrum on Bollworms. Amer. Ent., Ill (n. ser., I), pp. 251-252. Report of experiments with pyrethrum extract on the larvae. ' 1880. JoxES, R. W. — Bollworm devouring the Cotton Worm. Amer. Ent., Ill (n. series, I), p. 253. Recorded as eating the pupae of Alabama {Aletia) argiUacea. 1880. JoxEs, R. W. — Uselessness of Yeast Ferment. Amer. Ent., Ill (n. series, I), p. 296. Record of experiments with yeast ferment on bollworms. 1880. Riley, C. V. — AVorms on Cabbage — Bollworm feeding on Leaf. Amer. Ent., Ill (n. series, I), p. 254. Records larva feeding on the leaves of cabbage. 1880. Stelle, J. P. — Boll Rot caused by Bollworms. Amer. Ent., Ill (n. series, I), p. 250. Treats of the abundance and injuries of the bollworm in Texas. 1880. Stelle, J. P. — Road Dust Against Cotton Worms. Amer. Ent. I^I (n. series, I), p. 251. Mentions the fact that road dust diminishes destructiveness. 1881. Cook, A. J.— Canadian Ent., XIII, p. 215. First attack on corn in Michigan, in 1880. 1881. CoQuiLLETT, J). W. — HeliotMs armigera. 10th Rept. State Ent. Illinois, in Trans. Dept. Agric. Illinois, XVIII, 1880, append., p. 150, fig. 51, a-f. Brief description of the larva, with copied figures of the stages. *1881. LiNTNEK, J. A. — Ontario County Times, Nov. 9. History and habits. 1881. LiNTXEE, J. A. — The Corn Worm, HeUothis armigera. Cult, and Country Gentleman, Xov. 24, XL VI, p. 759. Character of larva and adult; ravages and feeding habits. 1881. MooRE, F. — Description of Xew Genera and Species of Asiatic Nocturnal Lepi- doptera. Proc. Zool. Soc. London, 1881, pp. 360, 362. Description of HeliotMs obsoleta Fab., as HeUothis succinea Moore. A struc- tural peculiarity of obsoleta is mentioned. 1881. Riley, C. V. — The Bollworm, alias Corn Worm. Ann. Rept. U. S. Commis- sioner Agric. f. 1881, pp. 85-92. Separate, W^ashington, 1883, p. 145. Practically an advance print from 4th Rept. \J. S. Ent. Comm. Vide Riley (1885). On food plants other than cotton. 141 1882. Feench, G. H.— 11th Ann. Kept. State Ent. Illinois, pp. 82-104. Description of the stages; ravages and remedies. 1882. Grote, a. R.— Description of New Noctuidse. Bui. Brooklyn Ent. Soc, III, p. 30. Description of HeUotJds obsoleta as Heliothis interjacens Grote. 1882. Kellicott, D, S. — Observations and Notes. Bui. Buffalo Soc. Nat. Sciences, IV, p. 61. Mentions injury to corn in Michigan. 1882. LiNTNER, J. A. — Heliothis armiger Hiibn. The Corn Worm. 1st Ann. Rept. on the Injurious and Other Insects of the State of New York, pp. 8, 38, 116- 126, figs. 27, 28. Addenda, p. 344. Good account with figures; short bibliography given. Plabits of moths arid larvae; food plants, distribution, injuries, and remedies. 1882-1883. Smith, J. B. — Synopsis of the North American Heliothinge. Trans. Amer. Ent. Soc, X, pp. 220-221. Descriptive notes; establishes synonymy of Heliothis obsoleta and Heliothis umhrosus. 1883. Butler, A. G. — On a collection of Indian Lepidoptera received from Lieut.- Col. Charles Swinhoe, with numerous notes by the collector. Proc. Zool. Soc. London, 1883, pp. 161-162. The synonymic Heliothis rubrescens listed, remarking that perhaps it is but a dark red variety oi Heliothis obsoleta. Suggestive remarks on the varieties of the latter. 1883. Grote, A. R. — Remarks upon the North American Heliothinse and their recent Literature. Trans. Amer. Ent. Soc, X, pp. 264-265. On the genus Heliothis; a criticism of Smith (1882-1883). 1883. Johnson, L. — Report on the Cotton Worm, Bollworm, and other Insects. Bui. 1 (old series), Div. Ent., U. S. Dept. Agric, pp. 53-58. Remarks on its abundance in Mississippi in 1882. 1883. Riley, C. V. — The Cotton Bollworm, or Corn Earworm. Insects in relation to Agriculture. Stoddart's Encyc. Americana, 1883, I, p. 141. Brief general account. 1884. Mendenhall, R. J. — Entomological Notes of the Season of 1883. Trans. Min- nesota State Hort. Soc, 1884, pp. 142-143. Mentions characters, food habits, injuries, and remedies. 1884-1887. Moore, F.— The Lepidoptera of Ceylon, III, p. 57, figs. 1, la, of pi. 150. Brief description of adult and larva; food of larva given as rosebuds; figures colored but- rather poor. 1884. Rathvon, S. S. — The Corn w^orm {Heliothis armigera) . Agric Pennsylvania, Rept. State Bd. Agric. f. 1883, pp. 238-244, fig. Good account of habits, life history, etc., on corn, including general descrip- tions of stages, with poor figures of the larvae on corn, of the adult, pupa, and cocoon. Contains many errors. 1885. Riley, C. V.— The Bollworm. 4th Rept. U. S. Ent. Commission, pp. 355-385. . An excellent account, including the principal kno\vn facts up to that time. 1885. Webster, F. M.— Insects Affecting the Corn Crop. Rept. Indiana State Bd. Agric, XXYII, pp. 200-201, pis. V, fig. 4; VI, fig. 1. Brief account, with synonymy. 1887. Meyrick, Ed w.— Monograph of New^ Zealand Noctuina. Trans. N. Zeal. Inst. XIX (n. series II), 1886, pp. 34-35. Distribution, description of adult, and larval food plants. 1888. Kent, G. H. — Some notes from Mississippi. Insect Life, I, p. 17. But little injury to corn and cotton in 1887. 142 L888. Kent, G. H.— Injurious Insects in Mississippi for 1888. Insect Life, I, p. 217. Mentioned as abundant on late corn; also injured cotton. 1889. BoNHAM, L. N. — Blackbirds rs. Bolhvorms. Insect Life, II, p. 47. Blackbirds observed feeding on boUworms in ears of corn. 1889. Bruner, L. — Report of the Entomologist. Ann. Kept. Xebraska State Bd. Agric. f. 1888, pp. 95-97. T7cZe Bruner (1891). 1889. CoQi'iLLETT, D. W. — The Corn Worm or Bollworm in California. Insect Life, I, pp. 331-332. Mentions pupation in the ears of corn. Food plants of larva; new parasite bred and described as Tachina armigera. 1889. Cotes, E. C— Indian Museum Notes, No. 1, I, pp. 50-51. Reference made to bolhvorms injuring poppy. 1889. Cotes, E. C. — Entomology Notes; HeUothis armiger. Indian Mus. Notes, I, pp. 97-103. An account of the insect as injurious to opium. 1889. Druce, II. — HeUothis aurniger". Biol. Centrali-Amer., Ins'ects, Lep. Het., I, pp. 299-300. Synonymy and habits; variability, 1889. Editors.— Notes and News. Science, N. Y., XIV, No. 346, Sept. 20, 1889, pp. 196-197. Bollworm active in all sections of the cotton belt; gives total loss to cotton from combined insect attack. 1889. Kent, G. H. — Notes of the Season from Mississippi. Insect Life, II, p. 283. Includes brief note on occurrence of the bollworm on cotton and corn in 1889. 1889. Riley, C. V., and L. O. Howard.— A Bollworm Letter. Insect Life, I, p. 320. London purple and Paris green advised. 1889. Riley, C. Y., and L. 0. Howard.— The Bollworm in Texas. Insect Life, II, pp. 20-21. A correspondent attributes a yearly loss to cotton of from S300,000 to 8400,000 from the bollworm. 1889. TowxsEND, C. H. T. — Some Michigan Notes Recorded. Insect Life, II, p. 42. Bolhvorms observed but once during a period of 12 years. In 1881 were fre- quently observed in green corn. 1889. AVashburx, F. L. — Corn Worm. Bui. No. 3, Oregon Agric. Exp. Sta., pp. 7-9, figs. K, 20, 22. An account of the insect in Oregon, with suggestions for remedies. Had been known in the State for about 8 or 10 years previously. Three generations are reported. Figures stages, and injured corn. 1889. WooDwoRTH, C. W. — Report of the Entomologist. Ann. Rept. Arkansas Agric. Exp. Sta. f. 1889, p. 146. Economic notes. 1890. Beckwith, M. H. — Report of the Entomologist. 2nd Ann. Rept. Delaware Agr. Exp. Sta., 1889, pp. 126-128, fig. 24, p. 132. A reprint of Bui. 4, Del. Agric. Exp. Sta. 1890. Kent, G. H.— Notes from Mississippi. Insect Life, III, p. 338. Bollworm reported as having reduced cotton crop fully two-fifths in 1890. 1890. LixTNER, J. A.— The Cut Worm. Cult, and Country Gentleman, July 24, 1890, LY, p. 590. Answer to correspondent; advises sugaring, and cites an instance in which isuccessful. 143 1890. Martin, G. A.— The Corn Worm or Boll worm. Amer. Agriculturalist, 1890, p. 418. Record of injury in New Jerse}', including notes on habits and treatment. 1890. MuRTFELDT, M. E.— Eutomological Notes for the Season of 1890. Bui. No. 23, old series, Div. Ent., U. S. Dept. Agric, p. 46. Noted as especially injurious in Missouri in 1890. 1890. Neal, J. C— Entomological Notes. Bui. No. 9, Florida Agric. Exp. Sta., p. 8. Deep winter plowing recommended. 1890. Olliff, a. S. — Insect Pests — The Maize Moth {Ileliothis armiger). Agric. Gaz. N. South Wales, I, pp. 125-127, PI. II, figs. 1-8. Tolerably good general account, with poor figures. 1890. Riley, C. V., and L. O. Howard.— The Boll worm. Insect Life, II, p. 317. Paris green recommended for poisoning the larvae. 1890. Riley, 0. V., and L. O. Howard. — London purple and Paris green for the Bollworm. Insect Life, III, pp. 123-124. Recommended for control of the bollw^orm, with directions for their use. 1890. Smith, J. B. — The Corn Worm. Report of the Entomologist. Ann. Rept. N. Jersey Agric. Exp. Sta. f. 1890, pp. 516-518. Unusual injury to corn mentioned; two broods recorded for New Jersey. 1891. Bruner, L.— Bui. No. 23, old series, Div. Ent., U. S. Dept. Agric, p. 9. Less destructive to corn than usual along the Mississippi River in 1890. 1891. Clark, J. W. — Damage to Geraniums by Heliothis; cannibalistic habit of the larva. Insect Life, III, p. 399. Notes damage to geraniums in greenhouse at Columbia, Missouri. 1891. Cotes, E. C— Agricultural Entomology. Jour. Bombay Nat. Hist. Soc, VI, p. 240. Lecture delivered before the Agricultural-Horticultural Society, Calcutta, March 19, 1891. The bollworm on pods of opium popjoy in India; larva omnivorous. Very interesting notes on local habits in regard to food and mode of pupation. Cotes, E. C. — Indian Museum Notes, II, p. 24. Remarks on habits and food plants. Hunter, W. N. — Injurious Insects of Nebraska. Insect Life, IV, p. 132. Serious injury to corn is reported in Nebraska in 1891. Mally, F. W.— The Bollworm of Cotton. Bui. No. 24, old series, Div. Ent., U. S. Dept. Agric, p. 50. A report of progress in a supplementary investigation of the bollworm. 1891. Mally, F. W. -^Report of Progress in the Investigation of the Cotton Bollworin. Bul. No. 26, old series, Div. Ent., U. S. Dept. Agric, pp. 45-56. Discusses distribution, food plants, characters and transformations, number of broods, hibernation, natural enemies and remedies. 1891. Riley, C. V. — Report of the Entomologist. Ann. Rept. U. S. Dept. Agric. f. 1890, pp. 240-241. Remarks on the supplementary investigation of the bollw^orm undertaken in . 1890. 1891. Riley, C. V.— The Outlook for Applied Entomology. Insect Life, III, p. 181. Arsenical poisons advised for the bollworm, with directions for use. 1891. Smith, W. W. — Abundance of Lepidoptera in New Zealand. Entomologist, London, XXIV, p. 213. Distribution and occurrence. Discusses theory of distribution. 1891. Townsend, C. H. T.— Notes of Interest. Insect Life, IV, p. 26. Includes reference to injury to corn by boll worms in New Mexico, during July, 1891. 22051— No. 50—05 10 144 1891'. TozzETi, Ad. Targioni. — Animali ed insetti del tabacco in Erba e del tabacco secco. Firenze-Roma, pp. 275-278, Tav. Ill, fig. 1, text fig. 96. Good account with synonomy, names, and description of the adult. Figures larval injury to tobacco, and gives habits, food plants, etc. Eemedies briefly noted. 1891. AVebster, F. M. — Early Published References to Some of Our Injurious Insect*, II. Insect Life, IV, p. 326. Records occurrence of what is probably Heliothis obsoleta in 1820 on cotton; and in 1842 on corn in Illinois. 1892. Arkle, J. — A Tomato Caterpillar {Heliothis armigera). Entomologist, London, XV, pp. 237-238. Life-history notes on larva? in tomatoes imported from Valencia; range and food plants. 1892. Bruner, L. — Report of the Entomologist. Ann. Rept. Nebraska State Bd. Agric. f. 1891, pp. 252-255. General considerations. Common injurious insect to corn in Nebraska. 1892. Garman, H.— Rept. Kentucky Agric. Exp. Sta. f. 1889, p. 9. Brief account of injury in Kentucky. 1892. Harvey, F. L. — Report of the Entomologist. Ann. Rept. Maine Agric. Exp. Sta. f. 1892, pp. 119-123, fig. 4. The bollworm or cornworm is figured and described with remedial measures. Apparently the first record of injury in Maine; one brood reported. 1892. Mullen, S. B. — Corn as a trap crop for the Bollworm. Insect Life, V, p. 48. Tomatoes reported protected by use of corn as a trap crop. 1892. Neal, J. C— Insects. Bui. No. 3, Oklahoma Agric. Exp. Sta., pp. 9-11, fig. 5. General account with old figure. 1892. Smith, J. B.— Report of the Entomologist. Rept. N. Jersey Agric. Exp. Sta. f. 1892, pp. 441-446. General considerations in New Jersey; number of broods. 1892. Smith, J. B. — Notes of the Year in New Jersey. Insect Life, V, p. 93. Includes reference to serious injury to tomato in New Jersey by the bollworm; locally known as the "heart-worm." 1892. TowxsEND, C. H. T. — The Possible and Actual Influence of Irrigation on Insect Injury in New Mexico. Insect Life, V, p. 78. Expresses the opinion that irrigation will destroy pupae of bollworm in the ground. _ 1892. TuTT, J. W.— The British Nocture and Their Varieties, III, pp. 121, 128. Its remarkable distribution mentioned; varies excessively. Varieties fusca Ckll., ochracea CklL, and uinbrosus Grote listed; subvariety eumaculata. 1893. Alwood, W. B. — Insects and Insecticides. Bui. No. 24, Virginia Agric. Exp. Sta., p. 13. Brief account, with remedial suggestions. Protecting corn by appHcation of strong tobacco decoction, etc., to the silks. 1893. Bairstow, S. D. — The Bollworm or Corn Worm of the southern United States — The Peach Underwing of the Cape. Agric. Jour., Dept. Agric. Cape Colony, S. Africa, 1893, VI, p. 81. Reported serious enemy to peaches in 1892, in Cape Colony. 1893, Cotes, E. C— Conspectus of the insects which affect crops in India. Heliothis armiger. Indian Mus. Notes, II, No. 6, p. 160. List of Indian food plants. 145 Editors. — The Maize Moth {Heliothis armigera, Hub.)- Agric. Gaz. N. South Wales, IV, pp. 213-214. Notice of injury, with discussion. Mally, F. W.— The Bollworm of Cotton. Bui. No. 29, old series, Div. Ent., XJ. S. Dept. Agric, pp. 73. Final report on investigations; treats of natural enemies, and habits; remedies and bacteriological experiments with insect diseases. Morgan, H. A. and F. H. Burnette. — Bui. No. 22, Louisiana Agric. Exp. Sta., p. 698. Record of experiments in growing sweet corn to avoid bollworm. injury. Rolfs, P. H. — Enemies of the Tomato. Bui. No. 21, Florida Agric. Exp. Sta., pp. 19-23. General account as an enemy to tomatoes. Smith, J. B.— Ent. News, 1893, p. 10. Injury to early tomatoes in New Jersey. Remedies. Stedman, J. M. — Injurious and Beneficial Insects. Some Insect Pests of the Farm and Garden. Bui. No. 45, Alabama Agric. Exp. Sta., pp. 32-34, 35-36, figs. Popular account, with figures after Riley. Webster, F. M. — Insect Foes of American Cereal Grains, with Measures for their Prevention or Destruction. 24th Ann. Rept. Ent. Soc. Ontario, pp. 91-92. Number of broods in the North ; suggests remedies. Weed, H. E. — Remedies for Insects Injurious to Cotton. Insect Life, VI, pp. 168-170. Consideration of remedial measures for the bollworm. Ashmead, W. H. — Notes on Cotton Insects found in Mississippi. Insect Life, VII, p. 25. Reference is made to an investigation of the bollworm in Mississippi. DuPre, J. F. C— Bui. No. 16, S. CaroHna Agric. Exp. Sta., p. 3. Notes destruction of tomatoes, and suggests hand picking as a remedy. Hampson, G. F. — Heliothis armigera. Fauna British India, II, pp. 174-175, .fig. 114. Good account with synonomy and figure; brief description of the larva, men- tioning rose buds as food. OsBORN, Herbert. — Corn Insects. Bui. No. 24, Iowa Agric. Exp. Sta., pp. 1003-1004, figs. 10, 11. Brief descriptive notes, life-history, and remedies included. Two broods for Iowa. Riley, C. V. — Report of the Entomologist. Ann. Rept. IT. S. Dept. Agric. 1893, pp. 199, 208. References to special bollworm investigations. Smith, J. B. — Notes of the Year in New Jersey. Insect Life, VII, p. 185. Reports serious injury to tomatoes in southern New Jersey. Webster, F. M.— Bui. No. 51, Ohio Agric. Exp. Sta., p. 138. Brief notes; number of broods. LouNSBURY, C. P. — Some Injurious Insects. Bui. No. 28, Mass. Agric. Exp. Sta., pp. 16-17, fig. 8, a-f. Brief account, with old copied figures of the stages. Lugger, O. — The Sweet-corn Moth or Tassel-worm. Bui. No. 43, Minnesota Agric. Exp. Sta., pp. 196-200, pi. 11, fig. 54. General account of life-history, enemies, and remedies, with figures of the stages from photographs. 146 1895. MussoN, C. T. — Entomological Notes. Agric. Gaz. N. South Wales, VI, p. 263. The army worm; brief account of occurrence and remedies. 1895. Weed, H. E. — Insects Injurious to Corn. Bui. No. 36, Mississippi Agric. Exp. Sta., pp. 150-152. Popular account of life-history with remedies. 1896. Lowe, Y. H., and F. A. Sirkine. — Report of the Entomologists, Kept. New York State Agric. Exp. Sta. 1895, pp. 559-565. Discussion with especial reference to injuries to sweet corn in southeastern New York in 1895. Fall plowing recommended for the north. 1896. Arkle, J. — Heliotliis armigera imported with tomatoes. Entomologist, Lon- don, XXIX, p. 334. Records importation; habits of larvre in confinement. 1896. AsHMEAD, W. H.— Proc. Ent. Soc. Washington, lY, p. 32. Brief remarks on the cause of variation in the adult. 1896. CocKERELL, T. D. A.— Bui. No. 19, N. Mexico Agric. Exp. Sta., p. 102. Brief note of injury to corn in New Mexico; food-plants of larva. Adult varieties mentioned. 1896. Hopkins, A. D. and W. E. Rumsey.— The Corn-ear Worm. Bui. No. 44, W. Virginia Agric. Exp. Sta.-, p. 282. Mentions number of broods; brief account. 1896. Howard, L. O.— Insects Affecting the Cotton Plant. Bui. No. 33, Office of Exp. Stations, U. S. Dept. Agric, p. 328. Full account, with directions for control. 1896. Price, R. H. — Saving Corn from the Boll worm. Amer. Gardener XVII, No. 83, p. 468. Brief note; clipping ends of young ears recommended. 1896. QuAiNTANCE, A. L. — Insect Enemies of Truck and Garden Crops. Bui. No. 34, Florida Exp. Sta., pp. 264, 309-314, 323, 326. Brief biological notes, and suggestions for control on tomatoes. 1896. QuAiNTAxcE, A. L. — Brief Notes on the More Injurious Insects of the Year. Rept. Florida Agric. Exp. Sta., 1896, p. 57. Larvae noted as feeding on the vines and leaves of tomatoes. 1896. Smith, J. B. — The boll worm; corn worm. Economic Entomology, Philadel- phia, pp. 303-305, figs. 342, 343. Popular account, with remedies. 1897. Froggatt, W. W. — Report upon Insect Pests found in the Northern District, May, 1897. Agric. Gaz. N. South Wales, VIII, p. 717. The most destructive pest to maize; urges protection of insectivorous birds; brief account. 1897. Garmax, H. — Notes on the Several Tobacco Insects, and on several imper- fectly known Diseases of Tobacco. Bui. No. 66, Kentucky Agric. Exp. Sta., p. 35. Note on injury to tobacco. 1897. Hillman, F. H. — Some Common Injurious Insects of Western Nevada. Bui. No. 36, Nevada Agric. Exp. Sta., p. 19. Brief notes; destructive to sweet corn and occasionally to tomatoes; two broods. 1897. Howard, L. O. — Some Miscellaneous Results of the Division of Entomology. Bui. No. 7, n. series, Div. Ent., U. S. Dept. Agric, p. 84. Notes from correspondents. Injuring strawberries in fall. 1897. Howard, L. 0.— Insects Affecting the Cotton Plant. Farmers' Bui. No. 47, U. S. Dept. Agric, p. 10. Revised account. Vide Howard (1896). 147 1897. Morgan, H. A.— Bui. No. 48, Louisiana Agric. Exp. Sta., p. 155. Moths observed in large numbers in grass, surrounding electric lights. 1897. Webster, F. M. and C. W. Mally. — Insects of the Year in Ohio. Bui. No. 9, n. series, Div. Ent. U. S. Dept. Agric, p. 41. Records injury to ripening peaches, to ripening tomatoes, and to geraniums in the fall, in greenhouses. 1898. Chittenden, F, H. — Insects Injurious to Beans and Peas. Yearbk. U. S. Dept. Agric, 1898, p. 255. Brief account of injuries to those crops. 1898. Curtis, W. P. — Heliothis armigera. Entomologist, London, XXXI, p. 45. Records importation from Portugal with tomatoes. 1898. Fernald, H. T. — Supplementary Report of the Zoologist. Rept. Pennsylvania Dept. Agric, 1898, l^t. I, pp. 426-427. Brief discussion; reported quite abundant; from two to three broods. 1898. Howard, L. O. — The Principal Insects Affecting the Tobacco Plant. Yearbk. U. S. Dept. Agric, 1898, p. 132. Brief account as injurious to tobacco. 1898. Hudson, G. V. — New Zealand Butterflies and Moths (Macrolepidoptera), Lon- don, pp. 32-33, figs. 40, 41 of pi. V. Occurrence, variation, food plants, and distribution. Poor colored figures of male and female. 1898. Quaintance, A. L. — Preliminary Report upon the Insect Enemies of Tobacco in Florida. Bui. No. 48, Florida Agric Exp. Sta., p. 185. Recorded as injuring tobacco buds; remedy suggested. 1898. Rolfs, P. H.— Diseases of the Tomato. Bui. No. 47, Florida Agric Exp. Sta., pp. 141-143. Hand picking of the infested fruit recommended. 1898. South, Richard. — Heliothis armigera. Entomologist, London, XXXI, pp. 17-19. History of in England to date; mentions injury in the United States, with food plants. 1898. Webster, F. M. and C. W. Mally. — The Army Worm and other insects. Bui. No. 96, Ohio Agric. Exp. Sta., pp. 15-18, pi. Ill, fig. 1; pi. IV, fig. 1. Number of generations in southern and northern Ohio. Tachinid parasites of larva. 1899. Cockerell, T. D. A. — Some Insect Pests of the Salt River Valley and Reme- dies for them. Bui. No. 32, Arizona Agric. Exp. Sta., p. 32. Brief notes; injury to corn; refers to the advantage of planting sweet corn late, in New Mexico, to avoid injury. 1899. Dearness, J. — The Cotton Bollworm in Canadian Corn. 29th Ann. Rept. Ent. Soc Ontario, 1898, pp. 64-65. Prevalence of the bollworm in corn in Ontario in 1898. 1899. Fletcher, James. — The Corn Worm. 29th Ann. Rept. Ent. Soc. Ontario, 1898, p. 82. Remarks on occurrence and ravages in Ontario. 1899. Fletcher, James. — Recent Addition to the List of Injurious Insects of Canada. Trans. Royal Soc Canada, series 2, V, section iv, p. 215. H. obsoletahy no means frequent, but occasionally very injurious to sweet corn. FiV/g preceding. 1899. Meyrick, Edw.— Macrolepidoptera. Fauna Hawaiiensis, I, pt. ii, pp. 137, 152. Localities in Hawaii; mentions adult variability and the synonymic variety ^'^'^f'>vin Walker; presence of a native race. 148 1899. QuAiNTAXCE, A. L. — Some Insects and Fungi Destructive to Truck and Garden Crops. Proc. 23d. Ann. Meeting Georgia State Hort. Soc, pp. 51-52. Serious injury to sweet corn and tomatoes noted. 1899. Smith, J. B. — Heliothis armiger. Insects of Xew Jersey. Suppl. 27th Ann. Eept. Xew Jersey State Bd. Agric, 1899. p. 426, fig. Brief remarks. 1900. Barlow, E. — Notes on the Insect Pests from the Entomological Section. Indian Museum. Indian Mus. Xotes, V, Xo. 1, pp. 22-23. Brief economic notes. 1900. Editorial. — Les Plantes de France. Leurs Chenilles et leurs Papillons. Le Xaturaliste, XXII (series 2, XIY), pp. 44, 55, 151. Larva recorded feeding on the following: Cucurbita, Cannabis, and Ajonc europceus, with brief notes on distribution. 1900. Froggatt, W. W. — Cutworms. Agric. Gaz. X. South Wales, XI, p. 530. Answer to correspondent. Larvae on tomatoes; recommends poisoning with Paris green. 1900. GossARD, H. A.— Ann. Kept. Florida Agric. Exp. Sta., 1899, p. 75. Mentions severe injury to tomatoes in Florida. j 1900. GuERCio, G. DEL. — Biological and Economical Xotes on the Bollworm. Xuove ' Relaz R. Staz. Agric, series I, 1900, Xo. 3, pp. 143-159. Description of stages and account of habits, life-history, and natural enemie> : list of remedies. Recommends tobacco decoction. 1900. Lea, A. M. — The More Common Insect Pests of the Farm and Garden. Jour. Dept. Agric. AVest Austraha, II, pt. 6, pp. 404-407. Brief notes. 1900. Leech, J. H. — Lepidoptera Heterocera from Xorthern China, Japan, and Corea, III. Trans. Ent. Soc. London, 1900, p. 22. Heliothis obsoleta and H. succinea listed separately with synonymy and distribu- tion of each. Lender succinea, Heliothis armiger is listed as a synonym. 1900. Quaintaxce, A. L. — Insect Xotes. Rept. Georgia Agric. Exp. Sta., 1900, p. 362. Includes brief notice of ravages of the bollworm. 1900. Sanderson, E. D. — The Corn Ear Worm. Ann. Rept. Delaware Agric. Exp. Sta., 1900, p. 209. Record of serious injury to sweet com in Maryland and Delaware. Three broods recorded. 1900. Smith, J. B. — The Corn Worru. Rept. of the Entomologist. Rept. X. Jersey Agric. Exp. Sta. f. 1900, p. 490. . , Extent of injury to corn in Xew Jersey. Fall plowing recommended. m 1900. Smith, W. W. — Heliothis armiger. Entomologist. London, XXXIII. pp. 201-202. Mentions erratic occurrence in Xew Zealand; moths captured by a plant. 1900. South wick, J. M. — Report of the Entomologist. Rept. Rhode Island State Bd. Agric, 1900, pp. 34-35. Record of injuries in Rhode Island; probably but a single brood. 1901. Froggatt, W. W. — Caterpillar Plague, with account of the Potato Pests at Windsor. Agric. Gaz. X. South Wales, XII, p. 241. Recorded as injuring potatoes; one to two inches beneath the soil during the day and feeding at night like cutworms. There called the common cutworm. 1901. Lochhead, Wm.— Insects of the Season of 1900. 31st Ann. Rept. Ent. Soc. Onta- rio, 1900, p. 75, fig. Remarks on occurrence in Ontario; one brood probable; poor figure of injury to corn. 149 1901. MuRTFELDT, M. E. — Drouglit, Heat, and Insect Life. Bui. No. 31, n. series, Div. Ent. U. S. Dept. Agric, p. 97. The effects of drought on the bollworm noted. 1902. Sanderson, E. D. — Insects Injurious to Staple Crops, New York, pp, 27, 201- 205, figs. 115, 124, 125. General account of the bollworm. 1903. Hampson, G. F. — Catalogue Lepidoptera Phalaense in the Collection of the British Museum, IV, pp. 45-46, fig. 18. Includes in the genus Chloridea, with text-figures of moth and details; synon- omy, and a long list of localities given. 1903. Hart, C. A. — Synopsis of Insect Collections for distribution to Illinois High Schools. Lepidoptera. Illinois State Lab. Nat. Hist., 19Q3, p. 38, fig. 51. Mentions food, broods, and habits, and that adults were common at lights in the fall. 1903. Holland, W. J. — Heliothis armiger Hiibner (The boll-worm). The Moth Book, N. Y., 1903, pp. 222-224, pi. xxvii, fig. 17, text-figs., 130, 131. Brief popular account; rather good colored figure of a male; text-figures after Riley. 1903. QuAiNTANCE, A. L. — The Cotton Boll Worm. Proc. 2nd Ann. Session Texas Cotton Convention, Dallas, Tex., Nov., 1903, pp. 50-60, figs. 1-4. Abstract of an illustrated lecture delivered before the Texas Cotton Conven- tion at Dallas, Tex. General account, with illustrations of the injury to corn and cotton. 1903. Sherman, Franklin, Jr. — The Cotton Bollworm. Entomological circ. No. 2, N. Carolina Dept. Agric. Oct. 31, pp. 1-6. Condensed account, with remedial measures. 1904. Forbes, S. A. — The more Important Insect Injuries to Indian Corn. Bui. No. 95, Illinois Agric. Exp. Sta., p. 397. General account as an enemy of corn in Illinois. 1904. Quaintance, A. L. — Bollworm. Proc. Ent. Soc. Washington, VI, p. 66. A few brief notes; records the number of eggs deposited by moths in confine- ment as 2,200. 1904. Quaintance, A. L. — The Cotton Bollworm: An account of the Insect, with results of Experiments in 1903. Farmers' Bui. No. 191, U. S. Dept. Agric, pp. 24. An account of the ravages, natural history, and habits of the bollworm, with results of a supplementary investigation of the insect in Texas in 1903. 1904. Quaintance, .A. L. — Boll Worm in Texas. Farm and Ranch, Texas, July 16, 1904, pp. 13, 17. Abstract of an illustrated lecture delivered before the Farmers' Congress, Col- lege Station, Tex., July, 1904. History of the bollworm in the Southern States, and scope of the work of the U. S. Department of Agriculture in Texas in 1904. 1904. Theobald, F. V.— The Cotton-boll Worm {Heliothis armiger). ' 2nd Rept. on Economic Zool., Brit. Mus., Nat. Hist., pp. 114-115. A statement of the information sent to the U. S. Department of Agriculture, on request, in regard to this insect. Gives distribution in India and Austra- lia, and methods used to prevent injury. 1905. Quaintance, A. L., and F. C. Bishopp.— The Cotton Bollworm: Some Obser- vations knd Results of Field Experiments in 1904. Farmers' Bui. No. 212, U. S. Dept. Agric. Results of investigations in 1904. INDEX. Page. Acacia sp 18 Africa, bollworm in 14, 19 Agelaiusphccniceus - 114 Alabama argillacea 13 Aletia 13,106 Alfalfa 18 eggs laid on 47 Allium canadense, eggs laid on 47 Amaranth 17, 47 Amarantus spinosus, eggs laid on ,47 Anosia plexippus 15 Aphiochastafuhgicola 126 nigriceps 126 Aphis maidis 94 Apiomcrvfi crampes 112 Archi/fdspiUn ntris 123 Ariliis rrisfdfas 112 Arizona, injury by bolhvorm in 29 Arsenical poisons 131 Asclepias tuberosa, eggs laid on 47 Asilidse 110 Asparagus 18 Astragalus caryocarpus 18 Atmospheric conditions, effect of, on eggs ... 54 growth 66 Attus cardinalis Ill fasciolatus Ill Australia, bollworm in 14, 20 Austroriparian area, destructivenessof boll- worm in 28 Avena saliva 18 Bacterial disease 124 Bxolophus bicolor 115 Baltimore oriole ; 115 Barley 18 Beans 18 character of injury to 71 eggs laid on 47 Bee martin 114 Bindweed 17 eggs laid on 47 Birds as bollworm enemies 113 Blackberries 19 Blackbird 114 Blue grosbeak 115 Blue jay 114 Bluebird 115 Blue-gray gnatcatcher 115 Bolls, character of injury to 70 Bombyx obsoleta= Heliothis obsoleta 11 Boreal zone, absence of bollworm in 25 Broods, number of 98 Page. Brown thrasher 115 Bud worm=bollworm 13 Bufo lentiginosus 112 valiceps ^ 112 Cabbage 18 California, occurrence of bollworm in 29 Calocoris rapidus 35 Calosoma angulatum Ill calidum Ill scrutator Ill Calycopis cecrops 105 Canada, inj ury by bollworm in 26 Canna indica 17 eggs laid on 47 Cannabis saliva 18 Cannibalism 79 among larvee 79 Cape gooseberry 20 Cardinal 115 Cardinalis cardinalis 115 Carnation 18 Carolina wren 115 Carolinian area, destructiveness of boll- worm in 27 Carpet weed, eggs laid on 47 Castor bean 19 Catalpa 19 Catbird 115 Centrums carolinus 114 Ceylon, bollworm in .' 20 Chsetochloa italica 18 Chenipodium sp 17 Chick-pea 18 Chipping sparrow 115 Chondestes grammacus strigatus 115 Chrysopa spp 108 Cicindela vulgaris 112 Citrullis vulgaris 17 Classification and synonymy 11 Coccyzxis americanus 114 Cocklebur 17 eggs laid on 47 Cnlaptes auratus luteus 114 Cold winters, effect on bollworm 26 Colinus virginianus 114 Collards 18 Color variation of larvae 56 effect of external conditions on . . . 63 Colorado grass 18 potato beetle 16 Common names 12 151 152 Conotelus obscurus 127 Copulation of moths 92 Corn, ear worin=bolhvorm 13 eai-s, damage to, by single larva 75 injury to. by boll worm 21 maturing, damage to. by single larva. 75 number of plants infested 78 oviposition on, by boll worm 42 preferred food of bollworm 21 sweet, percentage injured by boll- worm 22 young, damage to, bj^ .single larva 74 Corvus bmchyrhyncos 114 Cotton and cowpeas, comparative acreage in, by States 31 choice of different parts by larva. . . 71 damage to, by single larva 76 injury to, by bollworm in different States 23 by bollworm in United States 24 by other causes than bollworm 35 in relation to farm prac- tice 29 large acreage in relation to boll- worm injury 30 oviposition on, by bollworm 45 percentage injured yearly in U. S. by bollworm 25 percentage injured by bollworm in Texas 23 season of greatest injury to. by boll- worm 32 Cowbird 114 Cowpea 18 Co^vpeas, eggs laid on 47 Crab grass 18 eggs laid on 47 Cremnstogaster lineolata 108 Crested flycatcher 114 Crow 114 blackbird 115 Cucumber 17 Cucurhita pepo 17 Cucumis melo ^ 17 sativa 17 Cultivation, early and thorough 128 Cultural methods 128 Cyanociita cristata 114 Cyanosptia ciris 115 cyanea 115 Dahlia 17 Dakota, scarcity of bollworm in 27 Damage done by single larva 74 Datura stramonium . 18 eggs laid on 47 Delaware, destructiveness of bollworm in. . 28 Belphax maidis 94 Dendryphantes 7nd)iUs Ill Department of Agriculture, early investiga- tion of bollworm by 37 Deromyia angustipennis 110 umbrinus Ill Description of larval stages 57 I Page Destructiveness in relation to life zones in US 25 Diseases 124 Distribution in relation to life zones in U. S. 25 Dizoniasbicinctus ill Borymyrmex pyramicus 108 i Drosoph ila amjicloph ila 127 I punctulata 127 Duration of larval instars 63 Early fruiting cotton 129 Eating of shells and eggs by ncAvly hatched larvae 51 Ecdyses. number of 67 Ecdysis, process of 67 Economic .status in United States 21 Effective temperatures, relation to growth of larvte 64 relation to length of egg stage 52 relation to length of life cycle 102 Effective temperatures, relation to length of pupal stage 86 Effective temperatures, relation to number of generations 102 Egg, description of 41 development of 50 Egg laying, effect of fertilization on 49 plant IS stage, length of 52 Eggs destroyed by storms 55 distribution of, on cotton plants 46 effect of atmospheric conditions on . . . 54 submergence on 54 sun on 55 hatching of 50 in ovaries at death 49 infertile, deposition of 49 shrinking of 51 number laid by a single moth 48 parasites of 115 percentage that hatch , 52 Egj-ptian cotton, relative attractiveness of, to larvse 71 Embryology 50 Emergence of moths, time of 89 Era.c bastardii Ill lateralis Ill Erigeron canadense 17 Erythrina herbacea IS Eumenes bollii Ill Eupatorium serotinum 94 Euphorbia corollata 47 Euphorocera cla ripen nis 123 Euplectrus comstocJcii 122 Europe, bollAVOrm in 19 Euxesta annomr 127 Exarista ceratom iie 123 Falso sparverius 114 Fall plowing 128 Farm methods in relation to bollworm injury 29 FertUization. effect of, on rate of egg lay- ing 49 Fertilizers 129 153 Page. Field com, percentage injured by boll- worm 22 sparrow 115 Fig 18 Flicker 114 Florida, injury by bolhvorm to early toma- toes in 25 Flowers of cotton, character of injury to. . . 70 Food, choice of, by larvse 71 relation to larval growth 67 Food habits, cannibalism 79 carnivorous 80 choice of different parts of cotton plant 77 of moths.. - 94,95 of newly hatched larvse 68 preference of larvse for young fruit 72 relative attractiveness of Up- land and Egyptian cottons. . 71 Food plants of boll worm 17 Foreign countries, boliAVorm in 19 Forelius maccooMi 108 Freezing, effect of, on pupse 86 Frontina aletise 123 armigera 123 frenchii 123 Galeoscoptes carolinensis 115 Garden vegetables, scarcity of eggs on 48 Generations, number of 98 Genitalia of male 92 Geographical distribution 13 Geothylpis trichas braehydactyla 115 Geranium 18 Gladiolus 18 Gluttony of moths 93 Oenia capitata 123 Grape 18 Great-tailed grackle 115 Grosbeak 115 Ground cherry 18 Growth of larvae during instars 64 Guiraca cserulea 115 Habits of moths 93, 94 newly hatched larvse 68 Harpalus caliginosus-. Ill Hatching of eggs 50 Head casts of larvse, sizes of 65 Heart W()nn=bollworm 13 Hdiaiithiis sp 17 Helicohia helicis... 127 Heliopliila unipuiictata 104 Heliothis conferta=Heliothis obsolcta 11. interjacens = Helioth is obsoleta 11 obsolcta, wav.fascu 12 var. Jmivaiiciiiiis 12 var. ochracea 12 var. rubesccns 12 \ar.2im,brosa j2 var. umbrosa, sub-var. cu- macalata 12 pulverom=II. obsoleta 11 punctigera = H. obsoleta 11 Slice inea= II. obsoleta 11 umrbosus=^II. obsoleta \&v 11 uniformis = H. obsoleta 11 Page. Hemp 18 Hibernation of moths 104 Hibisctcs sp 17 Homalodisca triquetra 35, 106 Hordeum spp 18 Horned toad 113 Icteria virens 115 Ictems galbula 115 spurius 115 Ictinia mississip2yiensis 114 Idaho, occurrence of bollworm in 29 Illinois, destructiveness of bollworm in 28 Increase in numbers during season 104 Indian corn 17 Indiana, destructiveness of bollworm in... 28 Indigo bunting. 115 Ineffective methods of bollworm control . . 132 Infestation, progress of by generations 103 during season 103 Injury, character of, to corn 69 cotton 69 to early and late cotton compared. 74 Insects sometimes mistaken for the boll- worm 105 Instars, larval, description of 57 Ipomxa conwmtata 17 eggs laid on : 47 Japan, bollworm 20 Jimson weed 18 Johnson grass, eggs laid on 47 Kafir corn 18 Kingbird 114 Laphygma frugiperda 106 Largus cmctus 35 Larva, description of stages 57 Larvse, choice of food by 71 color variation of 56 effect of atmospheric conditions on growth 66 temperature on 66 growth during instars '. 64 growth of, in relation to effective temperatures 67 growth of, in relation to external conditions 66 growth of, in relation to food 66 habits of newly hatched 68 instars, duration of 63 mortality of young individuals 78 newly hatched, eating shells and eggs 51 effect of external conditions on . . . 68 number on a single cotton plant ... 78 parasites of 119 Late corn, planting of, in eastern part of cotton ) )e] t 32 LaUiiirns o,h>r