UNIVERSITY OF B.C. LIBRARY 3 9424 05047 296 5 PhUCESblNG-ONI at: J " - tffD-.'ji >^ MANUAL OF VEGETABLE-GARDEN INSECTS XI be TRural /iDaiuials Kditii) itv L. II. r.AILFA' ot Manu AL OF Gaki)KNIN«; — - linilcji Manual OF Fakm Animals — Harper Fa KM AND CtArdkn Hulk -liooK — Bailfy Manual of Fruit Inskcts — SUmjerlandant / C rosin/ Manl: AL OF Wk.kds — Georgia Thk Phuxing-.Manijal — Bailey Manu AL OF FiMiT DisF.ASFs — Ileslir dud Whetzel .Mant AL OF .Milk I'ijodu "IS — Stock'iii'i Mam- AL OF \'i:tii:TAi;Li;-( ) .\i;i)KN Inskcts- - C'roshj/ a „a LeoiKird Manu AL OF Tkkf Diskas Ks — Ii a II hi It :Manu AL OF 1Io.mi:-Makin< : — Tk// liensselaer. Rose, and Cannn MANUAL OF VEGETABLE-GARDEN INSECTS BY CYRUS RICHARD CROSBY AND MORTIMER DEMAREST LEONARD OF THE NEW YORK STATE COLLEGE OK AGRICULTURE AT CORNELL I'NIVEKSITV THE MACMILLAN COMPANY 1918 All rifffiis reserved COPTRIOHT, 191S, Bt TIIK MACMILLAN COMl'AXY. Set up and clcctrotypetl. Published September, iyi8. Xortoooli t^rrss J. S. Cu.«hiiiK Ci>. — Hcrwick & Smith Co. Norwood, Ma.H!)., U.S.A. JAMES FLETCHER STUDENT AND TEACHER FOR A QUAKTKH OF A CENTURY ENTOMOLOGIST AND I50TANIST TO THE DOMINION OF CANADA, NOTED FOR HIS STUDIES IN ECONOMIC ENTOMOLOGY AND FOR THE CLEARNESS AND ACCURACY OF THE PRESENTATION OF HIS WORK TO THE PUBLIC AND ENDEARED TO THE YOUNGER GENERATION OF WORKERS BY HIS KINDLY INTEREST AND ENCOURAGEMENT, THIS BOOK IS DEDICATED AS A TOKEN OF THE authors' ESTEEM Digitized by tine Internet Arciiive in 2010 witii funding from University of Britisii Columbia Library http://www.archive.org/details/manualofvegetabOOcros PREFACE In the present work we have attempted to bring together in concise and usable form what is known in regard to the habits, Ufe history and control of the insect enemies of vegetable-garden crops in the United States and Canada. ]\Iuch of this uifor- mation has been published in technical journals and in the bulletins and circulars of the State Experiment Stations and Federal Government, where it is available only to the special student who has access to the few large libraries that collect and preserve this type of literature. We have endeavored thoroughly to digest this mass of material and present it in a form adapted to the needs of the gardener and vegetable- grower. In regard to methods of control we have tried to eliminate as far as possible useless and impracticable recommendations and include only those found to be effecti\e under commercial conditions or such as would seem to be worthy of trial. It has seemed better to state frankly that the problem of control in certain cases has not been solved than to suggest remedies that would lead to disappointment. The chapter on cutworms and the accounts of several others of the lepidoptera wore written in collaboration with Dr. liobert Mathesoii. Wc arc under great obligation to Dr. \\ . T. M. Forbes for eritieistii and aid witli the lepidoptera; to Dr. F. (\ ^'an D\ke for the determination of beetles ; to Mr. (^harles Vin PREFACE W. Leiig for the fjift of sj)ccimcns ; to S. W. Frost for thi* use of photographs ; and to many others for similar fa\ors. Tlie drawings were made by Anna C. Strykc, Ellen Edmonson, Nellie H. Grosby and C II. Kennedy. Several of the illustra- tions are from photograi)hs previously published in bulletins by the late Prof. M. V. Slingerland, by Prof. G. \\. Ilcrrick and by H. II. Knight. C. R. Crosby. M. I). Lkoxakd. Cornell University, Ithaca, N. Y. May 28, 191S. CONTENTS CHAPTER I General Considerations PAGE 1 CHAPTER II Insects Injurious to Cabbage and Related Crops , Imported cabbage worm Potherb butterfly Southern cabbage butterfly Cabbage looper . Diamond-back moth Cross-striped cabbage worm Cabbage webworm Garden webworm Purple-backed cabbage Zebra caterpillar . Cabbage aphis Turnip aphis ^ Cabbage root-maggot Seed-corn Tuaggot Western radish maggot Harlequin cabbage bug Green soldier-bug Cabbage leaf -miners False chinch-bug . Cabbage curculio . Cabbage seed-stalk weevil Red turnip beetle . Other insects injurious to cahbage and related croi)s 4 7 7 9 12 14 10 18 19 21 22 27 29 30 37 38 42 43 47 19 50 50 51 CHAPTER III Pea and Bean Insects . * . . . . . . .54 Pea wee\il .......... 54 Rean wccxil ......... 57 Broad bean weevil ........ GO ix cox TEXTS Four-spotted boan weevil Cowpca wceNnl Bean leaf-beetle . Cirape eolaspis Bean Ladybird . . .* Bean thrips .... Pea aphis .... Bean aphis .... Garden flea-hopper Pea moth .... Bean leaf-roller Striped green bean caterpillar Graj' hair-streak .. Green clover worm Lima bean \ine-borer . Other pea and bean insects . CHAI'TKR IV Beet and Spinach Insect.s Spinach loaf-miner Beet leafhopi)er . Larper sugar-beet leaf-beetle Western beet leaf- beetle Sugar-beet webworm . Hawaiian beet webworm Spotted beet webwomi . Southern beet webworm Sugar-beet root-louse . S;)inach aphis Other beel and spinach insects Cll.M'TKI^ V iNSEf'T.S iNJURIOrs TO CrCTMHKH. S(irA'^lI ANH MkLON Striped cucumber beetle Western cucumber beetle Twelve-spotted cucumber beetle Western twehe-spotted cucumber beetle Belted cucumber beetle Squash bug CONTENTS XI Horned squash bug Melon leaf-bug Southern leaf-footed plant-bug Northern leaf-footed plant-bug Squash-vine borer Pickle worm Melon worm Squash ladybird Melon aphis Squash aphis Garden springtail Other cucumljer, squash and melon insects CHAPTP]U VI Potato Insects Colorado potato beetle Three-lined potato beetle Potato aphis Apple leafhoppcr Potato stalk-weevil Common stalk-borer Burdock borer Potato scab gnat Potato tul)er moth Other potato insects CHAPTER VII Tomato Insects Tomato worms Tomato stilt-bug . Eastern field wireworm Erinose of the tomato . Other tomato insects . CHAPTER VIII EcciPLANT Insects Eggi)lant tortoise 1)ectle Eggplant luce-bug Other egg])laut insects . 177 177 17S 179 Xll CONTENTS CHAPTER IX Insects Injurious to Cakiiot, Celehy, P \RSM1» AM) IvKl -ATKD Crops . 181 I Carrot rust-fly .... ISl Carrot beetle .... 1,S.J Black swallow-tail butterfly ISO Celery leaf-tyer .... ISO Celery looper .... I'.ll Tarnished plant-bug V.Y2 Negro-bug ..... !<>(•. Parsnip web worm 1<>7 Parsnip leaf-miner lU't Parsley stalk-wee\'il !'.»'.» Other carrot, celery and parsni]) insect s L'lM) CHAPTKR X Asi'AKAGUs Insects . Common as])aragiis beetle . Twelve-spotted asparagus l)eetle Asparagus miner Other asparagus insects 'JOl •JOl 2()S 'J 10 CIIAPTKK XI Corn Insects . Corn ear-worm Corn root-aphis . South(Tn corn root-worm Western corn root-worm Colorado corn root-worm Larger corn stalk-borer Lesser corn stalk-borer Brown fruit-chafer Stink-bugs . Other corn insects 211 •J 11 •J IS 'J'J'J 227 22S 221 > 2:51 2:i2 233 Sweet Potato Insects Tortoise lieetles . Sweet potato weevil CH.\I'TKi{ Xll 2.3.', 235 239 CONTENTS Xlll Sweet potato leaf-roller Sweet potato white-fly Other sweet potato insects CHAPTER XIII Onion Insects Onion maggot Onion tlirips Barred-winged onion fly Black onion fly Other onion insects PAGE 241 242 242 243 243 245 249 250 250 CHAPTER XIV Insects Injurious to Minor Vegetable Crops . . . 251 Rhubarb 251 Okra 253 Salsify 255 Pepper .......... 255 Water-cress .......... 257 Lettuce 258 CHAPTER XV Cutworms and Army-worms Spotted cutworm Well-marked cutworm . Greasy cutworm . Red-backed cutworm . Dark-sided cutworm Striped cutworm . Dingy (nitwonn . Shagreened cutworm Granulated cutworm . Clay-backed cutworm . Black army cutworm . Variegated cutworm White cutworm . Glassy cutworm . Yellow-licaded cut worm 260 262 263 2()5 267 268 270 271 272 273 274 275 276 278 279 281 XIV rOXTEXTS Spotted-lepfijed cutworm Speckled cutworm Clover cutworm . Bristly cutworm . Bronzed cutworm Army (-utworm Army- worm . Fall arm \'- worm . Beet army-worm . Yellow-striped army- worm Semi-tropical army- worm Other cutworms . Control of cutworms and armv-worms PAOE •JS2 2,S3 2S4 2S5 2S(i 2S7 2S.S 202 204 20r) 297 2«.)S 2<)S CIIAPTKFJ XVI Blister-Beetles Striped blistcr-ln'ctlc . ]Marfi;incd blister-beetle (Jray blister-beetle Asli-fjray lilister-beetle Black blister-beetle Nuttali's blister-beetle Spotted blister-beetle . Two-spotted blister-beetle Miscellaneous blister-beetles Cleans of controlliiif;; l)lisler-beetlos CHAl'TIlK XVil Flf:a-Beetle.s Potato flea-beetle Western potato flea-l)(>etl(> Tobacco flea-b(>etle ERfrplii'it flea-beetle Pale-striped flea-beetle Red-headed flea-beetle Smart weed flea-b<>etle . Striped cabl);itje flea-beetle Sinuate-striped iltu-beetle Western cabbai'e flea-l)eelle 302 302 3or> :iO(> 307 30S 300 300 310 311 313 314 31 S 310 320 321 323 323 324 320 327 CONTENTS XV PAGE Horse-radish flea-beetle 328 Spinach flea-beetle 329 Yellow-necked flea-beetle 331 Three-spotted flea-beetle 331 Larger striped flea-beetle 332 Sweet potato flea-beetle 332 Desert corn flea-beetle . 334 Hop flea-beetle 335 Means of controlling flea-lwetles 336 CHAPTER XVIII Unclassified Pests 338 Root-knot nematode . 338 Sugar-beet nematode . 342 Millipedes . 342 White grubs . . 344 Wireworms . . 347 Grasshoppers . 350 Red-spider . . 351 Slugs . . 354 Yellow bear caterpillar . 357 Salt-marsh caterpillar . 359 CHAPTER XIX Insects and Insecticides 361 Structure of insects 361 Insecticides , 368 MANUAL OF VEGETABLE- GARDEN INSECTS CHAPTER I GENERAL CONSIDERATIONS It was estimated by C. L. Alarlatt in 1909 that the annual loss caused to vegetable and truck crops in the United States by insect pests amounts annually to 20 per cent of their value, or $68,000,000. This sum includes the cost of insecticides and other expense incurred in fighting vegetable insects. Insects affect vegetable crops in various ways. They feed on the leaves, devour the roots, tunnel the stems and infest the seeds and fruits. In many cases their injuries to succulent parts of the plant give entrance to decay-producing organisms which greatly augment the damage. Insects also act as carriers of specific diseases, the most remarkable instances of this kind being the transmission of the curly-leaf disease of the beet by the beet leaf-hopper and the carrying over winter of the bacterial wilt of cucurbits by the striped cucumber beetle. The enemies of vegetables here treated are, with five excep- tions, members of that class of animals known as insects. These exceptions are : the red-spider and the mite producing erinose of the tomato, which are Arachnids ; snails or slugs, belonging to the molluscs ; millipedes belonging to the Myriapoda and the root-knot nematode, one of the true worms. Some vegetable insects are general feeders, attacking a great variety of plants, but the greater number are more or less B 1 2 MANUAL OF VECETA BLE-CARDEX IXSECTS restricted to a single family or other closely related group of plants, both wild and cultivated. Thus many beet insects also feed on weeds belonging to the goosefoot family, cabbage insects on weeds of the mustard family, potato insects on wild solanaceous plants and sweet potato insects on wild morning- glories. This fact, that certain insects form more or less definite associations with certain groups of plants, is of great practical importance and must be kept in mind when considering methods of preventing injury. It also explains why clean farm- ing is one of the most important factors in preventing insect injuries to vegetable crops. In fact, clean farming together with proper cultural practices often makes it unnecessary to re- sort to special remedial measures, or at least renders it possible to obtain more effective results from the use of insecticides. About 250 species of insects have been recorded as .serious enemies of vegetable crops in the United States and Canada l)ut a much larger number may occasionally become injurious. Only the mt)re important species are treated in the following chapters, arranged under the crops to which they are most injurious. Flea-beetles, blister-beetles, cutworms and other general feeders are discussed in separate chapters. CHAPTER II INSECTS INJURIOUS TO CABBAGE AND RELATED CROPS In this chapter are treated the more important insect enemies of cabbage, cauliflower, brussels sprouts, kohlrabi, kale, col- lards, radish, turnip, mustard and horse-radish. With the exception of horse-radish, these form a natural group of food plants that serves as the common host for a large number of insects, which, although showing a preference for certain crops, can also thrive on the others. Many cruciferous weeds are also food plants of these pests and may serve as centers of in- festation from which the insects spread to cultivated crops. The most important enemies of cabbage and related crops in this country have been imported from the Old World but some of the native insects have found in these succulent vegetables satisfactory food plants. Of European origin are the cabbage root-maggot, the common cabbage worm, the diamond-back moth, the cabbage aphis, the cabbage curculio and the cabbage seed-stalk weevil. The cabbage webworm had its original home in the Old World tropics and the harlequin cabbage bug spread into the ITnited States from Central America during the last half century. Horse-radish has relatively few insect enemies, the most important being the harlequin cabbage bug and the horse- radish flea-beetle. Cabbage and related crops are often seriously injured by cut- worms and flca-bcetlcs. These insects are treated in Chapters XV and XVn. 3 MANUAL OF VEGETABLE-GARDES IXSECTS The Imported Cabbace Worm Pordia rnp/i Linnaeus The common white cabbage butterfl\- of the T'nited States and Canada is a native of the Old World. It was first intro- duced into America at Quebec about 1860. Later independent introductions occurred at Xew York in 1SG8, at Charleston, South Carolina, in IST'-i and at Apalachicola. Florida, at about the same date. From these points as centers the insect spread rapidly and by ISSo it occupied practically the whole territory east of the Pacific slope. The favorite food plant of the im- ported cabbage worm is cabbage, but it also attacks cauli- flower, turnip, horse-radish, radish, mustard, gillyflower, nasturtium and sweet alyssum and it also feeds on a number of wild plants belonging to the mustard family. The cater- pillars are sometimes found abundantly on mignonette. The imported cabbage worm hibernates in the i)upal state and the white butterflies emerge in early spring, being among the first to ai)pear in our fields and meadows. Their flight is low and unsteady and they alight at fre(|uent iiiter\ ids. The female deposits her eggs singly on tlie mider surface of the lea\'es of the food plant. The egg (Fig. 1) is lemon yellow in color, nearly ^ inch in length and attached to the leaf at one end. It is broadest two tliinls of the distance from the base, and then tapers to the to)>, which is flattened. The surface is beau- tifully ridged lengthwise and crosswise. The egg hatches in about a week and the pale greenish yellow caterpillar begins feeding on the under surface of the leaf, which it skeletonizes. A little later the caterpillars are able to eat out holes in the leaves, only the larger veins remaining. When the plants are Fi(i. 1. — K«(;^ of tlic im- ported fiihbage huttcr- fly (X 15). INJURIOUS TO CABBAGE AND RELATED CROPS headinji;, the caterpillars often burrow rather deeply into the head in search of the tenderest leaves. They beconit> full grown in ten to fourteen days. The mature caterpillar (Fig. 2) is about an inch in length, velvety green in color and marked with a greenish yellow stripe down the back and an interrupted one on each side. When ready to pupate, J i' - - i uh-rMwn imp •, 1 .„ 1 I4- 1 1 cabbage worm (X IV). it seeks some sheltered place — ■ ^ ^ -^ under a cabbage leaf or on the underside of fence boards in which to transform to Fli;. '.i. — Iinpiirtccl cabliaL'c worm suspended for pupation (X I5). the chrysalis. ^Yhen a cabbage patch is near a house, these chrysalids are often found in great numbers under the edge of the clapboards. When about to transform, the caterpillar first spins a carpet of silk over the surface chosen and fastens a deli- cate silken girdle around its body at the first abdominal seg- in position (Fig. 3). After the chrysalis is held in place by ment, holding itself tightly transformation is complete the this girth. The pupa (Fig. 4) is about f inch in length and of a pale green or yellowish brown color. Fxcept in the case of those chrysalids which winter over, transformation to the butterfly takes place in a week to twelve days. The butterfly has an expanse of about If inches. The wings are nearly white in ground color often more or less suffused with yellowish. The tip of the Fi( 4. — Chrj^salis of imported cabbage worm ( X 2 J) . MANUAL OF VEGET ABLE-GARDEN INSECTS frcnit wingj is gfrayisli ; tluTc arc two Mack spots on the front win^' of the female and one in the male and in both sexes there is a black spot near the front marijin of the hind winj; . killed by spraying with paris green, 1 pound in oO gallons of water, or arsenate of lead (paste), 4 pounds in oO gallons of water. The first aj)pli-1218. 1889. U. S. Bur. Ent. Circ. 60. 190.5. U. S. Farm. Bull. 7()(). 1916. INJURIOUS TO CABBAGE AND RELATED CROPS 7 The Potherb Butterfly Pontia oleracea Harris Before the introduction of the imported cabbage butterfly, this species was abundant in the northern Fnited States and Canada east of the Rocky Moun- tains but soon became rare throughout the greater part of its range. The caterpillar of this species closely resembles that of the imported form but lacks the yellowish dorsal stripe. The butterfly has the upper surface of both pairs of wings and the under surface of the front wings nearly pure white. The hind wings are usually marked on the underside with gray stripes extending along the veins. Rarely the under surface is pure white (Fig. 6). References Riley, U. S. Ent. Kept, for 1883, pp. 115-117. Scudder, Butterflies of Eastern U. S., 2, pp. 1191-1204. 1889. Fig. G. The i)otlioi fly (X I). The Southern Cabbage Butterfly Pontia protodice Boisduval and Le Conte This cabbage-feeding caterpillar is widely distributed through- out the Tnited States but is more connnon southward, where it often causes serious injury to cruciferous crops. As in the case of the potherb butterfly, this species has decTcased in numbers and imi)()rtaiice since the introduction of its iMirojiean relative. The butterfly is known as the {hcckt red white. The ground color of the wings is white in the niali' and dirty white in 8 MAM'AL OF VECETABLE-GAIWES INSECTS the femal? and the upper side of tlie fore wings in both sexes is marked with several black spots (Imjj;. 7). The caterpiUar is about an inch in length, purplish green in color marked with four longi- tudinal greenish yellow stripes and covered with small black dots. The last two species may be con- trolled by the same . measures as recommended for use against the imported cabbage worm. I'lG. 7. — Thf souiluTii cab- bage butterfly, male (X I). References Rilrv. IT. S. Enl. Ropt. for l.SS:^, pp. 114-115. ScucldLT, BiitUTlIios of Eastoni U. S., 2, pp. 11(13-1170. IS89. TiiK Carrage Looper Aulographa brnssicfr Riley This well-known cabbage pest is a nati\e American insect widely distributed throughout the United States and occurring as far south as ^Mexico. In some localities, especially in the South, it is the most serious insect with which the grower of late cabbage and cauliflower has to contend. In addition to cruciferous plants such as cabbage, kale, cauliflower and turnip, the cabbage loo])er may also occasionally cause serious injury to lettuce, celery, beet, pea and i)arslev. It also feeds on tomato, j^otato, as])aragus, dandelion and dock and some- times attacks carnation and mignoiu-tte in greenhouses. On Long Island it is especiall.x injurious to late cauliflower and to lettuce that has been traiis|)lantt'd fnmi culdframes into the forcing houses. The insect as a rnle passes the winter in the pupal stage, although it is not improbal)le that occasionallx some of the INJURIOUS TO CABBAGE AND RELATED CROPS 9 Fig. «. — Egg of the cabbage looper (X 10). later emerging moths may hibernate. In any case, only a relatively small number survive the winter and consequently the first brood of the season is small and causes comparatively little injury. The female moth deposits her small whitish eggs singly or in small groups usually on the upper side of the leaves. The egg (Fig. 8) is about -g^ inch in diameter, pale greenish yellow or nearly white in color, nearly circular in outline and rounded above. The surface is beautifully marked with a series of ridges radiating from the apex. The length of the egg stage has not been deter- mined but it is probably not far from a week or ten days. The young larvje are pale green in color and feed at first on the outer leaves of the cabbage ; as they grow older, they become darker green and are marked with distinct white longitudinal lines. At this time they work in toward the center of the plant, and often bore into the form- ing head. The full-grown caterpillar (Fig. 9) is about Ij inches in length. It is pale green in color with a white stig- matal stripe and two dorsal stripes extending the whole length of the body. On each side of the dorsal stripe there is a fine white line. The caterpillar is narrower in front and has the body en- larged toward the posterior end which is bluntly trun- cate. Although the cater- pillars are close relatives of the cutworms, they crawl with a peculiar looping motion like the measuring-worms, due to no prolegs being present on the third and fourth abdominal segments. The catcrijillars attain tiieir growth in from two weeks to a montli, depending on the tenii)erature. Fig. 9. Full-growu cabbage looper (X If). 10 MAXi'AL OF VEGETABLE GARDEX INSECTS When mature the caterpiUar spins a Hjjht flimsy semi- transparent cocoon (V'\g. 10) of white silk ahout 1} inches in length, usually on the underside of the leaf. It consists of two filmy layers, an inner one close to the ])upa and an outer one coimected with the other by many fine threads. Soon after com])letin survive the winter, the first brood cateri)illars are gen- erally not abundant enough to cause much injur\- and are usually overlooked entirel.w The succeeding broods increase rapidly in inunlx-rs and inipur- tance, the last being the most destructix'c. Towards the end of the season, the l)r()o(ls over- laj) so that all stages of the insect are present on the cabbage plants at the same time. Tlic cablcigc |(Mi|)cr i> held in clicck by scNcral parasites and 11. — Pui>a,' of till- (•:il)l)aKC loopcr (X 2J). INJURIOUS TO CABBAGE AND RELATED CROPS 11 by a disease. Diseased caterpillars at first turn yellowisli and later take on an ashy hue {V\. 13). They become inactive, stop feeding and soon die. After death the skin breaks open and the body contents which have become liquid oozes out and becomes smeared on the leaves. Sometimes a large proportion of the caterpillars are de- stroyed by this disease late in the season. 12. — Moth of the cabbage looper ( X Ij)- Control. The cabbage looper is a difficult insect to poison because the caterpillars refuse to eat leaves coated with an insecticide and move quickly to some part of the plant that has been missed in spraying. Furthermore, it is not easy to spray a cabbage plant so as to cover all parts of the leaves, especially the underside of the outer leaves and those in the forming head. Experiments on Long Island have shown that good results may be obtained by thorough spraying with paris green, 1 pound in