For Reference NOT TO BE TAKEN FROM THIS ROOM fmmmmmBmmmammmmaaioammtmaamatt m4Mlmn^j^04{t(iwuf^H Property of N. C. EXPERiiMENT STATION Department of Entomology No. INSECTS INJURIOUS TO STAPLE CROPS. BY E. DWIGHT SANDERSON, B S.Agk., ENTOMOLOGIST, UELAWAllE COLLEGE AGRICULTURAL EXPERIMKNT STATION; ASSOCIATE PROFESSOR OF ZOOLOGY, DELAWARE COLLEGE. FIRST EDITION-. FIRST THOUSAND. NEW YORK : JOHN WILEY & SONS. I.ONDON- CHAPMAN & HALL, Limited. Copyriffht, 1902, BY E. D. SAISDERSON. ROBERT DRUMVOND, PRINTER, NEW YORK. PREFACE. The sources of information concerning the insects affecting our staple crops are widely scattered throughout the bulletins of the State Agricultural Experiment Stations and of the United States Department of Agriculture, a few books on Economic Entomology, and various other publica- tions. Few men but the entomologist have the desire or ability to glean an account of any given insect from tlie first-mentioned publications, if they know of the existence of others than those published by their own State station. The few books which have been written upon American Economic Entomology usually give but a brief and sum- mary account of any given insect, too brief — it seems to the writer — to give a very clear understanding of the matter. In preparing the following pages the author has been more and more impressed by the fact that for the control of most of the worst insect pests of our staple crops, the farmer must depend very largely upon general methods of farm practice. This being the case, it is essential that he have a correct knowledge of the pest to be combated ; such a knowledge of its life-history as will make plain the reason for the effect of any given ^jrocedure against it. Thus the better class of farmers may find a work in which each Yl PEEFACE. insect is treated somewhat comjirehensively as to life- history, habits, and remedies, yet without being exhaustive or technical, to be of considerable service to them. To furnish such a guide to the more intelligent class of prac- tical farmers has been the aim of the writer, w^io trusts that the following j^ages will be read as such and not as in any way a contribution to science. The author wishes most unreservedly to disclaim any originality for the contents of the work, and to state that unless otherwise noted all the facts are merely compiled from the writings of others. Free use has been made of the writings of all the most prominent American ento- mologists. Where the treatment of a group of insects has been largely drawn from one or two sources, they will often be indicated by quotations in the text. Many of the following chajiters or parts of them have previously appeared in various agricultural journals during the past three or four years, to the editors of which the author desires to express his thanks for their courtesy in allowing him to here republish them: namely. The Country Gentleman, The Farmers' Eeview, Farm and Fireside, Farm Xews, The National Rural, Texas Farm and Eanch, The American Agriculturist, The National Stockman and Farmer, and The Practical Farmer. The author is jjarticularly indebted to Prof. M. V. Slingerland, of Cornell University, for kindly reading 23ortions of the manuscrijot and for several suggestions of value; to Dr. L. 0. Howard for assistance in part of Chap- ter X; and to his wife, Anna Cecilia Sanderson, for a large amount of clerical assistance. K. I) WIGHT Saxdkksox. Newark, Del., February, 1901. SOUKCES OF ILLUSTRATIONS. Electrotypes of the following figures were purchased, being secured through the tindness of the parties named : Fig. 9, from Houghton, Mifflin & Co. ; Fig. 102, from the Iowa Ag. Exp. Sta., through Prof. H. E. Summers; Figs. 7, 136, and 137, from Dr. J. B. Smith; Figs. 51, 52, 60, 84, and 85, from Cornell Tniv. Ag. Exp. Sta., through Prof. M. Y. Slingerland: Figs. 25 and 28, from The Farmers' Keview, Chicago; Figs. 74, 75, 76, 77, and 78, from Dr. S. A. Forbes; Figs. 71 and 72, from The Country Gentleman, for which they were originally redrawn by the author; Fig. 53, from the Xebr. Agr. Exp. Sta., through Prof. L. Bruner; and Figs. 11, 24, 31, 50, 59, 61, 62,^64, 66, 67, 68, 79, 80, 81, 82, 83, 88, 89, 90, 91, 92, 93, 94, 97, 104, 105, 106, 107, 108, 109, 111, 112, 113, 114, 116, 117, 118, 119, 120, 121, 122, 123, 124, 126, 127, 128, 129, 131, 134, 135, 136, 143, 146, 154, 155, 156, 157, 158, 159, 160, 161, 162, from the United States Department of Agriculture, through the kindness of Dr. L. 0. Howard and Mr. F. H. Chittenden, of the Division of Entomology and the Division of Publications, to which gentlemen we are under especial obligation. The following figures were kindly loaned by the parties named: Figs. 29, 30, 32, 33, 34, 35, 36, 37, 38, 39, 40, vii Vlll SOURCES OF ILLUSTRATIONS, 41, 42, 44, 45, 4G, 47, 48, 110, and 150, from the Md. Agr. Exp. Sta., through Prof. A. L. Qiiaintance, these havmg heen first used by the author iu The Farmers' Review; Figs. Go, 132, and 133, from the Ky. Agr. Exp. Sta., through Prof. H. Carman; Fig. 125, from the Fhi. Agr. Exp. Sta., through Prof. H. A. Gossard; Figs. 54, 55, 56, 57, 58, 63, 70, 96, 98, 101, and 103, from the Ohio Agr. Exp. Sta., through Prof, F. M. Webster; Fig. 49, from the Minn. Agr. Exp. Sta., through Director W. M. Liggett; Figs. 12 and 95, from the DeL Coll, Agr. Exp. Sta.; Fig. 151, from the Peninsula Horticultural Society, through Prof. Wesley Webb. Figs. 19, 20, 21, 6(j, 138, 139, 140, 141, 144, and 147 were loaned by the author. Figs. 13, 14, 15, 16, 17, 18, 23, 26, 27, 99, 115, 145, 149, 152, and 153 were copied from prints. Figs. 1, 4, 5, 6, 8, and 10, and Figs. 2, 3, 22, 86, 87, and 100 and frontispiece are original from photos by the author, the photos of the latter numbers being loaned by the Del. Coll. Agr. Exp. Sta. TABLE OF CONTENTS. PAGE Preface v Sources of Illustrations vii CHAPTER I. Injury done Staple Crops by Insect Pests ..-.. 1 CHAPTER II. Structure and Development of Insects « 6 CHAPTER III. General Farm Practice against Injurious Insects 20 CHAPTER IV. Beneficial Insects 30 CHAPTER V. Insects Injurious to Grains and Grasses 44 CHAPTER VI. Insects Injurious to Wheat 90 CHAPTER VII. Insects Injurious to Indian Corn 125 CHAPTER VIII. " Weevil " in Grain 155 ix X TABLE OF COXTEXTS. CHAPTER IX. PAGE Insects Injurious to Clover 172 CHAPTER X. Insects Injurious to Cotton 188 CHAPTER XI. Insects Injurious to Tobacco 214 CHAPTER XII. Insects Injurious to the Potato 239 CHAPTER XIII. Insects Injurious to the Sugar-beet 252 CHAPTER XIV. Insects Injurious to the Hop-plant 269 CHAPTER XV. Insecticides 284 (TJ^, . / -1^^ b> INSECTS INJURIOUS TO STAPLE CROPS. CHAPTEE I. INJURY DONE STAPLE CROPS BY INSECT PESTS. Ever since the plagne of locusts in the time of the Pharaohs, insects have maintained a continual opposition to agriculture. History is replete Avith accounts of insect scourges and the enormous losses occasioned by them. And instead of diminishing with the advancement in agri- cultural methods, injurious insects have undoubtedly be- come both more numerous and more destructive in modern times. Every now and then we hear of communities assembling for prayer and fasting to appease the Almighty, whose wrath has hurled a new insect plague against them. But a little reflection will show that the?e scourges are entirely due to natural causes. In fact such injuries are very largely due to man himself, who, in trying to subdue Nature by the clearing and cultivation of the land, has deprived the insects of their natural food. Thus they must needs feed upon that which is substituted by him, and as it is less abundant than the former wild vegetation, the number of insects and the injuries they inflict are more 2 INSECTS INJURIOUS TO STAPLE CROPS. upparent. But the native insects are by no means entirely responsible for this condition. Foreign insects are con- stantly being imported in one way or another, sometimes already being established pests in other lands and some- times only becoming so under their new surroundings. These are even more injurious than those native, for whereas many of our native birds, insects, and diseases constantly prey upon native insects and thus keep their numbers in check, the enemies of imported pests rarely accompany them, and they thus increase at an alarming rate and do enormous damage before they are attacked by the natural enemies of similar native pests. American farmers have learned from sad experience of the severe losses occasioned by insects, but few realize their enormity when considered as a whole. Several cal- culations of these losses have been made by competent authorities, who practically agree that one-tenth of the total agricultural product of the United States, or $300,- 000,000, is but a conservative estimate of the loss annually sustained by this country. But when this statement has occasionally been made by the author it has been met with a look of incredulity which very plainly indicated that he was thought to have a very elastic imagination. A careful collection of such data as may be confided in as accurate shows that the above estimate is entirely correct. Con- siderably over one-half of this loss is upon the staple crops, the remainder being upon truck crops, fruits, domestic animals, and timber. Growing Cereals. — Probably no other insect does so wide-spread damage as the Hessian Fly, attacking our chief staple, wheat, as well as rye and barley. One-tenth of the whole crop, valued at 140,000,000, is generally con- INJURY DONE STAPLE CROPS BY INSFCT PESTS. 3 ceded to he destroyed by this pest every year, and in certain sections the loss often amounts to from 30 to 50 per cent. If the loss to rye and barley be put at one- fourth the loss of wheat, it amounts to about 11,000,000. From various estimates made at different times during that period. Prof. F. M. Webster states that 1^330,000.000 represents the loss from the depredations of the Chinch- bug since 1850, or 17,000,000 per annum, which has been largely confined to the States of the Mississippi Valley. Corn has a host of insect enemies. Frequently the Corn Root-worm has damaged the crop to the extent of 10 to 20 per cent in many of the largest corn-growing States. The annual loss on this crop due to insects is certainly not under 5 per cent, or $37,000,000. Thus with only the above figures we see an annual loss of 185,000,000 upon growing cereals. Stored Grain. — But stored grain has its insect pests also, which are especially injurious in the South. Mr. F. H. Chittenden, of the IT. S. Department of Agriculture, places the loss on stored corn in the seven Gulf States at $20,000,000, or 20 per cent of their crop. If only one- fourth of this amount, or 5 per cent, of the rest of the country's stored corn were thus lost, it would amount to $40,000,000. Twenty million dollars, or 3 per cent of the value of all other stored grain, certainly no more than cover the loss sustained upon it and other stored products subject to insect pests, which gives an approximate total of 160,000,000 damage to stored products. Grass and Hay. — A host of grass and clover insects damage the hay crop. Half a million dollars have fre- quently been given as the loss sustained from the Army- worm alone in individual States. Five per cent of the 4 IITSECTS INJURIOUS TO STAPLE CROPS. hay crop, or 120,000,000, fairly represents the loss upon this crop and pasture-lands due to insects. Cotton. — The cotton-plant has a number of serious enemies, of which the Cotton-worm, Boll-worm, and Boll- weevil are the worst. In 1880 the United States Ento- mologic^al Commission valued the annual ravages of the Cotton-worm at 130,000,000, but, thanks to their careful study of the pest, the damage done by it has been greatly lessened in recent years. But the Boll-weevil has now presented itself in Texas. In 1894 it damaged the Texas crop to the extent of 18,000,000, and its injuries are not reported as having diminished. Thus ^15,000,000 must be a low estimate for the insect depredations upon cotton. Tobacco. — The tobacco crop, valued at $25,000,000, has a horde of insect enemies at all stages of its existence, which will easily consume 8 per cent of it, or $2,000,000. Potatoes. — The Colorado Potato-beetle does not do that crop so serious an injury as formerly, but some new enemies to it have appeared, and a loss of $10,000,000, or about 6 per cent of the value of that crop, is un- doubtedly caused by our six-legged foes. Surely, when we include the injury done to fruits, truck crops, domestic animals, and timber, $300,000,000 is a conservative estimate of the price these apparently insig- nificant little insects are annually costing this country. Yet there is another aspect to the matter. '' One man's loss is another man's gain" is never more true than as regards these losses occasioned by insects. For, through wide-spread injury by them, prices rise; while if these injuries were not done and correspondingly large crops were placed upon the market, prices must surely fall. INJURY DONE STAPLE CHOPS BY INSECT PESTS. 5 These estimates of losses due to insects are then very largely comparative. Yet, to a large extent, they are still real losses, the same as are those occasioned by fire and storm. For though a small crop may bring better prices, it is usuall}' at the expense of individuals or communities which have sustained exceptionally heavy losses. AVere these losses evenly distributed among all those producing a given crop, there would be no real hardship to them; but such is by no means the case. All this, then, goes to emphasize the fact that the suc- cessful farmer — as the successful man in any other trade or j)rofession — is the one who is able to overcome obstacles which, though possibly ruining his neighbor, are making a good market for his special crop. And these insect pests can be largely overcome. The millennium will doubt- less come before the farmer will be able to stop fighting them, but a large part of the damage by them can be pre- vented at a cost which renders it profitable. Rational methods of general farm practice with the proper use of ap23aratus and insecticides, even such as are now known, and in which improvements are being constantly made, if intelligently used by American farmers, would save to them fully two-thirds of this enormous loss. •^^ CHAPTER II. STRUCTURE AND DEVELOPMENT OF INSECTS. The more experience the farmer has with insect pests, the more he comes to realize that if he would successfully combat them, he must have a certain amount of necessary knowledge concerning their structure and growth. In general, the artificial means which may be effectually used to combat an insect pest will very largely depend upon the anatomical structure of the insect, while control by general methods of cidture will depend upon a knowl- edge of the peculiarities of its life-history. The value of a proper understanding of these important factors in insect control is therefore apparent. General Structure of an Insect. The body of an insect is composed of three separate parts, the head, thorax, and abdomen (Fig. 1), each of which is composed of several rings or segments. To the head are attached the jointed antennae, or feelers, the compound eyes, and the mouth-parts, which are described below. Each of the three segments of the thorax bears a pair of legs, and adult insects usually possess one or two pairs of wings upon the last two segments of the thorax. The abdomen is composed of nine or ten segments, but 6 STRUCTUKE A^D DEVELOPMENT OF INSECTS. 7 bears no appendages save the ovipositor of the females of certain orders. Harvest-mites, or ^^ daddy-long-legs/^ sow-bugs, thou- sand-legged worms, and similar vermin are often popularly called insects, but all of them can readily be distinguished from true insects by their possessing more than six legs. \ ■^ i ?^ abd^^ ff i r Fig. 1. — Honey-bee, showing three principal regions of the body of an insect : — Ji, head; tJi., thorax; aJ/d., abdomen. (Original.) the harvest-mites and spiders having eight and the others many more. How Insects Grow. With rare exceptions insects hatch from eggs laid by the adult females. Upon hatching they are but little larger than the eggs, and often bear but little resemblance to their parents. Thus the young caterpillar would never be recognized as the immature stage of the butterfly by one unfamiliar with its transformations. Grasshoppers and some other insects, however, upon hatching from the egg bear a marked resemblance to the adult form, except that they lack wings. 8 INSECTS INJURIOUS TO STAPLE CROPS. Complete Metamorphosis. — But let us return to the cater- pilLir and follow it through its short hut interesting life. Upon hatching from the (igg it at ouce commences to feed and grows Tery rapidly. But before long an obstacle to further growth arises. Unlike higher animals, insects possess no internal skeleton or framework for the organs of the bod}^, but the outer skin becomes hardened and to it the muscles and ligaments are attached. This harden- ing of the skin is best seen in the horny wing-covers of the beetles and is due to the secretion of a hard substance called chitin. This chitin is secreted by all parts of the skin in greater or less degree, and thus forms a sort of shell for the whole body. Though this hardening is not so apparent in larvae as in adult insects, it is always present, and it is for this reason that when the young- caterpillar has made a certain growth it is forced to shed its skin, which refuses to expand further, in order to develoj) more fully. Thus the skins of insects are shed several times (see Fig. 2, h), — usually five or six, but sometimes as many as twenty, — this process being known as ^^ molting." During its life as a caterpillar, which is called the ''larval stage," and during which it is called a ^^arva," it is nn elongate, worm-like creature, with six short, jointed legs on the three thoracic segments, a pair of fleshy false legs or pro-legs on the last abdominal seg- ment, and probably several pairs of pro-legs between these and the true legs. No traces of wings can be seen, but the body is often covered with hairs, spines, or warty tubercles. But with the next molt the insect changes in appearance most radically, becoming a joupa, or chrysalis as this stage is termed for butterflies. During the pupal stage the insect remains dormant either in a small cell slightly under STRUCTURE AND DKVELOl'MEXT OF INSECTS. 9 the surface of the earth, or in a silken cocoon spun by the caterpillar, or merely attached to the food-plant })y a Fig. 2. — Complete Metamorphosis, The different stages of the Corn Ear-worm {HeliotMs armiger Hlibn. \ a, eggs on corn- silk; h, the first three larval stages; c, pupa from below; d, same from above; e, adult moth — all enlarged; h, about twice natu- ral size. (Original.) strand of silk or the cast larval skin. In many of the Diptera, — the order including flies, mosquitoes, gnats, etc., — however, the last larval skin is not shed, but hardens and forms a case — called a puparium — within which the pupal stage is passed. 10 INSECTS INJURIOUS TO STAPLE CROPS. The typical jmpa (Fig. 2, c, d) of a butterfly or moth is of a more or less oval shape, rather resembling the adult insect than the larva, with the wings and antennae tightly folded at the sides, the legs drawn up snugly together under them, and the head and mouth-parts bent upon the breast, or sternum. But all of these parts are not always recog- nizable, the legs and mouth-parts being sometimes lacking. Gradually the jidult insect develops, and at last the pupal skin is broken open and the airy butterfly emerges to enjoy a short life and perpetuate the species. Such a series of transformations is that commonly found among butter- flies and moths (Lepidoj)tera), beetles (Coleoptera), flies (Diptera), and bees (Hymenoptera), and is known as a complete metamorphosis. All of these insects normally pass through four stages, the Qgg, larva, pupa, and adult. Incomplete MetamorphosU. — In contrast to this mode of development is that of the grasshoppers (Orthoptera), bugs (Hemiptera), and some other insects. As already stated these are much like the adult upon emerging from the agg. With each molt they become larger and small wing- like pads gradually appear on the sides of the thorax. There is no dormant or pupal stage, the adult insect differing from the previous stages in having fully developed wings, being larger, and often by an accompanying change of markings. The immature stages of such insects are called nymphs^ and this development an incomplete meta- 'inorpliosis, having but three stages, the Qgg, nymph, and adult (Fig. 3). The time occupied by the complete life-cycle of an insect varies from a week or ten days for the plant-lice to thirteen or seventeen years for some Cicadas, and is entirely dependent upon the habit of the species and the climate. STRUCTURE AND DEVELOPMENT OF INSECTS. 11 A correct knowledge of the exact time and conditions under which the transformations occur for each individual Fig. 3. — Incomplete jMetamorpliosis of a Bug [Brachymena 4-jmsiic- lata). a, eggs: 6, adult bug; c, different stages of young bugs or nympLs. (Original.) insect pest is therefore often most essential when seeking means for its control. How Insects Feed. The material to he used in cumhating a given insect is almost entirely dependent upon the structure of its mouth- 12 IXSECTS INJURIOUS TO STAPLE CROPS. parts. Much Paris green is wasted upon insects unable to eat it and which it will, therefore, never kill. Insects may be roughly divided into two classes, those which bite and those which suck their food. Among the former are the beetles, grasshoppers, the larva3 of butter- flies and moths, and the larvae of saw-flies; and among the Ibr. MX.pA Kldh^ Fig. 4. — Front-view Face of Grasshopper {Schiziocerca americnna). ant., anUnma; oc, ocellus; ey., eye; cl., clypeus; Ibr., labrum, or upper lip; mx.p., maxillary palpus; lab. p., labial palpus; gal., galea, lobe of maxilla; lab., labium, or under lip. (Original.) latter are butterflies, flies, bees, and bugs, while the larvae of most flies and bees do not possess mouth-parts homol- ogous with those of the above. Biting Mouth-imrts. — Mouth-parts typical of those of biting insects are easily seen in the grasshopper (Figs. 4, 5, and 6). In brief, they consist of an upper and a lower lip, between which are two pairs of jaws which work trans- versely. The upper pair of jaws, or mandihies (md.), are stout, short, and horny, usually sharpened at the tip, STRUCTURE AND DEVELOPMENT OF INSECTS. 13 slightly serrated at the margins, and flattened at the base. The lower pair of jaws, or maxillcB {mx.), are longer, not so strong, and to each of them is attached an accessory lobe, and a jointed style called a palpus or feeler. At each Fig. 5. — Mouth -parts of Grasshopper, separated to show position and relation, a, from above the mouth; b, looking into the mouth; c. from below the mouth. Ibr.. labrum, or upper lip; md., man- dible or biting-iaw; mx., maxilla, or second jaw; lab, labium, or und(n' lip: ^lyp., hypopharynx, or tongue; mx.p., maxillary palpus. (Original.) side of the lower lip is another j^alpus, these palpi being sensory organs. Sucking Moutli-parts. — In the sucking insects these mouth-parts are prolonged into a tube through which the juices of the food plant — or animal — are sucked. In the plant-lice and other bugs the lower lip is elongated so that it forms a tube, and the max ill a? and mandibles consist of long hair-like bristles, or seta?, enclosed within this tube (Fig. 7). The tip of this beak is rested upon the surface of a leaf into which the setae are thrust, laceratino- tlie tissue, and by a pumping process of the mouth the juices are sucked up through the beak. The structure of the mouth-parts of the various orders of sucking insects varies 14 INSECTS INJURIOUS TO STAPLE CROPS. considerably, but all agree in that their food must Ije sucked up in a liquid state. Any application of a poison - Fig. 6. — Cicada, showing Mouth-parts of a Bug, a Sucking Insect. a, seen from below, beak or rostrum {ro. G. ) reposing between forelegs; b, head removed; e, eye; l})r., labrum; md., man- dlble-setae ; mx., maxillary seta^ ; lab., labium. (Original.) ous spray to the surface of foliage will be of no avail against them, though sure death to most biting insects STRUCTURE AND DEVELOPMENT OF INSECTS. 15 which chew the leaves, and sucking insects must therefore be killed by other means. How Insects Breathe. In the side of one thoracic segment and each abdominal segment except the last, of a caterpillar or larva, is a small Fig. 7. — Mouth parts of a Plant-louse; a, the jointed beak; b, the lancets, much enlarged; c, antenna; d, foot. (After J. B. Smith. ) oval spot, in the centre of which is a slit closed by two membranous lips. These apertures are called sjjiracles or stigmata (Fig. 8, st^-st^^), and are the openings of the respiratory system. Similar openings are to be found in all insects, though not so easily seen in the adults. Con- necting these spiracles is a pair of tubes on each side of the body, throughout its length, from which branch oil' 16 INSECTS INJURIOUS TO STAPLE CROPS. smaller tubes to all of its organs and tissues. Fresh air is thus inhaled to all parts of the body through these tubes (Fig. 8, tr). Fig 8. — Diagram of tracheal or breathing system of an Insect, .s-ij-s^jo, the ten pairs of spiracles; A, head; i?i_3, the three seg- ments of the thorax; Tr., the two main tracheal trunks; trs., trachea leading from the main trunk to the spiracle; tru., tra- chea connecting the two main trachea; tri., visceral trachea; tro., ventral trachea; tr., the anterior termination of the tra- chea; g.-g., nerve-cord with ganglia to wiiich go branches of the visceral trachea; au., eyes; a, antennae; p, palpi; m, man- dibles; jPi-p^, bases of the legs. (After Kolbe.) The blood of insects does not circulate through any system of tubes as it does in the higher animals. Along STRUCTURE AND DEVELOPMENT OF INSECTS. 17 the middle of the back, above the alimentary canal, is a long tube popularly called the heart (Fig. 9, ]i\ Fig. 10, dr). This heart is composed of a number of chambers each of which is funished with side valves for admitting blood from the body-cavity. The blood coming into the heart from the body- cavity is propelled forward toward the head, where it again flows into the body-cavity. Thus various currents of blood are maintained throusfhout the Fig. 9. — Ideal section through au iu.sect. a, ahmentaiy canal; h, heart; n, nerve-cord; s, stigmata: /, tracheal tubes; I, legs; w, wings. (From Riverside Nat. History.) body, but other than the heart there is no system of blood- vessels, the blood merely filling the body- cavity around and through the various organs and tissues. Constantly flowing around the respiratory tubes or tracheae, the blood is quickly and thoroughly purified, though the exact manner in which this is done is not definitely known. The respiratory system has absolutely no connection with the mouth or pharynx (Fig. 10, ^j^), as have the lungs of the higher animals, and if an insect is to be suffocated, it must be done by closing the spiracles. It is in this way 18 INSECTS INJURIOUS TO STAPLE CROPS. that tobacco-dnst, lime, pj'Tethruin, and similar insecti- cides kill sucking insects by ^penetrating the spiracles and choking the tracheal system. Whale-oil soap, kerosene emulsion, and the other "contact" insecticides, or ^' irri- tants," may also stop up the spiracles and thus cause death, but they act chiefly as "irritants," penetrating the Fig. 10. — Internal Anatomy of Silkworm. A, the upper, or dorsal, body-wall seen from within; B, the back of the silkworm re- moved, showing alimentary canal: C, alimentary canal removed, showing nervous system and tracheal trunks; t?'., trachea; d.v., dorsal vessel or heart; ph., pharynx or mouth; sti., supra- oesophageal ganglion; sp. sp., spiracles or breathing-pores; n, nerve-cord; ^r.^., tracheal trunk; oes., a^sophagus or throat; c/'., crop; s.g.. silk-gland; pro., proventriculus or grinding-stomach ; St., stomach; 7i.i., hind-intestine. (Photo, by author from Azoux model.) skin and thus killing the insect. When insects are killed by means of a gas such as carbon bisulfide or hydrocyanic acid gas, they are truly asphyxiated by a substitution of these gases for air, the same as are higher animals by the use of anaesthetics, STRUCTUKE AND DEVELOPMENT OF INSECTS. 19 Though arsenical poisons are generally used as sprays for biting insects, soft-bodied caterpilhirs and similar larv^ae are often killed by the use of contact insecticides, which affect them the same as sucking insects. The reader will observe that, almost without exception, the remedies advised for different insect pests in the fol- lowing pages are determined by some peculiarity, either of structure or develo^mient, of the insect to be combated. CHAPTER III. GENERAL FARM METHODS AGAINST INSECT PESTS. In" the following pages artificial means of combating insect pests, such as spraying with insecticides, are not as often the remedies or preventives given as those which consist of some method of general farm practice. That such should be the case is but natural, for the staple crops, being cultivated in large areas, can hardly be treated witli sprays or mechanical devices, in many instances, with any degree of profit. The best methods to employ against most of the insects affecting the staj^le crops are what might be termed cultural methods, consisting of some mode of culture or handling the crop which fatally inter- feres with the development of a given insect pest. Such treatment is far less simple in many instances, however, than the use of a spray-pump or powder-gun. In the latter case the farmer merely waits until he observes a crop being injured and then with a liberal application of poison destroys his insect enemies; but in using the former method he must have a more or less accurate knowledge of the life-history of the insect which he wishes to combat. It will also be necessary for him to observe or ascertain the usual dates of the transformations of various insects for his particular locality, as they vary considerablv for different latitudes and altitudes, and to make due allow- 20 GENERAL FAUM METHODS AGAINST INSECT PESTS. 21 auce for any variation of these dates on account of the peculiarities of the individual season. Looking Ahead. — Few farmers, in planning the manage- ment of their land and crops for tiie coming season, con- sider the effect which any given procedure will have upon the injurious insects with which they may have to contend. A field which has for several years been in wheat, corn, or tobacco may be sown with some other crop for the sake of soil improvement, or may even be favored with a green- manuriug of rye, crimson clover, or cow-peas; but how often is it considered necessary to rotate crops in order to lessen insect pests ? In most cases the answer would doubtless be, " Xot until some noticeable loss has been suffered from their injuries.'' That this is a mistake may be seen from a brief survey of the best methods for com- bating our worst insect pests. For this purpose let us take the list of sixty-three insects given in the Year Book of the United States Department of Agriculture for 1898 as a basis, it being carefully com- piled by experienced entomologists. But in passing, though foreign to our theme, it may be interesting to note that of these sixty-three insects twenty- seven have been imported from foreign climes, thirty-one are native, and four are of doubtful origin, so that we can correctly say that fully one-half of our worst insect pests are imported. Among those native to the United States are the Chinch-bug, Corn Root-worm, Cutworms, Locusts, and Colorado Potato- beetle; while among those imported are the Angumois Grain-moth, Cypsy Moth, Codling- moth, Cotton- worm. Sugar-cane Borer, Grain Weevils, Hessian Fly, and San Jose Scale. Of tliese sixty-three pests eight infest stored grains and 22 INSECTS IX.TURIOUS TO STAPLE CROPS. lionseliold goods, and may be exterminated by the fumes of carbon bisulfide; and five are insects affecting cattle, and are combated with various washes. Thus only fifty are really to be considered insects of the farm cro^is. Of these, three are controlled by '- ditching,'^ three by mechanical means or devices, and for two of them hydrocyanic acid gas is sure death, while a spray of whale- oil soajD is advisable for two others, a spray of kerosene emulsion for six, and of Paris green or London purple for fifteen, these sprays, etc. , being used largely for orchard pests, which comprise eighteen of the fifty. But for the control of many of the insect pests affecting the staple crops, and which are, therefore, of the greatest economic im2:>ortance, we have so far been unable to devise anything better than a judicious manipulation of purely natural agents, and for the control of twenty-three of the fifty farm insects listed, or nearly one-half, and 75 per cent of those outside the orchard, such methods must be mainly relied upon. Clean Farming. After a crop has been harvested, there is usually some portion of it which is allowed to remain on the land. In this refuse the insects peculiar to the crop often go on multiplying until winter, and greater damage to the crop in the following year is therefore probable. Thus the Wheat Joint-worm and the Corn Stalk-borer both winter in the stubble of those crops, the Potato Stalk-borer remains for some time in the vines, and numerous other cases might be cited. It is therefore of imj^ortance in our war- fare against insect pests that the remains of a crop, stubble, vines, leaves, or stumps, as it may be, should be GENERAL FARM METHODS AGAINST INSECT PESTS. 23 removed from the field as soon after it is harvested as possible Such material allowed to remain in the field also furnishes the adult insects an excellent place in which to hibernate over winter. Much can be done to rid a field of insects by cleaning it so thoroughly as to deprive them of shelter during the winter, during which time they hibernate under all sorts of rubbish, grass, and weeds, in fence-rails, loose bark of trees, etc. This fact may also often be utilized by first carefully cleaning a field and then leaving one or two piles of rubbish in which various insects will assemble during the winter, when they can be easily caught by burning the whole. Such a trap will be more effectual in catching the insects affecting truck crops than those of the staple crops. Weeds. But even when all the piles of litter and rubbish have been carefully cleared up many of our native insects will merely leave them for some common weed upon Avhich they will feed and breed during the season^ and, if it should be earlier than the cultivated crop, will continue upon it the following spring until the cultivated crop is to be secured for food. '• Volunteer *' plants should be included with weeds in this connection, as they frequently serve the same purpose. Thus the Cotton Boll-weevil feeds upon volunteer cotton during the spring, and the Hessian Fly on the volunteer wheat during late summer, while the Corn Root-louse lives on the roots of the smart-weed until corn is out of the ground. Then, too, many in- jurious insects feed in the larval or adult stage upon some common weed, while in the other stage they are injurious to a cultivated crop. The flea-beetles thus feed upon the 24 INSECTS INJURIOUS TO STAPLE CROPS. roots of Solonaceous weeds during the larval stage, and attack all sorts of garden and truck crops as adults; one of the Corn Bill-bugs lives in the roots of a wild grass as a larva, but is injurious to corn as a beetle. The w^eeder (!an^ therefore, be occasionally used as an insecticide as effectually as the spray-pump. Burning. To start a prairie fire in order to destroy all the insect life of the j)lain might ^irove to be poor policy, but the careful use of the torch has a distinct place upon the farm in controlling its insect foes. The burning over of stubble and grass land will very largely aid in or secure the entire extermination of Army-worms, Chinch-bugs, Locusts, and Wheat Joint-worms. Raking up and burning the vines will be excellent practice against the Squash-borer, Squash-bug, Potato Stalk-borer, and Hop Plant-louse, while the removal and burning of all wild ^^l^mi-trees in their vicinity will greatly lessen the damage to hops by the latter pest. Deep Fall Plowing. Deep fall plowing is being increasingly recommended for the reduction of many pests, and will be found to be of advantage for the Corn Stalk-borer, Corn Ear-worm, Cutworms, Locusts, and Wireworms. In both burning and fall j^lowing the object is to kill that stage in which the insect passes the winter. But this method does not affect all of these insects in the same manner. Some insects will be destroyed by having the cells in which they have gone to pass the winter broken up, and being thrown up to the surface, they will GENERAL FARM METHODS AOAIXST INSECT PESTS. 25 be killed by the weather before they again provide them- selves with winter quarters. Among these are those which hibernate over winter as larvs, and those which pass it in the pupal stage. Among the former may be mentioned the Cutworms and the Corn Stalks or Sngar-cane-borer Larvae. Of those passing the winter as pnpge, the Corn Ear-worm is a good example. It goes into the pupal stage in the fall, and this method of breaking up the pupal cells is practically the only way of combating it upon corn land. But whereas some insects are destroyed by exposing them on the surface, others may be literally buried alive and thus killed. One of the best instances of the value of fall plowing in this way is in the destruction of grass- hoppers' eggs. If they be turned under to the depth of five or six inches after they are laid in the fall, the young hatching from them in the spring will be utterly unable to regain the surface and will thus be smothered to death. Other insects which pass the winter in the pupal stage, but whose pup^e are encased in a tough cell not easily broken open, may also be killed by being turned under in this manner. In fact, even adult insects may be so handled. After the plants are all thrown out of the ground in Xovember the adults of the Mexican Cotton Boll- weevil can be readily caught in this way and plowed under so deeply that they can never regain the surface. Young grasshoppers are also destroyed in a similar manner just after they have emerged from the eggs in the spring. It is a homely, common-sense method, but with a correct understanding of their life-histories it may be used to good advantage against many of our most common and injurious insects. 26 INSECTS INJURIOUS TO STAPLE CROPS. Drainage. The Kice-weevil can be largely controlled by proper drainage, and the Corn Bill-bugs are usually injurious only on land adjacent to or recently reclaimed from swamp land, and disappear with the introduction of proper drainage. Fertilizers. In general, land covered with barnyard manure presents more favorable conditions for the development of insects than that fertilized with luineral fertilizers, sometimes furnishing them food and always affording a good shelter for the cold of winter. On the other hand, it is claimed that kainit, lime, and nitrate of soda are often of consider- able value in controlling, driving out, or preventing the attacks of insects. A liberal application of fertilizers in any form will always be of great value in preventing loss from root-feeding insects by enabling the plant to outgrow the injury and mature fruit in spite of it. Poultry. A flock of chickens or turkeys following the plow will pick up a great many White Grubs and Cutworms and can readily be trained to this — for them — rather pleasant task. In many tobacco-growing sections large flocks of turkeys are raised especially for destroying the Tobacco Horn- worm and are slowly driven through the tobacco-fields several times a day. Trap Crops. Doubtless the reason that trap crops are not more in favor Y/ith the farmer is because their successful use GENERAL FARM METHODS AGAINST INSECT PESTS. 27 requires more or less of a knowledge of the life-histor}^ and habits of the pest to be caught; 3^et this is easily acquired by a little observation and reading, and the men who combat these pests successfully are those who have such a knowledge of them. Let us consider, then, one or two of the more important cases where this principle may be used to advantage. The Harlequin Cabbage-bug is a southern insect, but it has recejitly been found in southern Pennsylvania and seems to be gradually working northward. When this insect has succeeded in reachiug the cabbage-field it is an exceedingly difficult matter to prevent serious injury by it. If, however, a crop of early kale is planted the previous fall, the bugs Avliich hibernate over winter will attack it in the. spring, aud may then be killed by spraying them with pure kerosene, and the danger to the cabbage crop be thus largely averted. The Corn Ear-worm, Tomato-worm, Tobacco Bud- worm, or Cotton Boll-worm, as it is variously known in different sections of the country, according to the crop which it most commonly infests, is one which must be treated almost entirely by means of a trap crop of corn. Unfortunately for that plant, however, this method can- not, of course, be of use in protecting the corn-field, where it must be controlled as best it may by breaking up the cells of the hibernating pup^ by late fall plowing. But as corn is the favorite food of the worms, and the moths will invariably deposit their eggs in its silk, tobacco, cotton, and possibly tomatoes may be largely protected by a proper handling of the corn crop. By planting an early crop of corn, the moths will deposit their eggs in the silk; and before the worms have become full grown it 28 INSECTS INJURIOUS TO STAPLK CROPS. should be cut and fed to stock. Another crop should have been planted near by, or in alternate rows with the previous one, so as to mature a little later, and it should be handled in the same manner. Even a third will prove to be of considerable value. In this way the worms will be trapped in the corn, and the more valuable crop pro- tected. Sweet corn is the best to use, and a few strips will often be found to be of great value when properly used. Numerous other instances of the successful application of this principle might be cited, and several are mentioned under the discussion of individual insects. AVith a correct knowledge of the habits of a given pest, the ingenious farmer will often find the method one of great value. Time of Planting. The proper time of planting is of importance in the protection of many crops from insect attacks. Late-sown wheat is usually exempt from the attack of the Hessian Fly. Late-planted corn is much less affected by the Stalk-borer than that planted earlier in the season. Rotation. A very important, if not indeed the most important, factor in insect control is the rotation of crops in such a manner that no single crop shall be continuously grown on the same land, or any two crops nearly related botani- cally. Allowing land to remain in meadow for some time forms a breeding-ground for White Grubs, Cutworms, and Wireworms, and if it is then desirable to cultivate the land, it should be planted in ^^otatoes or some such crop unrelated to the grasses. It may then be planted with small grains, and then with corn; for if the number of GENERAL FAini METHODS AGAINST INSECT PESTS. 29 these insects iu the grass land be at once concentrated upon the comparatively few corn plants, the injury will be much more severe than if the change be a gradual one, with first a crop not of the grass family which would be largely immune from their attacks, and then a small grain. The value of rotation is possibly best illustrated in the case of the Western Corn Eoot-worm, which is never injurious to corn after the land has been in a small grain or clover. The Hessian Fly, Wheat Isosoma, Wheat Plant-louse, Wireworms, and many other of our worst pests may be largely controlled by a rapid rotation, and their increase and consequent depredations are very often due almost entirely to a lack of such practice, which is also of the utmost importance in preventing soil depletion. Thus a proper understanding of the pests with which he has to deal and a timely consideration and application of these homely methods may be of the greatest value, and indeed often the only available means for the control of the larger part of the insect enemies of the general farmer. CHAPTER IV. BENEFICIAL INSECTS, PREDACEOUS AND PARASITIC. Ladybird-beetles. After his strawberries have been ruined by the Straw- berry-weevil, the garden truck by Cutworms, the wheat despoiled by the Hessian Fly, the melon-patch fallen a prey to plant-lice, and the fruit crop has been a failure on account of the Codling-moth, Plum Curculio, and San Jose Scale, it is scarcely surprising that the farmer does as one of my acquaintances did and '^orders the hands to kill everything that crawls." But such would be entirely too heroic a measure, and if strictly adhered to the remedy would be as bad as the disease, for it would mean not only useless labor, but the destruction of the most effective means whereby insect pests are held in check. We j^ride ourselves — and justly — that with our Paris green and kerosene sj^rays and gas tent most of the crops can be effectually protected ; but were it not for those other insects which feed u23on these injurious forms, what an enormous and, in some instances, almost futile task it would bsl Among these beneficial insects the little Ladybird- beetles of the family CoccineUidce are entitled to be in the first rank. Almost all the beetles and larvae feed upon 30 BENEFICIAL INSECTS, PREDACEOUS AND PARASITIC. 31 plant-lice and scale insects. Of such value are those feeding upon scale insects that not many years ago a large number of Australian species were imported into California that they might prey upon the San Jose and other scales. One of these was eminently successful and almost com- pletely destroyed the Cottony Cushion-scale. Of those feeding upon plant-lice, one of the most common is the Xine-spotted Ladybird (Coccinella novem- notata). This beetle is about one-fourth of an inch long, with black head and body. The wing-covers are orange- yellow marked with nine black spots — four on each side and one on the central suture. The larva has been fancied to resemble a miniature alligator; it is nearly twice as long as wide, almost black, marked with bluish and orange spots, and has long legs, which carry it around quite rapidly. The beetles hibernate during the winter and come forth in the scoring and lay their eggs wherever the young will be able to find food when they hatch. When the larva has satisfied its ravenous appetite and become full grown it fastens itself to the food-plant — seemingly by its tail, if such a term might be alloAved, — transforms to the pupa, and in a week or ten days the adult beetle emerges from the pupal skin. This life- cycle is repeated several times during the summer season, before the fall brood turns into winter quarters. Another very common form among plant-lice on garden truck is the little Adalia hipundatiu or Tw^o-spotted Lady- bird. It is slightly smaller than the preceding, and with only one black spot on each wing-cover (Fig. 11). Several other species in the genus Hippodamia are very useful, and among them the Convergent Ladybird {^Hippodamia convevgens) is one of the best known. Its 32 INSECTS INJURIOUS TO STAPLE CROPS. name is received from two wliite dashes on the black thorax, which converge posteriorly. The thorax has also '^ 03 CC c3 £ r 1 ^_| .- o 1=1 go. 0^< 25 M a white margin, and there are thirteen black dots on its orange wing-covers. These larva? and l^ectles are very common among the plant-lice on melon-vines, and are an important factor in their extermination. They have also BKNEFICIAL INSECTS, PREDACEOUS AND PARASITIC 33 been noted for eati7?g the Black Peach Aj^his and many other plant-lice. A form which is often very abundant among lice on corn Fig 12.— 1, the Fifteeu-spotltd Ladybird: a, larva eating plant- louse; b, pupa; d, beetle. 2, the Convergent Ladybird {Hippo- damia convergens., larva, pu])a, and beetle. 8, the Nine- spotted Ladybird {Coccinella 0-tiotata). 4, Megilla maculaia. (After Riley.) is Megilla macuhita. The head, thorax, and wing-covers are a dark pink, with two black spots on the thorax and ten on the wing-covers. Such numbers of these little fellows have frequently been found huddled together un- der the rubbish at the base of some tree in a last yearns cornfield that they might be , 1 1. ^1 1 i-P 1 FiGt- 13. — The Twice-stabbed t'dken up by tlie iiancltui Ladybird (Chilocorus Uvulne- without difficulty. Many ^ws): «, beetle; 6, larva. (After Riley. ) other species feed upon plant-lice, but the above are the most common, and all bear a resemblance to one another, being generally orange or red with black spots, and of a characteristic round or 34 INSECTS INJURIOUS TO STAPLE CROPS. oval form, flattened below, so that the legs may be drawn in under tlie wing-covers. Those Ladybirds which feed upon scales are much smaller and black, though sometimes s^iotted with red or orange. As fa,r as known, there is no .way in which these useful allies may be encouraged or increased in numbers, but it is trusted that the above may give such a brief view of their habits that fewer may be killed through ignorance concerning their true Avorth. Syrphus-flies. Besides the little beetles described above there is a family of flies, the SyrphidcBy many of whose larvae feed upon plant-lice. This family is a very large one, and thus the habits of its different mombers vary considerably. One of them so closely resembles a honey-bee as to be almost indistinguishable from it. The larva of this fly {Eristalis tenax) is one of the common Rat-tailed Maggots which is found in putrid matter. It is thought that the old '^ bugonia " superstition of the ancients that bees came from maggots in dead animals, etc., was due to the con- fusion of this fly with the honey-bee. In another group of the family, the adult flies of which also quite closely resemble bees, the larv^ are parasitic in the nests of honey- and bumble-bees, feeding upon their larvae. But the larvae of possibly the most typical portion of the family, embracing the genus Syrplms and its near allies, are entirely predaceous upon plant-lice. Rarely can a colony of plant-lice be found without some of these little enemies hard after them. BENEFICIAL INSECTS, PR:EDA('K01:S AND PAHASITIO. 35 The adult syrplius-fi}^ is a very striking insect, with its dark green metallic thorax, and abdomen variously banded with yellow and black. The female fly lays her eggs upon some plant bearing plant lice. The 1 a r v ae which hatch from these are elongate, flattened mag- gots,about one -half an inch long, with hardlv a trace Fig U. — Syrphm rihesii. (Au- ° -^ , thor's illustration. ) of a head, but with four small hooks, which serve as jaws, projecting from the more pointed end of the body. These maggots are often of a light green color, and so like the color of the plants as to render them most ditflcult to be recognized. The young larvae at once commence crawling over the plant in search of the aphids, and as soon as they come in contact with one it is firmly clasped by the small booklets until the juices are sucked from its body. In this manner very Fig. 15. — The Koot-loiise Syrphus-fly {Pipiza radicans). a, mag- got; b, piiparium; r, fly. (After Riley.) large numbers are destroyed, a single maggot of tlie American Syrphus-fly {Syrphus ainericanus) having been observed to eat twenty-five Apple Plant-lice {AjjJiis mali) 36 INSECTS INMURIOUS TO STAPLE CROPS. in as many minutes. When the larva is ready to pupate it attaches itself to a leaf, and- the larval skin dries up and forms a case or puparium inside of which the pupa remains until it transforms to the adult fly. Though most of these larvae feed upon plant-lice upon the leaves, one of them, the Root - louse Syrphus - fly {Pipiza radicans), lives entirely underground during that stage, and feeds upon the root-lice of the apple and the grape. None of this family are injurious, and as a large portion of them are so beneficial as to frequently destroy whole broods of plant-lice, they should not be disturbed in their good work if possible to avoid it. The Ground-beetles. If, as you scrape away the loose chips at the base of a tree in your door-yard, turn over an old log in the wood- land, or pick up a fallen fence-rail, you will scrutinize the inhabitants under these shelters, a number of shining black beetles varying in length from one-fourth to one and one-half inches will usually be noticed. If the city reader be not so fortunate as to be fa-miliar with or have access to these hiding-places, he may find large numbers of the beetles under any electric arc light during the warm summer evenings; for there they are having a sumptuous banquet upon the small flies and moths attracted by the glare. They are rarely seen at large during the day, as they are almost exclusively nocturnal insects, and from their habit of remaining almost entirely in or on the ground they are usually known as '^Ground-beetles.'' As might therefore be inferred, they are exceedingly valuable to the farmer by destroying large numbers of noxious insects which ])ass a part or all of their existence BENEFICIAL INSECTS, PUEDACEOIS AND PARASITIC. 3T ill the soil. Besides tlio glos^^y black forms which are most commonl}" seen, mniiy are brilliantly marked with gold, green, purple, and iridescent tints. The Fiery Ground-beetle {Calosoma caJidnni), so called on account of the wing-covers being dotted with bright gold, has many times been of great assistance in helping to rid a corn-field of Cutworms. The larvae of this insect Fig, 16.— The Fiery Ground- beetle ( Calosoma calidum). a, beetle; h, larva. (After Riley.) Fig. 17. -''The Searcher" {Car losoma serutator). (After Ri- ley.) are about one inch in length, of a dark brown color, with the skin of a hard, horny texture like that of the beetle. They have strong, prominent jaw\s, and at the posterior end of the body is a forked appendage looking much like another pair of jaws. It is not only surprising that these larvae will eat so large a number of cutworms, as they have frequently been known to do, but also that they will dare to attack such a formidable creature fully tliree or four times as large as themselves. But their assault is sharp and vigorous, and a single larva has often been seen 38 INSECTS INJURIOUS TO STAPLE CROPS. to kill and eat in a short time several fnll-grown cutworms. Many instances of the good work of this heetle are on record, among which one by the late Prof. J. A. Lintner might be cited, where he found them eating large numbers of the Corn-crainbus — sometimes locally known as the Corn Bud-worm. Another somewhat larger beetle, called by Prof. J. H. Comstock ^' the Searcher" {CaJosoma scru- t((ior), and in fact one of the largest of the family, is a brilliant metallic green, bordered with a dark purplish blue, and has the good quality of having a very particular appetite, causing it to kill large numbers of caterpillars, but eating only part of each. While in the earth as pup* large numbers of the Colo- rado Potato-beetles are destroyed by members of this family, and one species, Lehia grandis, which is peculiar Fig. 18. Lehia grandis. Riley.) (After Fi(i. 19.— The Murk}- Ground beetle (Harpalus culiginosuL . (After Riley.) in that the wing-covers are somewhat abbreviated, thus leaving the tip of the abdomen exposed, has been noticed on the plants eating the eggs and young larvae of this old potato pest. Another valuable species is one called by Dr. Riley the BEITEFICIAL INSECTS, PKEUACEOUS AND PARASITIC. 39 Murky Ground-beetle {Harpalus caligiiioms). Its larva is of considerable assistance to fruit-growers by eating large numbers of Curculio larvae, which it secures from the plums after tliey have fallen to the earth. From a glance Fig. 20.—^, larva of Murky Ground-beetle; B head of same; G , mandible. at its formidable jaws. Fig. 20, h-c, it is easy to conjec- ture the fate of man}^ a curculio grub. Thus here again are found some " bugs '' that are friends and not foes, worthy of all the protection that can be aiforded them, and well repaying such careful observation of their habits as may be bestowed upon them. Insect Parasites. Though large numbers of injurious insects are annually destroyed by those which are purely predaceous upon them, many more succumb to those minute forms which live parasitically within them. A few of these parasites belong to the order Diptern, or true flies, but most of them are classed in the order Hymenoptera, in which order are also included the saw-flies, ants, wasps, and bees. Of the half-dozen families of hymenopterous parasites one of the largest and most beneficial is that of the Ichneumon-flies. The illustrations will best show the form and structure of these insects, which the casual 40 INSECTS INJURIOUS TO STATLE CROPS. observer will luirdly be able to diftijiguisli from other families of the group. Bat it will be noticed that the fine yeius of the wings vary considerably in the different jDara- sites figured, and it is by these that the entomologist is enabled to separate the different groups and often to identify the species at a glance. Both this and the fol- lowing family are 2)eculiar in having an exceedingly long Fig. 21.— a Plant-louse Fiu-nnite (Aphidius gr-inaj'iaphis), showing above the parasitized louse from which it has issued. (Copied from J. B. Smith ) ovipositor or egg-tube, of which it will be seen that they make a very good use. It is with this extensile tube that the female deftly punctures the skin of some unsuspecting caterpillar, and under it inserts her eggs. In a few days there hatch from these a host of young grubs, which feed npon the Juices and tissues of the caterpilhir, but are seemingly careful to avoid injuring any of its vital organs, for as soon as the caterpillar reaches its full growth it BENEFICIAL INSECTS, PREDACEOUS AND PAKASITIC. 41 changes to a pupa, apparently iinaffected. But now the maggots have reached their full size, and each spms up a small silken cocoon inside the 2:»upa, entirely filling up its now dead shell, and instead of a beautiful moth apj^earing in the spring, from a round hole in the side of the pupa, or cocoon, a horde of small flies are seen to emerge. Thus large numbers of such pests as the Apple-tree Tent-caterpillar {CUsiocam2)a americaiia), Bag-worms Fig. 22. — Maggots of Pimj)la iriqiiisUor, a parasitic Ich fly, feeding on a caterpillar which had spun its cocoon ready to pupate. (Original.) ncumon- spun its cocoon and was {Tliyridopteryx ep1iemer(efor})iis), cater^jillars of the swal- low-tailed butterflies which feed upon parsley, carrots, etc., and a host of others, are consumed by members of this family. Those belonging to the genus Opliion are partial to the large American silkworms which produce some of our largest and most beautiful moths, and difficulty is fre- quently experienced in rearing a desired number of moths on account of the large ^^er cent of cocoons parasitized. The species of the family Braconidce are very similar to those of the preceding one, and contain some eqiiany 42 INSECTS INJURIOUS TO STAPLE CROPS. beneficial insects, feeding jis tliey do upon sucli pests as the Codling-moth, Web-worms, Plum-cnrciilio grub. Plant- lice, etc. Some of the more common forms of this family belong to the genus Microgaster, and their small white cocoons may frequently be seen almost covering one of our large tomato- or tobacco-worms (see page 237), the Fig. 23. — The Long-tailed O^hion {Ophion macrurum). a, adult; h, maggot. (After Riley.) pupae of which are often known as "' horn-blowers.^' Many mistake these cocoons for the eggs of the worms, and there- fore destroy some of their best friends. Though some thus spin their cocoons on the outside of the host, others remain inside of the parasitized insect until the adult fly emerges. Thus dead plant-lice may often be found with a large round hole in the abdomen — the only evidence of BENEFICIAL INSECTS, PKEDACEOUS AND PARASITIC. 43 where one of these pcarasites has emerged. For this reason as a general rule dry, shrunken plant-lice shonld never he destroyed. The Ohalcis-flies, which comprise another closely re- lated famih', are exceedingly minnte insects, sometimes not over one one-hundredth of an inch long. They are generally of a metallic black color, and the nsnal veins of the wings are almost entirely absent. Many of these flies are parasitic npon plant-lice, while a large number of their larva? live and mature in the eggs of other insects. Very similar to the Chalcis-flies in their habits of infest- ing plant-lice and insect eggs are some even smaller insects — in fact the smallest known, the largest being rarely over one twenty-fifth and the smallest only six or seven one- thousandths of an inch in length — with a correspondingly tremendous and unpronounceable name, known to science as the Proctotryjndce, But enough has been said to indicate the important j^art which the immense hordes of these apparently insignificant insects play in the economy of Nature, by often clearing off a most dreaded insect pest in a few days almost as if by miracle. CHAPTER V. INSECTS INJURIOUS TO THE GRAINS AND GRASSES. Ukder the above head several common insects which are injurious to almost all of the grains and grasses may be conveniently grouped, thus distinguishing them from those which affect a few or an individual species. White Grubs {Lachnosterna spj^.). Of all the insects attacking cereal crops none are better known than the so-called "white grubs/^ I say " so-called," for the Englishman has styled this larva the "cockchafer grub," the Frenchman calls it " ver blanc," and the German has named it the "engerling," while here in America the adult beetles are known both as May- beetles, June-bugs, and dor-bugs, and when flying in the windows and buzzing around the ceilings are often termed " pinching-bugs." In Europe white grubs have long been recognized as one of the agriculturist's worst insect foes, and their depredations were noted in this country as early as the middle of the seventeenth century. • Life-history. — As for most of our grain insects, grass land is their favorite haunt, and the female beetle usually lays her eggs in old meadows, though not infrequent!}^ in corn land. The eggs, which are glossy white, about one 44 INSECTS IXJUUIOUS TO THE GRAlJsS AND GRASSES. 45 eighth of an inch long, and broadly oval, are laid early in June and hatch in from 11 to 13 da3's. The grubs hatch- ing from these feed upon the plant-roots, growing but slowly, as they require a bout two years to become full- grown. Meanwhile, however, each grub does its full share of damage, especialh^ to corn and grass, and often to the smaller grains. Its attacks have also long been feared by the growers of straAvberries, potatoes, and garden truck. 46 INSECTS INJURIOUS TO STAPLE CROPS. as well as by nurserymen and greenhouse florists. The grub becomes full-grown in the summer of the second year after hatching from the egg. It then forms a small oval cell from three to ten inches below the surface of the soil, and here changes to the pupa. The pupal stage lasts slightly over three weeks. Late in August or early in September another transforma- tion takes place and the adult beetle wriggles out of the pupal skin, but remains m the earthen cell until the fol- lowing spring, when it comes forth fully hardened in May or June. The beetles at once pair, and the females deposit their eggs and soon die. Thus three full years are consumed in the complete life-cycle of each brood. hijiiry. — Having seemingly formed a dislike to the light of day from their long subterranean existence, the adult beetles feed and pair entirely at night. The foliage of almost all of the common forest- and shade- and occa- sionally fruit-trees suifers from their attacks. Injury to maple-trees has been specially observed. About 9 p.m. of an evening early in June, thirty-five beetles were once taken by the writer from a small silver-maple tree about eight feet in height, and they were equally numerous on all of a long row of these trees. But the grubs and beetles are too common to need description and may be recognized from the figures. It may not, however, be known that the term ^^ white grubs ^' is generally applied to the larvae of many distinct species of the genus Lachnosterna and one of Cyclocephala, which so far as known have practically the same habits, except that the larvae of the latter genus remain over winter as dormant larv^ and pupate in May. By cutting off the tap-root and feeding roots of corn. INSECTS IXJURIOUS TO THE GRAINS AND GRASSES. 47 white grubs have often been responsible for the total or partial failure of large areas of corn land. In 1805 the grubs so injured one twenty -year-old meadow of 250 acres in Illinois that the sod could be rolled up like a carpet over the entire field. Remedies. — Unfortunately, as regards remedies for this pest little is known. Though eaten by various birds and ^parasitized by a half-dozen or so insects, yet these natural enemies seem to be of little value for holding the grubs in check. Leaving land in meadow for several years is undoubtedly conducive to their rapid increase; and hence a short rotation in ^\'hicli clover follows grass and which is in turn followed by the small grains before corn will very largely prevent serious damage to the latter crop. Poisoned bran mash such as used for cutworms (see page 217) is reported as having been used successfully against the grubs by scattering it over infested land. If turned loose in infested grass land, swine will fairly gorge themselves on the grubs, and, prior to plowing grass land for corn, this will be found to be one of the best means for ridding it of grubs. The hogs will also feed as freely upon the beetles which drop to the ground from the trees and hide during the day, and hence they may be of considerable benefit in woodland adjoining infested fields. A flock of chickens or turkeys following the plow or culti- vator will also be found to consume not a few of the grubs. In Europe the beetles are systematically jarred from the trees in the early morning by organized bands composed mostly of women and boys, in much the same manner as we ** jar" for the Plum-curcnlio. But such methods, as well as spraying seem hardly practicable in our larger country, except possibly for young orchard-trees, which are often 48 IXSKCTS INJURIOUS TO STAPLE CROPS. seriously defoliated. As the beetles remain in the pupal cells over winter and are still tender, not fully hardened, deep fall plowing will destroy a large number of them by breaking open the pupal cells and exposing them to the weather, and by burying or crushing them. But possibly the best method of preventing serious injury by white grubs, and one which will not only be of benefit in securing immunity from the attacks of this as well as many other insect pests, but will also cause less drain upon the soil, is a judicioiTS rotation of crops, avoiding a continual growth of grass in any one field. Wireworms {Elateridm). Injury. — The ^o\\ has been properly prepared and the field carefully planted. Day after day the anxious farmer awaits the sprouting of the young shoots of grain. But all in v^nl Still no signs of growth appear. So, appre- hensive that he lose the use of the land, he removes the earth from some of the seed and there finds the kernels of corn or wheat either with a small round hole drilled through them or some " hard, smooth, shining, reddish or yellowish-brown, slender, cylindrical, six-legged larvae " still devouring the seeds, with their heads firmly embedded in them. If he be a man of any experience, he at once recognizes the work of wireworms and wastes no time in reseeding his field, for of all the insects attacking grain in the seed, these are the most common and destructive. If later on the resown seed secures a start, its growth is exceedingly liable to be stunted by the worms attacking the smaller roots, and it may even be killed when several inches high by their boring through the underground INSECTS IXJURIOL'S TO THE liKAINS AND GRASSES. 49 stalk. All the grains are attacked by wireworms, but wheat and corn suffer most, as well as potatoes, turnips, and many garden crops. Description. — Wireworms, which are the young of a number of beetles, which, from their habit of snapping ~^M ■^.-t s Fig. 25. The Corn Wireworm {Melanotiis The AVireworm of Drnsterius ele- crihulosus), enlarged 4| diam- guns, enlarged seven diam- eters. (After Forbes.) eters. (After Forbes.) their bodies up in the air, are known as ''click-beetles,'' are all more or less like Fig. 25 in general appearance. Although the common wireworms are usually suj^jjosed to be of but one kind, upon examination several species will 50 INSECTS INJURIOUS TO STAPLE CHOI'S. often be found which niiiy be distinguished by a compari- son of the caudal segment with the illustrations (Figs. 27 and 28). The adult beetles arc mostly about one-half to three-fourths of an inch long, decidedly flattened, of a dark brown coJor, with short heads and shield-shaped thoraxes, as in Fig. 2G. Life-history. — Land wliich has been in grass for several years is their native breeding-ground, and here the eggs Fig. 26. — A, Beetle of Wheat Wirew^^rm; B, Dmsterius elegnns, both enlarged about 4 diameters. (After Forbes.) are deposited. Much concerning the life-histories of these important pests is still unknown, but it seems safe to assert that the larvae require from three to five years to become full-grown. Thus the second year after grass land has been planted in grain is that in which the worst injury occurs, and this is especially true with corn, wliich covers the ground less completely than do the smaller grains, The larvffi become full-grown in midsummer, form a small earthen cell, and there transform to the pup^e. Three or four weeks later the adult beetles shed the pupal skin, but only a few of them make their way to the surface during / INSECTS INJURIOUS TO THE GRAINS AND GRASSES. 51 the fall, the most of the brood remaining in the pnpal cells as partially hardened beetles until the following spring. Means of Comldting. — Eemedies galore have been advised for these insects, almost every farmer having his Fig. 21.^ a, last segment of Melnnotus communis, dorsal view. (After Forbes.) B, the Wheat Vvlreworm. Agriotes 7n(incu8. a, b, c, d, details of month-parts, enlarge. I. (After Slinger- land.) favorite expedient, but in recent years a careftil testing has shown that a satisfactory remedy or preventive for wire- worms is vet to be discovered. Professors Comstock and Fig. 28. — C, caudal segment of the Wireworm of Drasterius elegnns D, caudal segment of the Wireworm of Asaphes decoloraiu^, much enlarged. (After Forbes.) Slingerland performed extensive experiments for nearly three years in attempting to sttccessfnlly combat these insects by (1) the protec^tion of the seed, and (2) the destruction of the larvse by {a) starvation in clear fallow 52 INSECTS INJURIOUS TO STAPLE CROPS. and supposedly immune crops, and {b) by the use of in- secticides and fertilizers. But all the remedies or pre- ventives tested resulted in failure, and this has been the experience of several other leading entomologists. It was ascertained, however, that they may be more or less checked by destroying the beetles. This can be done both by fall plowing or by trapping. By plowing late in sum- mer and keeping the earth stirred for a period of a month or so, large numbers of the newly transformed beetles which do not become fully hardened until spring, and pupae, will be destroyed. When the wireworms are numerous in re- stricted areas, as they often are on spots of low moist land, they may be effectually trapped with but little labor by placing under boards bunches of clover, or sweetened corn meal poisoned with Paris green. A short rotation of crops, in which land is never allowed to remain in grass for any length of time, will undoubtedly secure comparative immunity from serious attack. The Chinch-bug (Blissus le^icopteriis Say).* Though individually insignificant, when assembled in countless myriads Chinch-bugs have doubtless been of greater injury to the farmers of the Mississippi Valley than any other insect attacking grain crops, and are responsible for hundreds of millions of dollars' loss. Distrihntion, — This insect may be found over all the eastern United States to the Rockies, and in restricted *See "The Chinch-bug," F. M. Webster, Bulletin 15, n. s.. Div. Ent., U. S. Dept. Ag. ; Dr. S. A. Forbes, 12th, 16th, and 20th Ilepts. St. Ent. Illinois. INSECTS INJUKIOUS TO THE GIJATNS AND GRASSES. 53 localities in Cuba, Central America, Panama, Lower and Central California; but the area in which it has been most injurious lies in the Central and North Central States. During the last fire years, however, its attacks have been increasingly wide-spread in Ohio and Kentuck}^, and in August. 1898, some damage was done by it in Pennsyl- vania and New York. Description. — The adult bug is about one-fifth of an inch long, with a black body. Its white wings lie folded over Fig. 29.— The Adult Chmc\\-\i\xg{Blissus leucopterus Say) enlarged. (After Riley.) Fig. 30. — a, h, eggs magnified and natural size; c, young nymph; e, second stage of nymph; /, third stage; g. full-grown nymph or pupa; d, h, j, legs; i, beak through which the bug sucks its food. (After Riley.) each other on the back of the abdomen, and are marked by a small black triangle on their outer margins, while the bases of the antennae, or feelers, and the legs are red. The young bugs are mostly red, but vary in the different stages. Life-history . — During the winter the bugs hibernate in clumps of grass and under boards and rubbish. With the first warm days of spring they come forth and spread about the neighboring wheat-fields, but there do little harm. Very soon they pair, and the females, each of which is 54 INSECTS INJUllIUUS TO STAPLE CKUPSo Ft«. 81. — Corn-plant two feet tali infested with Chinch bu.os. (After Webster, Bull. 15, n. s., Div. Eat., U. S. Dept. Agr.) INSECTS INJURIOUS TO THE GRAINS AND GRASSES. 55 capable of laying 150 eggs, commence to deposit them either upon the roots or bases of the stalks. This occurs from the middle of April until the first of June, depend- ing upon the latitude and weather, and the eggs hatch in from two to three weeks. The nymphs often severely injure the small grains, and are full-grown about the time of harvest. As the wheat is harvested they spread to oats and soon to corn, but, curiously enough, though the adults have wings they prefer to travel from field to field on foot, much like Army-worms, and were it not for this fact we would be at a loss how to cope with them. Another lot of eggs are now laid under the unfolding leaves of the corn, and the young nym^Dhs emerge in about ten days. This brood lives upon corn, and when full-grown is that which hibernates over winter. South of the latitude of southern Illinois there is often an unimportant third brood. The most extensive injury is done by the mature nymphs and adult bugs of the first brood. Though no means is known for preventing the ravages of this brood in the small grains, every effort should be made to defend the young corn from its attacks, for, with the innumer- able little beaks of the adult insects sucking out its life, it soon succumbs when they are reinforced by the largely multiplied numbers of the second brood. Methods of Prevention and Destruction. — During the migration from the small grains to corn seems to be prac- tically the only time when this pest may be successfully combated. Just before harvest a narrow strip should be plowed around the corn-field and this thoroughly pulver- ized by harrowing and rolling, and then reduced to as fine a dust as possible by dragging over it a brush composed of dead limbs, or whatever contrivance is most convenient. 56 INSECTS INJURIOUS TO STAPLE CROPS. A log or block should now be dragged through this strip in such a manner as to form a deep furrow, with tlie incli- nation of its side next the corn as steep as possible. In attempting to climb this barrier, the dust will slide from under the bugs and large numbers of them will accumulate in the furrow, where, on a clear day, they will soon be killed by the heat if the temperature of the air be over 88 degrees Fahrenheit (the soil will then be 110 degrees Fahr.). The furrow may be kept clean by redragging the log through it as often as necessary. If the weather be cooler, the bugs should be further trapped by sinking holes with a post-hole digger about one foot deep every ten or twelve feet i]i the furrow. Large quantities will soon accumulate in the holes, and may be there crushed or killed with coal-tar or kerosene. Of course a sudden dash of rain will destroy such a furrow, and the bugs will then at once march on to the corn-field. In such an emergency a narrow strip of coal- tar, about the size of one's finger, should be run around the field a few feet inside the former furrow, with post- holes dug as before upon the outside of the line. Dislik- ing the smell of the tar, the bugs will again fall into the traps and may then be destroyed. As many strips may be made along the outer rows of corn as seem necessary to prevent their further progress. These strips of tar should be freshened whenever dust, straw, or rubbish has crossed them at any point. In this manner one Illinois farmer protected over 300 rods with less than a barrel of tar. That this method is practicable and efficient was thoroughly demonstrated by Prof. W. G. Johnson in a series of experiments in Illinois, in the report of whose work Prof. Forbes says: "In short, the success of this INSECTS INJURIOUS TO THE GRAINS AND GRASSES. 57 field experiment, tried under ver}^ difficult conditions, was substantially complete, and the value of this method of contest with the Chinch-bug seems established beyond controversy." Extensive experiments have been made in Illinois and Kansas in the use of the Muscardine fungus — Sporotrichum glohnUfenmi — against the Chinch-bug. Though the re- sults have often seemed to indicate its use to be profit- able, yet it has never so commended itself — even to ento- mologists— as of sufficient value to be brought into general use, and its value must still be considered as largely problematical. If the bugs have already become numerous in the outer rows of corn, most of them may be destroyed by a si)ray of kerosene, which, with a tar strip, will effectually pro- tect the remainder of the field. Such a spray may be either (1) in the form of an emulsion, composed of a ^' stock solution" of one pound of soap, one gallon of water, and two gallons of kerosene, prepared in the usual manner, and diluted with fifteen quarts of water; or (2) may be merely a mechanical mixture of about one part kerosene to four parts of water (20 per cent), which can be formed only by pumps with a special kerosene attachment, and which are now very largely doing away with the use of the soap emulsion. About a teacupful of this spray to a hill will be ample, and at this rate an acre will require about GO gallons at a cost of about one dollar. In case of serious attack by the Chinch-bug the farmer must at once prepare to devote to combating it the time of as many hands as his interests may require; for the above methods require constant and j^ersonal supervision, but, where carefully tested by practical farmers, have been 58 INSECTS INJURIOUS TO STAPLE CROPS. found to be the best and only means of preventing the loss of then' crops. Locusts {Acrididce). Plagues of destructive locusts — or what the American farmer terms grasshoppers — have been recorded since the dawn of history. In America the worst devastation has been done by flights of the Rocky Mountain or Migratory Locust [Melanoplus spretys Thos.), which swooped down upon the States of the western part of the Mississippi Valley in the years 1873-7G like a veritable horde of mountain robbers. Since then they have several times done considerable injury in restricted localities, but never in such numbers or so generally as to cause apprehension of another " grasshopper plague."' Concerning their recent distribution, numbers, and destructiveness, Mr. W. D. Hunter reported after the season of 1897 : '^ There was, this season, a general activity of this species throughout the permanent breeding region greater than at any time in many years. This was brouglit about by a series of dry years, which have resulted in the abandonment of farms in many places. It is, of course, well understood that the absence of serious damage since 1876 has been partially due to the settling w^ of valleys in the permanent region. I wisli to make it clear, how- ever, that the dryness is the primary and the abandoning a secondary cause. "' The Rocky Mountain Locust. Let us first consider this the most injurious species, as the other locusts differ from it in but few essential points other than in being non-migratory. INSECTS INJURIOUS TO THE GRAINS AND GRASSES. 59 To correctly understand its habits the reader should first divide the area which this species affects into three parts. Of these the (1) '' Permanent Eegion, including the highlands of Montana, Wyoming, and Colorado, forms the native breeding-grounds, where the species is always Fig. 32. — Rocky Mountain Locust. found in greater or less abundance.'^ * (2) The Sub- permanent Region, including Manitoba, the Dakotas, and western Kansas, is frequently invaded. Here the species may perpetuate itself for several 3^ears, but disappears from it in time. (3) The Temporary Region, including the States bordering the Mississippi River on the west, is that only periodically visited and from which the species generally disappears within a year. Spread. — When for various reasons the locusts become excessively abundant in the Permanent Region they spread to the Subpermanent Region, and from there migrate to the Temporary feeding-grounds. It is the latter area which suffers most severely from their attacks, but, for- tunately, they generally do not do serious injury the next year after a general migration. In the Subpermanent Region their injuries are more frequent than in the Tem- porary, but hardly as severe or sudden as farther east. Immigrating from their native haunts, flights of the grass- hoppers usually reach southern Dakota in early summer, Colorado, Nebraska, Minnesota, Iov\'a, and western Kansas *Bull. 25, U. S. Dept. Ag., Div. Entomology. C. V. Riley. GO INSKCTS INJURIOUS TO STAPLIC CROPS. during midsummer, and southeastern Kansas and Missouri during late summer, apj^earing at Dallas, Texas, in 1874, Fig. 33. — Rocky Mount aiu Locust. Different stages of growth of young. about tlie middle of October, and even later in 1876. As thus indicated, the flights are in a general south to south - Fig. 34.— Rocky Mountain Locusts, a, a, a, females in different positions, ovipositing; b, egg-pod extracted from ground, with end broken open; c, a few eggs lying loose on ground; d, e, show the earth partially removed, to illustrate an egg-mass already in place and one being placed ; / shows where such an egg- mass has been covered up. (After Riley. ) easterly direction, while west of the Rockies they descend to the more fertile valleys and plains, but without any such regularity as east. While the rate of these flights is INSECTS IXJUIllOUS TO THE GRAINS AND GRASSES. Gl variable and entirely dependent upon local weather condi- tions, twenty miles a day may be considered a fair average. The flights are more rapid and more distance is covered in the early part of the season, when, while crossing the dry prairies, a good wind will often enable them to cover 200 to 300 miles in a day. As they first commence to alight in their new feeding-grounds their stay is limited to but two or three days, but later in the season it is considerably lengthened, and, after being once visited, in an infested country swarms will be seen to be constantly rising and dropping during the middle of the day. Life-history. — Over all the infested area, and while still sweeping it bare of croj)s and vegetation, the females com- mence to lay their eggs, and continue to deposit them from the middle of August until frost. For this purpose '' bare sandy places, especially on high, dry ground, which is tolerably compact and not loose, ^^ are preferred. " Meadows and pastures where the grass is closely grazed are much used, wliile moist or wet ground is generally avoided.^' In such places the female deposits her eggs in masses of about thirty. These are placed about an inch below the surface in a pod-like cavity, which is lined, and the eggs covered by a mucous fluid excreted during oviposition. Erom two to five hours are required for this operation, and an average of three of these masses is deposited during a period of from six to eight weeks. As the time of ovipositing varies with the latitude, so the hatching of the eggs occurs from the middle or last of March in Texas till the middle of May or first of June in Minnesota and Manitoba. Until after the molt of the first skin, and often till after the second or third molt, the young nymphs are content to feed in the immediate 63 INSECTS IKJUUIOUS TO STAPLE CHOPS. vicinity of their birth. But upon such food becoming scarce they congregate together and in solid bodies, some- times as much as a mile wide, march across the country, devouring every green crop and weed as they go. During cold or damp weather and at night they collect under rubbish, in stools of grass, etc., and at such times almost GBcm to have disappeared; but a few hoars of sunshine brings them forth, as voracious as ever. When, on account of the immense numbers assembled together, it becomes impossible for all to obtain green food, the unfortunate ones first clean out the underbrush and then feed upon the dead leaves and bark of timber lands, and have often been known to gnaw fences and frame buildings. Stories of their incredible appetites are legion ; a friend informs me that he still possesses a rawhide whip which they had quite noticeably gnawed in a single night! By mathematical computation it has been shown that such a swarm could not reach a point over thirty miles from its birthplace, and as a matter of fact they have never been known to j^roceed over ten miles. As. the nymphs become full-grown they are increasingly subject to the attacks of predaceous birds and insects, insect parasites, fungous and bacterial diseases, as well as being largely reduced by the cannibalistic appetites of their own numbers. When the mature nymphs transform to adult grasshoppers and thus become winged, large swarms are seen rising from the fields and flying toward their native home in the Northwest. This usually takes place during June and early July in the North, and as early as April in Texas, so that it is frequently im.possible to distinguish the broods of the temporary region from the incoming brood which has migrated from the perma- INSECTS INJURIOUS TO THE GRAINS AND (UlASSES. 63 nent region. Although the eggs for a second brood are sometimes laid, these seldom come to maturity, and the species is essentially single-brooded. Emmies. — As before mentioned, large numbers of the nymphs are destroyed before reaching maturity by their natural enemies. Among these a minute fungus un- doubtedly kills many of those already somewhat exhausted, especially during damp weather. Almost all of our com- FiG. 35. — Antliomyia, egg-parasite, o, fly; h, puparium; c, larva; d, head of larva. (After Riley.) mon birds, as well as many of the smaller mammals, are known to feed quite largely upon them. A small red mite {TromhicUum locustanun Riley), some- what resembling the common Red Spider infesting green- houses, is often of great value not only in killing the nymjihs by great numbers of them sucking out the life- juices of the young hopper, but also in greedily feeding upon the eggs. The maggots of several species of Tachina-flies are of considerable value in parasitizing both nymphs and adult locusts. Their eggs are laid on the neck of a locust, and, G4 INSECTS INJURIOUS TO STAPLE CROPS. upon hatching, the maggots pierce the skin and live inside by absorbing its juices and tissues. When full-grown the maggots leave the locust, descend into the earth, and there transform to pupae inside of their cast skins, and from the pupa? the adult flies emerge in due time. The maggots of one of the Bee-flies (Systcecltus oreas) feed upon grasshopper-eggs, but their life-history is not INSECTS INJURIOUS TO THE GRAINS AND GRASSES. G5 fully known. The common Flesh-fly {SarcopJiaga car- naria Linn.), Fig. 39, is also very destructive, though largely a scavenger. Fig. 37.— Tachina-fly. {Exo- rista leucanice Kirk). (After Riley.) Fig. 38. — Tachina-fly. (E. lidvirauda Riley). (After Riley.) Fig. 39. — Common ¥\e^\i-^j {SareojyJiagn carnaria Linn.), a, larva; 6, pupa; c, fly. Hair-lines show natural size. (After Riley.) Fig. 40. — Various stages of a Blister-beetle {Epicauta vittaia). (After Riley.) But of all the insects attacking locusts, the Blister- beetles, which, unfortunately, are often known to its as very injurious to various garden cro^DS, are probably of the 66 INSECTS INJURIOUS TO STAPLE CROPS. most Tiiliie. The female beetle deposits from four to five hundred of her yellowish eggs in irregular masses in loose ground, and in about ten days there hatch from these eggs some " ver}^ active, long-legged larvae, with huge heads and strong jaws, which run about everywhere seeking the eggs of locusts/^ Each of these larvae will consume one of the masses or about thirty eggs. The subsequent life-history of these insects is very complicated on account of their peculiar habits, but the various stages are shown in Fig. 40. The Lesser Migratory Locust. Besides the Rock}'' Mountain Locust there is only one other species that truly possesses the habit of migrating, though to a far lesser extent, and which is therefore known as the Lesser Migratory Locust (Mekuioplus atlanils Eiley). It is considerably smaller than its western relative and somewhat resembles the Red-legged Locust both in size and appearance. The species of very vridely dis- tributed, occurring from Florida to the Arctic Circle east of the Mississippi, and on the Pacific sloj^e north of the 40th parallel to the Yukon. The habits and life-history of the species are in all essentials practically the same as of the former species except that they have no particular breeding-grounds. Injuries by this grasshopper were first noticed in 1743, almost seventy-five years before the first record of the Rocky Mountain Locust, and since then they have done more or less serious damage in some part of the territory inhabited every few years. Non-migratory Locusts. There are several species of locusts which, though lack- ing the migratory habit, and thus being more easily con- trolled, often become so numerous as to do serious damage INSKCTS IXJUlilOrS TO THE GRAIXS AND GRASSES. 6T Fig. 41. — The Two-striped Locust {Mel moplus hivittdtus Scud.). (After Pviley.) Fig. 42. — The DilTerential Locust {Melaiioplua differentialis Thos.) (After Riley.) Fig. 43. — The American Acridium {ScMstocerca americnna Scud.). (After Riley.) Fig. 44. — Rcd-leg-ged Locust (Mehinoplus femur-rubrum Harr.). (After Riley.) 68 i^'SECTS INJURIorS TO STAPLE CROPS. over limited areas. Both as regards the regions inhabited, its habits, and life -history, the common Red-legged Locust (Melajioplus feniur-7-uhrum Har.) hardly differs from the last species and is often found m company with it. It is non-migratory, however, and though its injuries are thns entirely local, they are often of considerable importance. Records of locust-j^lagues in California date back as far as 1722. Many of them were doubtless due to the Cali- FiG. 45. — The Pellucid Locust {Ctnnuula pellucida Scud.). (iVfter Einerton.) fornia Devastating Locust [Melnnoplus devastator Scud.), and in the last inyasion of 1885 this species outnumbered all others seven to one. Resembling the last two species in size and markings, the habits and life-history of this species are also supposed to be similar to them, though they have not as yet been thoroughly studied. Together with the last species the Pellucid Locust {Camnula pellucida Scud.) has been largely responsible for the losses occasioned by locusts in California, and has also been found in New England, but not noted there as specially destructive. INSECTS IXJURIOUS TO THE GRAIXS AND GRASSES. 60 Considerably larger than the preceding species are the Differential Locust {Melanoplus dijfereniialis Thos.) and the Two-striped Locust [Melanophis Mvittatus Scud.), of which the former is peculiar to the central States of the Mississippi Valley, Texas, New Mexico, and California, Fig. 46. — A Swarm of Grasshoppers Attacking a Wheat-field. (After Riley.) while the latter has a more extended range from Maine to Utah and as far south as Carolina and Texas. These two differ from the smaller species in laying only one or two masses of eggs, and the eggs of differ en fialis have often been found placed under the liark of logs, but otherwise their habits are very similar. The Two-striped Locust is 70 INSKCTS INJUIITOUS TO STAPLE CROPS. characterized by two yellowish stripes extending from the eyes along the sides of the head and thorax to the extremi- ties of the wing-covers, and is probably the species most commonly observed by the farmer. The Differential Locust. An nnusnally severe outbreak of the Differential Locust occurred in Mississippi and Louisiana in 1899 and 1900 and was quite fully investigated by Prof. H. A. Morgan^ and interestingly reported upon by him.* It seems that outbreaks of this grasshopper invariably occur immediately after an overflow of the Mississippi or crevasses through the levees, which inundate the surrounding country, caus- ing a rank growth of vegetation and rendering the land unfit for cultivation for a season or two, during which time the grasshoppers have every opportunity for rapidly increasing in abnormal numbers. *^ Should heavy rains prevail during May and June of the season immediately following the crevasse, nothing is heard of the ravages of grasshoppers; but should dry summers follow, the condi- tions for grasshopper propagation and development are much more favorable and complaints are common." " The habits of young grasshoppers to seek the soil-crevices during rain results in the burial of millions beyond the hope of resurrection. This, with the development and propagation of fungous diseases among the nj^mphs, are the most potent natural agencies which destroy grass- hoppers during wet summers." f In 1899 thousands of acres of cotton, corn, and other crops were totally destroyed *See Bulletin 30, n. s., Div. Ent., U. S. Dept. Agr., pp. 7-33. \ Morgan, 1. c, p. 33. INSECTS INJURIOUS TO THK GR.VIXS AND GRASSES. 71 or seriously injured, and only saved by a most persistent fight against the locusts. The eggs are deposited in a single mass of from 103 to 132, mostly from August 10 to September 15. The young hatch from the eggs during the first three weeks of May and, after molting five times, become full-grown by the last week in June. They mate about the middle of July, and the eggs are laid a few weeks later. Our largest American locust, the American Acridium (Schisfocerca ainericaiia Scud.), is practically confined to the Southern States from the District of Columbia to Texas, and thence south through Mexico and Central America, being rarely found in the Xorth. This species is essentially a tropical one, and has often been exceedingly destructive, being especially so in 1876 in Missouri, Tennessee, North Carolina, Georgia, and southern Ohio. Remedies and Preventives. — All of our destructive locusts having essentially the same life-history and habits except that of migrating, methods of combating them will apply almost equally well to all, but must, of course, be judiciously determined according to existing local condi- tions. Destruction of the Eggs. — Of first importance in this warfare is the destruction of the eggs. In Europe, where labor is cheap, this is often done by hand-picking. That would hardly do in a western corn-field or wheat-ranch, They may, however, be quite successfully destroyed either by fall plowing or harrowing. In harrowing, ''the object should be not to stir deeply, but to pulverize the soil as much as possible to about the depth of one inch. Where the cultivator is used, it would be well to pass over the ground again with a drag- or brush-harrow for this pur- 72 INSECTS INJURIOUS TO STAPLE CROPS. pose,* In this way many of the egg-pods may be broken up or left exposed on the surface. Prof. Morgan has shown that of eggs in land thus treated 80 per cent failed to hatch. By plowing in the fall to a depth of about eight inches the same result is more surely accomplished by turning the eggs under to such a depth that the young hoppers upon hatching are unable to reach the surface. This will be made more eifectual by then harrowing and rollirg, so as to compact the surface as much as possible. . Such plowing might even be profitable if done in very early spring were it then followed by the usual spring showers, but in all probability it Avould be better to wait till the young are hatching, when large numbers of them can be buried by plowing infested fields in a square from the outside inward. Destroying the Kymplis. — Burniug. — After hatching every effort should be made to destroy the locusts while still young. The burning of straw or hay stubble, dead grass, or rubbish, where it is present in sufficient quanti- ties, or even, if need be, by augmenting such with rows of straw, is one of the best methods, esj)ecially on cold days when the young hoppers are congregated under such materials. Several machines have been devised both for burning and crushing the nymphs, but all are of doubtful utility. Crushing. — When, however, the surface of the ground is smooth and hard, a heavy roller will crush large num- bers of the nymphs while they are still young, especially in the morning and evening. * Riley, Bull. 25, 1. c. INSECTS INJCUIOLS TO THE GRAINS AND GRASSES. To Duelling. — Of the various means devised for trapping the nymphs "ditching" is one of the best, and is of especial advantage when the crops become too large for the effective use of other methods. Simple ditches two feet wide and tw^o feet deep, with nearly perpendicular sides, form effectual barriers to young grasshoppers. The sides next to the field to be protected must be kept finely pul- verized and not allow^ed to become washed out or hardened. This may be done by a brush composed of dead branches Fig. 47. — Simple Coal-oil Pan or Hopperdozer. (After Riley.) being hauled through the ditch, which has been dug in a strip of finely pulverized soil. The young locusts tumble into the ditch, and, failing to climb the steep and slippery sides, die there, from their exertions and the heat, in large numbers. To avoid too great an accumulation, pits should be sunk in the ditch at short intervals, in which most of them will accumulate, and wdiere they may be easily buried. It would seem that grasshoppers w^ould be able to leap across such a small obstacle, but as a matter of fact, like the Chinch-bugs, which might fly across^ they very seldom do so. 74 INSF.CTS INJUiaoUS TO STAPLE CROPS. - Spraying Ditches. — Prof. Morgan states that '^upon river plantations many open ditches are indispensable, and when rains are sufficient to keep tlieni filled or partly filled with water they serve a most excellent purpose in the destruction of the young grasshoppers." " The experience of spraying ditch-banks soon developed the method of damming water in the ditches and covering the surface with coal-oil or kerosene emulsion. Before and after rains the ditches were dammed and the water Fig. 48.— The Price Oil-pan or Hopperdozer. (After Riley. ) covered Avith a 12 per cent coal-oil emulsion. The young grasshoj^pers were then driven into the ditches, with the result that very few, if any, escaped. In this way a single application of oil would last several days, as many millions may easily float upon the water of a ditch not more than two feet wide. Unless the grasshoppers are scattered too far from the ditch-banks no difficulty is experienced in getting them to move in the directiun of the oiled water on account of the ' homing' instinct.'' 7G INSECTS INJUUIOL'S lU Sl'Al'I.E CHOPS. Hopper dozers. — One of the methods most extensively tried i'or the destruction of the nymphs upon small or young crops is by the use of crude kerosene or coal-tar in one of the so-called ^' nopperdozers." '^The main idea embodied in these contrivances is that of a shallow recep- tacle of any convenient size, provided with high back and sides, mounted either on wheels or runners. If the pan is larger than, say, three feet square, it is provided with transverse partitions, which serve to prevent any slopping of the contents (in case water and oil are used) when the device is subject to any irregular motion. On pushing these pans, supplied with oil, over the infested fields, and manipulating the shafts or handles so as to elevate or depress the front edge of the pan, as may be desired, the locusts are startled and spring into the tar or oil, when they are either entangled in the tar and die slowly, or, coming in contact with the more active portion of the oil, expire almost immediately. A good cheap pan is made of ordinary sheet iron, eight feet long, eleven inches wide at the bottom, and turned up a foot high at the back and an inch high in the front. A runner at each end, extend- ing some distance behind, and a cord attached to each front corner, complete the ^^an at a cost of about §1.50 (Fig. 47). We have known of from seven to ten bushels of young locusts caught with one such pan in an afternoon. It is easily pulled by two boys, and by running several together in a row, one boy to each rope, and one to each contiguous pair, the best work is performed with the least labor." Larger pans may be drawn by horses. The oil is best used on the surface of water, from which the insects are removed with a wire strainer. Various modifications of this apparatus have been devised, but the more simple INSECTS INJL'KIOUS TO THE GRAINS AND GRASSES. 77 ones seem to be fully as effective as those more complicated for which fancy prices are charged for royalty. Destroy ing the Adults. — The destruction of the winged insects is an entirely hopeless task, for, though even large numbers are caught, so many will remain that the damage done the crops would be but very slightly diminished. One of the most promising means for averting the swarms of v/inged migratory locusts from alighting in the fields is by a dense smudge, in which some foul smelling substances are placed. Where strictly attended, and with favorable winds, this has often proved highly successful. To accomplish the best results farmers over an extensive area should combine in its use. The South African Fuugns. — In 1900 Prof. Morgan made a test of a fungous disease which had been found to destroy large numbers of grasshoppers in South Africa, to determine whether, after starting it by artificial proim- gation, it would spread sufficiently to destroy any consider- able number of locusts. The weather was favorable, rains being frequent. Early in August it was found that " over the areas where the liquid infection was spread diseased hoppers were abundant." *^ As many as a dozen dead grasshoppers could be found upon a single plant, and some upon nearly every weed on ditch-banks where grasshoppers were numerous. From the centres of infection great areas had become inoculated, spreading even beyond the planta- tions first infected." The property upon which it was placed became thoroughly infected with the fungus. Strangely, though many other species of grasshoppers were abundant, only the Differential was killed by it. Dr. Howard states that this disease has also spread and done effective work in Colorado. 78 INSECTS INJURIOUS TO STAPLE CROPS. Poisoning. — A mash composed of bran, molasses, water, and arsenic or Paris green, wliicli has been extensively used for cutworms, was found to be quite successful in the experiments of Mr. D. W. Coquillct in the San Joaquin Vallejs California, during 1885, for protecting orcliards, vineyards, gardens, etc., and might even be of some value for grain crops. Two pounds of Paris green, twenty- five pounds of bran, barely moistened with water and cheap molasses, will be about the correct proportion. It should be placed in the fields, a tablespoonful to each plant or vine. At this rate the cost per acre of vineyard, including labor, will not exceed fifty cents. The poison acts slowly, but if judiciously used will be found very effective, especially for the non-migratory forms. In Texas the mash has been found satisfactory in destroying the grass- hoppers attacking cotton. One planter* writes: "We are successfully using arsenic (for grasshoppers) at the following rates: 10 pounds of wheat bran, 1^ gallons sorghum molasses, 1 pound arsenic. Make a thick mash, sow broadcast on infected ground, and it will surely kill them. I used 40 pounds last year and made 49 bales ot cotton. My neighbors did not do anything and entirely lost their crop." However, Prof. M^organ concluded that 'Hhe mash cannot be relied upon in severe outbreaks, such as occurred in the delta, but may be used in limited attacks wliere the area affected would not warrant the more aggressive methods.'' * S. D. Harwell, Putnam, Callahan Co., Tex., Bull 30, n. s., Piv. Ent., U. S. Dept. Agr., p. 06. INSECTS INJURIOUS TO THE GRAINS AND GRASSES. 79 The Army-worm [Leucania unipiinda Haworth). Almost every year from some portion of this large country reports are received of the ravages of armies of worms sweeping over the grain-fields, like a horde of Vandals. Invariably, also, there has not been a single attack in the infested locality for a number of years, so that the farmer is at a loss to do anything to protect his crops, and by the time information can be received from an entomologist a large portion of them will already have been destroyed. Thus previous knowledge of the habits and remedies for these insects may be of value to him when injury by them is threatened. Being a species native to this country, these worms may almost alwa3^s be found east of the Rockies in low, rank growths of grass, which form their habitual breeding- grounds. Yet, though the moth is widely distributed, its chief injuries have been in belts from eastern Iowa to Maine, from northern Texas to northern Alabama, and east of the Blue Ridge Mountains to northern North Carolina. Even in these regions, however, the worms have never been recorded as injurious for two successive years, and the only recent wide-spread outbreaks have bee*n in 1861, 1875, 1880, and 1896, though serious injury is almost annually done in restricted localities. Only when their usual feeding-places are exhausted, or when through favorable climatic conditions or the destruction of large numbers of the parasites which hold them in check, they increase in abnormal numbers, do they assume the march- ing habit and mass in armies. Life-history. — In the North there are usually three broods each season^ and the insects pass the winter as half- 80 INSECTS INJURIOUS TO STAPLE CROPS. grown caterpillars; but in tlie South there may be as many as six broods, and the moths often hibernate over winter, laying eggs early in the sjiring. In the Northern States these young worms mature, change to puj)a3, and from them the adult moths appear early hi June, the May broods rarely doing serious injury. The female moths now lay their small yellowish eggs in rows of from ten to Fig. 50 — Army-worm Moth (Leueanin unipunctd), pupa, and eggs in natural position in a grass- leaf. Natural size. (After Comstock.) fifty, inserting them in the unfolded bases of the grass- leaves, and covering them with a thin layer of glue. Over seven hundred may be deposited by one female, and thus it is that the myriads of young worms appear when they hatch in about ten days, and form the destructive army of early July. The worms usually feed entirely at night, and thus whole fields will often be ruined before they are discovered, though a few generally feed during the day, as they all do during cloudy weather. The leaves and stalks of the grains and grasses form their favorite food, the heads usually being cut off, l)ut various garden crops have frequeutly been seriously injured. As a rule clover INSKCTS INJURIOUS TO THE GRAINS AND GRASSES. 81 is untouched, but even that is not always exempt. In from three to four weeks the worms become mature and are then about one and one-half inches long, of a dark-gray or dingy-black color, with three narrow, yellowish stripes above, and a slightly broader and darker one on each side, altogether much resembling cutworms, to which they are nearly allied. They now enter the earth and there trans- form to pnpae, from which the adulb moths come forth in about two weeks. These again lay eggs for a brood of worms which appear in September, but are rarely very injurious. The moths developing from this last brood either hibernate over winter or deposit eggs, the lar^^as from which become partially grown before cold weather sets in. •The moths very often fly in windows to lights, and are very plain little " millers "' The front wings are of a clay or fawn color, specked with black scales, marked with a darker shade or stripe at the tips, and a distinct white spot at the centre — on account of which they were given the specific name unipundii. The hind wings are some- what lighter, with blackish veins and darker margins. Enemies. — Were it not for other insects which prey upon the worm^, the army habit would undoubtedly be assumed much more often; but ordinarily these very efficiently reduce their number, and Dr. L. 0, Howard has recorded two instances in w^hich armies of w^orms were practically destroyed by them. Large numbers are always destroyed by the predaceous ground-beetles and their larvse, but their most deadly enemies are two small Tachina-flies. These lay from half a dozen to fifty eggs upon a worm, and the maggots from them enter the body of the worm and there absorb its juices and tissues, thus 83 INSECTS INJURIOUS TO STAPLE CHOPS. soon killing it. Ordinarily, when feeding at night, the worms are free from these parasites, bnt when the marcli- ing habit is assumed these little flies swarm aroand them on cloudy days, and before the next year will again have the voracious army under subjection. Thus worms with eggs upon them should never be destroyed if avoidable. Fig. 52. — The Farmer's Friend, the Red-tailed Tachina fly ( Win- themiit 4-pustulatreventive measures must be based upon a previous determination of the time of appearance of the broods for any given locality. Recently it has been shown that weather conditions largely determine the time of 104 INSECTS INJURIOUS TO STAPLE CROPS. appearance of the fall brood, a season of drought in early September retarding the emergence of the flies until rain falls. Professors Roberts and Slingerland state that ''a mild October and November often emphasizes the fly's destructiveness. A damp spring, even though a cold one, is also favorable to the development of the insect. On the contrary, dry hot summers are unfavorable, and often INSECTS INJURIOUS TO WHEAT. 105 cause a serious mortality to the earlier stages of the fall brood of adults; and a rainless August often retards the emergence of the flies until even our latest-sown wheat (in Xew York) is up and ready to receive their eggs. Just such weather conditions occurred in New York in 1900 and, we believe, were largely responsible for the fact that in many cases late-sown fields were as badly infested as those sown earlier/' If there be a normal rainfall in August, the flies will emerge as usual early in September and will lay their eggs on volunteer, early-sown, and trap strips of wheat, and late sowings will largely escape. Dr. A. D. Hopkins has recently worked out a most valuable law governing the time of appearance of this pest, and from which he has deduced a rule for '^the approxi- mate determination of normal dates for the ending of the fall swarm of the Hessian Fly in any locality " in West Virginia. "Take a knowm normal date of a place, of known latitude and altitude, correct this date to a corre- sponding date at sea-level, by adding one day to each one hundred feet of altitude above sea-level; then for any place north of this sea-level base subtract one day for each one- fourth degree of latitude and one day for each one hundred feet of altitude at the place to be determined, and for all points south add one day for eacli one-fourth degree of latitude and subtract from the result, as before, one day for each one hundred feet of altitude. The resulting date will be the approximate normal. . " To give an example of this method of determining normals, and to demonstrate its value, we will take, as the most important and reliable data, the results obtained by Prof. Webster, by actual experiments and observations, at Columbus and Wooster, Ohio. He found that the normal lOG INSECTS INJURIOUS TO STAPLE CROPS. dtito for the ending of the fall period of active flight or swarming of the fly at Colnmbus, latitude 40 degrees, was September 25th, and that the corresponding date for Wooster, latitude 40 degrees and 49 minutes, was Septem- ber 20th, which he states agrees almost exactly with results obtained in Indiana, and forms the base of conclusions, as set forth in his Bulletin No. 107." Columbus is 800 and Wooster 1000 feet above sea-level. By applying the above rule and computing the date of Wooster from that of Columbus, or vice ve^^sa, the same dates will be secured as those determined by Prof. Webster. Of the various farm methods of control the most im- portant is the late planting of winter wheat through the Central States. In the latitude and altitude of northern Ohio if this be done after September 12th the flies will all have laid their eggs before the plants sprout. The time of planting should be later the further south, but no arbi- trary dates can be given for the whole country, as those must be determined by altitude, latitude, and local condi- tions. Thus in extreme southern Ohio October 10th is stated to be a safe time, while in central Maryland, in the same latitude, wheat may commence to be sown between September 25th and October 5th. In northern Delaware farmers prefer not to sow until October 1st. Prof. Roberts states that though no definite dates can be given owing to injury being most serious after abnormal weather condi- tions, after which the dates would be different, yet that "^ New York wheat-growers have learned that wheat sown after the 20th to the 25th of September is usually much less infested. In Ohio and Michigan, as elsewhere, it has been found that wheat sown very early, i.e , about Sep- tember 1st, and late, i.e., after October 1st, is but slightly INSECTS IXJUllIOUS TO AVHKAT. 107 injured, while that planted during the middle of Se2)tem- ber is largely or wholly destroyed. Fig. 63 shows the proper dates for j^l^nting in Ohio as given by Prof. Webster. Various State experiment stations have issued bulletins giving the proper time to plant in those States, and should the rule given by Dr. Ilojikins prove to be applicable throughout the country, the problem of when to plant will be easily solved.* Inasmuch as most of the sj^ring brood remain in the stubble in the flaxseed stage after harvest, if the fields be then burned over, large numbers will be destroyed, but often this is impossible owing to the j^i'ictice of seeding wheat land to grass and clover, which is quite a common practice in many sections. By tlie destruction of all volunteer wheat the two supplementary broods may be reduced, and in the extreme North, where this is the principal means of carrying the insect over winter and spring wheat is grown, this will be found of considerable importance. By planting a few strips of wheat late in August or in the first weel: of September many of the flies will be decoyed into laying their eggs upon them, and by then plowing under these strips the eggs and larvae may be destroyed and the regular sowing thus 2)rotected. The trap strips should not be allowed to stand over about * See W. Va. Agr. Exp. Station, Bulletin Xo. 67 : The Hessian FlyinW. Va., A. D. Hopkins. Ohio Agr. Exp. Sta., Bulletins Nos. 107, 119 : F. M. Webster. Md. Agr. Exp. Sta., Bulletin Xo. 58: W. a. Johnson. U. S. Dept. Agr., Div. Ent., n. s. : The Hessian Fly in the United States, Herbert Osborn. Cornell University Agr. Exp. Sta., Bulletin 194: The Hessian Fly, I. P. Roberts, M. V. Slingerland, and J. L. Stone. 108 INSKCTS INJURIOUS TO STAPLE CROPS. , . ., ^^ : ,' LUCAS _ _ iwiLLlAMSl FULTON f ../"TottAWA Sept. 10 1 1899 !_ \:~ \. i-o-^y I \-\ — '^^^^ i~CUYAHOGA 'i GEAUGA j" ,.^.^ HENRY I v^ooD I SANDUSKY 1 ERIE . 1-., .; 1 ■ l*NCE I I WOOD I I I LORAIN I ^,\ TRUMBULl' ■J._. I |__ !" ! --— !^^ r . I iiMt-f I I SENECA . . ^'^'^i PUTNAM ! I f-^— ! I I • I LUKAIN I .^.i I [TRUMBULLJ j SeptilSj— i jpoRTAGEJ j ; HURON i i MEDINA ISOMMlf, , \ 1 ,--1 1 J MAHONING* I ' }VAN WERtJ ' |_ 1 ALLEN HANCOCK)' JASHLAND| -rrrrx Z\ I STARK \ I j Sept. 28, jcolumeianaJ ^L _.L -LSe^fgo_._.|.i».r--.^^| • r I J. ' l_,CARROLl_! ^,1 I MARION i I*— *■ i HOLMES ] J \ \\ f fcRAWFORO , , ■ „ ^ ,„ • iwYANDOTT IfilCHUNlV ; WAYNE j Sept. 28, '.COLUMEIANA} .=^ I — -1; „ I COSrtOc;.^!--, I ; SON i— 1 i..J I LOGAN i U. !u, ! .•'MCRROWI f-S \ ' I nci AU/A DC ' DARKE • ! CHAMPAIGN 1 MIAMI j. v-i--A ^ ' 1899 J" •-.., 1 .-I r i / ; GUERNSEY ! BELMONT 'I m- "A. CLARKE . i^ (FRANKLIN^ ^ |\;USKINGUM'-| ! PREBLE', ' ■_? IpickawaT^ Septh: 30 '- NE r I oct.i, ^fi - • I j GREENE <-)Ct. 1, j r 1 PERRY MORGAN I fS '., I ^—. '-_|. JFAYETTEJ 1899 !_,— ~ • :' ! ^ ^ ! BUTLER I h CLINTON! /warren j ( '' — L- j / \ HAMILTON C" ''T-'' f i \" CLER- HIGHLANO -j HOCKING I I ROSS . VINTON L, ATHENS ^S I Oct. 3.: :^^ f ' — i— , 1 PIKE I •*'E'GS *^"^^ jackson!_ . ■' I )<^ WASHINGTON Fig. 6B.— Map indicating, in bold faced type, the approximate dates immediately after which it is usually safe to sow wheat in the fall, in various sections of Ohio, in order to avoid the autumn attack of Hessian fly. Dates given in small type show when Avheat sown in the fall of 1899 escaped the fall attack, though it was in many cases totally destroyed by the spring attack. The difference between these dates is the variation from the normal, and where no dates are given between the cross-lines there waa no such variation. (After Webster.) INSECTS INJURIOUS TO WHEAT. 109 four weeks, or three or four days after the main crop is sown. Tliough none are exempt from attack, those varieties of wheat ^^ with large, coarse, strong straw are less liable to injury than weak-strawed and slow-growing varieties.'^ In Xew York in many localities in 1901 a wheat called Dawson's Golden Chaff was found to be but little injured, where others were nearly destroyed. However, in Canada, where this variety originated, it is as seriously injured as other kinds, and may become so in Xew York. Bearded Eed Wheat No. 8 was also found to be a very resistant variety, as were Prosperity, Democrat, Ked Rusisan, and White Chaff Mediterranean. It should be remembered, however, that none of these are invariably '' fl3'-proof/' and that though under certain conditions tbey maybe but little injured, in other localities and under less favorable circumstances they may be injured as much as any other sorts. Among other conclusions Prof. Koberts and his col- leagues state that the fly '-injures wheat more on dryish and poor land than on moist but well-drained, rich soils." Also, ''that the soil must be so well fitted and so fertile that a strong, healthy growth will be secured in the fall, though the sowing of the seed be delayed ten to fifteen days beyond the usual time. Such preparation of the soil will also help the wheat to recover from any winter injury. Thick seeding and vigorous growth also tend to ward off the fly.'' " Much stress should be laid on the proper fitting of the land for wheat Plowing should be done earty — at least six weeks before sowing^to give abundant time for the repeated working of the soil in order to recompact the subsurface soil and secure a fine but 110 INSECTS INJURIOUS TO STAPLE CHOPS. shallow seed-bed in which there has been developed, by tillage and the action of the atmosphere, an abundance of readily available plant-food. Manures and fertilizers should be kept near the surface and the young roots encouraged to spread out on the surface soil, thus avoiding much of the damage by heaving in winter and leaving the deeper soil for fresh pasturage for the plants during the following spring and summer." Prof. Webster strongly recommends the rotation of the wheat-crop, sowing it as far from where it was grown the previous year as possible. Where this has been judiciously done, individual farms have often remained free from serious attack when neighboring ones were badly injured. Remedies. — After injury by the fly has once become apparent in the fall, there is no application known by which it may be destroyed. The application of a liberal amount of fertilizer to land not already well fertilized will enable the plants to better withstand the injury and possi- bly outgrow it. Pasturing shee^D on early-sown fields would doubtless result in crushing many of the flaxseeds and larvae, and give the ground that compact, pulverized nature which it should have. Nothing is known as a remedy for injury by the spring brood. In summarizing his knowledge of means of controlling this pest, Prof. F. M. Webster, who is probably our best authority upon it, says: " After thirteen [now fifteen] years of study of the Hessian Fly^ I am satisfied that four-fifths of its injuries mmj he 2)r evented hy a letter system of agri- culture. For years I have seen wheat grown on one side of a division-fence without the loss of a bushel by attack of this pest, while on the other side the crop was invariably IK8EC"1S INJURIOUS TO WHEAT. lU always more or less injured. No effect of climate, meteorological conditions, or natural enemies could have brought about such a contrast of results. The whole secret was in the management of the soil and the seeding." Some Wheat-maggots. Very similar in its mode of injuring the wheat-stalk to the Hessian Fly is the Wheat Stem-maggot {Meromyza mnericana Fitch). The adult flies were first described by Dr. Fitch in 1856, tliough the work of the maggots had probably been noticed as early as 1821 by James Worth of Bucks County, Pa., and by the Michigan Farmer in Michigan about 1845. Extending from Dakota and Manitoba to Texas, the range of this insect practically covers all the eastern United States and southern Canada. Unlike the Hessia7i Fly it feeds and breeds upon wild grasses and is thus much more difficult to control. Prof. A. J. Cook found the larvae in both barley and oats in Michigan, Prof. Webster reared an adult from Blue Grass {Poa prate7isis), and Dr. Jas. Fletcher records it as breed- ing in Agrojyijrum, Descliampsis, Elynius, Poa, and Setaria viridis in Canada. Life-history.— lii\e the Hessian Fly the adult flies lay their eggs on fall wheat in September and October, and the young maggots when hatched work their way down into the stem, either cutting it off or causing it to discolor or die. The eggs are about one-fortieth of an inch long and of a glistening white color. The larvse are a light greenish color, about one-fourth of an inch long, tapering towards the terminal end while subcylindrical posteriorly, being quite elongate. The piipi^ are the same color as the 112 INSECTS INJUKIOUS TO STAPLE CROPS. larv^, but more rounded, being only one-sixth of aji inch long, and reveal the legs and wing-cases of the imago forming within tliem. The external case of the pupa, called the puparium, is merely the shrunken and hardened cast skin of the last larval stage, within which the insect Fig. 64. — Wheat Bulb-worm {Meromyza amerkana) a, mature fly; b, larva; c, puparium; d. infested wheat-stem — all enlarged ex- cept d. (After Marlatt, U. S. Dept. Agr. ) transforms to the pupa. The fly is abotit one-fifth of an inch long. It is of a yellowish- white color with a black spot on the top of the head, three broad black stripes on the thorax, and three on the abdomen, which are often interrupted at the sutures, so that they form distinct spots. The eyes are a bright green. The winter is passed by the larva3 in the young plants, and in spring they transform to pupae and adult flies. These in turn deposit eggs in such a position that the maggots issuing from them may readily feed upon the INSECTS INJURIOUS TO WHEAT. 113 succulent portions of the growing stalk. Numerous larvae thus sapping the life of the plant soon kill it outright or cause the top and head to wither and die. The adults of this brood emerge in July and lay eggs on volunteer wheat and grasses, the maggots working in the same manner as in the fall and coming to maturity so that another brood of flies lay eggs for the fall brood on the newly planted wheat. Owing to the fact that this insect breeds also in grasses during late summer it is much more difficult to combat than were it confined to wheat as its food-plant, as is the Hessian Fly. Jieniediex. — '' If the grain is stacked or threshed and the straw stacked or burned/' says Prof. AVebster, " it is clear that the number escaping would be greatly reduced,'' for, as the adults emerge soon after harvest, they would escape to deposit their eggs were the straw left in the fields, but ^Mt is not likely that those in the centre of the stacks would be able to make their way out, and the threshing- machine vv'ould destroy many more.. How much could be accomplished by late sowing of grain is uncertain, as the females are known to occur abundantly up to October. If plots of grain were sowed immediately after harvest in the vicinity of the stacks, many of the females could, no doubt, be induced to deposit their eggs therein, and these could be destroyed by plowing under." Burning of the stubble will also aid in keeping this jiest under control. There are several undetermined species of flies belong- ing to the genus Oscinis, and very closely resembling the common house-fly in miniature, being about one-fourth as larcre, whicli have nracticallv the same life-historv as tlie Wheat 8tem-maggot and injure the wheat in tlie same 114 INSECTS INJURIOUS TO STAPLE CROPS. manner. They will not need consideration by the prac- tical farmer other than in applying methods of control as already given. One species of this genus, determined by Prof. H. Garman as Oscinis variabilis Loew and christ- ened the American Frit-fly, has been found common in Kentucky and Canada, but is so nearly identical in Fig. 65. — The American Frit-fly (Oscinis virinMlis Loew). a, larva or maggot; b, puparium; c, adult fly. (After Garman.) appearance and habit in the larval stage that it can with difficulty be distinguished from the Stem-maggot. That these pests do not do more injury is probably due to a considerable extent to the fact that large numbers of them are destroyed by a small hymenopterous parasite, known as CoBlimis meromyzce Forbes, which very commonly infests the larvse, and by other parasites and predaceous insects. Rarely will these pests do serious damage, but very often INSECTS INJURIOUS TO WHEAT. 115 it is sufficient to merit consideration, and only a knowledge of their life-history can give a key to their successful control. IXJURIXG THE LEAVES AND HEAD. The Wheat-louse {Nectar o pi mr a avenm^2^.^. History and Distrihution. — At comparatively long inter- vals the wheat crop is extensively injured by the Wheat- louse or Grain-aphis. In 1861 and 1862 serious damage was done throughout New York and New England, which seems to have been the first serious outbreak of the jDest in this country, it being a native of England. Since then the crop of 1889 throughout Kentucky, Ohio, Indiana, Illinois, Wisconsin, and Michigan was the worst damaged, sometimes to the extent of 60 per cent. The follow^ing year the lice appeared on the eastern shore of Maryland in large numbers, causing a total failure of the crop in some sections, and in 1894 they did serious damage in Washing- ton and northern Idaho, wdiere they had been known for some years. Though no record of its distribution is to be found, it would seem probable from the above that the Wheat-louse occurs throughout the northern half of the United States, as no mention of its occurrence in the South is found. Like many aphids it rarely becomes excessively injurious, being usually held in check by internal parasites, ^Dre- daceous insects, diseases, and weather conditions. Just how far the weather is directly responsible for their increase or decrease is unknown; but it has been observed that an outbreak is usually preceded by several dry seasons, and that cold, damp weather during late sjoring and early summer seems to favor their development. Parasitic 116 INSECTS INJURIOUS TO STAPLE CHOPS. fungous diseases — mostly of the genus Empusa — are one of the most important checks to the multiplication of plant-lice, and, as they require wet weather for their best Fig. 66. — Wbeat-louse Parasite (Aphidius gr, young larva?; c, full-grown larva; d, cocoon from which adult has emerged; e, f, adult insects — e, male; /, female, a and />, natural size; c-f, enlarged. (After Riley and Marlatt, U. S. Dept. Agr.) stated by a Maryland man, cutting fully one-half of them. No more recent damage has been recorded, and owing to the slight damage usually done no remedies have received a practical test. Deep fall plowing might be of advantage by burying the larvae so deeply that the adults would be unable to escape. 122 INSECTS INJURIOUS TO STAPLE CROPS. INJURING THE HEAD. The Wheat-midge {Diplosi.^ tritici Kirby). History. — While the Hessian Fly attacks the stalk of the wheat-plant, another species of the same genus, known as the Wheat-midge, or " Red Weevil," often does very serions damage to the maturing head. It, too, is a foreigner, having first been noticed as injurious in Suffolk, England, in 1795, though probable references to its depredations date back as. early as 1741. ''In ' Ellis^s Modern Husbandman' for 1745 the attacks of the vast numbers of black flies (the ichneumon j^arasites) are noticed in the following quaint terms : ' After this we have a melancholy sight, for, as soon as the wheat had done blooming, vast numbers of black flies attacked the wheat- ears and bio wed a little yellow maggot which ate up some of the kernels in other parts of them, and which caused multitudes of ears to miss of their fulness, acting in some measure like a sort of locust, till rain fell and washed them off; and though this evil has happened in other summers to the wheat in some degree, yet if the good providence of God had not hindered it they might have ruined all the crops of wheat in the nation.^ (Hind's '' Essay on Insects and Diseases Injurious to Wheat Crops,' page 76.)" * It seems probable that it was first introduced into America near Quebec, where it ''ajDpears to have occurred" in 1819, and was first observed in the United States in northwestern Vermont in 1820. It did not become very destructive, however, until 1828, from which time until 1835 it kept increasing in such numbers as to cause the *The Wheat-midgc. Bulletin No. 5, Vol. 1, 2d Ser., Ohio Ag. Exp. Sta., F. M. Webster. INSECTS INJURIOUS TO WHEAT. 123 abandonment of the wheat crops in some localities through- out northern New England. Serious damage was reported as due to this pest every few years until about 1860, being most severe in 1854, — in which j^ear Dr. Fitch estimated the loss in Nevv York alone at 815,000,000, — 1857, and Fig. 70. — Wheal -midge (Diplosis triU-i). a, female fly; h, male fly; c, larva from below. (After Marlatt, U. S. Dept. Agr.) 1858. Since then no wide-spread injury has occurred, though local outbreaks are frequent, and it has spread south to the Gulf States and westward to Iowa, Minnesota, and Arkansas. Life-lmtovy. — The adult flies are small, two-winged insects, about an eighth of an inch long, of a yellow or orange color. They appear about the middle of June and lay the eggs "'in a small cavity at the summit of, and formed by a groove in, the outmost chaff covering the incipient kernel.^' They hatch in about a week, according to Dr. Fitch, and the maggots burrow into the fonning t.ernels. The maggots are of a reddish color, and when 124 INSECTS INJURIOUS TO STAPLE CUOI'S. an car is badly infested give it a reddish tinge, on account of which the insect is often called the '' Eed Weevil." When full-grown the larvae enter the ground and usually form cocoons, in which they pass the winter in the pupal stage, though they often hibernate without such protec- tion. Though doubtless there is usually but one brood in a season, observations by Prof. F. M. Webster and others seem to point to the fact that there sometimes are two broods, as adults have been observed from August into November. Besides wheat, the wheat-midge also sometimes injures rye, barley, and oats. Remedies. — Plowing infested fields in the fall so deeply that the midges will be unable to reach the surface upon developing in the spring is by far the best means of con- trolling this 2^est; while burning the stubble previous to plowing, and a rotation of the crop, will also be of con- siderable aid.* * See "The Principal In. ect 1 nemies of Growing Wheat," C. L. Marlatt, Farmers' Bulletin, No. 182, U. S. Dept. Agr. CHAPTER VIL INSECTS IXJURIOUS TO CORN IN^JUKIKG THE ROOTS. Corn Root-worms. The Western Corn Root-worm {Diahrotica longicornis Say). The farmers and entomologists of the Central States have long known this as one of the worst pests with which they have to deal, and its progress eastAvard through Ohio has been a matter of considerable interest. Hidorii. — Outside of entomological collections, the beetle was hardly known until 1878, when it first appeared in Illinois in such numbers as to cause any wide-spread damage. First observed by Say in 1823, who gave its habitat as Arkansas Territory, it was not again noticed until found numerous upon sorghum by Prof. AV. S. Robinson of Kansas in 1866, who gave a large thistle as its native food-plant. In 1874 Prof. C. V. Riley received a larva from Kirkland, Mo. , which had been found bur- rowing into the roots of corn with considerable injury, and again in 1878 from Eureka, Mo. Prof. Webster states that in Illinois from the spring of 1874 he collected only two specimens until the fall of 1877, when quite a number were taken in corn-fields. A rapid increase in numbers occurred during the next three years, and by 1880 its 125 126 INSECTS INJURIOUS TO STAPLE CROPS. injuries to corn in Illinois were so severe as to demtind investigation. At tliat time it was stated by several farmers that the larvae had been noted feeding on corn- FiG. 11. — Diahroiicd longicornis Say. a, beetle; h, larva — Western corn root-worm; c, pupa; d, egg; d' , portion of egg enlarged (X40); e, mandible of larva; /, Lead of larva from above. Hair- lines at sides natural size. (Redrawn from Forbes.) Fig. 72. — a, Diahrotien 12-punctata Ollv. Beetle of Southern corn root-worm; b, Diabrotica mttata Fab. Striped Cucumber- beetle. (Redrawn from Forbes.) roots for ten or twelve years, and that serious damage had been done for at least seven years. Thus it is evident that in all probability the injuries to corn commenced in Missouri and Kansas during the early ^70's, and, as soon INSECTS INJURIOUS TO CORN. 127 as the larvae had acquired a decided taste for corn, spread gradually eastward into Illinois, where that is the staple crop. In the spring of 1882 Professors Forbes and Webster began a careful study of the life-history, habits, and injuries of the insect, and to them we owe almost all our knowledge of it. At that time its injuries were found to be general throughout western Illinois, north of Centralia, and also in southeastern Iowa, destroying from five to ovei' fifty per cent of the crop. In 1885 Prof. Webster found it abundant at Lafayette, Indiana, where the owner of one large estate estimated his loss at fifteen per cent of the wiiole crop, or a cash loss of $60,000. Unnoticed in Ohio till 1892, in that year it was reported from Hamilton County, in the extreme southwestern corner of tbe State, and was also found in Van Wert County, in tlie nortlnvestern part. Since then it has steadily advanced, each year spreading over one and one- half counties to the eastward, until in 1895 it had been reported from over almost the entire western half of the State. jS^o special notice has been seen of any spread. While thus spreading eastward, it has become generally recognized in Kansas, Nebraska, Iowa, northern Missouri, Illinois, and Indiana. Though never known to have been seriously injurious east of Ohio, the writer found ears of corn in a field near Ithaca, N. Y., which had been planted in that crop for several years, attacked by large numbers of the beetles. On September 15, 1897, the corn w^as fairly alive with the beetles, as many as a dozen being found eating the silk of a single ear, generally well under the husk. Mr. Harring- 128 INSh:CTS INJURIOUS TO STAPLE CROPS. ton has found the beetles on thistles as far east as New Brunswick. The only previous records of it in New York are those of Prof. Webster, who quotes Mr. Fred. Blanchard of Lowell, Mass., as having specimens from New York, and Mr. Ottomar Reinecke of Buffalo, who wrote that he had collected it there on willow j^rior to 1880. Though these statements are doubtless correct, there certainly is no record of it during the last fifteen years, and never of its having been injurious. Life-liistory. — The life-history of the pest, though not comjDletely known, is 3'et comparatively simple. The eggs are laid in the early fall, within a few inches of the base of the stalk, from one to five inches deep in the soil. The larvae hatch from June to August, and at first eat the small roots entire, and then commence burrowing under the outer layers of the larger roots, causing the stalks to be easily blown over if on a rich loam, or small ears and a general dwarfing of the plant, if on poorer land. The adult worm is nearly white, with brown head, a little less than half an inch long by less than one-tenth of an inch in diameter. Three pairs of short legs are found on the segments immediately back of the head, but otherwise the long, cylindrical body appears perfectly smooth to the unaided eye, though seen to have numerous hairs and bristles under the microscope. Before pupation the color becomes slightly darker and the body shortens, becoming more like a common grub. They then leave the roots, form a small oval cell in the soil, transform to pup^e, and in a short time come forth as adult beetles The beetles are of a greenish or greenish-yellow color and about one-fourth of an inch long, resembling in form INSECTS INJURIOUS TO CORN. 129 the common Striped Cucumber-beetle. The adults are found in the fields from the latter part of July until the corn-silk becomes brown and dry, and often later, feeding upon the silk and pollen, thus doing more or less damage, though slight when compared with that of the larva3. Though feeding almost entirely upon corn, they have occasionally been recorded as eating various weeds, clover, beans, cucumber- and squash-vines, apples of which the skin had been broken, cotton-flowers, pumpkins, and various fungi. [Remedy. — See below.) The Southern Corn Root-worm or Twelve-spotted Diabro- tica (Diabrofiva (hiodecempu)ictata Oliv.). This beetle is distinguished from the above by being larger and having three transverse rows of four black spots on the wing-covers. Its larva, which has very similar habits and is very injurious, by eating the corn- roots in the South, has not been knovrn to do so in the North, but is everywhere exceedingly abundant. The beetle is ]3robably best known as attacking squash-, melon-, and cucumber-vines, of which it eats voraciously both leaves and fruit, but has also been noticed on clover, cabbage, cauliflower, beans, beets, hops, cotton, chrysan- themums, and various fruit-trees. Remedy. — The remedy for both these pests is so simple and effective that it would seem that no one ought to suffer from their injury. As far as known, they have never been injurious to corn after a j^revious crop of wheat, rye, or barley, though the field may have been infested before that, and a crop of corn is then safe for at 130 INSECTS INJURIOUS TO STAPLE CROPS. least two years. Thus a simple rotation, which is also to bo recommeuded on many other grounds, is entirely effectual. * The Corn-root Web-worm (Crambus caliginosellus Clem.). Injury. — When young corn-plants are seen to stop growing, become deformed, and to die off in such numbers as to frequently necessitate replanting, upon examination of the roots the iujury will often be found to be due to the work of a small caterpillar. Two or three, very often five or six, and sometimes as many as eight or nine will be found at the base of a plant about an inch below the surface of the soil, and not o\er four to six inches from the stalk, usually being in close proximity to it. Each larva is covered with a fine, loose web, to which cling particles of earth, forming a sort of case, and on account of which these insects are known as Web-worms. Where the web-worms are present in any number they will often necessitate the second, third, and sometimes a fourth planting, making the corn very late and involving considerable expense. The worms bore into the youug stalks just above the ground, frequently cutting them off entirely. Later on the larger stalks are gouged out at or slightly above the surface of the ground, and the larvae burrow into the folded leaves, which when they unfold have several transverse rows of three to five holes. On *See : 1882. Forbes, S. A. First Ann. Kept. 12th Kept. St. Ent. 111.. p. 10. 1890. Forbes, S. A. 6tli Ann. Rept., p. 71. 1892. " " Tth " " pp. 146, 154. 1894. Webster, F. M. Bull. No. 51 Ohio Ag. Exp. Sta., p. 89. 1896. '' " " " 68 '' " " " p 39. INSECTS iXTURIOtJS TO CORK". ISl account of this habit these insects are sometimes known as '^bnd-worms/^ Strong plants will often make a new start and survive the injury, but remain much behind those not attacked, while most of the weaker plants will decay and rot off. Tlie Motli. — As one walks through jiasture or grass land, many little white and yellowish moths are seen flying about on all sides, but quickly disappear as they alight on the grass. If a single individual be watched more closely, it will be noticed that in alighting upon a blade of grass it quickly rolls its wings very tightly around its body, and hugs up close to the grass so that it is hardly distinguish- able from it. Projecting from the head in front is what appears to be a long beak or snout, on account of which these moths are often known as '•snout-moths,"' but which really consists of the j)alpi or feelers. The '^ Grass- moths," as they are sometimes called, belong to the genus Cramius and include several common species, being marked with silver stripes and bands, as well as golden lines and markings, so that they often present a very handsome appearance. Life-liistory. — These are the parents of the Web-worms which do so much injury to the young corn-roots, the principal depredators ujjon corn belonging to the species Oramlus caliginoselhis. They lay their eggs in grass land in May or early June, dropping them on the surface among the rubbish or vegetation, or attaching them to the grass. They are oval in form and of a yellowish color, each being marked with regularly placed ridges. About two hundred eggs are laid by each female. In from six to ten days the eggs hatch. The young larva3 soon form their loose silken webs or tubes at or a little below the surface of the soil, 132 INSECTS INJURIOUS TO STAPLI-: CKOl'S. Fig. 73. — The Corn-root Web-worm {Cramhvs ailiginosellnb) n larva; b, pupa; c, moth; d, segment of larva; e, parasite (After Johnson. ) INSECTS INJURIOUS TO CORN". 133 burrowing among the roots, and feeding upon the stalk and outer leaves, or killing the phint by attacking the crov>'n. The larvs vary considerably in color, from a yellowish white, through pink, to a reddish or brownish shade, and are studded with small tubercles, each bearing a tuft of bristly liairs. The larvae become full-grown in from five to seven weeks and are then from one-half to three-fourths of an inch long. During the latter part of July they form cocoons, sometimes in the larval tubes, in which they pass the pupal stage and from which the moths emerge some twelve to fifteen days Liter. Eggs are laid in grass lands during August and September for another brood, the larv» hatching in September and October and becoming part-grown before winter. They hibernate in their webs over winter, and as soon as the grass commences its growth in the spring they are to be found feeding upon it, becoming full-grown early in May. Preventive, — As the natural food of these insects is grass, it is not surprising that corn planted on sod land should be worst injured; and though the injury 'done the grass may not have been noticeable, wdien the available food is so greatly diminished by substituting for grass land the comparatively few hills of corn the injury becomes much more serious and apparent. Though the planting of corn on sod land is a most common practice, injury by this and many other insect pests of corn — most of w^hose native food is grass— might be avoided by planting any other crop than a grain, such as potatoes. Otherwise plowing late in the fall and harrowing so as to expose the larva? to the weather, or plowing so deeply that they will be buried so that they cannot regain the surface, will do much to pre- vent injury the next season. Inasmuch as the moth will 134 INSECTS INJURIOUS TO STAPLE CROPS. not It^iy her eggs upon plowed land, if the land he plowed early she will he driven to other fields; hut the exact time of oviposition varies for different latitudes. Generous fertilization Avill aid the plants in overcoming injury very considerahly. Dr. J. B. Smith advises "the application of all the necessary potash in the form of kainit, put on as a top-dressing after the field is prepared for planting," and sa3"s: "Fall plowing and kainit as a top-dressing in spring will, I feel convinced, destroy by all odds the greater proportion of the web worms that in- fest the sod, and would also destroy or lessen many other pests which trouble corn during the early part of its life.'' The Corn Root-louse (Aphis maidiiuaUcis Forbes). Description. — Where joatches of corn become dwarfed, the leaves becoming yellow and red, with a general lack of vigor, one may well be suspicious of the work of the Corn Root-louse. Though such an appearance may be due to the Root-blight or the Grass Root-louse [Schizo- neura panicola Thos.), the cause of the trouble may usually be ascertained by an examination of the roots. If due to root-lice, they will be readily seen gathered together in large masses. The Root-louse may be recog- nized by being of a blnish-green color, with a white, waxy bloom, of an oval form, with two short, slender tubes projecting from the posterior part of the abdomen. These have open ends and were formerly supposed to excrete the sweet liquid " honey-dew '' upon which the ants feed, and were therefore called " honey-tubes. '^ If the Grass-louse be the depredator, however, it may be recognized by its white color, its blackish head and markings, and the absence of the honey-tubes, their position being indicated INSECTS INJURIOUS TO CORN. 135 by two small openings surrounded by narrow brownish rings. The latter species is common upon the roots of grasses, among which may be mentioned bhie grass, timothy, and Paniciim glahruw, and though it rarely becomes of any great economic importance, it is well to be able to distinguish it from the more injurious Corn Eoot- louse. Distrihution and Food. — The Corn Root-louse has been reported from Illinois, where it occurs in all parts of the State, Maryland, Xew Jersey, Delaware, Indiana, Ohio, Kentucky, Minnesota, and Nebraska, so that it doubtless occurs to some extent through the whole Corn Belt. Besides broom-corn and sorghum no other cultivated crop has been known to have been injured l)y this pest, though it feeds in early spring and even as late as June upon the roots of smaitweed, purslane, Fortiilaca solcracco, ragweed, foxtail, and crab-grasses. The economic bearing of its feeding upon these weeds will be seen in discussing the life-history. Care of the Ants. — If you will break open the nests of the small brown ants {Lasius niger and var. alienvs), which are common in corn-fields which have been infested w^ith the root-louse, during the winter, you will doubtless find many of the little black aphis-eggs, which have been carefully stored by the ants and which will be well cared for by them during the winter. They are of a glossy black color and an oval shape, and will sometimes be found in small piles in the chambers of the ants^ nests. On warm days the ants bring them up to the warmer surface- soil, and in cold weather carry them far down into the unfrozen earth. With the appearance of the young smart- weed plants [Polygo7ium pcrsicaria) in early spring, the 130 INSECTS INJURIOUS TO STAPLE CROPS. eggs commence to hatch. The ants at once lay hare the smartweed roots and carry their young wards to them, where large colonies soon become established. Life-liidory — If the field is not planted in corn, the lice will later feed upon the roots of the pigeon-grass or purslane. About the first of May the second generation of lice commences to appear, among them being both winged and wingless forms. Like most j^lant-lice, this brood, and all daring the summer, are produced by females known as agamic females, without any intervention of the male form, the young lice being borne directly by the female without any Qgg stage. Such females are called viviparous in contrast to those laying eggs, which are called ovijDarous, and such a process is termed " budding '' or partlienogenesis. The little brown ants again transfer the lice to the roots of the young corn-plants about this time, burroAving around the roots of the corn so as to lay them bare, and even carrying hither winged lice. All through the summer they attend the lice, burrowing around the roots of the corn, and carrying them from plant to plant, in return for which, upon stroking the lice with their antennae, the lice give off the sweet " honey- dew" upon which the ants feed; indeed, the lice have been well likened to herds of cattle, cared for by the ant herds- men. The first three generations each require about nineteen days to become full-grown. During the summer the lice continue breeding with extreme rapidity, the broods becoming mature in an average of eleven days, , some twelve broods occurring before the middle of Sep- tember. During the summer both winged and wingless agamic females occur, but about the middle of September appears a brood of wingless lice including both true sexes. INSECTS INJUIITOUS TO C()R:N'. 137 The females of this brood hxy the eggs until the middle of November. This generatiou is usually carried by the ants to their nests, of which they are given the freedom and in which they lay their eggs. Bemcdics — Owing to the fact that the lice do not migrate until the second generation, a rotation of crops will be of considerable service in checking their injuries, as corn planted on uninfested land will not be attacked until it has been able to secure a good start, and if well fertilized may be able to successfully withstand the injuries of the lice. The proper fertilization of plants infested with root-insects is always of the greatest importance, and usually the corn-plant will readily throw out sufficient roots to enable it to mature a crop, if the soil contains sufficient nourishment and is under proper cultivation. As the ants not only care for the lice during spring and summer, being largely responsible for their spread, but house the eggs in their nests over winter, any means by which the nests may be destroyed together with their inmates, the adult ants, their larvae, and aphis-eggs, will therefore be of considerable value in controlling the lice. Deep fall plowing and harrowing, thoroughly breaking up the ants' nests just before early winter, has been found to accomplish this end to a large extent, and is also excellent practice for destroying the hibernating larv^ of cutworms and the Corn Stalk-borer. Furthermore, inasmucli as the lice feed upon various weeds in early spring, if these be kept cultivated out, the probability of injury to the corn will be greatly lessened. These weeds are usually thickest in low spots, and it is in just these places that the lice appear first and do their worst damage. Injury done by the Corn Eoot-aphis is often overlooked 138 INSECTS INJURIOUS TO STAPLE CROPS. '■-' "■'■':>liiSi Fig. 74.— The Corn ^o is removed and Fig. 96. — Continued. before the larvae have advanced to the pupal stage. If the roots are thrown up to the hot sun and dry winds at this time, they will dry out and thus starve the young larva?, 176 INSECTS INJURIOUS TO STAPLE CROPS. thereby preventing their developing and migrating to other fields." A more frequent and thorough rotation of the crop will thus be of value. Meadow-maggots. (See page 90.) INJURING THE STEM. The Clover Stem-borer [Laugmna mozardi Fab.). Early in June one frequently finds the beetles of the Clover Stem-borer here and there in the clover-field. They are slender, shining beetles, about one- third of an inch long, with red head and thorax and bluish-black Fig. 97. — Clover Stem-borer {Languria moz((rdi). Shows the eggs natural size and magnified, the beetle, larva, and pupa much enlarged, and above, a clover-stem with the larva at work in it. (After Comstock.) wing-covers. The beetles themselves seem to do little or no harm. Hibernating over winter, they lay the eggs in the pith of the stems early in June, and the larvae emerg- ing from these feed upon the pith of the stem, often ver}- seriously weakening or killing it. The larvae become full- grown in a short time, transform to pupge, and the beetles appear by August. Clover is only one of a dozen food-plants of this insect, which is widely distributed. It rarely does any consider- IN^SECTS INJURIOUS TO CLOVEll. 177 able injury whore clover is regularly cut in early summer and fall, and need not be feared when this is not neglected. iNJURixG tup: leaves. The Clover Leaf-weevil (Pliytonomus pundcdus Fab.). TJie Clover Leaf-weevil is also a native of Europe, and made its first appearance in this country in the same sec- FiG. 98.— Clover Leaf-weevil {Phytonomus punctatus Fabr.). a, egg magnified and natural size; b b b b, larvce; c, recently hatched larva;^ d, head of larva; e, jaws of the same; /, cocoon; g, same magnified to sliow tlie meshes; 7^ pupa; i, weevil, natural size; j, the same magnified; k, top view of the beetle; I, tarsus and claws of the beetle; m, antenna of the beetle. (After Riley.) tion of western l^ew York as the root-borer, in 1881. Its injuries during that and the following year seem to have been the worst on record. Since then it has spread east 178 INSECTS INJURIOUS TO STAPLE CROPS. into Connecticut, south to Maryland and AVcst Virginia and as far west as Ohio and Micliigan. Every few years the weevils and larva? destroy much of the foliage, but rarely are as bad the next season. The weevil is about one-third of an inch long, of a stout, oval form, with a long, thick snout. It is of a brown color, with several narrow gray lines above and broad gray stripes on each side, and with twenty rows of small, deep punctures on the wing-covers. Life-liistorij. — In early fall the females lay their eggs in crevices among the stems near the base of tlie plant. The young larvae emerging from them are without legs, but manage to climb quite well by means of the prominent tubercles on the lower surface of the body. They are light yellowish green, which usually becomes deej)er green as they grow older. The larvse become partially grown before winter sets in, when they go into a dormant stage, hiding in rubbish or under the soil till spring, when they continue to feed upon the foliage and become full-grown in May and June. The larvae feed mostly at night and will not be noticed during the day, when they lie protected around the base of the phmt. The injury done to the foliage is very characteristic, the edges of the leaves being eaten in a very regular manner as shown in the illustration. Before transforming to the pupa the larva constructs a very deli- cate cocoon of a greenish-yellow color, which is left on the surface of the ground. In this the joupal stage is passed, occupying about a month, the beetles being most common in Julv and Ausfust. The damage which the beetles do to the second crop of clover is fully equal that done by the larva? to the first, and is more apparent, because the soil is then dry and the plant makes a slower growth. In INSECTS INJURIOUS TO CLOVER. 1?9 some cases the beetles have been known to hibernate ovei winter, when the larv^ would occur correspondingly earlier. Enemies. — The reason that this insect has not become a more serious pest is, that as often as it becomes excessively ■ abundant the larvae are attacked by a fungous disease AV'hich carries them off by the millions. When affected by this they climb to the top of a blade of grass, curl tightly around the tip, and soon die, first becoming covered with a white mold and then turning to a jelly-like mass. The spores of the fungus become scattered to healtlw indi- viduals, which soon succumb. Larva? affected in this manner may be easily recognized, and when diseased larvae are found in any quantity care should be taken not to pasture cattle on land infested with them, as instances are on record in which there seems little doubt that cattle have been seriously poisoned by eating these diseased larvae. The Clover-mite (B?^yoMa praieiisis). The spraying of fruit-trees for various in sect -pests in winter has been found to be one of the best means of keeping in control those which hibernate or whose eggs are on the trees during that season. One of these is the Clover-mite {Bryohia pratensis), an insect Avidely dis- tributed and of most variable habits. As its name indicates, this insect is nearly related to the common red spider of greenhouses, belonging to the family of vegetable-feeding mites {Tetranychidce), and with which it is often confused. It is, however, about twice the size of the red spider, being fully three-tenths of an inch long. Though knovrn as the Clover-mite, on account of its feeding upon that jDlant, yet this insect was first known 180 INSECTS INJURIOUS TO STAPLE CROPS, as, and is still, an important enemy of fruit-trees, more especially on the Pacific coast and in the Western States, but also in other sections of the country. The most injury seems to have been done to clover in the Central States as far south as Tennessee, though it has suffered somevi^hat even in the East. When attacked by the mite the leaves of the clover or fruit-trees become yellow and have a sickly appearance, as Fig. 99. — The Clover-mite {Bryobia pratensis). if affected with a fungous disease. Especially upon the upper sides of the tender leaves of clover the juices are extracted over irregular areas, looking more or less like the burrows of some leaf-mining larvae. Owing to the small size of the mites they may be doing considerable damage to the foliage and yet remain unnoticed; but in the egg stage the pest is much more readily detected and INSECTS i:N^JrilTOFS TO TLOVER. 181 attacked. In the more northern States the eggs are laid in the fall, and do not hatch until the next spring. Further south, however, the adult mites hibernate over winter. The eggs are of a reddish color, laid upon the bark of trees, especially in the crotches, and in the West are sometimes so thickly placed as to cover considerable areas two or three layers deep. When the adult mites leave the clover-fields in the fall to fiiul hibernating quar- ters upon fruit-trees for the winter, they often become quite a nuisance by invading dwelling-houses which are in their path. This is more j)articularly the case throughout the Mississij^pi Valley. I^einedies. — AVhen swarming into a house their progress may be arrested by spraying the lower part of the building, walls, etc., with 23ure kerosene as often as necessary. Inside the house they may be destroyed by the use of pyrethrum powder (Persian insect-powder), burning brim- stone, or S23raying with benzine, care being taken not to bring the latter substance near the fire. The only practical way of protecting clover from the mite is by destroying the eggs and hibernating mites upon the fruit-trees in winter. This may be done by burning all the prunings and thoroughly spraying the trees with kerosene emulsion diluted with five parts of water, or with a mechanical mixture of twenty or twenty-five per cent kerosene and water. Such a si^raying will also j^rotect the fruit-trees from tlie mite, and will also destroy numerous other insects, such as the j^ear-leaf blister-mite, which hibernates upon the trees. Such small insects, so minute as to usually escape notice, are often responsible for a poor growth, and should be i)roperly checked whenever known to be injurious. 182 INSECTS IXJURIOUS TO STAPLE CROPS. The Destructive Pea-louse or "Green Dolphin" (Xectaro- pli ora p is i Kalt . ) . Considerable injury was done to both red and scarlet clover by this pest in the spring of 1900 in Virginia, Dela- ware, and Maryland, and to crimson clover in Delaware in 1890. In Europe the " Green Dolphin '' has been known as one of the worst pests of peas, vetches, and clovers for the past century. The aphids leave the clover about May 1st in the above States, and feed upon peas during the early summer, practically destroying the crop of late peas in 1899 and 1900. During October and November they return to the clover and pass the winter upon it. Many predaceous and parasitic insects prey u2:>on this pest, but it is held in check, especially on clover, chiefly by a fungous disease (Empusa aj^hidis). This disease is prevented by dry weather, and hence the pest is most injurious in dry seasons. As yet no remedy for the pest on clover or means for prevention of injury are known.* IXJUEIXG THE SEED. The Clover-seed Midge {Cecidofuvia legumhiicola Lint.). This is also a native of western New York, where its first injuries were recorded in 1878, but since then it has spread to almost every section where clover is grown, and is so serious a pest that it has become quite an art to raise a crop of clover-seed. The parent of all this trouble is a *See Bull. XLIX, Del. Agr. Exp. Sta., "The Pea-louse," E. D. Sanderson ; and Circular 43, 2d Ser., Div. Ent., U. S. Dept. Agr., F. H. Chittenden. f wg. apt. Fig. 100. — The Ve?L-\o\i^e [Nectarophora pisiKdiii.). p, pupa: irg., winged viviparous female; apt., wingless, or apterous, vivip- arous female and newlv born young, all enlarged. (Author's illustration in Bulletin 49, Del. 'Coll. Agr. Eip.'Sta.) 183 184 INSECTS INJURIOUS TO STAPLE CROPS. little fly, resembling a mosquito, but only about one-tenth as large; so small, in fact, that it is rarely noticed. Life-liistory. — The eggs are laid among the hairy spines of the clover-head or beneath the bracts around the head. They are of a reddish color and scarcely one-tenth of an inch long. When the maggots emerge from them they Fig. 101. -The Clover Seed-midge (^Cecidomyia leguminicola). fly; h, larva, enlarged. (After Riley.) a, enter the undeveloped florets, which they often prevent from flowering. In this case some of the flowers in the head will bloom, but the field as a whole does not blossom as usual. Once inside the floret the maggots feed on the developing seed. They are of a dark-red color, of a plump, oval form, and without feet. When full-grown they leave the florets and drop to the ground, into which they enter and form a little, tough, papery cocoon, just under the surface. In it they transform to the pupa, which ulti- mately transforms to the adult fly. In the North two broods of the midge occur each year. The maggots of the flrst and principal brood become full- grown about the middle of June, and those of a smaller INSECTS INJURIOUS TO CLOVER. 185 one following during July and August. White and alsike clover have not been molested by the midge to any extent, but good judgment and a knoAvledge of the habits of the insect are needed to harvest a crop of seed from the red or mammoth. Remedies. — Two methods are in practice for controlling this pest. The first, wxll adapted for dairy farms, consists in pasturing the clover until the 10th or loth of June, and then securing a late crop of seed. The other method is to cut the clover for hay before the maggots have become full-grown and left the flowers, and then harvest a late crop of seed. Usually for red clover this will be any time during the latter part of June, and some two wrecks earlier for the mammoth, as the latter will not mature a crop of seed if left later. But the exact time for cutting must depend upon the latitude and season, and to secure success will need good judgment on the part of the farmer. K good rule for red clover is to start the seed crops a few days before timothy-heads apjDcar. The Clover-seed Caterpillar {Grajjholitlia inter stinctana Clem.). The larva of a small moth known as the Clover-seed Caterpillar [GraijholitJta inter sti7ict.ana Clem.) has also done serious damage to the seed in Iowa and is common in clover-fields elsewhere. The greenish-white larvse are about one-fourth of an inch long, and destroy the seed by gnawing through the florets at the base. The larvae pupate in thin cocoons spun in the clover-head, and from them emerge the small brown moths, which lay eggs for another brood at the base of the head. Three broods occur in Iowa; in June, August, and September. 186 INSECTS INJURIOUS TO STAPLE CROPS. The remedies advised for the midge have also been found satisfactory for this pest. Fig. 103. — Clover Seed-caterpillar {GraplwlitJia inter stinrtana^. a, caterpillar; 6. pupa; e, moth, all much enlarged; d, moth natural size. (After Osborn.) Fig. 103. — 0\oYex 'R2LY-yvorm.{PyraUscostaUs). 1 and 2 show larvae suspended by threads; 3 represents the cocoon; 4, the pupa; 5 and 6, the moths; and 7, larva in a case which it has spun; all natural size. (After Riley.) INJURING THE HAY. The Clover-hay Worm {Pyralis costalis Fab.). Even after all the above pests have been successfully combated, another insect, known as the Clover- hay AVorm, IXSECTS IXJURIOUS TO CLOVER. 187 often does clover-hay considerable injur}^ in the mow or stack. The caterpillars will usually be noticed toward the bottom of tlie stack if that part be searched in March or April. They are shown natural size in the illustration, and are of a dark-brown color, each segment being ringed with a band of darker brown. Hay infested by them has a moldy appearance from the numerous fine silken threads which they spin through it, often forming webs, and is so badly chewed and covered with w^ebs as to unfit it for stock. Life-histonj. — The laiva? forjn small silken cocoons in the cracks and crevices of the barn, from which the moths emerge early in June. As soon as the females find some clover-hay they deposit their eggs upon it, and from these the worms emerge and continue the destruction. Usually no serious injury is done except where clover-hay is kept over the second year or longer. When it is fed out each spring, before the next crop is harvest^ed, there is no food for the young caterpillars, and they perish before the new crop comes in. Remedies. — Thus these worms may be easily controlled by: 1. Xever stacking clover-hay two successive seasons in the same place. 2. Cleaning the mow out each spring so that no old clover w411 be left over in the barn until the new comes. 3. Never patting new clover-hay on top of old, in stack or mow. Though the clover-plaut has numerous and serious enemies, almost all of them may be controlled by simple means, the successful use of which depends almost entirely upon a thorough understanding of the habits of the insect to be fought. CHAPTER X. INSECTS INJURIOUS TO COTTON. INJURING THE LEAVES. The Cotton-worm (Aletia xylina Say). Best known of all the insect enemies of the cotton-plant is the Cotton-worm. Though the subject of numerous extensive investigations, it is such an ever-present pest that practical information concerning those habits which must be considered in successfully combating it is always perti- nent. Let us commence, then, with the new year, and follow the species through the season. L\fe-liidory. — During the winter months the adult moths hibernate in the most southern portion of the cotton belt, principally Florida and Texas, in the rank wire-grass occurring in the more thickly timbered regions. Only a few of these survive, but they are very capable ancestors, and in early March lay their eggs upon ratoon cotton where it is only an inch or two high. The eggs are laid singly, usually upon the under surface of the leaves, preferably near the top of the plant, and about five hundred are laid by each female moth. They are of a flattened convex shape, bluish green in color, and with a number of prominent ridges converging to the apex. In midsummer the eggs hatch in three or four days, but in the spring and autumn a much longer period is required. 188 INSECTS IXJURIOUS TO COTTON, 189 When first emerged from the eggs the young larvae are of a pale yellow color, but soon assume a greenish tinge, and are marked with dark spots, which become more dis- tinct after the first molt. Thev then become marked as Fig. 104.— Egg of Cotton Worm- moth, a, top view; h, side view; greatly enlarged. (From Fourth Kept. U. S. Entom. Comm.) Fig. 105. — Cotton-caterpillar. a, from side; h, from above — t w i c e natural size. (Fourth Kept. U. S. Entom. Comm.) when adult, being more or less striped with black and are distinctly greenish. During the early season the green worms are the more common, while later the black forms predominate. The appetites of these caterpillars are only too well known to the cotton-grower. At first they are content with eating only the under surfaces of the leaves, occasionally piercing through. Then the leaves commence 190 Il^SECTS INJURIOUS TO STAPLE CROPS. to look ragged, and Avlien these become scarce the tender twigs and bads are attacked. When excessively abundant, like the Boll-worm, the larger larvae develop cannibalistic Fig. 106. — Pimpln conquisitor, one of the principal Parasites of the Cotton-caterpillar, a, larvae, enlarged: h, head of same still more enlarged; c, pupa; d, adult female enlarged; e, f, end of abdomen of adult male, still more enlarged. (From Fourth Kept. U. S. Entom. Comm.) Fig. 107.— Cotton Worm-moth, a, with wings expanded in flight; h, wings closed, at rest— natural size. (After Kiley.) tendencies and often feed upon the weaker caterpillars. It requires from one to three weeks for the larv^ to become full-grown, during whi(jh time it is necessary for them to shed their skins some five times. The caterpillar now crawls into a folded leaf, which INSECTS INJURIOUS TO COTTON. 191 sometimes is eaten away so that the pupa hangs exposed, and there sj)ins around it a silken cocoon and transforms to the chrysalis or pupa. In this stage the insect remains dormant for from one week to a month, when the adult moth emerges. The imago is of a dull olive-gray color with a wing- expanse of about one and one-third inches, with wings marked as shown in Fig. 107, and sometimes with a purplish lustre. Like most of its relatives of the Xoctuidce^ or ''night-flying moths,'' it flies only after sunset, but, unlike them, it is not confined to the nectar of flowers for fool, -''s its mouth is peculiarly adapted to piercing the skin ol rij)e fruit and feeding upon its tissues. They are strong flyers, the moths of the later broods frequently flying as far north as Canada. At such times they have been known to do serious damage to peaches in Kansas, and to cantaloups in Wisconsin. The first two broods develop rapidly, and in the extreme South and by early April the moths emerge and are carried northward by the prevailing winds. Eggs deposited by them develop into moths, which, in turn, fly further northward, and thus the worms are gradually found throughout the whole cotton belt, though with a consider- able confusion between the various broods. At least seven broods occur in the far South and three at the northern limit of the species range. With this number of genera- tions, it is readily perceived, considering the number of eggs laid by each female, how such great numbers of the caterpillars may arise by the latter part of the season, in a region where practically none remain over winter. The progeny of a single moth after four generations would amount to over 300,000,000,000 individuals, or, if placed 192 INSECTS INJURIOUS TO STAPLE CROPS. end to end, at the end of the third brood there would be enough to encircle the earth at the equator over four times. Eyiemies. — It is thus very fortunate that the cotton- worms have many deadly enemies which commence their warfare upon them as soon as the first aj^pearance of spring, and continue it with increasing ardor throughout Fig. 108. — Cotton-worm ^gg-Y>dir2i^\te {Trichogramma pretiosa). a, adult female, greatly enlarged; b, ovipositor; c, female antenna; d, male antenna. (From Fourth Kept. U. S. Entomological Commission.) the season. A little insect which lives inside of the eggs and is known to science as Trichogramma pretiosa is one of the most efficient of these. Mr. Hubbard once observed in Florida that from 75 to 90 jDer cent of the fourth brood of eggs and 90 per cent of the fifth were destroyed by this parasite, while only three or four eggs in a hundred escaped in the sixth brood. One of the most useful parasites of the caterpillar was noticed to destroy nearly all of the chrysalids of the last II^SECTS INJURIOUS TO COTTOX. 193 brood as early as 1847. The eggs of these insects are laid upon the caterpillars, and the maggots hatching from them bore into the worm and there feed upon its tissues. It transforms to a pupa as usual, but the pupa soon dies, and large numbers are thus killed. Several similar parasites prey upon the cotton-worm, among the more important of which may be mentioned EiqAedrus comstockii. It is to be regretted that we have no way of encouraging the good work of these valuable parasites. But the common insec- tivorous birds which eat large numbers of the worms, especially when they are yet scarce in early spring, may and should be protected by enacting and enforcing the most stringent laws against their wanton destruction. Remedies. — Paris green is an effectual and now widely used remedy for this pest. When the United States Entomological Commission made their extensive investi- gations of remedies for cotton-insects in the early 80's, they devised some very tremendous apjiliances for spraying this upon as many as sixteen rows at once. But such machines have not proved practical, and it was found useless to attempt spraying over four rows at once. In fact they have never been used throughout the South in other than in an experimental capacity. Besides the general use of the dry Paris green by dust- ing it upon the plants as described below there have been several important factors which have so worked against the cotton-worm that the problem of keeping it in check is now considered practically solved by many authorities. The most important of these, and a most beneficial change as regarded from other than an entomological standpoint, is the diversification and rotation of crops, now coming to be more and more widely practiced by the 194 INSECTS INJURIOUS TO STAPLE CROPS. progressive agriculturist of the South. This alone has been very largel}^ responsible for checking the rapid spread of the pest. Now that the seed has become such a valuable joroduct of the cotton-plant, smaller varieties with many seeds and a short fibre are being grown, in contrast with the rank- growing, long-fibre sorts formerly preferred. Thus the rows are more open, the work of the worms is more readily detected, and remedies more easy of application. With these advantages in their favor, the more southern planters have come to realize the importance of destroying the early broods, and by doing so have been able to keep them in a state of comparative subjection. For many years the most commonly used and. exj)erience has shown, effective remedy is the use of the dry Paris green. It is usually dusted upon two rows of j^lants, from bags fastened at the ends of a pole, and carried by a man on horseback, who can thus poison from 15 to 20 acres per day. These sacks are about ten inches long by four inches in diameter, open the whole length of one side and firmly sewed at the ends. Eight-ounce Osnaburg is the best cloth for the purpose. A strip of oak or strong wood about one and one-half by two inches, and five feet long, has a one-inch hole bored through it at five inches from each end, and to this the sack is tacked, fastening one of the edges of the opening to each of the narrow sides of the pole. The sacks are filled through the holes in the pole. When freshly filled a slight jarring will shake out a sufficient amount of the poison, but when nearly empty the pole should be frequently and sharply struck with a short stick, or S2:)aces in the rows will be missed. The poison has been found most effective without the admix- INSECTS IJ^JURlors TO COTTOK. 195 ture of flour. If that be added, lighter cloth should be used for the sacks. The remedy for the cotton -worm is sim23le and effective. It simply needs careful watching, especially upon the part of the southernmost planters, and prompt work immedi- ately upon its appearance. Cutworms. For very few plants could a list of their insect- pests be made without mentioning the destructive cutworms (see page 214: to 217), and cotton is no exception. Their char- acteristic manner of cutting off the young plants at the surface of the soil is so familiar to every planter and trucker that no discussion of their life-history and habits is here necessary. The best method for their destruction is by distributing through the field bunches of clover or grass poisoned with Paris green. This may be best done by spraying a patch of grass or clover with the poison, then cutting it, loading it on a wagon, and scattering bunches over the field with a fork. For best results such traps should be spread over the field just as the plants are appearing above ground, or even a day or two before ; some care is necessary in so doing this that it will not result in injuring the young leaves. Grasshoppers. A much similar treatment will prove effectual for grass- hoppers, which frequently do considerable damage to the foliage. Twenty-five pounds of bran, one pound of white arsenic, mixed dry and then slightly moistened with water and cheap molasses, will form an excellent '^ mash "for their destruction, by placing a teaspoonful at the base of 196 INSECTS INJURIOUS TO STAPLE CROPS. each plant. Some fourteen different kinds of grasshojipers have been known to injure cotton, but of these the Ameri- can Acridium [ScUistocerca ame7'icana) and the Differential Locust (see page 69) are the most injurious. Fig. 109. — Granulated Cnt-worm {Agroiis annexa). n, larva; /, pupa; 7i, adult— natural size. (After Howard, U. S Dept. Agr.) Fig. 110. — The American Acridium {ScMstocerca americana Scud.). (After Riley.) Caterpillars. Many species of Lepidopterous larvae occasionally defoli- ate the cotton-plant, among the most common being the Bag-worm {Tliyridopterijx e2)hemercBformis), Fall Army- worm (Laphygma friigiperda) (see page 84), Garden Web- worm {Loxostege similalis) (see page 260), and the Leaf- roller [Caccecia rosaceana). Any of these may be destroyed INSECTS IXJURIOrS TO COTTOX. 197 by applying Paris green in a spiay or dust, as for tiie cotton-worms. Ftg. 111. — Garden. "Web- worm {Loxostege similalls). a, larva, en larged; b, side view of abdominal segment of same; c, dorsal view of anal segment; d, pupa; /, moth, enlarged. (xlfter Riley, U. S. Dept. Agr.) Plant-lice (Aphidce). The plant-louse Avhich is most frequently found injuring the leaves of the cotton-plant is the same as the melon- louse {Aphis gossypii). As upon melons, its worst injury is done while the plants are yet young, and in such cases the best practice is to destroy the infested plants and replant in their place. A spray of kerosene emulsion and water or similar irritant will kill them, and sometimes may be used to advantage; but owing to the rapid and hardy growth of the plant, and the fact that large numbers of them are consumed by their insect enemies, plant-lice are seldom of any great importance. IXJURIXG THE STALK. If it escapes the cutworms, the stalk of the plant will not be troubled further with insects, as long as it is in a healthy condition. Occasionally plant-bugs puncture the new growth, but such damage is rarely of importance. One of the boring-beetles, known as Ataxia crypta (Fig. 112), has been supposed to injure the stalk b}^ boring in 198 INSECTS INJURIOUS TO STAPLE CROPS. it, but investigation shows that its eggs are laid only upon stalks which have already been damaged in some other manner. Fig, 112. — Cotton Stalk borer (At xi' cryytci). a, larva from above; h, larva from side; c, tunneled cotton-stalk showing exit-hole; d, adult beetle — all enlarged except c. (After Howard, U. S. Dept. Agr.) INJURING THE BOLL. Sharpshooters. Bolls are frequently damaged by leaf -hoppers, known to science as Homalodisca coagulata, which injury is termed ''Sharpshooter work" by the planters. Usually they do not make their appearance till after the first of June. Before that they prefer the foliage of poplar and other shade trees near the cotton-field. Where the injuries are of annual occurrence it would be well to ascertain the trees upon which the insects are feeding, early in the season, and give them and neighboring undergrowth a INSECTS INJURIOUS TO COTTON. 199 thorough spraying with strong kerosene emulsion during May. ^^ Fig. 113. — Hoimdodisca codgulata. ((, aclull female seen from above; b, same, side view. (After Howard, U. S. Dept. Agr.) "Cotton-stainer." The Red Bug or Cotton-stainer [Dysclerciis suturelhis) once did considerable damage to the bolls in Florida, Georgia, and neighboring parts of Alabama and South Carolina, but of late years has devoted most of its atten- tion to oranges. Early in the season they stunted the bolls and made them abortive by sucking the vsap; but the most serious damage was done later, wdien they entered the open bolls, "puncturing the seed and damaging the 200 INSECTS INJURIOUS TO STAPLE CROPS. fibre " by their yellowish excrement. This indelible stain greatly depreciated the market value of the fibre, and was a vexing loss. Though never of commerical impor- tance, it was found by experiments that a rich orange dye could be made from these insects, which could be easily Fig. 114. — The Red Bug or Cotton-stainer {Dysdereus suturelluft) enlarged, a, nymph; h, adult. (From "Insect Life.") fixed upon silks and woolens by an alum mordant. In winter these insects congregate in heaps of cotton-seeds, and by using these as traps the insects may be killed with hot water. Several other insects attack the bolls, but never very extensively. Among them is a weevil (Arcecerus fascicu- latus) often mistaken for the Mexican Boll-weevil and which closelv resembles that insect. It is a '^ cosmopolitan - +j ^ ^ '^ ^ f re ij ^ ^ •" •- ^ ^' §-? si'i5 ■^ z: o o X C) .Z3 :^ X _ _ b/: .rH 5 =fH ^^ .9 r r ■r >> t:; r — :z •^ — ^ > ^ .u, ^ — =c ■ ^ F— I -r - > a :2 >> ^ ir ^ — > -ri =0 :J. — t: ^ cT - -^ X u .B p bio ■? s bO d > - ^ -5 ^ 5 •-.. C ? ii -<"- -"^ X "te "o JJ J -5 ^ .2 ^ " a C ^ ^ ':/: - ::. INSECTS INJURIOUS TO COTTON. 201 insect living in the pods of various plants, among others in those of the coffee-plant in Brazil, but is never shown to attack healthy plants/' Various leaf -eating caterpillars often gnaw the bolls, but will be destroyed by poisoning the foliage as previously described. If the Paris green be aj^plied for the Cotton-worm, and the general methods advised for the control of the Boll- worm and Mexican Boll-Aveevil be followed out, little fear need be had of these minor insects, though a knowledge of the best remedies for them is always desirable in case of their apppearing in unusual numbers. The Cotton Boll-worm (Heliothis armiger Hubn.). The Cotton Boll-worm is one of the pests most widely dreaded by the cotton-grower, and differs from the Cotton- worm in that it is found in other parts of the world as well as America, and is not restricted to a single plant-food, Tlie Moth. — The adult moth is about the same size as the Cotton-worm moth, but has a larger body and a greater variety of markings. When at rest the fore wings of the Cotton Boll-worm moth are slightly parted, while in the Cotton-worm moth they are closed. The Boll-worm moth varies much in color; both wings are bordered with dark bands, the wing-veins are black, and there are other black spots upon the fore wings. It may generally be seen about dark, and hides itself during the day in cow-peas and clover, sipping the honey from the blossoms of these and other honey-secreting plants, but does not, like the Cotton- worm moth, feed upon fruit. Life-history. — It deposits its yellowish-white eggs upon all parts of the cotton-plant, but prefers the silk and 202 INSECTS INJURIOUS TO STAPLE CROPS. tassels of corn. If hatched on the cotton-plant, the worms attack the young buds or bolls, rapidly destroying them. Tlie young worms resemble the cotton-worms, and walk like the familiar measuring- worms, but are darker in color. With age the w^orms exhibit great variety in appearance, from light green to dark brown or rose, and may be either striped or spotted or perfectly plain. The life of the insect from egg to adult averages about thirty -eight days, and there are usually five generations each year. The worms of the first brood, as a rule, appear about the first of May, and feed almost entirely upon the young leaves and buds of the corn; the second brood, appearing in early June, eat the tassels and forming ears of corn; the third brood, in July, attack the hardening ears. The fourth and fifth broods, appearing successively in August and September, appreciate the cotton as food, the corn having become too hard. About the middle of October the worms of the last brood descend into the earth to pupate, which state lasts from one to four weeks. Food. — The worm is known by various names according to the plant upon which it feeds, as, for instance, the Cotton Boll -worm, the Corn Ear-worm (see page 151), and the Tomato Fruit-worm. It is also found upon ^^eas, beans, tobacco, pumpkins, squash, and many flowering plants. A strange but mitigating characteristic of this pest is its tendency to feed upon its kind, especially if large numbers are crowded together, thus materially reducing its own numbers. Remedies. — Poisoning the young worms by spraying with arsenic was a method formerly used, but as it proved only partially successful, and as another and better method has been discovered, it is now comparativel}'' little used. INSECTS IXJURIOCS TO COTTOX. 203 The more effective method of keeping the insect in con- trol is the result of practical experience, and consists in the wise use of what are known as trap crops. Let five acres be planted with cotton and corn alternately with every seventy-five or one hundred acres of cotton, or in tlie same relative proportion for smaller areas. Of the five acres, for every twenty-five rows of cotton let five rows he left vacant. In these five vacant rows plant, as early as possi- ble, one row of an early-maturing sweet corn, planted sparsely, as only a small number of plants are desired. During the silking period let frequent search be made for the yellowish-white eggs, and when fresh eggs Cvin no longer be found let the silk ends of the corn covered with eggs and young worms be cut off and destroyed by burn- ing or feeding to stock; or better still, to insure perfect safety, let the entire plant be destroyed. Let three other rows be planted with dent corn so as to bring the silking period about the first of July. The larger number of eggs which will be laid on these three rows should be allowed to mature for the j^i'^servation of the natural enemies which parasitize the eggs and young worms. The crowded condition of the worms in these rows will result in a large amount of cannibalism, so that only a small number will reach maturity, recompense for which will be found in the parasites. But to entrap these individuals, let the fifth row be planted so as to reach the silking j^eriod about August first, and let this row be cut and destroyed as soon as the laying of eggs upon it ceases. It has been found that the corn produced from the second planting Avill generally j^ay for the expense of cultivation and the sacri- fice of the five rows of corn. In many cases, if the other two be properly cared for^ the third planting will not be 204 INSECTS INJURIOUS TO STAPLE CROPS. 1 r. ^ '-0 z ACRE CORN AND OTTO ^z S2aP c o •:: H aj o < t '^ o « ? .n O o r tn ^ o r "^^ b so S o CC CC >z; ?5 z z < S -< o o ACR^ CORN AND OTTO W Z ^^ K Z z 'i^ rri tf P aj o; 05 2 o u D H " o p .n O o t so S o CRES FTON 5iH CC ^ y^ K ^ ^ b g -^. ^ O -< o oo5^