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UNIVERSITY OF ILLINOIS, 
 
 Agricultural Experiment Station. 
 
 URBANA, MAY, 1896. 
 
 BULLETIN NO. 44. 
 
 INSECT INJURIES TO THE SEED AND ROOT OF 
 INDIAN CORN * 
 
 INTRODUCTORY. 
 
 The corn insects now recognized as in some way and to some 
 extent injurious to some part of the plant number 214 species, 
 of which 1 8 are known to infest the seed, 27 the root and the sub- 
 terranean part of the stalk, 76 the stalk above ground, 118 the 
 leaf, 19 the blossom, that is the tassel and the silk, 42 the ear in the 
 field, 2 the stacked fodder, and 24 the corn in store, either whole 
 or ground. The greater part of this long list, which is doubtless 
 by no means really complete, is composed of those whose injuries 
 are now so slight or rare as to constitute a possible menace rather 
 than to cause a serious loss ; but the history of economic ento- 
 mology, and even of the entomology of this one plant, teaches us 
 that we can rarely tell in advance what to expect of any possibly 
 injurious species. In fact, some of the insect enemies of corn now 
 most destructive were not many years ago almost unknown even to 
 the entomologist the northern corn root worm and the corn root 
 aphis, for example. 
 
 The principal insect species infesting this plant are the seed- 
 corn maggot and the wireworms, attacking the seed ; these latter 
 
 *This article is an abstract, with occasional minor alterations, of the more strictly 
 economic parts of the Seventh Report of the writer as State Entomologist of Illinois, 
 first published in February, 1895. 
 
 209 
 
210 BULLETIN NO. 44. 
 
 insects, the white grubs, the corn root worms, and the root aphis, 
 affecting the roots ; the cutworms and root web-worms, the army 
 worm, the stalk-borer, the corn worm, the bill-bugs, the chinch 
 bug, the corn flea-beetle, and the grasshoppers, injuring stalk and 
 leaf; the corn worm, the corn root worms, and the grasshoppers, 
 eating the flower structures and the ear ; and the meal-moth and the 
 weevils devouring the kernel in the granary or the meal in the bin. 
 Of these, by far the worst at present are the wireworms, the corn 
 root worms, the white grubs, the root lice, the cutworms, the 
 chinch bug, the grasshoppers, and the army worm. 
 
 The most serious ordinary injuries to corn, those which the 
 plant is least able to sustain, are injurious to the seed and root, 
 particularly those occurring early in the year ; but they are, for- 
 tunately, those against which precautionary or preventive meas- 
 ures may be most readily taken, and with the best effect. 
 
 ' GENERAL INDICATIONS OF INJURY. 
 
 Before beginning a description of injuries to each part of the 
 plant, a few practical hints may be given which will aid to a recog- 
 nition of insect attack from the general aspect of the field or from 
 the appearance of the entire plant. 
 
 1. If corn largely fails to appear in due time after planting, 
 the farmer need not content himself with a surmise that his seed 
 was poor or that the weather has been unfavorable, but should 
 examine the seed itself for evidence of the work of one of several 
 insects (wireworms, seed-corn maggots, grass maggots, etc.} attacking 
 it in the earth. 
 
 2. If the young plants make an unequal start, some hills ap- 
 pearing earlier and growing more thriftily than others at the very 
 first, the roots should be searched for the corn root louse; and even 
 those hills should be examined in which the corn has not yet come 
 up, as this louse sometimes infests the sprouting plant before it 
 appears above ground. 
 
 3. The ab'undant occurrence of ants in the corn field, sinking 
 their burrows among the stalks of the hill, is evidence of the 
 presence of the corn root louse in their company. 
 
 4. If the growth of the corn is arrested or retarded in patches 
 throughout the field, the leaves turning first yellow and then red, 
 it is likely that the roots are infested by the same root louse, to be 
 discovered by carefully digging up the hill and picking or gently 
 shaking off the earth to expose the roots at their origin. If no 
 insect enemy is found, the difficulty is quite likely to be due to a 
 fungus attack known as the root blight of corn, a discussion of 
 which does not come within the scope of this article. [See page 234.] 
 
l8g6.J INSECT INJURIES TO SEED AND ROOT OF CORN. 211 
 
 5. If single stalks or entire hills are killed or withered when 
 a foot high or less, search should be made among the roots and on 
 the stalk below the surface for the wireworms and the white grubs 
 
 6. If the corn falls readily in a windy storm and does not 
 afterward rise, and if it may be pulled up easily after the ear has 
 begun to form, it is probable that the roots are infested by the corn 
 root worms or that they have been eaten by white grubs. 
 
 7. If the plant remains green too long, maturing slowly, and 
 if the field contains many sterile stalks or soft, imperfect nubbins, 
 it is likely that the common corn root worm, in some of its stages, 
 will be found in or among the roots if search be made before Sep- 
 tember I. If large numbers of grass-green beetles one-fifth of an 
 inch in length (about the size of a common red ladybug) are seeft 
 on the silks and tassels of the corn, or feeding upon the fallen 
 pollen collected at the bases of the leaves, or upon the blossoms of 
 ragweed or other flowering plants in the field, the crop has suffered 
 from an attack of the corn root worm, of which these beetles are 
 the adult, and the ground should be planted to some other crop 
 the following year. 
 
 8. A deformed and unequal growth of the foliage, especially 
 of that unfolding from the roll of leaves at the growing tip of the 
 plant, with more or less irregular and ragged injury, when the corn 
 is from one to two feet high, is often due to an attack by the first 
 generation of the corn worm, the second generation of which bur- 
 rows in the kernels of the ear of corn during late summer and 
 early fall. 
 
 9. On the other hand, the presence of elongate holes, placed 
 side by side in an orderly manner, in short rows extending across 
 the well-opened leaf, is commonly the mark of an injury done when 
 the corn was smaller by the corn bill-bugs, several species of which 
 will be described when injuries to the leaf are under discussion. 
 
 10. An irregular eating away of the leaves of young corn, 
 and a similarly irregular gnawing of the stalk near the ground 
 when the plant is less than a foot in height, should lead to an 
 examination of the earth about the base of the hill. If fine particles 
 and small lumps of earth are found more or less closely webbed 
 together in a mass approximating the size of a hickory nut, some 
 one or more of the species of root web-worms are doubtless at work 
 in the field. 
 
 11. The cutting of the young corn at or below the surface of 
 the ground is an injury too well known as the work of the cut- 
 worms to require more than bare mention here. 
 
 12. The appearance in the side of the stalk of a hole about the 
 size of a straw, with a brown moist powder exuding, is evidence of 
 
212 BULLETIN NO. 44. [May, 
 
 the presence of the stalk-borer, an insect which often does a great 
 and practically irremediable damage to young corn in early spring, 
 especially in low grounds, by burrowing the stalk, pushing more 
 or less of its excrement out at the mouth of its burrow. 
 
 13. A similar, equally evident burrowing of the ear, the ex- 
 crement from which escapes by a hole through the green husks or 
 becomes mixed through the silks at the tip of the ear, betrays the 
 presence of the corn worm already mentioned under 8. 
 
 14. The eating away of the blade of the leaf in late summer 
 and autumn so as to make large irregular holes, which may multiply 
 and increase in size until they finally leave only the stripped midrib 
 and the bare stalk the injury being commonly very much worse 
 ^ilong the edges of the field is commonly due to grasshoppers. 
 
 15. In the corn crib or granary the commonest serious mis- 
 chief is the peppering of the kernel with little round holes, each 
 the diameter of the head of a pin, the first suspicion of which will 
 frequently be aroused by the appearance of fine particles of meal 
 sifting down somewhere within sight. The insect most likely to 
 be responsible for this mischief is the corn -moth; but various weevil 
 species may also be involved. 
 
 SYNOPSIS OF INJURIES. 
 
 A. INJURIES TO THE SEED IN THE EARTH. 
 
 1. Injuries by ants, which hollow out the kernel, commonly scat- 
 
 tering the meal through the dirt. Page 214 (Fig. i and 2.) 
 
 2. Injuries by small beetles, which gnaw the kernel from without, 
 
 commonly beginning at the germ. Pages 215-217 (Fig. 3, 
 4, and 5.) 
 
 3. Injuries by footless maggots, which bury themselves in the 
 
 seed. Page 218. 
 
 Seed-corn Maggot. Page 218 (Fig. 6, 7, 8, and 9.) 
 Black-headed Grass Maggot. Page 220 (Fig. 10.) 
 
 4. Injuries by six-legged larvae, which gnaw or bore through the 
 
 kernel. Page 220. 
 
 Pale-striped Flea-beetle. Page 221 (Fig. n, 12 and 13.) 
 The Banded Ips. Page 222 (Fig. 14, 15, and 16.) 
 Wireworms. Pages 224-233 (Fig. 17-32.) 
 
 B. INJURIES TO THE ROOTS. 
 
 5. Roots deadened, hardened, or dwarfed, without apparent loss 
 
 of substance. Page 235, 
 
l8g6.J INSECT INJURIES TO SEED AND ROOT OF CORN. 213 
 
 a. Small brown or yellowish ants abundant in the hills, and 
 
 bluish green or whitish root lice (plant lice and mealy 
 bugs) on the larger roots. Page 235. 
 
 The Corn Root Aphis. Page 237 (Fig. 33-37.) 
 
 The Grass Root Louse. Pages 256, 257 (Fig. 40 and 41.) 
 
 b. No notable number of insects present. The lowest roots 
 
 dead; surface of underground part of stalk with brown- 
 ish corroded spots, interior of this part darker, at least 
 at the joints, while the spaces between may be seem- 
 ingly healthy. (Root blight of corn, a bacterial disease; 
 not entomological.) Page 234. 
 
 6. Roots evidently injured or destroyed by perforations, gnawing, 
 burrowing, decay or other loss of substance. Page 257. 
 
 a. Roots eaten away, not burrowed or perforated, and without 
 
 rotten or withered tips; tap-root commonly gone or 
 decayed. White grubs in soil among or beneath the 
 roots. Page 257. 
 
 White Grubs. Pages 257-280 (Fig. 42-48.) 
 Prionus Grubs. Page 281 (Fig. 49-51.) 
 
 b. Roots penetrated, perforated, irregularly burrowed, and more 
 
 or less eaten off and eaten up. Underground parts of 
 stalk also similarly injured. Page 282. 
 
 Wireworms in soil among the roots. Pages 224-233 (Fig. 
 
 17-32.) 
 Small, slender, soft-bodied, yellowish white grubs in the 
 
 roots and earth. (The Southern Corn Root Worm.) 
 
 Page 282 (Fig. 52-56.) 
 
 c. Roots visibly penetrated and perforated scarcely at all; 
 
 sometimes decayed at tips, but not eaten away. Princi- 
 pal injury interior, in form of minute burrows which 
 are commonly longitudinal, discoverable on peeling or 
 splitting the root, the burrows sometimes containing 
 minute slender white six-legged larvae, with brown head 
 and neck and brown patch on last segment. (The 
 Northern Corn Root Worm.) Page 287 (Fig. 57-61.) 
 
214 BULLETIN NO. 44. [May, 
 
 A. DETAILED DISCUSSION OF INJURIES TO THE SEED. 
 
 i . Injuries by ants, which hollow out the kernel, commonly scat- 
 tering the meal through the dirt. 
 
 Injuries to corn by ants are of two kinds : one indirect but 
 serious; the other direct, but of little importance because quite 
 rare. The former will be treated in connection with insects affect- 
 ing the root, since it is by rearing, transporting, and fostering 
 the root lice of corn that ants are most injurious ; and the latter 
 is given here in its place as an injury to the seed in the earth. 
 
 Occasionally in searching for the causes of the failure of corn 
 to germinate, or to grow thriftily after making its appearance, a 
 kernel may be found wholly or partly hollowed out, the mealy 
 interior being not devoured, but scattered about in the earth, 
 while the outer shell of the seed remains but little disturbed. The 
 agents of this small mischief will frequently be found still buried 
 in the cavities they have excavated most commonly ants of a 
 minute pale yellow species, a little more than a sixteenth of an 
 inch in length. This injury to corn requires no treatment so far 
 as is now known, and probably admits of none. I have seen two 
 species of ants engaged in this injury to planted corn in Illinois : 
 one the common little house ant*, which frequently becomes a 
 nuisance in pantries, especially if sugar is exposed to its visita- 
 tions (see Fig. i); and the other a larger, outdoor species, well 
 shown in Fig. 2. 
 
 The first of these ants (Fig. i) was 
 found by me abundant in many fields of 
 corn, both new and old, at Normal, Illinois, 
 in June, 1883, and at Champaign in May, 
 
 1886, where they were usually collected 
 about the kernels in the earth, and fre- 
 quently more or less hidden in little cavities 
 excavated in the softened grain. May 19, 
 
 1887, they were very abundant in a field of 
 corn on sod in Champaign county, eating 
 
 i G .~\.-Solenopsis molesta, ^ the planted kernels. In autumn the 
 
 worker; enlarged eighteen same species has been detected by us 
 
 diameters. indulging a similar appetite, but in a way 
 
 to do no harm. September 11-21, 1893, it was found feeding on 
 
 and within kernels of corn at the tips of ears which had evidently 
 
 been injured previously by crickets and grasshoppers. The solid 
 
 substance of the grain is not actually eaten by these ants, a fact 
 
 which I demonstrated by dissection of the ants, but it is simply 
 
 *Solenopsis molesta, Say (=S. debilis, Mayr). 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 21$ 
 
 gnawed away, doubtless for the sake of the sweetish and oily 
 fluids of the softened kernels. If plants start from seeds thus 
 injured, they are shorter than those adjacent, and have a stunted, 
 weak appearance. 
 
 This species has also been several times noticed by us in Sep- 
 tember in attendance upon the root louse of corn, sharing with 
 several other species of ants the cares and benefits of this associa- 
 tion. It occurs more frequently, according to our observations, 
 at this season of the year, with the corn root lice infesting purs- 
 lane than with those upon the corn itself. I have also recorded in 
 my Thirteenth Report (p. 112) observations of injuries to ripe 
 strawberries by this house ant. 
 
 The second species referred to 
 in this connection (Fig. 2) was seen 
 by us in Champaign, May 13, 1887, tear- 
 ing off fragments from a kernel of 
 sprouted corn just below the surface 
 of the soil, disposing of them much as 
 does the species mentioned above. 
 Many other grains were found in differ- 
 ent parts of the same field similarly 
 injured, being sometimes, indeed, com- 
 pletely excavated. The abundance 
 of this species and the obscurity of 
 the injury suggest that it may do 
 greater mischief than would appear FlG - *-Myrmica scabrinodis lobi- 
 
 " . corms, worker ; enlarged eight 
 
 from this Statement. and one-half diameters. 
 
 This species, like the preceding, feeds in fall upon kernels of 
 corn at the tip of the ear in the field, most frequently following 
 injuries by other insects, but certainly sometimes hollowing out 
 the grain without their aid. 
 
 Its relations to the corn plant louse will be described in another 
 article. 
 
 2. Injuries by small beetles* which gnaw away the kernel from 
 withoiit, commonly beginning at the germ. 
 
 Three common beetles have been detected by us and reported 
 by others as engaged in a somewhat noticeable injury to seed 
 corn in the earth, two of them among the most abundant of our 
 
 * Beetles commonly have four wings, the front pair of which are usually hard, thick, 
 and opaque, fitting more or less closely upon the hinder part of the body above, and 
 similar in appearance to the rest of the upper surface. Beneath these, and next to the 
 body, may be found the membranous hind wings, generally entirely concealed except 
 during flight. The segment bearing the hind legs is fixedly attached to the hind body, 
 but by a movable articulation. They also have a biting mouth furnished with two pairs 
 of jaws. 
 
2l6 
 
 BULLETIN NO. 44. 
 
 [May, 
 
 FlG. 3. Agonoderus pallipes, imaigo ; en- 
 larged four and one-fourth diameters ; 
 its work in seed corn. 
 
 Illinois insects, and the third also common, but too small to be 
 noticed frequently by the ordinary observer. 
 
 The first of these is an oblong pale brown beetle (Agonoderus 
 pallipes) with a blackish cloud on the back, from a half to a third of 
 
 an inch in length and about a 
 third as wide as long. It will be 
 easily recognized by the illustra- 
 tion (Fig. 3). It is a species of 
 common notoriety (although it 
 has never received an English 
 name) because of its annoying 
 abundance at lights in early 
 spring. Hibernating as an adult, 
 it leaves its winter quarters with 
 the first warm sunny days, and 
 flies abroad at night in countless 
 myriads. Shortly afterwards the eggs are laid in the earth, and a 
 new generation comes forth abundantly in June and July. The 
 adults themselves may be found, however, throughout the year. 
 It is possible that more than one generation occurs in a season. 
 We have noticed, in fact, a disagreeable abundance of these 
 beetles at lights on warm September evenings. The species 
 ranges throughout all, or the greater part, of the United States and 
 Canada. 
 
 It was first made known to me as injurious to seed corn in the 
 ground by a note from Mr. Thomas Huber, of Illinois City, Rock 
 Island county, dated June 4, 1883, and accompanied by a specimen 
 of the beetle "found in seed corn, buried in the kernel, eating the 
 germ and part of the inside." In Bulletin No. 12 of the U. S. 
 Department of Agriculture, Division of Entomology (p. 44)^ 
 Professor Riley reports the receipt of this beetle during the sum- 
 mer of 1885, with the information that it was injuring young corn 
 by gnawing into the seed and by eating the sprouting roots. One 
 of these observations was confirmed by the sending of a specimen 
 together with an injured grain. The exact amount of damage was 
 not stated, but it was said to be quite extensive. Even before these 
 observations I had myself detected this beetle injuring the roots 
 of corn to some small extent;* a point determined by the dissec- 
 tion of specimens taken in corn fields, among the roots. Nearly 
 half the food of these dissected specimens, however, consisted of 
 fragments of chinch bugs, and other insect remains. The character 
 and amount of this injury to corn have not heretofore been such as 
 
 "Twelfth Rep. State Ent. 111., p. 43. 
 
1896. J INSECT INJURIES TO SEED AND ROOT OF CORN. 2I/ 
 
 imago ; enlarged six and 
 one-half diameters. 
 
 to call for protective treatment, but if the beetle should become 
 sufficiently destructive to make such measures profitable, it is likely 
 that "a satisfactory remedy will be found in soaking all seed corn for 
 a short time before planting in some arsenical solution, such as 
 Paris green or London purple, in water. Such a course will not 
 injure the germinative quality of the seed, and will probably result 
 in the death of all beetles which attempt to gnaw the seed."* 
 
 ' The fact that a common small shin- 
 ing black dung beetle, Aphodius granarius 
 (Fig. 4), very abundant in stable manure, 
 where it feeds in part on fragments of un- 
 digested grain, may under favoring con- 
 ditions transfer its attentions to seed 
 corn in the hill, gives occasion for brief 
 mention of this insect here. 
 
 Our only knowledge of this injury 
 comes from Professor C. H. Fernald of 
 
 the Massachusetts Agricultural College,t FlG - ^Aphodius granarius, 
 who received specimens of this beetle 
 from Lancaster, Massachusetts, with the 
 statement that they had been found destroying seed corn in the 
 ground before it sprouted. 
 
 The third of these small beetles, 
 Clivina impressifrons (Fig. 5), is included 
 among insects injurious to seed corn 
 upon the evidence of a single observation 
 made by Mr. F. M. Webster in Indiana. 
 He says : " I received from Whitly 
 county, Indiana, a considerable number 
 of these beetles, with the statement that 
 they were found in a piece of ground 
 which had been broken the preceding 
 spring, the field being swampy and of a 
 black soil, like those infested by wire- 
 worms. The beetles attacked the seed 
 grains as soon as the latter became 
 moistened. When received, one of the 
 beetles had burrowed into a kernel 
 of corn in the vicinity of the germ, 
 
 ..." . . , , FlG. 5 Clivina impressifrons, 
 
 and was engaged in devouring the sub- enlarged eight and one- 
 
 Stance." half diameters. 
 
 *Bull. No. 12, U. S. Department of Agriculture, Division of Entomology, p. 45. 
 tBull. No. i, Hatch Experiment Station, Mass. Agr. Coll., p. 3. 
 
2l8 BULLETIN NO. 44. \May, 
 
 3. Injuries by footless maggots, which bury themselves in the 
 seed grain. 
 
 Two rather common injuries to seed corn in the ground are 
 due to small white maggots without legs, one apparently headless, 
 with much the form and general appearance of a very small blow- 
 fly larva, and the other with a smooth, conspicuous head of a shin- 
 ing jet black color. The first is known as the seed-corn maggot, 
 and infests corn only, as at present understood; and the second is 
 the black-headed grass maggot, normally a grass insect, as its 
 name implies, and injurious to corn only when this follows grass. 
 Both these maggots penetrate the kernel, feeding on the mealy 
 inner part, and leaving the outer shell. The first changes in the 
 course of the summer to a small two-winged fly of the general form 
 of the house-fly, and the second becomes a slender, small black 
 gnat, roughly resembling the mosquito. The fly of the seed-corn 
 maggot is little likely to be noticed in its winged state, but the 
 gnat of the grass maggot is frequently seen in very large numbers 
 on and near the ground in early spring. 
 
 THE SEED-CORN MAGGOT. 
 (Pkorbiafuscipes, Zett.) 
 
 FIG. 6. Seed-corn Maggot ; enlarged eleven diameters. 
 
 This maggot penetrates the grain commonly after it sprouts 
 but before it appears above ground, killing the germ or the g^ow- 
 ing shoot and finally hollowing out the interior so as to leave only 
 the harder, outer parts of the kernel. In specimens of injured seed 
 received by us from Altamont, Illinois, the larva had bored a round 
 hole in the grain near the edge, and mined in a circular direction 
 around the germ. In other grains it had entered at the tip of the 
 germ, and in some beside the sprout. In one plant containing a 
 full-grown maggot about two-thirds imbedded in the kernel, a root 
 about three inches long had formed, and a 
 yellowish stalk had grown two inches in 
 height. Still other grains had almost the 
 whole interior eaten out. Unsprouted ker- 
 nels, softened by lying in the earth, are also 
 FIG. 7. Seed corn injured by frequently penetrated in a way to destroy 
 Seed-corn Maggot. ^he germ. Commonly these injuries are 
 trivial in amount, but in at least one instance mentioned by Dr. 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 2IQ 
 
 Riley in his First Report as State Entomologist of Missouri (p. 154), 
 the crop of a field in New Jersey was practically destroyed. This 
 insect is now known to attack not only sprouting corn in the earth, 
 but also the roots of cabbages, radishes, onions, beans, and mustard, 
 and the eggs of locusts (grasshoppers). 
 
 The adult is a small two-winged fly, about a 
 fifth of an inch in length of body, not unlike a 
 house-fly in general appearance, but smaller, and 
 of a lighter form. It is widely distributed, having 
 been reported from Europe, where it seems to 
 have originated, and also from Canada, New 
 Jersey, and New York on the east, to Indiana, 
 Illinois, and Missouri on the west. Its life history 
 is as yet incomplete, no continuous experimental 
 work having been done upon it throughout the 
 year. Our miscellaneous observations and breed- 
 ing-cage work give us thus far direct evidence of 
 only a single brood, the maggots of which have 
 been seen by us from May I7th to June I3th, the 
 pupae from June 7th to i5th, adults emerging 
 from June nth to August 7th. It probably agrees 
 with other species of its genus having somewhat 
 similar habits in hibernating as a winged fly. It is quite likely also 
 that later broods appear, but not in corn. 
 
 FIG. 8. Pupa of 
 Seed-corn Mag- 
 got; enlarged ten 
 and one-half 
 diameters. 
 
 FIG. 9. Fly of Seed-corn Maggot ; enlarged eight 
 and two-thirds diameters. 
 
220 BULLETIN NO. 44. {.May, 
 
 THE BLACK-HEADED GRASS MAGGOT. 
 (Sciara, sp.) 
 
 When the spring is cool and wet after corn-planting, so that 
 the softened seed lies long in the ground without sprouting, this 
 is especially liable to certain kinds of injury ; and it is under 
 these conditions that the black-headed maggot seems most 
 likely to affect it injuriously. Rotting grain is, indeed, un- 
 doubtedly preferred by this insect, but it has occasionally 
 been seen to infest kernels which had begun to grow. It 
 lives normally in old sod, feeding chiefly, or perhaps 
 altogether, on decaying vegetation there, and will be found 
 in noticeable numbers in corn fields only where the field 
 was in grass the preceding year. These maggots penetrate 
 FIG. io. and hollow out the kernel, often leaving nothing more than 
 an empty hull. A score or more of them may infest a single grain. 
 They are also frequently noticed in rich garden ground and 
 among potted plants, where they are. accused by gardeners of eat- 
 ing the roots and hollowing out the bulbs. 
 
 They are slender, footless, white maggots (except that the 
 head is jet black), about a third of an inch in length when full 
 grown, and of nearly uniform diameter throughout. The body is 
 soft and flexible, and the movements of the maggot are sluggish. 
 The species is very common throughout the State, and, doubt- 
 less, throughout the country at large, but it has been noticed in 
 its relation to grass and corn only in an article in my Thirteenth 
 Report (p. 57). 
 
 The larva was first brought to my notice as a corn insect in 
 May, 1883, through Dr. Boardman of Stark county, who forwarded 
 specimens to my office with the information that this insect was 
 destroying newly planted corn in that county by eating out the 
 substance of the germ, sometimes as many as three or four larvae 
 to a single kernel. The field had been a pasture previously 
 partly blue grass and partly timothy. Other fields of the neigh- 
 borhood were abundantly infested, but only where the ground had 
 been in grass the preceding year. 
 
 May 30, 1883, the same larva was observed at Towanda, 
 McLean county, abundantly infesting corn on old sod, and other 
 similar observations were made to July io of that year. 
 
 4. Injuries by six-legged larvce which gnaw or bore through 
 the kernel. 
 
 The six-legged insect larvae which infest corn in the earth are of 
 very unequal importance, the so-called wireworms being found 
 
I896.J INSECT INJURIES TO SEED AND ROOT OF CORN. 221 
 
 more injurious to seed corn than all other insects taken together, 
 the larva of the banded Ips being only occasionally reported to 
 infest corn in the earth, and the other that of the pale-striped 
 flea-beetle having been seen but once in this situation. Probably 
 ninety-nine per cent, of the six-legged kernel-eating insect larvae 
 will be found to be wireworms of one or another species ; and the 
 greater part of these will usually belong, in Illinois, at least, to a 
 single species which may well be called the corn wireworm. (See 
 Fig. 26-29, p. 230.) 
 
 PALE-STRIPED FLEA-BEETLE. 
 (Systena t<zniata> Say.) 
 
 FIG. ii. Larva of Pale-striped Flea-beetle; enlarged nineteen diameters. 
 
 The larva of the pale-striped flea-beetle is a stiff, sluggish 
 insect, slender and small, less than a fourth of an inch in length 
 and about one-eighth as wide, dull, of a very pale yellowish color, 
 minutely roughened and hairy, the thoracic segments with a regu- 
 lar geometrical pattern of longitudinal depressed lines. It is also 
 distinguished by its peculiar form, which narrows noticeably from 
 behind forward, the head being very small. 
 
 FIG. 12. Side view of Pale-striped Flea-beetle. 
 
 In the only case in which it was found infesting growing corn 
 (Champaign, May 17, 1886)* the larva had partly buried itself in 
 the kernel beside the sprout. This and others of the species found 
 among the roots were bred to the beetle stage on sprouting corn, 
 pupating May 26th to June 7th and emerging as adults on the I7th 
 of June. The great abundance of this insect in the beetle stage so 
 common as often to keep the leaves of the cockle-bur peppered 
 with small holes where these beetles have fed makes even so 
 slight a hint of its capacity for mischief both interesting and im- 
 
 * See "Canadian Entomologist," 1886, Vol. 18, p. 177; " Entornologica Americana," 
 Dec., 1886, Vol. II., p. 174. 
 
222 
 
 BULLETIN NO. 44. 
 
 {May, 
 
 portant. The adult insect also feeds on corn, as reported by 
 Glover on the authority of a correspondent, according to whom 
 these bettles nearly destroyed a field of corn at Chambersburgh, 
 Pa., eating the leaves and leaving the bare stalks standing. The 
 edges of the leaves may be gnawed away, sometimes nothing but 
 the midrib being left, or the leaf may be riddled with small holes. 
 The agricultural injuries of the bettle are not confined to the 
 corn plant, however, but it has been found by various entomolo- 
 gists to feed on beans, potatoes, beets, 
 clover, strawberry and blackberry leaves, 
 and the muskmelon, among useful plants, 
 and also on purslane, cockle-bur, plantain, 
 ragweed (Ambrosia), pigweed ( Ama- 
 rantus), and lamb's-quarters (Chenopo- 
 dium). 
 
 Beetles of this species have been 
 taken by us at frequent intervals from 
 April 8 to September 2, much the most 
 
 FIG. i 3 .-Pale-striped Flea- abundantly in June and July. Our sub- 
 beetle; enlarged ten diameters, stantial knowledge of its life history de- 
 pends, however, on the single breeding experiment already men- 
 tioned. Four larvae were collected May 17, 1886, and placed at 
 once in breeding cages with sprouting corn. May 26th a pupa was 
 found lying on the earth in the cage. Tnne 7th another pupa was 
 noticed yet in the earth, and on the I7th of June three adults had 
 emerged, and one pupa about mature was taken from the cage. 
 
 THE BANDED IPS. 
 (Ips fasciatus, Oliv.). 
 
 FIG. 14. Larva; 
 
 enlarged eight 
 
 and one-third 
 
 diameters. 
 
 FIG. 15. Pupa ; enlarged 
 nine diameters. 
 
 FIG. 16. Imago ; enlarged eight 
 diameters. 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 223 
 
 Among the insects attacking the kernel in the earth, is the 
 larva of a beetle, which in the adult state is abundant everywhere, 
 feeding upon a great variety of vegetable substances, fresh or in a 
 state of decay. The adult beetle has long been known as occasion- 
 ally and slightly injurious to corn in the ear ; but the fact that the 
 larva may infest seed corn after planting, although first noted by 
 us in 1883, has not hitherto been published. 
 
 My first observation to this effect was made at Normal, 111., 
 June i8th of the above year. In a field of corn a part of which had 
 been in pasture for fifteen years preceding, while the remainder 
 had grown turnips the year before which, however, had not been 
 removed from the ground large numbers of these larvae were 
 found in and about the seed kernels.* From the first, stalks were 
 growing fully two inches high. Occasionally a larva was seen in 
 the space between the rows, but nearly all were concentrated in 
 the hills of corn. Considering the ordinary habit of the species, 
 it is quite likely that the beetles were attracted to this field by 
 rotten turnips remaining in the ground. 
 
 June 16, 1885, larvae were very abundant at Mt. Pulaski, in 
 central Illinois, in the kernels of ears left in the field which had 
 been turned under by the plow and had commenced to grow. 
 May 16, 1887, a number were taken in a similar situation from a 
 mass of sprouting corn at Urbana, 111. 
 
 As an adult, this species was reported by Walsh in 1867, on 
 the testimony of an anonymous correspondent, to have done an 
 extensive injury some years before to sweet corn in Minnesota 
 by burrowing in the ear; and Dr. John Hamilton, of Toronto, 
 Canada, says that it is often found in the green ears of maize, but 
 only in such as have been injured by birds or other animals. Sep- 
 tember 13, 1893, it was brought to my office by an assistant, Mr. 
 Marten, with several injured kernels of corn, from the exposed tip 
 of the ear, which the beetle had burrowed into or eaten away 
 irregularly. In one other case reported under this same date it 
 was found burrowing into doughy grains beneath the husk, more 
 than an inch from the nearest exposed kernels, the natural infer- 
 ence being that the grains had not been previously injured. This 
 very common species must consequently be classed as one of the 
 minor insect enemies of corn, which it injures both as larva and 
 adult much more seriously, "however, in the former stage. 
 
 The feeding habits of the larva are very much less known. 
 Our own notes show, besides its occurrence in corn, that it breeds 
 in rotten apples. The species appears from our observations to 
 
 *The field had been twice planted because of a partial failure of the first seed, and 
 the kernels of both plantings were infested. 
 
224 BULLETIN NO. 44. \May, 
 
 hibernate as an adult, and to give origin during the year to at least 
 two generations. The larva enters the earth to transform, making 
 a friable earthen cell. 
 
 WlREWORMS. 
 
 Failure of the seed to start, or a sudden withering of the corn 
 plant when a foot or two in height, especially if the field was 
 broken up from grass one or two years preceding, are always 
 sufficient to warrant a suspicion of injury by wireworms. These 
 hard, smooth, shining, reddish or yellowish brown cylindrical six- 
 legged larvae* are indeed much more destructive to seed-corn, 
 under ground, in Illinois than all other insects taken together. 
 They may begin their injuries to the seed almost immediately 
 after planting, commonly burying their heads in it at first, some- 
 times eating entirely through the kernel, and even devouring it 
 completely. If they attack the growing plant they are likely to 
 eat the smaller roots, or to penetrate or bore through the larger 
 ones, dwarfing or killing the corn ; and later, when the young plant 
 is several inches high, they frequently kill it outright by boring 
 their cylindrical channels directly through the underground part 
 of the stalk. They are far the commonest in corn on ground 
 which has lain for several years in grass, and are much more likely 
 to do serious mischief the second year after the breaking up of the 
 sod. They should be sought for diligently on such lands whenever 
 the seed fails to grow, or when the sudden withering of the plant 
 hints at a serious damage to it under ground. At such times practi- 
 cally all the wireworms in the field will be found in the hills of 
 corn or in their immediate vicinity, sometimes as many as ten or 
 a dozen in each hill. 
 
 FIG. 17. Larva of Drasterius elegans; enlarged seven diameters. 
 
 Although wireworms are rarely distinguished by farmers as of 
 different kinds, there are no less than one hundred species of these 
 insects known to occur in Illinois in the adult or beetle stage, 
 and eight species of the larvae (the so-called "wireworms" them- 
 selves) have been found by us here injurious to corn. These corn 
 wireworms have, however, so strong a family resemblance that 
 
 *This general description of the wireworms does not apply to one very peculiar 
 form (Cardiophorus), taken by us but once in Illinois. 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 22$ 
 
 they are little likely to be confused with any other insect by the 
 fairly good observer who has once learned to recognize any one 
 of them. They vary in length, when full grown, from half an inch 
 to an inch and a quarter, but agree in their hard, crust-like surface, 
 nearly destitute of hairs; their brownish color, varying from 
 yellowish to reddish ; their slender bodies, distinctly segmented, 
 and of about equal diameter throughout their length ; their flat- 
 tened heads, with jaws borne in front and extending horizontally 
 forward ; the six pairs of short, stout, jointed legs on the three 
 segments following the head ; the absence of legs of any kind on 
 the eight segments thereafter; and the single sucker-like proleg 
 on the under surface of the last segment of the body the thir- 
 teenth, counting the head as one. This terminal segment is often 
 peculiarly finished above concave or convex, notched, toothed, 
 or lobed at the sides and end, or, in one species, with a pair of 
 conspicuous round openings on the upper surface. Taken in the 
 fingers, the wireworms bend and wriggle with surprising strength, 
 and easily slip out of the grasp. 
 
 They live regularly and normally in grass lands, feeding on 
 roots of grass, where, however, their numbers are rarely sufficient 
 to produce any notable effect upon the sod. It is only when con- 
 centrated in the comparatively scanty vegetation of a field of 
 young corn in spring, or occasionally 
 in young wheat or other small grain, 
 that they do any very marked or im- 
 portant harm. They are to be found 
 in grass of every description, from 
 prairie sod and the coarse and rank 
 sedges along the borders of marshes, 
 to the cultivated grass of our pastures 
 and meadows. 
 
 The commonest form of attack on 
 the corn, as seen by the farmer, is, 
 perhaps, the burrowing of the worm 
 into the seed kernel, either before or 
 after it has sprouted. All the species 
 treated in this paper have been seen 
 with their heads buried in the kernels, FlG . l8 ._zv/^ /**. beetle; 
 
 either in the field or in breeding-cages, enlarged seven and ahalf diameters. 
 
 Frequently attacks in the field have been so severe, particularly 
 the first or second year after the sod has been broken, as to 
 require planting a second or third time. Drasterius elegans (Fig. 
 17 and 1 8) and Melanotus fissilis have been taken in the act of per- 
 forating stalks just above the root. In a field at Peru, Illinois, 
 
226 
 
 BULLETIN NO. 44. 
 
 {May, 
 
 examined July, 1883, as much as six per cent, of the corn in the 
 field had been killed in this way, sometimes two or three larvae 
 being found in a single stem. 
 
 FIG. 19. Cardiophorus sp., larva, dorsal view ; enlarged four diameters 
 
 The roots of the corn are also eaten to a greater or less extent 
 by all the species, the damage from this cause being sometimes 
 quite considerable. .A field in Alexander county visited in June, 
 1886, had spots of one hundred to two hundred hills not more than 
 a foot high, while the balance of the field was four or five feet 
 high. Many hills in these spots were gone. In the smaller hills 
 many small, slender, peculiar-looking larvae of an unknown species 
 of Cardiophorus were found. (Fig. 19.) In some instances they 
 had almostcompletely destroyed the roots of the corn ; in others 
 the roots were bored through and the outer surface eaten away so 
 a? to almost destroy their usefulness. 
 
 FIG. 20. Wheat Wireworm ; enlarged five diameters. 
 
 Agriotes mancus is so destructive to wheat as to be known as 
 the "wheat wireworm " (Fig. 20, 21, and 22). Drasterius elegans 
 is also known to infest this crop, as do other species as well. Rye, 
 barley, and oats also suffer from wireworm attacks. Dr. Fitch 
 also found them burrowing in timothy bulbs. Wireworms taken 
 from a dense clover sod and placed in our breeding-cages, where 
 they were supplied only with grass and clover, gave us images of 
 Asaphes decoloratus. (Fig. 23, 24, and 25.) 
 
 FIG. 21. Side view of Wheat Wireworm. 
 
 Among root crops, potatoes often suffer from being bored into 
 and by having the surface gnawed and corroded by the worms ; 
 but turnips, it is said, appear to be more infested by them than any 
 other root crop. 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 22; 
 
 Besides the crops already mentioned Dr. Fitch names the fol- 
 lowing, which the wireworms are known to attack or are recorded 
 as attacking: mangel-wurzel, cabbage, carrots, beets, onions, 
 lettuce, rape, hops, strawberries, pinks, carnations, dahlias, lobelias, 
 and numerous other garden flowers. They have also been reported 
 to me by a horticultural friend as destroying planted peach pits in 
 the earth. 
 
 GENERAL STATEMENT OF LIFE HISTORIES. 
 
 The injurious species agree fairly well in the main features of 
 their life history, changing to the dormant pupae in the earth in 
 July or sometimes in August, and changing again some three or 
 four weeks later to the brown or 
 reddish beetles commonly known 
 as "click beetles" or "jumping- 
 jacks" hard, somewhat hairy in- 
 sects, of slender oval form, distin- 
 guished at once by their peculiar 
 habit of springing into the air with 
 a sudden click when placed upon 
 their backs. A large part of these 
 fully developed beetles remain un- 
 der ground until spring, enjoying 
 there the protection of the oval 
 earthen cavity or cell formed by the 
 larva as a preparation for pupation. 
 A part, however, come forth from 
 the ground in fall, passing the winter 
 
 in sheltered places, and the re- FlG - 22. Beetle of Wheat Wireworm ; 
 , .... enlarged seven diameters. 
 
 mamder emerge in spring, laying 
 
 their eggs most commonly in grass lands in the earth. "Of their 
 subsequent life history little is yet definitely known. It seems 
 certain that all live more than one year as wireworms in the earth, 
 and observation of the various sizes of larvae of the same species 
 to be found in the field at once, usually supports the common im- 
 pression that the period of life in the larval stage does not extend 
 beyond two years ; a fact which, taken in connection with the 
 death and decay of grass roots the first year after breaking up the 
 sod, serves to explain the greater damage done by wireworms the 
 second year the ground is in corn. The number of wireworms 
 having been little diminished since the crop was changed, and 
 their original food having practically disappeared, they are com- 
 pelled to concentrate upon the corn either the newly planted seed 
 or the young plant while it is still very small. 
 
228 BULLETIN NO. 44. [May, 
 
 NATURAL ENEMIES OF WIREWORMS. 
 
 Only a single parasitic fly has been bred by us from wireworms. 
 Comstock and Slingerland frequently found them killed in their 
 breeding-cages by a fungus determined by Professor Roland 
 Thaxter as probably Metarrhizius anisoplice. Those killed by this 
 disease have the body filled by the growth of the fungus, and 
 assume a woody appearance. An Asaphes larva turned out by the 
 plow at Champaign May 10, 1886, was infested by a parsitic fungus 
 of another genus, very much like Cordiceps. 
 
 FIG. 23. Larva of Asaphes decoloratus; enlarged three and 
 three-fourths diameters. 
 
 In my work on the food of birds,* I found that some seven- 
 teen species eat to some extent "click beetles," or their larvae, the 
 wireworms. These insects constitute about two per cent, of the 
 food of five species of the thrush family the robin, and the brown, 
 the hermit, the wood, and the Alice thrushes. The examination 
 of the food of these birds continued throughout the year, and the 
 proportionate amount of these beetles eaten was found to be 
 greatest during the months when they were most numerous; but 
 even then the quantity destroyed was scarcely sufficient to affect 
 materially their average numbers. Mr. E. V. Wilcox,t while 
 studying the food of the robin, at the Ohio Agricultural Experi- 
 ment Station, found in the stomachs of twenty-seven of these 
 birds, shot in April and May, "click beetles" amounting to three 
 and one-half per cent, of their food. Of the remaining species of 
 birds known to eat them, none take enough to make more than a 
 fraction of one per cent, of their food, except, perhaps, the crow. 
 Dr. Fitch says that "wireworms and their progenitors, the snap- 
 ping beetles, constitute the favorite food and principal sustenance 
 of these birds [crows]. "f 
 
 * Bull. 111. State Lab. Nat. Hist., Vols. I and II. 
 
 t Bull. Ohio Agr. Exper. Station, No. 43, (1892), p. 127. 
 
 j Eleventh Rep. (Trans. N. Y. State Agr. Soc., (1866), p. 542. 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 22Q 
 
 FIG. 24. Last segment of 
 
 larva of Asaphes decoloratus; 
 
 much enlarged. 
 
 FIG. 25. Beetle of Asaphes 
 
 decolor atus; enlarged four and 
 
 a fifth diameters. 
 
 PREVENTION AND REMEDY. 
 
 Probably no class of agricultural insects has had prescribed for 
 it a longer list of artificial remedies than the wireworms, and cer- 
 tainly no such list has been of less practical value. After many 
 generations of experience with their work in this country and in 
 Europe their injuries continue at present practically unchecked by 
 any treatment consistent with the methods of American agriculture. 
 
 Even poisons of the most deadly sort applied to corn previous 
 to planting, or to food lures distributed through the ground for the 
 purpose of drawing off the attention of these insects from corn, 
 have proved almost entirely valueless, both in my experience and 
 in the more elaborate trials made by Comstock and Slingerland in 
 New York. Late fall plowing, breaking open the pupal chambers 
 within which the recently transformed adults pass the winter, will 
 probably have the effect to diminish generally the number of 
 these beetles during the following year. Comstock and Slinger- 
 land have also ascertained that the adult beetles are susceptible to 
 certain poisons judiciously distributed with certain attractive kinds 
 of food ; and I have to suggest a systematic rotation intended to 
 interpose between grass and corn a crop not vulnerable to the 
 wireworms. Otherwise we are substantially without a hint of any 
 means of diminishing the ravages of these insects other than the 
 time-honored resource of the corn farmer, namely, late planting of 
 his corn the second year after sod, and late replanting if the first 
 planting is destroyed. In the latter case it is well to plant between 
 the rows, allowing the first corn to stand as long as is consistent 
 with a proper cultivation of the field. All the wireworms being at 
 
230 
 
 BULLETIN NO. 44. 
 
 \May, 
 
 the time concentrated in the old hills of corn, if these be destroyed 
 when the field is planted the second time, the wireworms still 
 active in the earth are forced to attack the freshly planted kernels 
 as their only food resource. 
 
 FIG. 26. Corn Wireworm ; enlarged four diameters. 
 
 The first experiments with poisons for the wireworms of which 
 we have definite record, were made at my office in 1885, and 
 reported briefly in my "Miscellaneous Essays on Economic Ento- 
 mology" (p. 18), printed the following year. 
 
 =s A 
 
 FIG. 27. Side view 
 
 of a middle seg- 
 ment of Corn Wire- 
 
 FIG. 28. Last segment, 
 
 dorsal view ; greatly 
 
 enlarged. 
 
 FIG. 29. Beetle of 
 
 Corn Wireworm ; 
 
 enlarged four and a 
 
 half diameters. 
 
 Later, in May, 1888, we fed thirty-seven wireworms on corn 
 soaked for seven days in a mixture of water and Paris green. 
 The corn was covered with a coating of the green poison, and was 
 eaten freely by some of the worms without killing them. Twelve 
 wireworms fed on corn soaked in Fowler's solution diluted with an 
 equal quantity of water were not affected, although a portion of 
 the corn was eaten. Twelve others, fed on corn soaked in an 
 alcoholic solution of arsenic, were not injured by the poison, 
 though feeding freely on the corn. Experiments in June and 
 July, when wireworms were fed on corn soaked in a solution of 
 arsenic in boiling water, were less satisfactory because the larvae 
 were so near pupation that they ate little or none, pupal cells 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 231 
 
 being formed five days after the experiment began. Corn soaked 
 in a solution of strychnine four grains to a half pint of water 
 over night, and fed to seven wireworms June 28, 1888, had not 
 affected them by July 5th, although the corn was slightly eaten. 
 Twelve worms supplied with corn soaked twenty-four hours in an 
 alcoholic solution of corrosive sublimate June 27, 1888, did not eat 
 the corn. 
 
 A repetition of these experiments in June and July, 1891, by 
 a different assistant and under somewhat different conditions, 
 gave substantially the same results. June 27, 1891, corn was 
 soaked in a saturated solution of potassium cyanide and fed to 
 three wireworms. July 3d one grain of corn was slightly eaten, 
 and July roth one grain was badly eaten and one worm missing 
 probably eaten by mice that had obtained access to the cage. 
 July 2Oth several grains were badly eaten; July 27th the remaining 
 two worms were active, but the corn was untouched; and the 
 experiment ended without effect. 
 
 In many of the experiments, particularly when alcoholic solu- 
 tions were used, or where the corn was soaked for a considerable 
 length of time in arsenical solutions, it failed entirely to germinate ; 
 while in experiments where the grain was simply wet and rolled in 
 the arsenites, or soaked for only a few hours, it grew almost as 
 freely as did untreated corn in check lots. 
 
 FIG. 31. Side view of a middle 
 segment of larva of same species, 
 showing muscular impression, spira- 
 cle, etc. 
 
 FlG. 30. Beetle of Melanotus com- 
 munis; enlarged four diameters. 
 
 FIG. 32. Last segment of same, 
 dorsal view ; greatly enlarged. 
 
232 BULLETIN NO. 44. \May, 
 
 These experiments with the arsenical poisons and strychnine 
 agree substantially with those of Messrs. Comstock and Slinger- 
 land, published in November, 1891, and show that it is not practi- 
 cable to protect the corn by means of them, even were it possible 
 to use them without retarding or preventing the germinating of 
 the seed. 
 
 Coating the kernels with tar and soaking them in a solution 
 of salt, a solution of copperas, a solution of chloride of lime and 
 copperas, in spirits of turpentine, and in kerosene oil, have been 
 tried by Comstock and Slingerland without encouraging results. 
 
 Applications of kerosene emulsion and pure kerosene made to 
 the worms in the earth were found by me in 1885 practically 
 ineffective, any strength sufficient to kill the larv.ne killing vegeta- 
 tion also. Similar results were obtained by Comstock and Slinger- 
 land, who, after using crude petroleum, an emulsion of the same, 
 and a common kerosene emulsion, concluded that the last is more 
 promising than the others, but that it cannot be profitably applied on 
 a large scale. Experiments made by them show also that even a 
 clean fallow for an entire season will not starve out the worms; 
 that neither buckwheat, mustard, nor rape crops frequently 
 recommended to clear the earth of wireworms will accomplish 
 the desired result; and that salt applied at the rate of 1,600 pounds 
 to the acre a heavy dressing neither drives the wireworms 
 deeper into the soil nor causes them to migrate to any appreciable 
 distance ; that kainit used as a fertilizer, even in very large quanti- 
 ties, had little effect if any on the wireworms;* that muriate of 
 potash four to six tons to the acre (an excessive amount) is but 
 slightly effective ; that lime at the rate of even two hundred 
 bushels per acre does not injure wireworms ; that chloride of 
 lime must be used in impracticable quantity to produce any 
 marked effect ; and that gas-lime, although capable of destroying 
 the wireworms, must be applied in such great quantities that its 
 use is impracticable on large areas. Bisulphide of carbon poured 
 into a hole in the earth near the infested hill destroys the wire- 
 worms, but at an excessive cost. 
 
 The most promising remedy for wireworms, in my judgment, 
 is one which has unfortunately not been experimentally tested, 
 
 *These results are inconsistent with those reported by Prof. J. B. Smith in the I2th 
 Ann. Rep. N. J. Agr. Exper. Station (for the year 1891), p. 412. Here Professor Voor- 
 hees, Chemist of the Station, is said to have applied kainit and muriate of potash sepa- 
 rately to two sections of a fourteen-acre piece of corn on ground always badly infested 
 by wireworms and cutworms, leaving a strip between these sections without treatment. 
 Care was taken that the sections should be similar with respect to quality of land, situa- 
 tion, etc. As a consequence, the kainit section was reported as almost entirely exempt 
 from injury by insects, the muriate section as but little infested, and the intermediate 
 strip as almost destroyed. It is evident from the context that this experiment had been 
 made some years before, apparently not under the inspection of an entomologist. 
 
l8g6.J INSECT INJURIES TO SEED AND ROOT OF CORN. 233 
 
 but which is, nevertheless, precisely based upon our knowledge of 
 the life history, food, and habits of these insects. It consists of a 
 rotation in which clover follows always upon grass and is itself 
 followed by corn. According to this plan pastures and meadows 
 of grass might lie unchanged for several years, being plowed, when 
 broken up, in late summer or early fall and sown to clover in the 
 spring either with oats, or on winter wheat or rye sown the fall 
 before. The clover should be allowed to stand a second year, and 
 might then be followed with corn with positive assurance that the 
 wireworms originally in the sod would by that time have entirely 
 disappeared. From the regular rotation for grain lands, grass 
 would be thus excluded. In such a rotation corn might be fol- 
 lowed by small grain, this by clover, and this by corn. While the 
 wireworms might produce some visible effect on the small grain 
 the first year after grass, this would usually be much less serious, 
 at any rate, than the damage to corn. 
 
 The general entomological effect of some such management 
 could not fail to be beneficial, since it would apply to cutworms 
 and white grubs as well as to the wireworms now under discussion. 
 The system of rotation now common in central Illinois is, indeed, 
 seriously defective in the fact that the plants composing it Indian 
 corn, small grains, and grasses are all of the same botanical 
 family and consequently subject in large measure to the same 
 enemies. Any variation of this system which will introduce as a 
 regular link in the chain a crop belonging to some other and widely 
 different family of plants, will serve the general purpose of that 
 here proposed. 
 
 B. DETAILED DISCUSSION OF INJURIES TO 
 THE ROOTS. 
 
 Injury to the roots of corn in spring and early summer may 
 be indicated to the close observer by the aspect of the growing 
 crop. If the corn fails to appear in spring, the difficulty may not 
 be due to poor seed or to injuries to the kernel, but may be caused 
 by an early insect attack upon the young roots, which may even 
 kill the plant outright before the sprout has broken ground. The 
 root louse of the corn and the wireworms are most likely to be 
 concerned, in this form of injury. 
 
 Later in the season, when the plant is a few inches high, the 
 uneven growth of the corn will often attract attention, patches 
 here and there advancing slowly in comparison with parts of the 
 field adjacent, and in a way not to be accounted for by differences 
 of soil. In such cases, white grubs, wireworms, corn-root worms, 
 
234 BULLETIN NO. 44. [May, 
 
 or plant lice should be sought for. Combined with this uneven 
 growth, or possibly in times of drouth without it, the farmer may 
 notice yellow patches in his field, the color being most pronounced 
 upon the lower leaves. The root louse of the corn will be found 
 responsible in most cases for this partial discoloration, but any of 
 the species just mentioned may produce a similar effect,* or it 
 may be caused on the lower part of the stalk by the chinch bug. 
 
 An especially significant symptom of more or less serious 
 mischief is the presence in the field of numerous burrows of ants, 
 commonly placed in or immediately near the hills of corn, and 
 most conspicuous shortly after rains. This invariably indicates the 
 presence of root lice in the field, although if the corn be small a 
 careful search may fail to detect them at the time. The nature of 
 the association between the ants and the root lice is such that the 
 former prepare the way for the latter early in the season by sink- 
 ing their burrows among the corn roots, thus giving the lice access 
 to them. 
 
 If at about the time the ear is beginning to form, and from 
 that time onward, the stalks of corn are easily prostrated by wind 
 and rain, and do not readily rise again, it will commonly be found 
 that the hold of the plant upon the earth is abnormally slight, so 
 that the hill may be pulled up too easily. This condition of the 
 plant is due to a loss of roots, usually to be attributed to one of 
 the corn root worms, or, more rarely, to the white grubs. Some- 
 times, however, a similar appearance is given late in the season to 
 a field infested by the chinch bug, which by abstracting sap from 
 about the base of the stalk just beneath the surface of the ground 
 will often prevent the shooting forth of the so-called "brace- 
 roots," which serve to anchor the top-heavy stalk more firmly in 
 the earth. 
 
 * A condition of the corn very similar to that just described is not due to insect 
 attack at all, but, as is supposed, to a bacterial disease of the roots known as the corn 
 root blight, fully described by Prof. T. J. Burrill in Bulletin No. 6 of the Illinois Agri- 
 cultural Experiment Station (August, 1889). In this disease the corn stops growing in 
 .patches, becoming yellow and usually slender, and sometimes dying while young. The 
 yellow color is most pronounced upon the lowest leaves. On pulling up the plant, the 
 oldest and the lowest roots are seen to be injured and usually dead, the bottom part of 
 the stalk to which these roots are attached being similarly affected. If split through the 
 middle, the inner tissue of this lower part is seen to be of a uniform darker color, and a 
 slight discoloration, becoming less and less pronounced above, appears in the next 
 succeeding joints, while the parts between them are seemingly healthy. On the sur- 
 face, when carefully cleared of dirt, brownish corroded spots may be found, sometimes 
 covered with a firm gelatinous material. 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 235 
 
 i . Some of the roots deadened, hardened, or dwarfed, without 
 loss of substance. 
 
 a. Small brown or yellowish ants abundant in the hills, 
 and very small, bluish green or whitish, oval, thick- 
 bodied root lice on the larger roots. 
 
 PLANT LICE AND MEALY BUGS. 
 (APHIDID.E AND COCCID.E.) 
 
 . Associated with ants in hills of corn, the observer may find 
 any one or more of eight species of minute, soft, thick-bodied, 
 six-legged insects, sometimes winged, but usually without wings, 
 and always of very sluggish habit and slight power of locomotion. 
 When exposed, they may show little or no signs of disturbance, 
 but if shaken off the roots into which their stout jointed beaks are 
 thrust, they will probably crawl slowly and clumsily about, making 
 movements almost too sluggish and aimless to look like efforts to 
 escape. The ants which have nested in the hill will, however, 
 commonly seize these little insects in their mandibles and hurry 
 away with them into concealment. 
 
 By far the greater part of those answering to the above 
 description to be found in the corn field, will usually be plant lice 
 (aphides); and will mostly belong, in fact, to a single species, the 
 corn root aphis; but a few may be "mealy bugs" (genus Dactylo- 
 pius, family Coccidae), recognizable as such by their general 
 resemblance to the kinds of "mealy bugs" common in green- 
 houses. They may be readily distinguished from the plant lice by 
 their thicker, clumsier bodies, and by the almost rudimentary size 
 of their legs and antennae. They are always covered with a mealy 
 or powderly excretion of minute particles of wax, and never have 
 honey tubes, or cornicles, on the back of the abdomen both, 
 however, characters in which they agree with some of the lower 
 plant lice. From all the corn-infesting plant lice they may. be 
 technically separated by the fact that their tarsi are single jointed, 
 and bear but a single tarsal claw, while the plant lice of this group 
 have two tarsal joints and a pair of tarsal claws. 
 
 Plant lice are among the most prolific of insects,* producing 
 several generations annually, but they are commonly held severely 
 in check by climatic, meteorological, and biological conditions; 
 that is, by season, weather, and plant or animal parasites. They 
 
 *Slingerland has bred twenty-five generations of a plant louse {Myzus ac/iyrantes?) 
 in a single year (Science, Vol. XXI., 1893, p. 48); and Buckton shows (A Monograph of 
 British Aphides, Vol. I., p. 80) that a single rose aphis (Sip/ionophora rosce) might give 
 origin, at its normal rate of unchecked multiplication, to over thirty-three quintillions of 
 plant lice in a single season, equal in weight to more than a billion and a half of men. 
 
236 BULLETIN NO. 44. [May, 
 
 are, consequently, capable of rapid and enormous increase when 
 any of these checks are temporarily weakened to any considerable 
 degree. As they affect the plant by abstracting the elaborated 
 sap upon which its vital activity depends, the injury done is usually 
 general, and especially is this true if the root be the part infested. 
 Some species, however, in addition to this general drain upon the 
 life of the plant, cause a distinct local deformity to root or leaf in 
 the nature of a gall, which protects them at the same time that it 
 secures them food. Any crop liable to their attack in force is 
 never long free .from danger, but, on the other hand, a seemingly 
 irresistible outbreak may disappear as quickly as it came, a slight 
 and almost imperceptible change of conditions often taking tre- 
 mendous effect on these delicate insects.* 
 
 Economically, plant lice may be divided, according to the 
 peculiarities of their life histories, into several groups or classes. 
 Some generation, or some part of some generation, may grow 
 wings, fitting them for rapid dissemination, or the species may be 
 without winged representatives. They may live through the whole 
 season of their active life above ground, on exposed parts of the 
 plant; they may spend the whole season under ground, upon the 
 roots; or they may alternate, spreading each year from roots to stalk 
 and leaves and back again. Whatever part of the plant they infest, 
 they may live on a single host species, they may spread indefinitely 
 from one to several others, or they may migrate definitely, by 
 means of a fixed generation, from one species to another, requir- 
 ing thus for their continuance two plant species often extremely 
 unlike. 
 
 Finally, the sexual, oviparous generation (commonly the last 
 to appear in fall) may leave its eggs on the exposed parts of the 
 plant last infested, or it may deposit them in the earth among or 
 on the roots of its host. In the former case the destruction of the 
 plant, or of its remains, will destroy the lice ; in the latter, the 
 eggs rest like a seed in the earth to stock the ground the follow- 
 ing spring with a horde of young, ready to infest the succeeding 
 crop if suited to their tates and habits. 
 
 All the plant lice of our present list of species infesting the 
 roots of corn are, so far as known, subterranean only, producing 
 no galls, but leaving their eggs in the earth over winter. They 
 infest more than one plant, spreading from one to another species 
 in an indefinite manner, not definitely migrating. The corn and 
 grass root lice. (Aphis maidiradicis and Schisoneura panicola) 
 
 *A marked illustration of this fact is afforded by the somewhat recent history of the 
 grain louse (Sip/wnophora aveiuz) in Illinois. (See Seventeenth Report State Ento- 
 mologist of Illinois, p. X.) 
 
l8g6.J INSECT INJURIES TO SEED AND ROOT OF CORN. 237 
 
 develop early in the season winged forms by which they easily 
 spread from field to field. 
 
 Six species of plant lice, belonging to as many different genera, 
 have been found by us habitually infesting corn roots in Illinois. 
 By far the most important of these is that commonly known as 
 the corn root aphis. This is, in fact, the only one on the list which 
 infests corn primarily as a principal food plant, the others being 
 essentially species of the meadow and pasture, attacking corn but 
 lightly, and most commonly only when it follows grass. 
 
 The association of all these species with ants, which care for 
 them in many ways, some of them indispensable, and feed in turn 
 on excretions of their insect charges, is a fact of special economic 
 significance, since the ant most active in preserving the plant- 
 louse species must be taken into account as a factor in the eco- 
 nomic problem. 
 
 THE CORN ROOT APHIS. 
 
 {Aphis maidiradiciSy Forbes.) 
 (FiG. 33 37.)* 
 
 FlG. 33. Corn Root Aphis, oviparous 
 female; enlarged fourteen diameters : 
 a, hind tibia, showing sensoria. 
 
 FIG. 34. Male of same species ; en- 
 larged twenty-five diameters: a, 
 antenna. 
 
 No insect affecting corn is more deserving of the attention of 
 farmers and entomologists at the present time than the corn root 
 aphis. It ranks as a corn pest with the chinch bug and the army 
 
 * A colored plate of the oviparous female, and of winged, wingless, and pupa forms 
 of the viviparous female of this species, was published in the Seventeenth Report of the 
 Illinois State Entomologist. 
 
238 BULLETIN NO. 44. \May, 
 
 worm, less injurious at any one time than these are locally and 
 occasionally, but overtaking them, on the other hand, by its gen- 
 eral distribution and the constancy of its attack. Although it lives 
 upon the roots throughout the life of the plant, the principal 
 damage is done at the same time as that caused by wireworms 
 while the corn is still small. It contrasts with the corn root worms 
 with respect to the time of its most injurious activity, the latter 
 coming in at about the time when the aphis generally begins to 
 loosen its hold ; but the two agree in the fact that they make their 
 first appearance in spring only on ground which has been in corn 
 for at least a year preceding. The common root worm is confined 
 throughout the season to the field in which it hatches, while the 
 aphis presently scatters abroad, more or less freely according to 
 the percentage of the second and succeeding generations which 
 develop wings. On the other hand, although its worst mischief 
 coincides with that of the wireworms, it is not commonly the case 
 that both are especially injurious in the same fields, the wireworms 
 following grass of the first and second year preceding, and the 
 plant louse most commonly infesting corn on old corn ground only. 
 As lands recently in grass are most likely to contain the white 
 grubs also, it is not a common thing to find the corn root aphis 
 early in the spring in grub-infested fields. 
 
 Its life history is now probably very well understood, but 
 thoroughly effective remedial measures, I regret to say, are not 
 yet certainly known. Rotation of crops will often greatly decrease 
 or even prevent injury by dispersing the attack, but we have no 
 conclusive proof that this measure diminishes to any considerable 
 extent the number of root lice in the country during any one year. 
 It is therefore probable that this insect is increasing slowly in 
 average numbers from year to year, and it may yet bring serious 
 disaster to agriculture throughout the whole region best adapted 
 to the culture of Indian corn. 
 
 Although I have no data for a precise account of its distribu- 
 tion, it has been recognized by us in all parts of the State from 
 Cairo to the extreme northern limit, and has been definitely re- 
 ported outside Illinois, from Maryland, New Jersey, Indiana, 
 Ohio, Kentucky, Minnesota, and Nebraska. It is altogether likely 
 that it occurs in larger or smaller numbers throughout the whole 
 corn belt. 
 
1896.] INSECT INJURIES To SEED AND ROOT OF CORN. 239 
 
 FIG. 35. Corn Root Aphis, wingless vi- 
 viparous female ; greatly enlarged : 
 a, apex of abdomen showing corni- 
 cles, tubercles, and cauda. 
 
 FIG. 36. Pupa of same species ; en- 
 larged twenty-one diameters. 
 
 INJURY TO CORN. 
 
 The corn root louse is a suctorial insect, taking only fluid food 
 through a stiff beak, which it thrusts into the tissues of the plant 
 it feeds upon, producing thus no external injury, nor, indeed, any 
 local internal effect discoverable by ordinary methods of observa- 
 tion. Indications of injury by this insect are consequently all of 
 a general character, affecting the entire plant, and do not materi- 
 ally differ from those caused by severe drouth, except in the fact 
 that they are likely to be unequal in different parts of the same 
 field in a way to indicate no connection with the amount of re- 
 tained moisture in the soil. 
 
 A noticeably greater abundance in early spring in the lower 
 parts of an infested field seems to be due to the greater abundance 
 there of young weeds on which the corn root aphis feeds at first. 
 As soon as the corn starts to grow it may become infested, and 
 even be killed outright before it appears above ground. We have, 
 in fact, found the root louse on the plant as early as May gth, only 
 four days after the field was planted. 
 
 The dwarfing of the plant, especially in patches here and there, 
 with a yellowing or reddening of the leaves beginning of course 
 with the lowest ones and a general apparent lack of thrift and vigor, 
 are sufficient to cause suspicion of injury by this louse, a suspicion 
 which will be confirmed in part if numerous burrows of ants are 
 seen in or near the hills of corn. The presence of ants in the field 
 may be overlooked after the ground has been recently cultivated, 
 
240 
 
 BULLETIN NO. 44. 
 
 [May, 
 
 but can scarcely escape attention shortly after a rain, when these 
 little insects actively open up their burrows, heaping up the little 
 pellets of earth about the openings of their nests. 
 
 FIG. 37. Winged viviparous female of Corn Root Aphis ; 
 enlarged sixteen diameters. 
 
 The appearances described may, nevertheless, be due either to 
 the corn root blight a disease not caused by insects, and hence 
 not treated in this report or to the grass root louse, a species 
 likewise attended by ants, but far less injurious to corn than the 
 aphis under discussion. If the damage be due to the root blight, 
 the root lice themselves will be few or wanting ; and if to the 
 grass louse, the fact may readily be ascertained by an examination 
 of the roots of the corn. 
 
 The root aphis of the corn is of a bluish green color, slightly 
 whitened by a waxy bloom. The form of the body is oval, and 
 on the hinder part of the back are two short, slender, but con- 
 spicuous, tubes, standing erect or projecting slightly backwards, 
 which may be seen by the glass to have open ends externally. 
 These are called the cornicles of the aphis, or, sometimes, the 
 "honey tubes," it having been formerly supposed that they were 
 the source of the abundant excretion upon which the ant at- 
 tendants of the lice eagerly feed. The grass louse (Fig. 40 and 41), 
 on the other hand, is white in color, with a blackish head and other 
 blackish markings, but without any tint of green; and it has no 
 trace of cornicles, their place being taken by two minute openings 
 in the corresponding segment of the body, each surrounded by a 
 delicate brownish rim. 
 
 The evidences of serious injury by the corn root aphis are, in 
 short, an unusual dwarfing and discoloration of the corn, an abund- 
 ance of small brown ants in the field, nesting among the hills, and, 
 finally, the presence of the bluish green insects themselves upon 
 the larger roots of the corn, especially near the base of the stalk. 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 241 
 
 The amount of injury may vary from a scarcely noticeable 
 check upon the growth of the plant to a total destruction of the 
 corn over considerable patches, up to half an acre or more. This 
 more serious effect is, however, rarely, if ever, produced by the 
 root louse alone. Like most insect enemies, especially those of 
 suctorial habit, which abstract the sap of the plant they feed 
 upon, the corn root aphis serves to intensify the effect of drouth 
 and other unfavorable influences, and it is often difficult to say 
 how much is to be ascribed to the action of the insect pest and 
 how much to other causes cooperating. 
 
 There is some evidence to the effect that a too serious check 
 to the growth of the corn results in the early evolution of a great 
 number of winged plant lice of the second spring generation, 
 whose escape from the fields in which they start so breaks the 
 force of the attack that in a favorable season very badly damaged 
 plants may rally and make good corn; but if the insect injury is 
 followed or reinforced by drouth, the corn may grow sluggishly 
 the whole season through, and either fail to ear, or bear small 
 imperfect nubbins only. Sometimes a field not infested the year 
 before is permanently damaged- in June, or even late in May, as 
 the result of an early accidental concentration of the winged lice 
 originating in other fields. 
 
 INJURY TO OTHER PLANTS. 
 
 No other crop plants are especially liable to injury by this 
 aphis, unless possibly we should except broom corn and sorghum. 
 Although not at all uncommon on these plants, it does not com- 
 monly thrive on them, and so far as my observations have extended, 
 can scarcely be called injurious to them. It has been observed in 
 the field, however, or bred in the insectary, on the roots of a 
 number of other species of plants, some of which are, in fact, 
 important to its maintenance. Many of the first generation hatch 
 from the egg in the field before the corn is ready to receive them, 
 and at this time young smartweed plants and foxtail-grass (Polyg- 
 onum and Setaria) are their principal resource. These plants 
 harden early and lose the succulence which makes them especially 
 desirable to plant lice, a fact which accounts in part no doubt for 
 the early transfer of the lice to corn; but in fields of small grain, 
 Setaria and Polygonum may continue to support the corn root 
 louse at least until the second generation is well matured. Indeed, 
 I have found this insect on the roots of smartweed more than a 
 foot high as late as June I7th. Crab-grass (Panicum) also becomes 
 infested, but less abundantly than the Setaria, and from the latter 
 part of June throughout the rest of the season the aphis breeds 
 
242 BULLETIN NO. 44. [May, 
 
 abundantly on the common purslane (Portulaca oleraced). We 
 have occasionally found it so abundant on purslane plants far 
 removed from corn fields beside paths in lawns and in other 
 similar situations that one might well regard this as a purslane 
 aphis, if it were not for the fact that this weed starts too late in the 
 season to serve as food for the earlier generations. 
 
 We have, further, experimental evidence that the corn root 
 aphis can live on roots of ragweed (Ambrosia), having transferred 
 May 8, 1889, half-grown young of the second generation from 
 smartweed roots to this plant, where they lived and fed until they 
 acquired wings, five days later. The fall oviparous generation and 
 the one preceding it have been repeatedly reported by my field 
 assistants who were constantly dealing with the root aphis and 
 knew its characters perfectly to have abundantly infested dock 
 (Rumex crispus), fleabane (Erigeron canadense), mustard (Brassica 
 nigra), sorrel (Oxalis stricta), plantain (Plant ago major), Hungarian 
 grass (Setaria germanica), pigweed (Amarantus hybridus), and 
 squash; but as these statements were not verified by successful 
 transfers from these various plants to corn, they rest only on 
 determinative evidence, notoriously unreliable with respect to the 
 plant louse species. Indeed, an attempt at transfers of the sup- 
 posed corn aphis found on squash, sent me from Ohio by Prof. 
 C. M. Weed, entirely failed. A similar result was reached in an 
 attempt to transfer known corn root lice from corn to wheat and 
 oats, begun April 22d, 1889. Insects placed on roots of wheat in 
 breeding-cages April 22d continued to live there until May 5th, but 
 without producing young. May nth, however, all had left the 
 plants. An earlier experiment, begun April loth, had a like ending, 
 and a precisely similar result was obtained in a parallel experiment 
 with oats. 
 
 The repugnance of this insect to the roots of small grain was 
 repeatedly shown also by field observations. Fields of oats and 
 wheat on old corn grounds, sometimes known to have been badly 
 infested by the root aphis the preceding year, ofte'n contained in 
 April and May large numbers of these root lice and their asso- 
 ciated ants, the former feeding on the roots of smartweed and 
 pigeon-grass growing with the grain, but never being seen on the 
 roots of the grain even where these and the grass roots were 
 closely interlaced. 
 
 The relation of this louse to other plants than corn has an 
 important economic bearing. For example, in fields on old corn 
 ground, the first generation of plant lice are very noticeably more 
 abundant early in spring in the lower parts of the field than else- 
 where, especially in those parts so situated as to receive the wash 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 243 
 
 from the remainder. I can at present only account for this 
 unquestionable fact by the very much greater abundance here of 
 young smartweed plants, doubtless due to the washing down of 
 the seeds left on the ground in fall. This seems especially likely 
 to be the true explanation, since the difference in the number of 
 plant lice on low and high ground in the same field diminishes 
 greatly or entirely disappears with the advent of later generations 
 and the scattering of the winged lice abroad. 
 
 LIFE HISTORY. 
 
 General Statement. The corn root aphis passes the winter as 
 an egg in the earth, in corn fields or, rarely, in other grounds 
 where purslane grows late in fall, always, so far as known, only 
 in the nests of a small brown ant about an eighth of an inch long, 
 known to science as Lasius niger or its variety, L, niger alienus, 
 This ant is the constant companion of the root louse throughout 
 the year, living in burrows among the roots of the corn. The 
 aphis eggs begin to hatch about the* time of the opening of the 
 seed leaves of the smartweed or heartweed (Polygonumpersicaria), 
 abundant in cultivated ground. This first of the spring generations 
 is readily distinguished by characters of form and color from all 
 that follow. Appearing usually before the corn is planted, it is 
 dependent at first, in our region, almost wholly upon the young 
 smartweed plants. The roots of these are laid bare by the bur- 
 rows of the ants, and upon these roots, within their narrow tunnels, 
 the lice will usually be found thickly clustered. Later, if the field 
 be not planted to corn, our common species of pigeon-grass 
 (Setaria) divides the attention of the lice, offering in fact, for a 
 little time, a more succulent herbage than the rapidly growing 
 smartweed. 
 
 The second generation begins to appear about the 1st of May, 
 we have one breeding-cage record of the 28th of April, and by 
 the middle of that month may be itself mature. Many of this 
 generation are winged, while others are without wings,* the 
 winged form first occurring about May loth.t These "migrant" 
 root lice may live at first, like those of the preceding generation, 
 upon smartweed and pigeon-grass, but more commonly they are 
 transferred to corn by the little brown ant already mentioned, 
 either in the same field or after they have flown to another. These 
 ants not only carry from weeds to corn the root lice already in 
 
 *Two young of this generation, born of the same mother in a glass tube enclosing 
 a corn root, were kept by us until adult, when one proved to be a wingless aphis and 
 the other winged. 
 
 f This generation is at its best from May I $th to 2oth in average years in central Illinois. 
 
244 BULLETIN NO. 44. [May, 
 
 their possession, but burrow hills of corn in advance, eagerly 
 seizing and conveying to their subterranean galleries winged root 
 lice which come their way. 
 
 The succeeding generations are not of special economic inter- 
 est with the exception of the last to occur the autumnal, bi-sexual 
 brood, by which the eggs are laid. Both males and females of 
 this brood are wingless, and live in the earth 'like their parents, 
 occurring there from the middle of September to the middle of 
 November. The eggs which they lay are taken in charge by their 
 attendant ants and cared for during the winter. 
 
 Number of Generations. The eggs of the corn root louse begin 
 to hatch as early as April loth, this process continuing, according to 
 our observations, until May 2d. Our numerous breeding-cage 
 experiments, Although not one of them is continuous throughout 
 the year, enable me nevertheless to give a fairly full account of 
 the number and succession of generations. According to these 
 the first three generations have an average life of nineteen days, 
 while the fourth to the twelfth follow each other at an average 
 interval of about eleven days*. Many of our observations show that 
 a much earlier start and a more rapid growth are common, and 
 that a greater number of generations may consequently occur. 
 
 No special attempt was made to determine the number of 
 individuals a single female may produce or the relative produc- 
 tiveness of the various successive generations. The fact is however 
 worthy of record that a single stem mother placed on a corn root 
 in a breeding cage May 4th, brought forth her first young May 6th 
 and her twelfth and last May I5th. At this time the first-born was 
 a pupa, acquiring wings on the iQth. The stem mother lived until 
 the 22d, and was then placed in alcohol. Another female of a 
 midsummer brood brought forth fifteen young. 
 
 According to the results of experiments conducted for the 
 purpose of determining the number of moults of the corn root 
 aphis, and the intervals between successive moults, we find that 
 this species moults four times, at average intervals of three or four 
 days. Our most successful observations upon this and several 
 other nice points of individual life history were made on isolated 
 specimens, each placed upon the root of a potted plant which was 
 then passed through a small glass tube and covered with earth ex- 
 cept where the tube enclosed it. To prevent the escape of the 
 plant louse the ends of the tube were lightly plugged with cotton- 
 wool. 
 
 Migration to Uninfested Fields. The last autumnal brood of 
 the corn root aphis lives, so far as known, only upon roots of corn 
 and purslane, the latter being usually infested in corn fields only, 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 245 
 
 and in these situations, consequently, the eggs are left from which 
 young hatch the following spring.* This first spring generation 
 being always without wings, the root aphis is practically confined 
 for a little time to fields previously in corn. As a considerable 
 part of the second generation acquires wings, a general dispersal 
 of adults begins almost as soon as the corn is out of the ground. 
 .These winged root lice do not, however, become sufficiently 
 abundant for a considerable time thereafter to noticeably affect 
 fields not in corn the year before. Previous to the first of June 
 this distributed attack can scarcely be detected, and not until July 
 ist have we found it really serious anywhere. 
 
 The evolution of winged root lice is not confined to any single 
 generation, but continues throughout the season in numbers vary- 
 ing according to some law not yet ascertained. It is to be noticed, 
 however, that we have taken the winged form in August but once, 
 although our collections of wingless specimens were made on 
 twenty-seven days within that month. In September also the 
 winged louse is relatively rare, occurring but three times in twenty 
 collections made on as many different dates. By November the 
 viviparous generations are all dead, as a rule, and the species is 
 thereafter represented only by the sexual generation and the egg. 
 
 RELATION TO ANTS. 
 
 Seven kinds of ants have been found by us fulfilling the rela- 
 tion of host, guardian, and nurse to the corn root aphis. The oc- 
 currence in this relation of all but two (Lasius niger and Lasius 
 niger alienus, Fig. 38 and 39) is so rare that they need receive here 
 no more than this passing mention, especially as their services to 
 the aphis are, so far as observed, the same in character and value 
 as those of the much more abundant species. 
 
 The fact has already been mentioned in this paper that the 
 sexual egg-laying generation of the corn root aphis the last to 
 appear in fall is born in the galleries of the nests or homes of 
 ants, and that here the sexes pair and the females drop their eggs. 
 As one explores these nests in November, when the root louse 
 eggs are being laid, he is struck with the relative independence of 
 these oviparous adults, which are allowed to wander unattended 
 through the burrows of their hosts as far as a foot or more from a 
 corn root. We have found them, however, still feeding as late as 
 November 5th, and laying eggs November 2ist. These eggs, which 
 are yellow when first deposited, but soon become shining black, 
 
 *Among more than fifty lots of " stem mothers " of the corn root aphis collected 
 by us in the field, every one was found in ground which had borne corn for at least the 
 year immediately preceding. 
 
246 BULLETIN NO. 44. [May, 
 
 and turn green just before hatching, are at first scattered here and 
 there, as it happens, but are finally gathered by the ants for the 
 winter in little heaps and stored in their galleries, or sometimes in 
 chambers made by widening the gallery as if for storage purposes. 
 If a nest is disturbed, the ants will commonly seize the aphis eggs 
 often several at a grasp and carry them away. In winter they 
 are taken to the deepest parts of the nests (six or seven inches be-, 
 low the surface in some cases observed) as if for some partial pro- 
 tection against frost; but on bright days in spring they are 
 brought up, sometimes within half an inch or less of the surface, 
 sometimes even scattered about in the sunshine, and carried back 
 again at night a practice probably to be understood as a means of 
 hastening their hatching. I have repeatedly seen these ants in 
 confinement with a little mass of aphis eggs, turn the eggs about 
 one by one with their mandibles, licking each carefully at the same 
 time as if to clean the surface. These anxious cares are of course 
 explained by the use the ants make of the root lice, whose ex- 
 creted fluids they lap up greedily as soon as the young lice begin 
 to feed. They are not, however, wholly dependent on this food 
 supply, at least in early spring, as I have seen them kill and 
 drag away at that season soft-bodied insect larvae, doubtless to 
 suck their juices out as food. This has been a somewhat rare oc- 
 currence, however, and has rarely been noticed by us among ants 
 which had plant lice in their possession. Once, however, ants of 
 this species occurring abundantly in corn fields were observed 
 September 22d to carry bits of dead insects into their burrows, to- 
 gether with a living corn root louse. 
 
 That the young of the first generation are helped by the ants 
 to a favorable position on the roots of the plants they infest is 
 quite beyond question. It is shown (i) by the fact that in many 
 cases the aphis could not get access to such roots unless these had 
 been previously laid bare by the tunneling of the ants, and (2) by 
 the behavior of ants with mines already constructed, when the 
 root aphis is offered to them. We have repeatedly performed the 
 experiment of starting colonies of ants on hills of corn in the 
 insectary and exposing root lice from the field to their attentions, 
 and in every such instance, if the colony was well established, the 
 helpless insects have been seized by the ants, often almost instantly, 
 and conveyed under ground, where we would later find them feed- 
 ing and breeding on the roots of the corn. In many cases in the 
 field, we have found the young root aphis on sprouting weeds 
 (especially pigeon-grass), which have been sought out by the ants 
 before the leaves had shown above the ground; and, similarly, 
 when the field is planted to corn, these ardent explorers will 
 
1896.] INSECT INJURIES TO SEED AND ROUT OF CORN. 247 
 
 frequently discover the sprouting kernel in the earth, and mine 
 along the starting stem and place the plant lice upon it. 
 
 We have also abundant evidence that ants excavate hills of 
 corn in very early spring, when they have as yet neither eggs nor 
 plant lice in their possession, and some days before the possible 
 appearance of the second or winged generation. I can only account 
 for this practice on the supposition that these ants expect later to 
 obtain eggs or young with which to stock their burrows, made 
 ready in advance. Certainly this is true with respect to the second 
 generation of the root aphis. When winged lice of this brood 
 begin to appear, it is a common thing to find the small brown ant 
 scattering far and wide over fields not previously in corn, and con- 
 taining consequently no plant lice in any stage, burrowing there 
 the hills of corn, and carrying underground such corn root lice as 
 come within their range. 
 
 I need hardly say that the relations above described between 
 the corn root aphis and these ants continue without cessation 
 throughout the year, the succeeding generations being quite as 
 useful to the ants as those whose history I have thought it worth 
 while to follow in detail. 
 
 NATURAL ENEMIES. 
 
 Although various insect species, mites, ground beetles, and 
 the like, have been found in more or less suspicious relation to the 
 corn root lice in our breeding-cages, and even in the fields, no 
 known case has occurred with us of destruction by an insect enemy. 
 It is, indeed, a remarkable fact that not a single hymenopterous 
 parasite has ever been bred from the corn root aphis in all our 
 long experience with that insect. It is true that root lice are much 
 less parasitized than those feeding in more exposed positions, but 
 they are nevertheless by no means commonly free from parasitic 
 attack. 
 
 The only natural check upon the increase of this root aphis 
 which has come immediately to our notice is a parasitic fungus, 
 Entomophthorafresenii, detected October 16, 1889, infesting sexual 
 individuals of this species found on roots of the curled dock 
 (Rumex crispus} at Champaign, Illinois. Affected specimens were 
 of a creamy or whitish color, and were literally crammed with the 
 small oval granular spores of the Entomophthora. 
 
 ECONOMIC PROCEDURE. 
 
 Our present knowledge of the life history of the corn plant 
 louse suggests four possible methods of attack, (i.) We may 
 
248 BULLETIN NO. 44. \May> 
 
 try the effect of a change of crop after any notable plant-louse 
 injury to corn, in the expectation that corn planted on ground 
 which contains no plant-louse eggs will become so slightly or so 
 slowly infested, if at all, that no harm need be anticipated. (2.) 
 We may resort to fertilizers and other applications made to the 
 young corn hill in spring in the hope of killing the lice outright 
 or of supporting the plant against their attack at a time when this 
 is likely to be most injurious. (3.) Since the small brown ant 
 cares assiduously for the eggs in winter and spring, we may 
 assume provisionally the necessity of such care and strive to find 
 means of so disturbing the nests of the ants or of breaking up and 
 dispersing their contents in late fall or in winter that their stores 
 of aphis eggs cannot be recovered by them, and so shall be left 
 to perish. (4.) Taking account of the early hatching of the eggs 
 in spring several days, as a rule, before the usual time for plant- 
 ing corn, and the dependence of the young lice for food at that 
 time on sprouting weeds in the field, especially smartweed and 
 pigeon-grass, we may seek to handle the ground in such a man- 
 ner that there shall be no sufficient start of vegetation to keep the 
 lice alive. We may also delay somewhat, if necessary to this end, 
 the planting of the field to corn. 
 
 Rotation of Crops. There can be no doubt that a judicious 
 rotation of crops has the effect at least to diminish injury by the 
 corn plant louse by distributing its attack ; and there is also con- 
 siderable reason to believe that it must result in the destruction, 
 direct or indirect, of a certain proportion of the insects themselves. 
 Corn planted on ground not previously stocked with plant-louse 
 eggs must escape at any rate until invaded from without by winged 
 individuals of the second generation, and then, as a rule, it will be 
 no more subject to injury than the other fields in its neighborhood. 
 On the other hand, as the corn root aphis has never been known 
 to infest to an injurious extent any other crop following corn, 
 there is very little probability that the escape of the corn will be 
 balanced by damage to other crops. 
 
 We have many observations going to show that wheat and 
 oats and the smaller grass-like plants in general are commonly 
 soon deserted by such corn root lice as commence to breed on 
 them a fact which indicates that these plants are less suitable 
 than corn to the maintenance and multiplication of these insects. 
 We have also considerable reason to believe that many winged 
 plant lice flying about in search of feeding and breeding grounds 
 must be destroyed by some of the innumerable accidents to which 
 these feeble and helpless insects are necessarily exposed. This 
 measure of rotation may consequently have the effect to diminish 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 249 
 
 to an important extent the number of corn root lice in later gen- 
 erations. Precise proof on these points is, however, very difficult 
 to secure. Artificial breeding experiments are altogether too 
 variable in result to serve the purpose, as our own attempts at a 
 solution of this question show; and evidence must be sought in the 
 field especially by making detailed comparative observations of 
 parts of the same previously infested fields, planted here to corn 
 and there to small grain. The relative abundance of the lice late 
 in May and early in June will go far to show the comparative 
 utility of these crops as a food resource to the corn root aphis. 
 
 Applications of Fertilizers and Insecticides. Various field obser- 
 vations have given us reason to conclude that fertilization of the 
 soil will serve to support corn under the drain of aphis injury, 
 especially by enabling a stunted plant to rally more rapidly and 
 completely after the insects have begun to scatter. The rapidity 
 and vigor with which, in rich ground and in a fairly favorable 
 season, corn will outgrow an apparently fatal injury by the root 
 aphis is, in fact, often quite surprising. Apart from this general 
 statement I have only to report the result of a single series of plat 
 experiments tried in 1891 with various fertilizers mingled with 
 petroleum, crude and refined, as an insecticide, and with applica- 
 tions of salt, wood ashes, and lime. 
 
 A plat of ground ten hills square, containing ninety-seven 
 hills of corn, was selected on the University experimental farm at 
 Urbana June 18, 1891, and surround-ed by a continuous line of six- 
 inch boards sunk about three inches into the ground, with close- 
 fitting joints, and with the earth well tramped both outside and in. 
 The upper edge of the boards was thickly covered with coal-tar, 
 subsequently kept fresh by repeated applications. These meas- 
 ures were intended to prevent all interference with the experi- 
 ment, either by escape of the insects within the plot or by invasion 
 from without. June 26th this enclosure was enlarged to contain 
 twenty-three hills more. Fertilizers, and mixtures of fertilizers 
 and petroleum, were applied to the hills of corn June i8th and 23d, 
 being worked into the soil about each hill; and on the 26th lime, 
 ashes, and salt were similarly applied. Of the ninety-seven hills 
 in the first enclosure, forty-eight were found in the beginning to 
 contain root lice and ants, and of the twenty-three hills in the 
 second lot sixteen were similarly infested. 
 
 Three fertilizers were applied : superphosphates, muriate of 
 potash, and sulphate of potash, each at the rate of three pounds to 
 twenty hills of corn, and in each case half the hills under experi- 
 ment were treated with the pure fertilizer and the other half with 
 a mixture of fifteen ounces of petroleum to three pounds. One- 
 
250 
 
 BULLETIN NO. 44. 
 
 \May, 
 
 third of the above amounts were applied June i8th, the petroleum 
 in these cases being the crude Lima oil, and the remaining two- 
 thirds, June 23d, when refined petroleum was used. The following 
 notes are condensed from the memorandum filed at the time by 
 the assistant* in charge of the experiment: 
 
 Experiment I., Superphosphates. Experiment II., Superphosphates and Petroleum. 
 
 June 29, I. Ants and root lice numerous. 
 
 " 29, II. Both insects present but less numerous than in I. 
 
 July i, I. Ants and lice abundant. 
 
 " I, II. Ants present but no lice. 
 
 " 7, .1. Ants and lice abundant. 
 
 " 7, II. A few ants but no lice. 
 
 " 15, I. Ants and lice comparatively abundant. 
 
 " 15, II. Ants and lice both present but fewer than in I. 
 
 Experiment III., Muriate of Potash. 
 Petroleum. 
 
 Experiment IV., Muriate of Potash and 
 
 June 29, III. A few ants and lice found. 
 
 " 29, IV. Dead plant lice discovered in one hill, both ants and lice occur- 
 ring generally but not abundantly. 
 July I, III. A few ants but no lice. 
 " i, IV. Ants alone discovered on roots about one foot from the hill, just 
 
 outside the fertilized area. 
 7, TIL Ants and root lice found. 
 " 7, IV. Ants but no lice. 
 " 15, III. Ants plentiful ; lice common. 
 " 15, IV. Few ants and lice detected. 
 
 Experiment V., Sulphate of Potash. 
 Petroleum. 
 
 Experiment VI., Sulphate of Potash and 
 
 June 29, V. Ants present but no lice. 
 
 " 29, VI. A few ants present but no lice. 
 
 July i, V. Neither ants nor lice were found. 
 
 " i, VI. A few ants and lice in one hill. 
 
 " 7, V. Ants and lice numerous. 
 
 " 7, VI. Both insects present. 
 
 " 15, V. No ants or lice detected. 
 
 " 15, VL Small colony of ants and a few lice in one hill. 
 
 The weather during the period covered by the above experi- 
 ment was generally dry, but abundant rains occurred June 20th and 
 2ist, which seemed to dissolve the fertilizers and wash them into 
 the ground. 
 
 The lime, ashes, and salt experiments were entirely without 
 effect, ants and plant lice occurring abundantly in all parts of the 
 plat treated throughout the entire period of observation to July 
 28th. This plat served consequently as a check upon the preced- 
 ing experiment. 
 
 Although the effect of the other applications seems from the 
 above notice to be quite marked, the experiment is nevertheless 
 indecisive, since the hills treated were not dug up when examined 
 from time to time, but only searched as carefully as was possible 
 
 *Mr. J. S. Terrill. The work was, however, done under the immediate supervision 
 of Mr. John Marten, one of my present entomological assistants. 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 2$I 
 
 without injuring the plants. July 28th, when all the hills were re- 
 moved, they seemed, according to Mr. Marten's report, to be about 
 equally infested, all appearance of difference having then vanished. 
 It will thus be seen that these experiments have little value 
 except as hints towards future work. The differences observed 
 may nearly all have been due to a repellent effect of the sub- 
 stances applied, in consequence of which the ants withdrew their 
 charges deeper into the earth, with little diminution perhaps of 
 the injury to the corn. 
 
 Breaking iip Nests of Ants. In one experiment, begun Novem- 
 ber 25, 1890, a strip of corn stubble three rods wide and ten rods 
 long near the University premises at Champaign, was plowed six 
 inches deep, half the strip being thoroughly harrowed also. The 
 ants' nests among the corn hills were thus turned out and thor- 
 oughly broken up, except that in a few cases the plow did not go 
 the full depth of the nests, but left the bottom undisturbed. The 
 harrowing knocked the dirt out of the roots of the corn and broke 
 up the fragments of the nests remaining in the clods. April 18, 
 1891, when the ground was again plowed, five ants' nests were 
 found in this plat and thirteen in an equal strip beside it. All of 
 these outside nests contained ant larvae of various sizes, while 
 those inside the strip contained no ants but worker adults. Ten 
 of the former lot of nests and three of the latter contained root 
 lice also, on smartweed roots. 
 
 In another precisely similar experiment, begun upon the 
 same day in an adjoining field, a strip was plowed two and a half 
 rods wide by twelve rods long, half of this being thoroughly har- 
 rowed, as before. The plowing averaged six inches in depth, 
 but the plow ran considerably deeper under the corn rows, and 
 the ants' nests were well broken up and scattered. April i/th of 
 the following spring the ground was plowed for corn and thor- 
 oughly examined to determine the result of the experiment. The 
 part which was harrowed contained three ants' nests, the remain- 
 der six ; while on an equal strip adjoining, thirty were found. 
 None in the strip plowed in fall contained young ants, while 
 every one of those outside contained them. Several wingless 
 females were seen in the nests, one of them in the plowed strip. 
 
 Neither the weather at the time nor that of the following 
 winter was especially favorable to the success of such an experi- 
 ment, the mercury reaching a maximum of 49 F. on the day the 
 experiment began, and the winter following that of 1890-91 
 being unusually open and warm. Further, there had been more 
 than a week of warm spring weather previous to April i8th, the 
 mercury reaching 72 on the gth, 75 on the I3th, and 77 and 78 
 
252 BULLETIN NO. 44. [May, 
 
 on the 1 7th and i8th respectively temperatures at which ants as 
 active as the little Lasius niger alienus might well disperse them- 
 selves and begin new colonies in unoccupied ground. 
 
 These experiments afford, perhaps, scarcely a sufficient basis 
 for a final conclusion as to the economic value of this method, but 
 so far as they go they are most encouraging. If we compare the 
 treated plats with the check plats beside them, we find (i) that the 
 ants' nests in the former were less than a third as many as in the 
 latter; (2) that all in the plowed and harrowed plats were destitute 
 of ant larvae while in the check plats all without exception con- 
 tained such larvae; and (3) that in the single plat first mentioned 
 the ants' nests containing lice were less than a third as numerous 
 as those in the plat outside.* 
 
 From the above we can only infer the disastrous effect of this 
 late fall and winter plowing upon the ants themselves, and, pre- 
 sumably, also upon the plant louse eggs they have in charge. It 
 seems also quite probable that some, if not all, of the nests found 
 April i8th in the experimental plats had been established there by 
 worker ants in spring, and were not remnants of the nests previ- 
 ously broken up, and if this were the case the root lice found in 
 them had doubtless been brought in from without. 
 
 Starvation Experiments, April 15, 1889, twelve young root 
 lice recently hatched were placed in a cavity in the moist earth, 
 which was covered with a glass slip so placed as to allow an exami- 
 nation of the interior. April 2Oth two of these root lice died; the 
 next day half the lot were dead; April 22d only two were living; 
 April 23d but one; and on April 24th, nine days from the beginning 
 of the experiment, all were dead. 
 
 May 14, 1888, a number of corn root lice of various ages, taken 
 from the roots of young smartweed in the field, were placed in a 
 glass vial with moist earth, the mouth of the vial being covered 
 with gauze. On the i8th all were still alive, but by the 20th all 
 had died, the earth in the vial still remaining moist. 
 
 April 30, 1890, a number of eggs were placed in a cavity in 
 sterilized earth and left to themselves. May ist one young louse 
 appeared from the only egg of the lot which hatched, and May 3d 
 this one was dead. It appeared from the foregoing that young of 
 this species hatching in the earth and kept without food would die 
 in from two to nine days. 
 
 As a field application of this fact, an attempt was made April 
 16, 1889, to starve the young lice in the ground by keeping down 
 the growth of young weeds. A piece of ground was thoroughly 
 
 *By an unfortunate oversight no mention was made in the notes on the second 
 experiment, of root lice in either the plowed strip or check. 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 253 
 
 harrowed in two directions with a cutaway disk harrow, and the 
 weedier parts of the plot, several times additional. April 20th, how- 
 ever, ants and lice were found both within and without the har- 
 rowed strip; but the ants had no plant-louse eggs in their 
 possession where the ground had been harrowed. The result of 
 this treatment was not especially encouraging, the young weeds 
 sprouting so freely and abundantly in the moist earth, to a depth 
 of four or five inches, that it seemed impossible to reduce the food 
 supply of the lice to any considerable extent by mechanical 
 methods. 
 
 Our present knowledge of effective economic procedure for 
 the corn root aphis may be summarized in the form of the follow- 
 ing recommendations: (i) that the fertility of the ground should 
 be maintained as a general safeguard, and that cultivation should 
 be so managed especially that of the lower parts of the field as 
 to prevent so far as practicable the seeding of pigeon-grass and 
 smartweed among the corn; (2) that infested fields should be 
 plowed deeply and thoroughly harrowed late in fall or during 
 some suitable early winter interval; and (3) that a somewhat 
 rapid rotation of crops should be systematically followed, corn 
 usually being allowed to grow on the same ground but two years 
 in succession. While some work remains to be done with refer- 
 ence to the precise value of these methods in practical application, 
 there is no longer any doubt of their substantial usefulness, at 
 least as a means of holding in check the injuries of the corn root 
 aphis. 
 
 ON THE ANTS ATTENDANT UPON THE CORN ROOT APHIS. 
 
 FIG. 38. Small Brown Ant (Lasius niger alienui), female ; enlarged 
 four and a half diameters. 
 
 Lasius niger and its variety aliemts are so far the most abund- 
 ant of the seven species of ants which we have found in attend- 
 ance upon the corn root aphis that a discussion of the economics 
 
254 BULLETIN NO. 44. [May, 
 
 of this relation need scarcely take account of any other species ; 
 but as the most promising protective measures against this aphis 
 are based on our knowledge of the life history and habits of this 
 commonest corn-field ant, an accurate account of the latter is to 
 be desired. Our notes on this subject cover the entire period 
 since 1883, and enable me to give a fairly complete history of this 
 species throughout the year. 
 
 Life History. The winged sexual forms, male and female, of 
 this ant begin to appear each year as early as the latter part of 
 June (the 2ist to the 27th), hatching from pupae which may have 
 formed late in May (27th and 28th, by our notes). The emergence of 
 males and females from the pupa continues throughout the season, 
 certainly into October and probably to November, but the males 
 perish before the winter. The females, however, having been fer- 
 tilized and deprived of their wings, begin their separate excava- 
 tions in fall, or continue with the workers in nests already estab- 
 lished. There they hibernate, sometimes at least, commencing to 
 lay their eggs in fall, and living in spring through April and May. 
 We have found the eggs of this species only November loth, 
 April 25th, and May 20th; but exceedingly small larvae certainly very 
 recently hatched have been collected by us May 5th to iQth, July 
 I5th, and September 2ist. Our experiments have not, however, 
 been conducted in a way to distinguish between eggs and young 
 coming from fully developed females and those from fertile workers. 
 The larvae hatching from time to time throughout the summer 
 may be found as pupae from the latter part of May through June, 
 July, August, and September, to October 3Oth, and even, according 
 to a single observation made at Urbana, to November 2Oth. 
 
 Haunts, Actions, and Habits. The nests or burrows of this 
 ant, in which these breeding operations are carried forward, are 
 
 widely distributed in corn fields and 
 grass lands, especially in the latter, 
 along the borders of roads and paths, 
 and also under stones and boards, 
 in and under decaying logs, and in an 
 indefinite variety of situations. In 
 corn fields they are established almost 
 wholly in the hills of corn, and remain 
 here among the old corn roots 
 throughout the season. As this is the 
 commonest and most generally dis- 
 tributed of all our ants in Illinois, an 
 exhaustive list of its places of habita- 
 
 tion would have little P resent interest - 
 
 fourth diameters, Jt has never been found by us to form 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 255 
 
 large settlements, or making mounds or conspicuous structures of 
 any kind; but simply scatters its little burrows almost indiscrim- 
 inately, living in small families rather than in great colonies or 
 city-like aggregations, and piling up only a small temporary heap 
 of pellets around the mouth of its burrow. When its mines are 
 explored they are found to consist of irregularly radiating and con- 
 nected tunnels, rarely going to a greater depth than six or eight 
 inches, or extending outward over a horizontal area of more than 
 twelve or fifteen inches. Here and there in their course or at 
 their extremities and at various depths are chamber-like enlarge- 
 ments in which their eggs and young and the eggs of the corn root 
 aphis are preserved and cared for. Here also considerable collec- 
 tions of the worker ants are usually found, especially in winter, 
 and in times of summer drouth, and in these chambers the fe- 
 male resides and lays her eggs. 
 
 In April, May, and June the workers seem to be most num- 
 erous and active. In July and August their activity declines, 
 particularly in the hottest and dryest weather, although if nests 
 be opened at these times the ants will be found in abundance. 
 Again, in September, a period of bustling activity begins which 
 continues until checked by the winter cold. 
 
 In ordinary winter weather of the milder sort, these ants are 
 not absolutely motionless, but if disturbed crawl slowly and 
 stupidly about, sometimes even painfully attempting to perform 
 their usual duties of restoration and repair. We have not explored 
 their nests in the coldest weather, when the ground is frozen 
 to a considerable depth. 
 
 During the first warm days of spring the thoroughly awakened 
 ants begin to open up their burrows to the surface, and carry 
 their own eggs and young and the eggs of the plant lice in their 
 possession upwards and downwards according to the varying 
 warmth of different layers of the soil. When the sun is shining 
 brightly in the middle of the day they bring their charges to the 
 more superficial chambers of their nests, or even expose them on 
 the surface, but keep them farther downward at night and in cold 
 and cloudy weather. The effect of this care upon the plant-louse 
 eggs is shown by the earlier hatching of those cared for by the 
 ants, and by the diminished number of those which fail to hatch 
 at all. 
 
 Although this ant is evidently chiefly dependent for food 
 upon the corn root aphis and other plant lice fostered by it, it is 
 not strictly limited to this resource but, early in spring especially, 
 has been found by us with freshly killed insects in its possession 
 caterpillars, carabid larvae, and the like. Sometimes in mid- 
 
256 
 
 BULLETIN NO. 44. 
 
 [May, 
 
 summer also it resorts to animal food. July 16, 1884, in digging 
 into a hill of corn infested by the root aphis and this ant, I un- 
 earthed a carabid larva. This was suddenly attacked by one of 
 the ants, which pounced upon it just behind the head. The larva 
 struggled vigorously, but the ant soon fastened its jaws on the 
 under side of the neck, just behind the head, and a little to one 
 side of the middle line. After this the struggle lasted only a few 
 seconds, when the larva became completely quiet, and allowed 
 this ant and another to drag it away without the least resistance. 
 I watched this operation for a few minutes with a glass, and then 
 put both ants and larva into alcohol. Although the larva did not 
 visibly bleed when bitten, it was apparently dead, and did not 
 struggle at all when put into alcohol. 
 
 June 2, 1891, an ant of the above species (Lasius niger) was 
 found with a dead chinch bug in a wheat field, and three others 
 were seen dragging live chinch bugs over the ground, one of 
 which bareley showed signs of life, a second of which moved its 
 legs more vigorously, while a third, which an ant was dragging 
 along by the beak, seemed scarcely at all disabled. 
 
 THE GRASS ROOT LOUSE. 
 {Schizoneura panicola, Thos.) 
 
 FlG. 40. Grass Root Louse, winged viviparous female; enlarged eighteen diameters: 
 
 a, antenna. 
 
 This species was discovered on the roots of Panicum glabrum 
 and other grasses by Mr. H. Pergande, at St. Louis, Mo., in 
 November, 1877, and first described by Dr. Thomas in 1879 in the 
 Eighth Report of the State Entomologist of Illinois. The first 
 observations of its occurrence in this State on corn were made in 
 1883, and it has been seen by us more or less abundant on the 
 roots of various plants every year during the past eleven years. 
 Its economic importance is but small, owing to the usually trivial 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN- 257 
 
 numbers in which it occurs on corn, and the evanescent character 
 of its attack. It is often important, however, that the corn farmer 
 should be able to distinguish it from the far more dangerous corn 
 root aphis a matter of no difficulty to a fairly good observer. It 
 may be told at once from that species by its white or .yellowish 
 color, and by the absence of the projecting cornicles or honey- 
 tubes characteristic of Aphis, these being replaced in the present 
 species by a pair of minute circular openings on the hinder part of 
 the back, each delicately rimmed with brown, and surrounded by 
 a small dark patch. 
 
 FIG. 41. Grass Root Louse, wingless viviparous female ; enlarged 29 diameters. 
 
 2. Roots evidently injured or destroyed by perforations, gnawing, 
 
 burrowing, decay, or other loss of substance. 
 
 a. Roots eaten away, not burrowed or perforated, and with- 
 out rotten or withered tips. Tap-root commonly gone 
 or decayed. White grubs in soil among or beneath the 
 roots. 
 
 THE WHITE GRUBS. 
 
 GENERA LACHNOSTERNA AND CYCLOCEPHALA. 
 (Fio. 42-47.) 
 
 White grubs or "grub worms" are among the immemorial 
 enemies of agriculture on both sides of the Atlantic, and in both 
 Europe and America the problem presented by their injuries on 
 the farm and in the fruit and vegetable garden still calls for 
 thoroughgoing investigation and scientific treatment. In fact, 
 the steady increase of their numb'ers in this State probably con- 
 nected with the gradual enlargement of the area laid down in grass 
 has made such an investigation of their life histories, habits, and 
 economic relations simply imperative and indispensable. 
 
 They infest a great variety of plants, nearly all of which have 
 an agricultural value, many of them being the great staple crops 
 
258 BULLETIN NO. 44. \May, 
 
 of the farm and garden. Grasses of every kind, all the small 
 grains, Indian corn, potatoes, beets, and the root crops generally 
 are liable to destruction by them, as well as strawberries and 
 young fruit trees, young evergreens, larches, and young forest 
 trees of various kinds. 
 
 Like most other injurious insects of the first class, they are 
 liable to great variation and fluctuation of numbers in different 
 localities and in successive years, sometimes getting the tempo- 
 rary mastery of a considerable tract, appropriating nearly its 
 whole growth of vegetation to their own use, and then, within 
 a year or two, disappearing from view for a time as an injurious 
 agency. Apart from these seemingly spontaneous fluctuations of 
 numbers, they are most likely to cause great loss when the crop 
 on ground infested by them is changed by rotation from one 
 affording them an abundance of food to one yielding a relatively 
 scanty growth as when grass lands are planted to corn. A num- 
 ber of grubs which would produce no visible effect in a dense 
 sward, may be sufficient to devour completely a field of young 
 corn. 
 
 They hatch most commonly in grass lands (although frequently 
 also in corn), from eggs laid there by various kinds of beetles, all 
 commonly confused under the general name of "June beetles" or 
 "May beetles" or "dor-bugs." These large, thick, short, snuff- 
 brown beetles, a half inch to more than three-fourths of an inch 
 in length, nearly as thick from above downwards as they are wide, 
 and about half as wide as long, are universally known because of 
 their great abundance in May and June, during which months 
 they fly at night, filling the air at dusk with their hoarse buzzing, 
 and often invading lighted rooms in our houses, where they bump 
 and bumble about, as awkward as frolicking cart horses. In this 
 stage the insects are but short-lived, the males dying soon after 
 the sexes pair, and the females living but a few days after they 
 have laid their eggs in the ground. 
 
 The young grubs hatching among the roots of grass or grass- 
 like plants commence to feed at once, and live in the earth in the 
 larval stage for at least two years (so far as known), most of them 
 changing to the dormant pupa from the middle of June to Sep- 
 tember of the second or third year after hatching, and becoming 
 fully developed "June beetles" again, still in the earth, in August 
 or in September of this same year. These beetles do not, as a 
 rule, emerge from their earthen cells until the following spring, 
 but spend the winter at rest, each in the underground cavity made 
 originally by the grub while preparing to pupate. In May and 
 June they come out and pair and lay their eggs as already related. 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 259 
 
 A single species (Cyclocephala immaculatd) has a slightly different 
 life history, the grub not pupating until spring. (Fig. 45-47.) 
 
 Our common and destructive white grubs all belong to the 
 genera Lachnosterna and Cyclocephala, by far the greater number 
 of species and individuals to the former genus, of which there are 
 thirty-two species known to occur in Illinois. The genus Cyclo- 
 cephala, on the other hand, contains but one species in this state. 
 The life histories of these various kinds are not sufficiently differ- 
 ent to make discrimination of species a matter of practical 
 importance, and for economic purposes, consequently, the white 
 grubs may usually be classed as one. 
 
 No wholly, or even fairly, satisfactory defence against them 
 has yet been discovered, but in the contest with so abundant, so 
 widespread, and so destructive an insect even imperfectly pro- 
 tective measures, or merely palliative ones, are worthy of the 
 most careful attention. The practice of the farmers of the Old 
 World, where a contest against closely related insects of like habit 
 has been waged from time immemorial, is not usually applicable 
 to American agriculture, but may nevertheless become so as con- 
 ditions gradually change with the denser settlement of this 
 country and a corresponding increase in the value of our agricul- 
 tural products. I have consequently summarized the economic 
 procedure of England, France, and Germany for the "cockchafer 
 grub," the " ver blanc" and the " engerling," the names by which 
 the European "white grubs" are known in those countries re- 
 spectively. 
 
 INJURIES TO CORN AND OTHER VEGETATION. 
 
 The injuries of the American white grubs to corn may begin 
 as soon as the roots of the young plant become large enough to 
 attract the attention of a hungry insect, and m'ay range accord- 
 ing to the age of the plant, the kind of weather, and the age and 
 abundance of the grubs all the way from a slight and temporary 
 retardation of growth to an immediate and complete destruction 
 of all the corn. An early loss of the tap-root exposes the plant to 
 severe suffering by early drouth, and it is often so reduced in 
 vigor from root injury that it fails to form brace roots at the 
 proper time, and hence has so slight a hold upon the earth that it 
 cannot keep itself erect or recover itself after prostration by a 
 windy summer storm. 
 
 In any case where the plant is yellowed, or dwarfed, or killed 
 outright, especially if these appearances be most marked on the 
 higher, lighter parts of the field, the presence of white grubs 
 may be suspected. 
 
26O BULLETIN NO. 44. 
 
 As the roots of an infested plant are evidently eaten away, 
 injury by the white grub is not easily mistaken for any other, 
 and the presence of the conspicuous insects themselves, in the 
 earth among or beneath the roots, will commonly confirm the 
 diagnosis. If they are not thus found where other evidence points 
 to them as the cause of the injury, they may frequently be dis- 
 covered by digging down a foot or two in the worst-injured tracts. 
 
 As a fair illustration of the extent and general effect of a 
 severe attack on corn, our observations of their work in a twenty- 
 acre field near Champaign, Illinois, are worthy of detailed report. 
 This field of rich, black land had been heavily fertilized with straw- 
 pile manure and seeded to timothy in 1884. It was pastured con- 
 tinuously until 1888, when it was left for hay, yielding a good crop 
 of clean timothy that year. The sod was broken in the spring of 
 1889, and planted to corn May roth, immediately after breaking. 
 This first planting was taken by web worms and cutworms, but the 
 second grew well, and promised an excellent crop until about 
 tasseling time, when the owner noticed that much of the corn had 
 a yellowish and unhealthy appearance, and that it blew down 
 readily when the ground was wet. These fallen hills pulled up 
 easily, and the roots had a stubbed appearance, as if cut off near 
 .their origin. A search in the earth where the corn had stood com- 
 monly yielded six to twelve white grubs to a hill. The crop on 
 two or three acres of the highest land was a total failure, and the 
 yield was light on the lower ground. 
 
 The following year (1890) the field was plowed April 28th and 
 planted again to corn, although an abundance of grubs were 
 noticed when the plowing was done. Several hundred were, in 
 fact, collected by us April 28th for breeding-cage experiments, 
 nearly all belonging to the species L. rugosa (Fig. 42, 43, and 44). 
 An estimate based at this time on a count of the grubs found 
 within the length of a rod. in a fourteen-inch furrow, gave between 
 six and seven hundred to the square rod, or at the rate of two 
 hundred and eighty-eight pounds per acre. By the time the 
 young corn was six inches high about two-thirds of it had been 
 destroyed by the grubs. The field was not replanted, but about 
 the loth of June it was twice harrowed and sown to hemp. On 
 account of the lateness of the season and a midsummer drouth 
 the hemp did not grow well, and about a hundred bushels of corn 
 were finally taken from this twenty-acre field. July 26th, in the part 
 of the field which had been worst infested, but three grubs and a 
 single pupa were found in digging with a spade twenty holes, 
 ranging in depth from a foot to twenty-six inches. On the ist of 
 September a trench four feet long, three feet wide, and two feet 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 26l 
 
 deep was dug in this same part with the result that only one adult 
 June beetle and two long-dead larvae were found. In another 
 space eight feet long by three feet wide two adults and a single 
 living larva were dug out, all the foregoing being within a foot of 
 the surface. In two large areas turned over at the margin of the 
 worst-infested spot, two living larvae and one adult were taken, the 
 former among the corn roots and the latter about ten inches down. 
 
 From these field observations, and parallel extensive breeding 
 operations in the insectary, we have reason to infer the trans- 
 formation to the imago stage during the season of 1890 of the 
 .greater part of the white grubs in this ground. 
 
 In 1891 the entire field was sown to hemp ; but in 1892, three 
 years after breaking, it was planted again to corn and again heavily 
 injured by grubs. August 25th, a general survey of the field 
 showed that no part was free from them, and that probably every 
 acre had been injured more or less. The damage was most serious 
 now on the lower ground, where a tract of about two acres bore 
 only a few scattered stalks with ears. Most of the corn here had 
 failed to tassel, and much of it had died when from eight or ten 
 inches to about three feet high. Patches of a rod to two or three 
 rods across on which the corn was dead or worthless were to be 
 found in all parts of the field. Nearly all the foxtail-grass (Setaria) 
 had also been killed, the roots being cut off just below the surface, 
 and even the common purslane (Portulaca) was similarly de- 
 stroyed. Most of the grubs were at this time within three inches 
 of the surface, and were well scattered through the ground, being 
 by no means confined to the hills of corn. In one selected area 
 of four feet square, which included only two corn hills, eighty- 
 one grubs were dug up, some scarcely beneath the surface, and 
 none deeper than three inches. In another area of equal size, 
 containing three corn hills, one hundred and thirty-six grubs were 
 found, twenty-one of them in a single hill. Here, however, a few 
 had burrowed to a depth of six inches. The grubs were at this time 
 apparently from two-thirds to three-fourths grown, the most abun- 
 dant species being L. rugosa the same as that of the previous years. 
 
 FIG. 42. Grub of Lachnosterna rugosa; 
 enlarged two and a half diameters. 
 
 FIG. 43. Last segment of grub, 
 seen from beneath ; enlarged 
 six diameters. 
 
262 
 
 BULLETIN NO. 44. 
 
 [May. 
 
 In addition to affording an excellent illustration of the destruc- 
 tive capacity of the common white grubs, this record is of special 
 interest as evidence that L. rugosa at least will lay its eggs and 
 breed abundantly in fields of corn. On .no other supposition can 
 we explain the appearance of such vast numbers of partly grown 
 larvae three years after the ground was broken from grass in the 
 spring; three years, that is, subsequent to the latest time at which 
 the eggs could possibly have been laid in the grass. It seems very 
 likely that this second lot of grubs was hatched from eggs laid in 
 the corn in the summer of 1890 by the beetles which came out of the 
 ground in this same field. If this inference be correct, it follows 
 that planting to hemp for a year will not clear the ground of grubs. 
 A somewhat similar inference of a readiness to breed in corn 
 is to be drawn from our observations on another plat of about 
 four acres on the University farm near Urbana. This field, broken 
 
 up in the spring of 1890 and 
 put into corn, was planted irt 
 1891 partly to corn, and partly 
 to oats; in 1892 to oats and 
 corn again, but with the areas 
 reversed; and in 1.893 to corn. 
 On this the third year from 
 sod, more than half the corn 
 fell flat on the ground by the 
 middle of September, most of 
 the roots being eaten off by 
 white grubs, of which three or 
 four were commonly to be 
 found in a hill. Owing to the 
 consequent weakening of the 
 plant the brace roots failed to- 
 form, the ears which set were small and very often imperfect, and 
 a large percentage of the stalks were barren, the total height of 
 the plant varying from six or eight feet to less than a foot. Even 
 the tallest stalks were slender and unhealthy in appearance, the 
 lower leaves, and sometimes practically the entire foliage of the 
 plant, being as dry and brittle as in midwinter. Those stalks 
 which had been killed early were usually so decayed as to be 
 readily pulled apart at the nodes. 
 
 From these data we must conclude that the species concerned 
 which was either inversa or fusca may live as a larva through 
 four full years, making the entire life history cover a five-year 
 period, or else that the eggs were laid later than 1889 in either 
 corn or oats. 
 
 FlG. 44. Beetle of Lachnosterna rugosa, male; 
 enlarged two and a fifth diameters; a, last 
 two ventral segments. 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 263 
 
 The white grubs taken by us in corn fields under circumstances 
 to satisfy us that they either were or had been feeding on the 
 roots of corn belong to eight species, as follows: Lachnosterna 
 fusca, trtstis, inversa, hirticula, rugosa, gibbosa, and ilicis, and 
 Cyclocephala immaculata. Of these L. fusca, inversa, and rugosa 
 are much the most common in such situations; and to them by 
 far the greater part of the damage done to corn by the white 
 grubs in central Illinois must be attributed. 
 
 Next to Indian corn, the crop most generally and seriously 
 injured in Illinois by grubs is grass; and here the loss is the more 
 serious because continuous and usually unnoticed. A very large 
 number of these insects may live their long lives in the sod, feed- 
 ing steadily at the roots, and thus diminishing the yield without 
 actually deadening any continuous area. It is only when through 
 uninterrupted multiplication they become excessively abundant, 
 or when severe drouth checks the growth of vegetation, that 
 brown patches may appear in midsummer, sometimes merging in 
 areas of an acre or more over which th'e turf, loosened by a 
 destruction of its roots, may be rolled up like a carpet. 
 
 That they were original inhabitants of the wild prairie sod is 
 shown by the common testimony of old settlers, and by Walsh 
 in the "Practical Entomologist" (Vol. I., p. 60), where he reports 
 that in 1845 ne found white grubs eating off young corn when it 
 was a foot in height, in a field broken from prairie land the pre- 
 ceding year. 
 
 Patches of wheat, barley, and other small grains may be simi- 
 larly killed, all underground parts of the plant being completely 
 eaten up; but clover is scarcely ever damaged to any considerable 
 degree, and grubs are relatively rare in clover sod mixed with 
 grass. Their injuries to potatoes have often been reported, and 
 are generally well known, and they are among the worst insect 
 enemies of the strawberry grower. In regions where the sugar 
 beet is an important crop, they are among the chief injurious 
 insects to be taken into account. Young larches and evergreens 
 are sometimes killed by them in the nursery rows, and probably 
 every kind of delicately rooted shrub and of young fruit and 
 forest tree is liable to destruction by them. 
 
 No general list of their food plants has ever been prepared, 
 and nothing whatever is known of preferences with respect to 
 food among the different species of grubs. That they may live 
 for a considerable period on earth alone is shown by Dr. Riley, 
 who says that he has known the larvae of the common May beetle 
 to feed for three months on nothing but pure soil;* and Professor 
 
 *St. Louis "Globe-Democrat," March 25, 1876. 
 
264 BULLETIN NO. 44. [May, 
 
 Perkins, of Vermont, has kept individuals of all ages alive for 
 weeks, and sometimes for months, in sand more free from organic 
 matter than the soil of any field fit for growing crops.* The 
 remarkable fact that the grubs may eat locusts' eggs in the ground 
 has been mentioned in the First Report of the U. S. Entomologi- 
 cal Commission (p. 305). 
 
 The beetles of the white grub feed most frequently on the 
 leaves of various species of trees. Oak, hickory, ash, box elder, 
 elm, chestnut, butternut, black walnut, basswood, hackberry, hazel, 
 willow, black locust, mountain ash, tame and wild cherry, and pear 
 are the species positively known by us, by personal observation, 
 to be eaten by the adult beetles of various species; and apple, 
 plum, Lombardy poplar, sweet gum (Liquidambar), maple, and 
 birch may be added to the list on other authority. When a tree 
 is much infested, the leaves are eaten entire except perhaps a stub 
 of the petiole, or the petiole and a part of the midrib. Even the 
 bark of the younger twigs may be gnawed away. Two species, 
 hirticula and fusca, have been charged with an almost wanton 
 injury to the foliage of trees (oak and chestnut) done by gnawing 
 through the leaf petioles without eating the leaves (Proc. Ent. 
 Soc. Washington, Vol. II., p. 59), and we have noted the same 
 habit as occasionally exhibited to some small extent in the "artificial 
 forest" on the University premises at Urbana. The imagos 
 sometimes eat the leaves of blue-grass also, and we have once 
 found them feeding on heads of clover and once on corn. Several 
 species have been known to eat the leaves of raspberries ("Insect 
 Life," Vol. I., p. 366). 
 
 These notes on the food of the beetles are of interest because 
 of the damage sometimes done by these insects, especially to 
 trees on lawns, during the brief period of their excessive abun- 
 dance in May and June, but still more because it is in the adult stage 
 that the white grubs are most susceptible to organized attack. If 
 they are ever thoroughly mastered by the farmers of America, it 
 will apparently be by concerted measures, possibly supplemented 
 by legal requirement, for the destruction of June beetles before 
 they have laid their eggs. 
 
 LIFE HISTORY AND HABITS. 
 
 The adult beetles of the more abundant genus Lachnosterna, 
 hibernating in the earth in the cells where they originated, emerge 
 in spring and early summer at periods varying according to the 
 species of beetle, the general advancement of the season, and the 
 character of the weather at the time. Warm and genial days in 
 *Fifth Ann. Rep. Vt. Agr. Exper. Station (1891), p. 151. 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 265 
 
 spring often bring them suddenly out in myriads where previously 
 only scattered individuals have been seen, and their flight at night 
 is of course more free when the weather is warm than when their 
 energies are chilled by cold and storms. 
 
 As a rule, the males are not only the first to appear, but sur- 
 pass the females in number, taking the season through. They also 
 come to lights much more freely than the females, as is shown by 
 a comparison of our collections made at lights with those made 
 the same night from trees on which the beetles were feeding. 
 The 7th of May, 1891, for example, a collection of L. inversa made 
 with a lantern trap contained 1, 210 males and twenty-four females, 
 a ratio of fifty to one, while we took from trees the same night 
 one hundred and twenty-two males and seventy-three females 
 less than two to one. Taking all our collections of this species for 
 the summer of 1891, we find that in those from lights (1,418 speci- 
 mens) the males are to the females as fifty-one to one, while in 
 those from trees (271 specimens) the ratio was one and one-half 
 to one. This is, however, much greater than the usual difference 
 in other Lachnosternas, the species evidently varying with refer- 
 ence to their sensibility to light. 
 
 However taken and at whatever part of the season, it is rarely 
 that the females exceed or even equal the males in the same 
 collection. Throwing together 2,600 specimens of several species, 
 taken at frequent intervals throughout the season of 1891, the 
 sexes of which we have separated, it appears that the ratio of males 
 to females at lights was 16.5 to I, and from trees and various 
 surface shelters (839 specimens) 1.3 to I. My data on this subject 
 may be conveniently exhibited in the following tabular form : 
 
 
 
 At I 
 
 ,ight. 
 
 On Tr 
 
 ies, etc. 
 
 Species. 
 
 Dates. 
 
 No. of 
 specimens. 
 
 Ratio of 
 male 
 to female. 
 
 No. of 
 
 specimens. 
 
 Ratio of 
 male 
 to female. 
 
 Fusca . 
 
 April 18 June 4 
 
 QA. 
 
 2 2 
 
 TO7 
 
 T 1 
 
 
 April 29 June 24 
 
 185 
 
 4 6 
 
 oC2 
 
 I ^ 
 
 
 April 29 June 28 . . 
 
 I 4l8 
 
 m .0 
 
 271 
 
 I e 
 
 
 May 7 
 
 I 
 
 i .4 
 
 
 
 Gibbosa 
 
 May 15 June 24. . 
 
 42 
 
 IS-O 
 
 2O 
 
 2.^ 
 
 
 
 
 
 
 
 The adult beetles emerging from the ground, flying about at 
 night* in search of food, pair in the trees, to which they resort in 
 myriads, and retreat again to the earth by day. Their first flight 
 is made in the early evening, beginning at dusk, as they pass from 
 
 * A single species has been observed to fly by day in Utah. (Proc. Ent. Soc. 
 Washington, Vol. II., p. 241.) 
 
266 BULLETIN NO. 44. [May, 
 
 the ground where they have lain hidden by day to the trees on 
 which they feed. With the advent of day they fly from the trees 
 to the earth, and hide themselves an inch or less underground, or 
 sometimes merely creep under fallen grass and other similar 
 shelter. 
 
 Particulars concerning this retreat to their hiding places at 
 the dawn of day are given in notes made by Mr. John Marten 
 and Mr. Philip Hucke, detailed for night-work on June beetles 
 May 19, 1891. 
 
 3:45 a. m. Mr. Hucke reports the occasional dropping of a 
 beetle from trees in the artificial forest (chiefly butternuts and 
 hickories) where these observations were made. At 4:05, an occa- 
 sional beetle still dropping to the ground without making any 
 effort to fly. At 4:10 the air suddenly became full of flying beetles. 
 One and then another began to make a buzzing noise with its 
 wings, when, as if at a general signal, they deserted the trees in 
 thousands, and by 4:25 everything was still again and nearly 
 every one was gone. 
 
 Within the woods the beetles flew to a distance from the 
 trees about equal to the height from which they started, the lower 
 ones on the trees making a somewhat longer flight proportionally. 
 Striking against the weeds and undergrowth, they folded their 
 wings, and by 4:30 o'clock reached the ground within a hundred 
 feet of the trees from which they took their flight. Probably in a 
 clearer place they would make longer flights. 
 
 The Egg- Some of the species begin to lay their eggs in the 
 earth early in June, and this operation is in progress for about a 
 month. The eggs are placed from an inch to three inches beneath 
 the surface, each enclosed separately in a cavity just large enough 
 to hold it, several, however, being frequently placed near each 
 other, but never, according to our observations, in a common cell. 
 There appears in no case any special preparation of the soil or 
 chamber containing the egg, the statement commonly made to 
 the effect that the eggs are laid in a ball of earth being clearly 
 erroneous. The eggs are oblong-oval when first deposited, but 
 soon swell by absorption to a nearly spherical form. The males 
 begin to die not long after pairing, and the females also perish as 
 their ovaries are spent. The eggs hatch in from ten to eighteen 
 days, according to our experiments. As the data upon which 
 these statements are based are few, they may profitably be given 
 in some detail. 
 
 Larval Period. Our knowledge of the length of life of the 
 white grubs in the larval stage is based solely upon inferences 
 mostly drawn from the varying sizes of the grubs that appear in 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 267 
 
 collections made at any given time. Since the eggs are all 
 deposited practically within a month, and since the larva grows 
 but slowly, differences in size due to variations in time of hatching 
 must be but small. It is easily seen, however, from almost any large 
 collection made in spring or early summer at one time and place 
 that grubs of the same species or group can be readily assorted 
 into two lots differing notably in size, and never, so far as my 
 observation goes, into more than two.* This is readily to be ex- 
 plained on the supposition that the larger specimens are two years 
 old that season and that the smaller have hatched from eggs laid 
 the preceding summer. Upon this supposition the Lachnosterna 
 larva lives as a grub a trifle over two full years, changes to the 
 pupa and imago at the beginning of the third year of its life, and 
 emerges from the earth an adult, prepared to lay its eggs, at the 
 end of this three-year period. 
 
 The growing grubs feed, of course, only during the season of 
 growing vegetation, usually retiring from the middle to the last of 
 November to a depth beneath the surface varying according to 
 the severity of the winter weather, and coming up again within 
 reach of food commonly some time in March or early April. 
 
 The time and place of hibernation have their especial economic 
 interest, since while in their usual winter quarters the white grubs 
 are far beyond the reach of any agricultural operations. The dis- 
 tance to which they retreat in this latitude is about a foot and a 
 half, if I may judge from a single observation made November 29, 
 1886, in a badly infested field of wheat in Sangamon county, Illi- 
 nois. Here, around the margins of denuded patches, the ground 
 being frozen some four inches deep, the white grubs were found 
 repeatedly in numbers averaging four or five to the square foot at 
 a depth varying from a foot and a half to two feet. In 1890 they 
 had already come up, in the pastures, from their winter quarters 
 by the 24th of March ; were still at the surface in their usual num- 
 ber during the latter part of October; and had not wholly with- 
 drawn by November 2$th although at this last date most had gone 
 beyond the reach of the plow. Notwithstanding this well-marked 
 habit of retreat at the approach of winter, they occasionally linger 
 at the surface and hibernate at a depth scarcely greater than that 
 at which they are to be found during the summer season. 
 
 Pupation and Formation of the Beetle. The full-grown white 
 grubs, presumed to be two years old according to the preceding 
 section, will live an active life in the earth, feeding freely from 
 
 * To verify this statement it is necessary that the observer should learn to dis- 
 tinguish species or at least groups of species of these insects in the grub and larval 
 stage. 
 
268 BULLETIN NO. 44. \May, 
 
 March to June or July, during which months they change to the 
 pupa a few inches under ground, in oval cells made by the grub by 
 turning about in the earth. In this smooth-walled chamber the 
 cuticular remnant of the last moult will be found enclosed with the 
 pupa that is, the crust of the head of the grub and shriveled frag- 
 ments of its last skin. Our first date for this pupal transformation 
 of L. inversa is June 13, 1889, but Professor Perkins notes the 
 pupation of two larvae out of several hundred early in May. In 
 this chamber they lie until August or September, when they 
 change to the June beetle, fusca and gibbosa as early as August 
 nth, and others at least individuals of implicita, for example 
 not before September i/th. A small percentage of the adults 
 thus formed late in the summer and in early fall, may escape from 
 the earth before the winter opens, but this is relatively a rare 
 occurrence, the great mass of the generation continuing through 
 the winter in the pupal cells within which they originated. They 
 are to be found in winter from no more than two or three inches 
 to about ten inches beneath the surface. Hence they escape in 
 spring, as already described, pairing and laying their eggs for the 
 generation following. 
 
 From the foregoing it will be seen that the white grubs of the 
 genus Lachnosterna hibernate in two stages only, those of larva 
 and imago, the grubs themselves representing at least two gen- 
 erations. 
 
 Cyclocephala. (Fig. 45-47.) The white grubs of the genus 
 Cyclocephala differ from those of the various species of Lachno- 
 sterna in so far, at least, as to hibernate in the larval stage, to 
 pupate in May and June, and to emerge as beetles in June and July 
 later on an average than the species of the other genus. Pupa- 
 tion is consequently earlier than in Lachnosterna, and the 
 emergence of the imago occurs later in the season, the essential 
 difference being that adults of Cyclocephala escape from the earth 
 one or two months after the completion of their larval life, while 
 those of Lachnosterna continue in the earthen cells as pupae and 
 images about ten months. The difference in the economic appli- 
 cation of these biographies is not, however, very great, since the 
 period of active larval life of Cyclocephala seems to terminate on 
 an average only three or four weeks before that of Lachnosterna. 
 My detailed notes on the transformation of white grubs belonging 
 to this genus are but few in number, but as they accord with those 
 already given by entomologists, they serve to support the common 
 statements concerning the life history of these beetles. 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 269 
 
 Our only species in Illinois is C. immaculata, and its larvae 
 occur in grass with the other white grubs, and have been found 
 infesting corn on sod. 
 
 FIG. 45. Grub of Cyclocephala immaculata; en- 
 larged three and a third diameters. 
 
 FIG. 46. Last segment of grub, 
 seen from beneath ; enlarged 
 six diameters. 
 
 NATURAL ENEMIES. 
 
 In the struggle for existence the white grubs and the June 
 beetles enjoy many pronounced advantages, and are subject to 
 relatively few and feeble checks on their multiplication. The large 
 size and the subterranean habit of the grubs protect them in great 
 
 measure against two of the three prin- 
 cipal classes of natural enemies of insect 
 larvae ; namely, birds and insect para- 
 sites. They are more liable to fungus 
 parasitism, it is true, but many kinds of 
 much less abundant insects suffer far 
 more heavily therefrom, and authentic 
 reports of the notable destruction of our 
 American white grubs by fungus para- 
 sites are rare. The beetles are espe- 
 cially protected by their large size and 
 heavy armor, by their nocturnal habit 
 and their skill in hiding themselves by day, by the enormous 
 numbers in which they appear, and by the relatively short term of 
 their adult life. Cold and heat, drouth and wet weather have little 
 noticeable effect upon these insects in any stage, and even star- 
 vation does not kill the grubs, for in the absence of other food they 
 can live for months on earth alone. 
 
 Great as the number doubtless is of individuals of the several 
 species which fall victims during the year to various enemies and 
 other hostile agencies, the evidence now before us does not warrant 
 us in placing any considerable reliance on these natural checks to 
 the multiplication of the white grubs, but we are rather led to con- 
 clude that American agriculture must look to its own resources for 
 
 FIG. 47. Beetle of Cyclocephala 
 immaculata; enlarged three 
 diameters. 
 
270 BULLETIN NO. 44. [May, 
 
 a remedy. If, however, we take into account the fact that our 
 common white grubs are native insects, most of them living 
 originally in the prairie sod, which formed a denser, more uniform, 
 and more continuous covering to the surface of the country than 
 the crops now raised by the farmer, and further recall the fact that 
 under these primitive conditions these insects rarely produced any 
 conspicuous effect upon our native vegetation, we may infer with 
 some confidence that they are not likely to increase indefinitely 
 and inordinately, but that the natural checks which held them 
 primitively within a certain well-defined limit will reassert them- 
 selves under the not very different conditions of a developed agri- 
 culture. Such data as we have concerning the enemies of these 
 insects, animal and vegetable, are presented here more as an 
 indication of the incompleteness of our knowledge, than because 
 of their present practical value. 
 
 Birds. White grubs and June beetles are eaten to some 
 extent by a considerable variety of birds, doubtless by many more 
 than my cullings of the scanty literature of this subject have 
 brought to light. 
 
 In my own studies, I have found June beetles eaten by the 
 robin, catbird, brown thrush, wood thrush, hermit thrush, blue- 
 bird, and meadow lark; Mr. E. V. Wilcox has found both June 
 beetles and white grubs in the stomachs of robins ; and Glover 
 long ago recorded the occurrence of June beetles in the stomach 
 of a woodpecker (Rep. U. S. Comm. Agr. 1865, p. 38). Dr. A. K. 
 Fisher reports the occurrence of these beetles in the food of the 
 red-tailed hawk, the red-shouldered hawk, the broad-winged 
 hawk, the sparrow hawk, the screech owl, and the great horned 
 owl; and white grubs in that "of the red-shouldered hawk, the 
 sparrow hawk, and the barred owl. Dr. C. V. Riley's assistants 
 recognized fragments of the beetles in the stomachs of six English 
 sparrows, and four large white grubs in one of this species, out of 
 five hundred and twenty-two specimens examined. 
 
 To this list I can add only the crow and the blue jay, on the 
 authority of Dr. B. H. Warren, author of the " Birds of Pennsyl- 
 vania," the chuck-will's widow ("Insect Life," Vol. II., p. 189), the 
 king-bird (Lintner), and the crow blackbird, whose habit of picking 
 up white grubs after the plow is a matter of common observation. 
 
 Of these twenty species, taking into account their numbers 
 and their feeding habits, I judge that the robin, the catbird, the 
 brown thrush, and the crow blackbird devour much the largest 
 numbers of these insects,* although it is possible that if the 
 
 *Nine out of forty-four robins shot by me in April, May, and June had eaten June 
 beetles; six catbirds out of forty-one: and twelve brown thrushes out of forty three 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 271 
 
 smaller insectivorous hawks the sparrow hawk especially were 
 permitted to increase freely they would equal or surpass any of 
 these, because of the greater number of insects which they take 
 at a meal. Chickens, ducks, and turkeys are fond of white grubs, 
 and may often be seen scattered over freshly plowed ground in 
 search of them and other subterranean insects. 
 
 Mammals. The only native mammals known to feed on these 
 insects in any considerable numbers are moles, ground squirrels, 
 and skunks none of them very likely to be tolerated by the 
 farmer, whatever may be their insectivorous habits. 
 
 Among the domestic animals, pigs are well known as eager 
 hunters for white grubs, in search of which they dilligently root 
 up an infested turf; a fact which may sometimes be advantageous- 
 ly applied for the protection of corn to follow upon grass. 
 
 Insects. The special insect enemies of the white grubs now on 
 record belong to three or, possibly, four species, two of them 
 hymenopterous and one dipterous, a second dipterous insect bred 
 by us from dead white grubs being doubtfully parasitic. To this 
 number I am able to add another hymenopterous parasite, Pelecinus 
 polyturator, a remarkable insect whose larval history has hereto- 
 fore been wholly unknown. From a collection of white grubs 
 obtained from an orchard at Champaign, Illinois, May 9, 1892, and 
 kept in a breeding cage at my office inscctary, a specimen of 
 Pelecinus polyturator emerged August 26, 1892. As the parasite 
 was seen in the act of emerging from its pupal envelope, there can 
 be no doubt of either the fact or the date. An examination of 
 the remains of the grub containing the pupa skin of the parasite 
 showed that the former belonged to the species L. gibbosa. My 
 office specimens of the adult of this parasite are recorded under 
 nine collection numbers, all bearing dates in late summer and 
 arly fall July 2ist, 26th, August 1st, 2d, nth, i6th, 28th, and 
 September ist and i6th. It is hence probably single brooded, 
 maturing in July and August. 
 
 Perhaps the most destructive insect enemy of the white grub 
 is Tiphia inornata, Say, a hymenopterous species which we have 
 never bred, but which has been reported by Dr. Riley to occur 
 occasionally in very large numbers in ground infested by Lach- 
 nosterna larvae. He says: " One can scarcely dig for half an 
 hour in any soil in this part of the country, without meeting with 
 a curious egg-shaped cocoon, of a pale golden brown or buff color, 
 and with a soft exterior surface, in touch as well as in color remind- 
 ing* one of the punk used by dentists. Upon cutting this cocoon 
 open, it will be found to consist of about a dozen delicate layers, 
 the outer ones soft and loosely spun, the inner ones more and 
 
2/2 BULLETIN NO. 44. [May, 
 
 more compact and paler in color. Within this cocoon, if fresh, 
 there will be found a whitish grub which, though lacking legs, has 
 the joints of the body, at the sides, swollen so as to look like the 
 fleshy pseudopods possessed by many larvae. * * * From hav- 
 ing repeatedly found the head parts of some Lamellicorn larva 
 attached to these cocoons, I had long suspected that such larvae 
 formed the food of this Tiphia, and on carefully examining these 
 head-parts I recognized them as belonging to the common white 
 grub. But all doubt as to this fly's being parasitic on said white 
 grub ceased when, in 1872, Mr. A. W. Smith, of St. Louis, brought 
 me a number of the cocoons which he had taken from a low part 
 of his farm on the Illinois bottom, where the white grub was very 
 thick, and the yellow cocoons so numerous as to attract attention. " 
 
 Ophion bifoveolatum is likewise reported by Riley as a white 
 grub parasite (Proc. Ent. Soc. Washington, Vol. II., p. 134), and 
 this was quite probably the species of Ophion bred at my office in 
 1886. From white grubs brought to the insectary April 27th the 
 specimen emerged May nth, but was lost from my collections 
 before being determined specifically. 
 
 A tachinid fly has also been found parasitic on the grubs 
 (Proc. Ent. Soc. Washington, Vol. II., p. 134), and a second fly, 
 Microphthalma nigra, Macq., has been repeatedly bred by us 
 from the dead bodies of white grubs. The habits of the family 
 Dexidae, to which this last mentioned insect belongs, make it 
 doubtful, however, if these flies may not have developed from 
 eggs laid on the bodies of grubs already dead. 
 
 Tiphia inornata, mentioned above, ought probably to be 
 called a predaceous rather than a parasitic insect, as it attacks the 
 grub from without, and devours it bodily. Ants destroy white 
 grubs in breeding-cages, and very possibly attack them sometimes 
 in the field. It is quite likely that various other predaceous insect 
 species, ground beetles especially, may devour white grubs occa- 
 sionally, as has indeed been suggested by Riley (Sixth Ent. Rep. 
 Mo.), but I have no record of precise observations to that effect. 
 The fact that the beetles may sometimes fall a prey to carnivorous 
 insects, is shown by two specimens brought to my office by a 
 student of the University, May 21, 1891. One of these was an 
 example of L. hirticula, which he had found with the tip of its 
 abdomen torn open, crawling up a stem of grass. The other was 
 a Chlcenius tomentosus, found clinging to the Lachnosterna and 
 feeding upon its viscera, partly drawn out of the wound. The 
 frequency with which mites are found clustered upon white gr*ubs 
 in their earthen cells, especially upon those recently dead or in 
 a weakened condition, has given rise to the supposition, hitherto 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 2/3 
 
 not experimentally verified, that these mites may be parasitic on 
 the grubs. 
 
 On the whole, the general tenor of our own observations, as 
 well as those published by other entomologists, must lead us to 
 attach comparatively little economic importance to the insect 
 enemies of white grubs, whether predaceous or parasitic. 
 
 Reptiles and Amphibians. The fact that the toad occasionally 
 eats June beetles has been reported (Proc. Ent. Soc. Washington, 
 Vol. I., p. 69), and could no doubt be verified extensively by dis- 
 sections of toads made at times when the June beetle is abroad. 
 Frogs must likewise be placed on the list of the natural enemies 
 of these beetles. Prof. Perkins, of the University of Vermont, 
 has found as many as ten in the stomath of a single frog of medium 
 size. It is altogether likely that insectivorous reptiles, serpents 
 especially, would be found to destroy a still greater number of 
 these insects, but no studies have been made, to my knowledge, 
 on this point. 
 
 Fungi. But one contagious disease of the American white 
 grub occurring in nature has been positively and definitely con- 
 nected with a fungus parasite. This parasite (Cordyceps melolon- 
 thce) has been several times referred to in economic literature, 
 first in the "American Journal of Science and Arts" (August, 
 1824). It was treated at length in an illustrated article published 
 by Riley in the "American Entomologist " for June, 1880. Accord- 
 ing to a correspondent of Walsh's in 1869, it has sometimes been 
 very common in Virginia ; and Mrs. Treat reported the occurrence 
 of thousands of infested specimens in Benton county, Iowa, in 
 1865. Perkins mentions it as infesting grubs of Lachnosterna in 
 Vermont. This species is, so far as known, incapable of artificial 
 cultivation, and could consequently be used for insecticide 
 purposes only by distributing as carriers of infection white grubs 
 which had been in contact with others infested with it. Indica- 
 tions have not been wanting of the occurrence of a bacterial disease 
 native to our Lachnosterna larvae, but no precise studies have been 
 made sufficient to warrant the assertion that such bacterial diseases 
 really occur. The common insect parasite, Sporotrichum globu- 
 liferum, the so-called white fungus of the chinch bug, has never 
 been found by us infesting Lachnosterna larvae in a state of nature, 
 although these larvae have been proven quite susceptible to it in 
 the course of our experimental work. June beetles have been 
 frequently found, however, with this fungus growing upon their 
 dead bodies, but, for all that is clearly known to the contrary, it 
 may have taken its start upon them after the death of the beetles. 
 
 In Europe, according to Giard and Krassilstschik, three dis- 
 
274 BULLETIN NO. 44. [May, 
 
 eases of the European white grubs have been detected: one of 
 them due to a fungous infection by the species most commonly 
 known as haria densa, Link, (=Botrytis tenella, Saccardo); and 
 the other two, bacterial diseases studied by the last named author. 
 
 PREVENTIVE AND REMEDIAL MEASURES. 
 
 If we use the word remedy for measures intended to arrest an 
 injury already begun, and prevention for measures applied in 
 advance of such injury, we must say that efficient remedies for 
 the injuries of white grubs are but little applicable to their work 
 in corn, and that we are confined consequently, for the main pur- 
 poses of this article, to a discussion of preventive measures only. 
 Such measures of prevention may be either local or general: 
 applied, in the first case, to the field in which corn is to be planted, 
 and intended to forestall injury in that field only; or, in the second 
 case, applied elsewhere or more comprehensively, with a view to 
 a more general effect in reducing the number of white grubs over 
 a larger area. 
 
 Local preventive measures can take effect only on the white 
 grubs themselves, while the most valuable general measures are 
 those directed to the destruction of the June beetles before their 
 eggs are laid. 
 
 Local Prevention. It is now well settled, as has been shown 
 in the preceding pages, that at least some species of the white 
 grubs may be freely and abundantly bred in fields of corn; but it 
 still remains true that by far the greater number of those in the 
 country at any time have arisen from eggs laid by the beetles in 
 ground bearing a crop of grass; and that corn is consequently 
 much more likely to be damaged if planted on sod than if it fol- 
 lows clover, some small grain, or corn itself. The first effort of 
 the corn farmer threatened by these insects should consequently 
 be directed to clearing the grubs out of the grass land which he 
 wishes to plant to corn. For this purpose it is very desirable that 
 hogs should be pastured for a considerable time on meadows or 
 pastures before plowing for corn, and that they should also be 
 given the run of the field while it is being plowed. This measure 
 will be practically useless, however, under ordinary circumstances, 
 if resorted to later than October or earlier than April, as in the 
 interval between these months the grubs will be beyond the reach 
 of pigs, buried in their winter quarters. 
 
 Further, I do not, myself, in the least doubt the great profit 
 to the average farmer of providing for the collection of white 
 grubs after the plow, by hand, in soil where they are particu- 
 larly abundant, especially where any kind of cheap labor may 
 
l8g6.J INSECT INJURIES TO SEED AND ROOT OF CORN. 275 
 
 be had. In estimating the value of this method, we should bear 
 in mind the fact that a small number of grubs may do a great 
 amount of harm to young corn on comparatively clean ground, 
 because of the small amount of vegetation offered to them as 
 food while the corn is young. 
 
 Next, we should take into account the relatively small damage 
 done to clover by the grubs, and the further fact that we have no 
 present evidence that the eggs of the June beetle are ever laid in 
 clover land. It is consequently a good practice, so far as grub 
 injury is concerned, to insert clover (sown perhaps with oats) 
 between grass and corn in the rotation ; and this is especially to be 
 advised on light soils, not perfectly adapted to corn. Here it will 
 have the effect not only to eliminate the grubs in part, but also to 
 diminish the damage to the following crops of corn by increasing 
 the strength of the land, thus helping the corn plant to withstand 
 such loss of roots as it may nevertheless be subjected to. In this 
 connection it need hardly be said that a generous treatment of the 
 soil by heavy fertilization, thorough cultivation, and the like, will 
 diminish loss to corn by enabling plants attacked to throw out new 
 roots more vigorously to take the place of those eaten by the 
 grubs. Indeed, by some most intelligent and successful farmers, 
 high fertilizing with frequent rotation is regarded as the essential 
 and sufficient defense against these insects. 
 
 The management of corn on lands containing grubs should 
 also be directed especially to the protection of the plant from 
 drouth, as, in the presence of these insects, dry weather takes a 
 double effect by retarding root growth under circumstances which 
 require it to be vigorously stimulated instead. 
 
 To prevent the laying of the eggs of the June beetle in the 
 corn field in May or June, it is desirable that the ground should be 
 kept practically free from weeds at that time, as it is well known 
 that a surface growth of vegetation is a strong attraction to these 
 insects searching for places suitable for the support of the young. 
 Some of our more recent observations show that the beetles are 
 likely to deposit their eggs in the field from which they themselves 
 have emerged, provided that it offers them suitable conditions a 
 fact which makes it clearly inadvisable that a field which is badly 
 infested one year, should be planted to corn the next. 
 
 General Prevention. The principal and most effective prevent- 
 ive measures of general promise are those for the collection and 
 destruction of the June beetles before they have laid their eggs. 
 They are practically confined to the following four methods, men- 
 tioned in the order of their importance : (a) shaking and jarring 
 down the beetles at night from the trees in which they feed, and 
 
276 BULLETIN NO. 44. {May, 
 
 their collection on sheets or cloth-covered frames similar to those 
 in use for the peach and plum curculio; (b) exposing light traps 
 early in the evening in places frequented by the beetles; (c) the 
 spraying of trees to which they resort, with Paris green or other 
 suitable insecticide ; and (d) the turning of pigs into woodlands, 
 forest plantations, and the like, where the June beetles conceal 
 themselves by day. 
 
 These are all measures calling for cooperative action by all, or 
 at least the greater part, of the farmers of a neighborhood, since 
 it is useless to expect any pronounced effect from isolated and 
 individual action. They can only be carried out by previous 
 agreement of those interested, by the offer of premiums for the 
 beetles, or by the passage and enforcement of laws bearing equally 
 upon all. In estimating the value of these methods it should be 
 remembered that each female beetle is the average equivalent of 
 a large number of grubs. 
 
 In illustration of the effectiveness of the first mentioned of 
 these methods, I quote from notes of Assistants Marten and 
 Hucke, made in 1891. 
 
 May igth, 2:40 a. m. Shaking the trees in the University 
 forest plantation made the beetles fall very easily, the second 
 shake generally getting all, or nearly all, there were in a tree. 
 Those shaken from the trees made no effort to fly up again, and 
 only one such came to the lantern trap near by. 
 
 3:45 a. m. The beetles apparently as abundant as ever on 
 butternut and hickory. The lightest shake of either of these 
 trees brings down the beetles by dozens. Butternut trees six to 
 eight inches in diameter drop them in considerable numbers when 
 shaken by the hands so easily are they detached. 
 
 From other notes it is apparent that the June beetles cling 
 more closely to the trees early in the evening, from eight to ten 
 o'clock, a fact doubtless to be connected with the gradually stupe- 
 fying effect of the night dews and the cooler air towards morning. 
 
 This is the standard method in both France and Germany for 
 the control of injuries by the European white grubs. The results 
 attained in the former country are shown by an article, " La 
 Chasse aux Hannetons," published in the Revue de deux Mondes 
 for 1878. In consequence of an offer of premiums for beetles in 
 the department of Seine- Inferieure, 1,149,000,000 of these cock- 
 chafers were collected and paid for in that year, at an expenditure 
 of $16,000. It was estimated that these beetles would have given 
 origin the following year to 23,000,000,000 white grubs. The 
 proprietor of an establishment for the manufacture of sugar from 
 beets, whose crop was seriously affected by the ravages of the 
 
I896.J INSECT INJURIES TO SEED AND ROOT OF CORN. 277 
 
 grubs, offered a prize of $4 for each one hundred kilogrammes 
 (about two hundred and twenty pounds avoirdupois) of the beetles, 
 and obtained as a consequence 28,000,000 cockchafers equivalent 
 to 560,000,000 grubs the following year. 
 
 Details of the common procedure in France are given by A. 
 Walle's in " Bulletin de la Socie'te Centrale d'Apiculture et d'ln- 
 sectologie" for June, 1890. " It would be a mistake," he says, "to 
 wait until the cockchafers [English name for the European equiva- 
 lent of our June beetles] have emerged, since the whole benefit 
 of the capture of the beetles will be lost if the females are given 
 time to lay their eggs. Measures for the destruction of these 
 insects must be taken, consequently, from the time that a few 
 begin to appear. Further, if in certain parts of the territory 
 involved the capture of the beetles is neglected, the good effect of 
 the procedure will be considerably diminished. These two points 
 are essential and imperative. 
 
 "The cockchafer catchers should be provided with hooked 
 poles, with an awning cloth, or the like, and with bags for their 
 catch. It will be well for them to go in little groups, and to make 
 their rounds from the time of the first appearance of the insect. 
 This last observation is most important. On the I2th of May, for 
 example [in France], no more than twenty per cent, of the cock- 
 chafers captured in the trees will be females. A little later, on 
 the contrary, the males will have disappeared, and scarcely any 
 but females will be found. These, however, will have laid their 
 eggs. 
 
 "The beetles may be most easily shaken down from the trees 
 in which they are concealed, at the dawn of day, when they are 
 still stupid with the coolness of the night, and this is, consequently, 
 the time at which these collections should be made. Two persons 
 will do well to work together when tall trees are to be visited. 
 One strikes the branches and shakes them by means of the hook 
 fastened into the end of his pole, while the other picks up the 
 beetles. They can, of course, change places occasionally. When 
 there is grass under the trees a cloth must be spread to catch the 
 beetles, which would otherwise often be lost. It will be very easy 
 to clear trees of smaller size by shaking them energetically, but 
 not violently enough to break them. 
 
 "It is perhaps in the canton of Mayenne that the cockchafer 
 hunt is pursued by the inhabitants with the greatest method, 
 energy, and perseverance. There those engaged in the chase of 
 the beetles are divided into squads of four (men, women, or 
 children), each of which is furnished with the following instru- 
 ments: (i) A sheet of burlap three yards by two, in the ends of 
 
278 BULLETIN NO. 44. [May, 
 
 which two flexible sticks are fastened. Strings intended to sup- 
 port the apparatus are attached to these sticks. (2) A long pole 
 armed with an iron hook. (3) A sack of coarse cloth. The squad 
 being thus equipped, two hold the sheet extended under the 
 branches. Owing to the flexibility of the rods at the end, the 
 surface of the sheet easily takes the concave form of a common 
 hammock. The branches are then shaken with the hand or with 
 the hooked stick, and the cockchafers fall upon the cloth and 
 accumulate in the center." 
 
 Between 2 and 5 o'clock a.m. is the best time for capturing our 
 American June beetles. If they are thus collected in very great 
 numbers, they may be most conveniently killed by throwing them 
 into tubs or barrels of water with kerosene on the surface. If the 
 number is so great as to be likely to be offensive if left to decay, 
 they may be scattered upon the fields as a fertilizer. 
 
 The foregoing method is but little likely to be brought into 
 use on the scale required to make it effective unless the white 
 grubs become, at least locally, more destructive than they are at 
 present in any part of the State of Illinois. It is quite within the 
 bounds of possibility, however, that this or some similar method 
 will be ultimately forced upon the American farmer. 
 
 Our June beetles are strongly attracted by lights; a disposition 
 which may be used for their destruction in fields. An apparatus 
 consisting of a lantern suspended over a tub of water, placed in or 
 near trees or groves resorted to by the beetles, will often collect 
 large numbers of the adult insects, which, flying against the 
 lantern, drop into the water, where they are readily killed if a little 
 kerosene has been poured over the surface. This method is, 
 however, of little value as compared with that above described, 
 since it attracts males in very much greater proportion than 
 females sometimes fifty of the former to one of the latter. It is 
 also ineffective on moonlight nights, and when the weather is cool 
 or windy ; is much more expensive; and, under the most favor- 
 able circumstances, less thoroughgoing. Its effect is shown by 
 office notes made in 1888 and 1891. June 9th of the former year 
 one hundred and twenty-seven beetles were caught in a pan fifteen 
 inches across partly filled with water and kerosene, above which 
 an ordinary lantern was suspended, the apparatus being placed on 
 a bench under trees, in Urbana, 111. A similar experiment, made 
 May 7, 1891, with a tub of water and oil and a common kerosene 
 lamp yielded 1,290 beetles, of which all but forty-one were males. 
 In this case the trap was placed in a small forest plantation on the 
 University farm in Urbana. These beetles were all taken between 
 7:45 and 9:15 p. m., after which only now and then one would 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 2/9 
 
 come to the light. Later in the season no doubt the proportion 
 of females to males would have been greater ; but statements 
 made in another part of this article, under the head " Life History 
 and Habits," show that the disproportion continues throughout 
 the season. 
 
 The spraying of trees most resorted to for food is a possible 
 measure, since the beetles are killed by arsenical poisons a fact 
 demonstrated by laboratory experiments made by us in 1888 with 
 oak leaves dipped in Paris green mixture, one ounce to twenty 
 gallons of water. The expense of a general application of such 
 an insecticide will, however, prevent its common use. 
 
 When pigs can be turned, in May and June, into groves, 
 orchards, or forests infested by the beetles, they cannot fail to 
 destroy immense numbers of them, since they eat them eagerly, 
 and can easily find them, hidden as they commonly are by day 
 barely under the surface of the ground. This is a measure only 
 occasionally applicable. 
 
 Remedial Measures. Direct remedies for the attacks of white 
 grubs are either inapplicable to the corn field, are of doubtful 
 economic value, or are too little understood, as yet, to make them 
 worthy of recommendation. For example, kerosene emulsion 
 may properly be applied to infested lawns, and, if followed by a 
 copious watering, may kill large numbers of the grubs, but the 
 cost of this material and treatment will preclude its use against 
 grubs in corn; and kainit and other potash fertilizers (the sulphate 
 especially) will destroy grubs in the earth, but for this purpose 
 must be used at a rate inadmissible in farm practice more than a 
 ton per acre according to Prof. Perkins (Fifth Ann. Rep. Vt. Agr. 
 Exper. Station, p. 152). 
 
 Among remedial measures of uncertain value may be men- 
 tioned the cultivation and dissemination of the fungas parasites of 
 the white grub uncertain because not yet thoroughly tested, and 
 because such tests as have been made do not demonstrate the 
 practical utility of the method. 
 
 These parasitic fungi do, however, sometimes spontaneously 
 destroy immense numbers of white grubs in the field, and some of 
 them can be easily cultivated in quantity outside the body of the 
 insect almost as easily as mushrooms may be grown for the 
 market. The subject of the fungous diseases of these insects is 
 therefore a very suitable one for investigation, and should undoubt- 
 edly be most thoroughly studied from every point of view. 
 
280 BULLETIN NO. 44. [May, 
 
 THE GREEN JUNE BEETLE. 
 (Allorkina nitida, L.) 
 
 FIG. 48. Green June Beetle: a, larva; 6, pupa; c, male beetle; all enlarged \y z 
 diameters; d, e,f,g, mandible, antenna, leg, and maxilla of larva, more enlarged. 
 
 The larva of the green June beetle, Allorhina nitida, commonly 
 known as a white grub where it occurs, is distinguishable from the 
 species of Lachnosterna and Cyclocephala by its somewhat larger 
 size when full grown; by the thick covering of short stiff hairs 
 easily visible to the naked eye; but especially by' the difference in 
 its method of locomotion upon a hard surface. The common white 
 grubs (Lachnosterna) creep only by means of their legs, dragging 
 the heavy abdomen clumsily along; but the larva of the green June 
 beetle, when thrown upon a hard surface, turns immediately upon 
 its back, and moves somewhat easily in this position by alternate 
 contraction and expansion of the segments of the body, using the 
 stiff hairs upon the back as an aid. 
 
 This is a southern species, and in the Southern States largely 
 replaces Lachnosterna, its larva being there known as the white 
 grub. In Central Illinois it occurs but rarely, but becomes notice- 
 ably abundant in the southern part of the State, where it has been 
 occasionally reported as injurious in a small way. Although it 
 has not been found in corn fields, its food and habits are such as to 
 make it altogether likely that under favoring circumstances it 
 might injure corn in the same manner as the Lachnosterna larva 
 or rather as the larva of Cyclocephala, which it more closely 
 resembles in its life history. The grub is normally a grass insect, 
 but infests likewise strawberry fields, and has been found by Dr. 
 Riley to feed in confinement upon the roots of wheat. It seems 
 to be less dependent upon living vegetation than even the white 
 grubs, apparently living much more generally upon a rich soil. 
 Indeed, the beetles seem to be attracted to manured land when 
 about to lay their eggs, or to that which has been heavily mulched 
 or contains an unusual amount of decomposing vegetation. 
 Townsend has found them living in clean earth under circum- 
 stances to indicate a carnivorous habit. 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 28l 
 
 The life history of this insect is, as already intimated, different 
 from that of Lachnosterna, especially in the fact that pupation of 
 the larva takes place in May, the beetles issuing in June. Its 
 length of larval life is not known, nor the precise time or place of 
 oviposition. 
 
 PRIONUS GRUBS. 
 
 FIG. 49. Prionus grub ; natural size. 
 
 The occasional occurrence in corn of large thick-bodied grubs 
 belonging to a different family from the common white grubs of 
 this article, calls merely for general mention. These are the larvae 
 of two species of large brown, flattish, long-horned beetles, and 
 belong to the genus Prionus (P. imbncornis and P. laticollis}. 
 They are sometimes common in prairie or pasture sod, where they 
 feed upon the roots of grass, and have also been a few times 
 reported in corn fields in Illinois and Missouri, doing an injury 
 apparently identical with that of the white grubs. These grubs 
 are at once distinguishable from the latter insects by their greater 
 size (3 mm. in length and nearly half as thick when full grown), 
 by the form of the body (tapering from the head backwards), and 
 by the fact that it is little, if at all, curved. They are, further, at 
 once distinguishable by the rudimentary and inconspicuous char- 
 acter of their legs. They are much more generally known to 
 economic entomology for their injuries to the roots of the vine 
 and apple and some forest trees than for their agricultural relations. 
 
 FIG. 50. Pupa of Prionus; 
 natural size. 
 
 FIG. 51. Beetle of Prionus 
 laticollis; natural size. 
 
282 BULLETIN NO. 44. f May, 
 
 b. Roots penetrated, perforated, irregularly burrowed, and more 
 or less eaten off and eaten up. Underground parts of stalk 
 usually also similarly injured. 
 Wireworms in soil among the roots. 
 
 (For a discussion of the wireworm injury to corn, see this 
 report, p. 224.) 
 
 Small, slender, soft-bodied, white or yellowish-white grubs in the 
 roots and earth. 
 
 THE SOUTHERN CORN ROOT WORM. 
 
 (Diabrotica i2-punctata, Oliv.) 
 (Fig. 52-56.) 
 
 Injuries to corn by the southern corn root worm have not 
 been seen by us in Northern Illinois and but rarely in the central 
 part of the State, but they are more likely to occur southward. 
 Outside this State they have been recognized by entomologists in 
 Ohio, Indiana, Kentucky, Arkansas, Mississippi, Louisiana, Ala- 
 bama, South Carolina, Virginia, and Maryland. As the beetle 
 occurs from Canada southward through the Atlantic region, and 
 thence to Minnesota, Kansas, Louisiana, and Mexico, it will prob- 
 ably be found much more generally present in corn fields than the 
 above report would indicate. 
 
 Its injuries are very similar in general character and effect to 
 those of the much more abundant and better known northern corn 
 root worm (Diabrotica longicornis), with which they have doubtless 
 frequently been confounded. They are distinguishable with some 
 difficulty from those due to the various species of wireworms, and 
 it will often require the recognition of the larva itself to determine 
 positively to which of these two classes of insects a given root 
 injury is due. The presence of this root worm in the field gives 
 origin to the usual general effects of the loss of roots by the plant, 
 varying according to the age of the corn, the gravity of the injury, 
 and the kind of soil and weather. A conspicuous damage, notice- 
 able on a casual inspection, may vary from the death of the plant 
 to a slight retardation of its growth or to a general spindling, 
 yellowish, and unhealthy look. 
 
 In the young plant, about six inches high, the characteristic 
 perforations of the stalk underground may result in the sudden 
 withering of the whole plant, or, more commonly, in the killing of 
 the central leaf or tuft of growing leaves an appearance which 
 has given to this insect the common name of the " bud worm " in 
 some of the Southern States. In certain instances the plant has 
 been killed, as in Maryland, almost as soon as it has sprouted. 
 
 As the season advances, the corn in affected fields is likely to 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 283 
 
 be uneven in size, and later, as the plant becomes top-heavy with 
 growth, it may fall to the earth when the soil is softened by rains, 
 and especially during windy storms. Having once so fallen, it 
 will, if badly injured, fail to rise again; and it may further be seen 
 that the plant has but little hold upon the ground, a whole hill, 
 perhaps, being readily pulled up with one hand. As a consequence 
 of the loss of roots and the general weakening of the plant, many 
 stalks fail to set the ear, or form only a nubbin. The injured 
 plant also matures slowly, remaining green longer than the aver- 
 age, and being thus especially subject to injury by frost. 
 
 A closer examination of the young plant will commonly show 
 a perforation of the underground part of the stem either at or 
 near the upper circle of roots. Later, as the corn plant increases 
 in size, the roots themselves are seen to be gnawed irregularly, 
 great holes or notches being eaten out, first in one direction and 
 then in another, until the roots are severed or consumed. In the 
 larger roots the larva may perhaps completely bury itself, but it is 
 much more likely to eat in and out- irregularly than is the smaller 
 northern corn root worm presently to be described. It differs 
 from this last species likewise in the fact that it commonly devours 
 everything as it goes, leaving little or no refuse in its burrows; 
 and in the further fact that it works all along to some extent in 
 the base of the stalk, which it penetrates, but not deeply, finally 
 causing the stalk to blacken and rot where water gets admission 
 to its injuries. Its attack on corn is also earlier, briefer, and much 
 more vigorous and destructive, owing to the larger size of the 
 larva and its more rapid growth and earlier maturity. Even in 
 well-grown corn it very commonly bores into the stalk beneath 
 the upper circle of brace roots, or behind the sheath of the lower 
 leaf ^habits in which it differs from the northern corn root worm. 
 
 Search for this root worm should be made in or about the 
 injured parts from the middle of May to the middle of August in 
 the latitude of the southern half of Illinois. It is a soft, slender- 
 bodied, worm-like insect, a little over half an inch in length when 
 full grown, and nearly ten times as long as thick. The surface is 
 slightly wrinkled or warty, white when young, and yellowish when 
 old. The head is dark brown, sometimes nearly black, and there 
 is a pale brown leathery patch on the top of the segment next 
 behind the head, and a nearly circular similar patch on the top ,of 
 the last segment of the body. The legs are very short and small, 
 and the skin bears only a few long scattered hairs. 
 
284 
 
 BULLETIN NO. 44. 
 
 FIG. 52. Southern Corn Root Worm, dorsal view; enlarged five diameters. 
 
 JL. 
 
 FIG. 53. The same, side view. 
 
 It seems most likely to attack early planted corn, and hence 
 in the Northern States has been found most frequently in sweet 
 corn. An injury of fifty per cent, is a not unusual effect of its 
 presence in Southern Illinois, and elsewhere it has been reported 
 as sometimes destroying almost every hill when the corn was young. 
 This corn root worm has not been taken in the act of injury 
 to the roots of any other plant than corn, but has once been seen 
 eating off a stem of young wheat in fall.* Lugger found the pupae 
 among the roots of a common prairie plant, the cone flower (Rud- 
 beckia), but says nothing of injury to that plant; and my assistant, 
 Mr. Marten, reports the occurrence of young larvae among the 
 roots of Cyperus strigosus and Scirpus fluviatilis two sedges com- 
 mon in moist low lands, the roots of which presented the same 
 appearance of injury as those of infested corn. 
 
 The food of the adult Diabrotica 12- 
 punctata is widely varied, apparently 
 much more so than that of the northern 
 Diabrotica. It has been for a long time 
 commonly known as a squash beetle, 
 eating both leaves and green fruit of 
 squashes, melons, and cucumbers. We 
 have seen it eating into pumpkins, 
 sometimes to the depth of half an 
 inch, and feeding upon clover blossoms 
 and upon the leaves of tame and wild 
 sunflowers (Helianthus). We have found 
 it in May eating away the edges of the 
 leaves of young corn in the field, and in 
 July and August making small round 
 holes in corn leaves in our breeding 
 cages. In September and October it has 
 occasionally been taken from the tip of 
 
 FIG. 54. Beetle of Southern 
 Corn Root Worm; enlarged 
 five and two-thirds diameters. 
 
 * Webster, in Bull. 45 (1892), Ohio Agr. Exper. Station, p. 203. 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 285 
 
 the ear of corn, feeding on the silk, and once in August we saw 
 it gathering up fallen corn pollen. It has also fed upon ragweed 
 leaves in our breeding cages in August. By other observers it 
 has been reported to feed on the petals of various flowers, includ- 
 ing roses, dahlias, cosmos, and the cotton plant; upon young 
 volunteer oats (December), on certain moulds, on the horse nettle 
 (Solanum canadense), on cabbage, cauliflower, and beans; and on 
 the leaves of plums, cherries, apricots, and raspberries. Webster 
 has also seen it eating unripe kernels of wheat and corn. 
 
 LIFE HISTORY. 
 
 As is very commonly the case with American injurious insects, 
 the life history of this beetle is incomplete. Our studies of it are 
 deficient not only in continuity of experimental work, but even in 
 a number and distribution of observations and collections, sufficient 
 to give us a fair ground of probable inference. We are especially 
 uncertain as to the 7 number of broods and the stage or stages of 
 hibernation. In the latitudes of Central and Southern Illinois it 
 seems most likely that this is a two-brooded insect, but, if so, data 
 published from Alabama and Mississippi would make it extremely 
 probable that it is three-brooded there. Webster's observations 
 in Indiana would lead us to suppose that it hibernates as an adult, 
 he having found it feeding upon volunteer oats as late as Decem- 
 ber I4th, and abroad in spring as early as April l/th, at which time 
 the sexes appeared in copula. 
 
 Our own voluminous collection records of the adult do not 
 clearly bear out the suppositions made above concerning the 
 hibernation and the number of annual generations of this species. 
 Without ever having made any special search for it, I find that we 
 have actually obtained it in eighty-two collections, mostly of a 
 miscellaneous character, ranging from April 20th to November 
 1 5th. We have thus taken the imago once in April, six times in 
 May, eight times in June, sixteen times in July, twenty-eight in 
 August, eighteen in September, four in October, and once in 
 November a gradual rise in frequency from April to August, and 
 a similar gradual decline thence to the end of the season. In our 
 special collections of hibernating insects this species has not, 
 appeared; and in our large electric-light collections, made from 
 May to September in 1886 and 1887, it occurred infrequently, and 
 in no case until July. 
 
 As we now understand the subject we may say that in the 
 latitude of the southern half of the State the eggs are laid in May 
 and June, that the root worms do the greater part of their mischief 
 also in these months, pupating from the middle of June to the last 
 
286 
 
 BULLETIN NO. 44. 
 
 \May y 
 
 of July, and yielding the beetle in July and August. The new 
 generation commence to pair by the beginning of the month last 
 mentioned, and young larvae of the generation following may be 
 found early in September. 
 
 I need only add that the eggs are placed, either singly or in 
 groups of two to twelve or more, according to Riley's observations, 
 below the surface of the soil near the plants, in cracks or imme- 
 diately about the base of the plants. 
 
 FIG. 55. Pupa of Southern Corn Root 
 Worm, dorsal view; enlarged ten 
 diameters. 
 
 FIG. 56. Ventral view of same 
 
 NATURAL ENEMIES. 
 
 So far as now known, the most effective natural check on the 
 multiplication of this insect is a bacterial parasite {Bacillus rufans) 
 observed by me to infest the larva, killing about three-fourths of 
 a considerable collection of these corn root worms brought from 
 Jacksonville July 19, 1889. We do not yet know what part of 
 the larva is first attacked by this Bacillus, but by the time the 
 resulting disease has reached a fatal stage, it swarms in all the 
 fluids of the root worm, which have become practically a pure 
 culture of this bacterial species. Infested larvae lose their charac- 
 teristic yellowish tinge, becoming gray and somewhat swollen, and 
 after death they change color through pinkish to dull dark red, 
 the internal organs breaking up to a fluid pulp, held for a con- 
 siderable time in the tough cuticle of the dead larva. The fluids 
 of such specimens have a milky appearance in the pale worms and 
 a reddish tint in the others. This last color is due, not to the 
 color of the bacilli themselves, but to an excreted coloring matter 
 diffused through the fluids in which they grow. In artificial 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 287 
 
 cultures, consequently, a number of which I made in 1889, a 
 similar color is imparted to the culture medium, whether this be 
 solid or fluid. 
 
 I have discovered no insect enemy of this species, but Dr. 
 Riley reports the rearing of two dipterous parasites of it; one 
 from the larva and pupa, and one (a tachinid) from the beetle. 
 Professor H. Garman notes the occurrence of small numbers of 
 predaceous beetles and larvae in summer and fall with young root 
 worms in the earth. He also mentions some internal parasites of 
 the imago Gregarinae and nematoid worms. 
 
 Notwithstanding the abundance of the adult Diabrotica and 
 its general distribution upon a great variety of plants, it seems but 
 little noticed by birds. It has occurred but once in my own 
 studies of the food of birds (in July, eaten by a catbird), and was 
 not once recognized by Dr. Riley's assistants in their studies of 
 the contents of the stomachs of one hundred and two English 
 sparrows which had eaten insects. 
 
 REMEDIAL MEASURES. 
 
 Until the life history of this species is better known, measures 
 of prevention or of remedy can scarcely be intelligently discussed. 
 The fact that its injuries to corn occur without apparent reference 
 to the crop of the previous year makes it unlikely that the favorite 
 method of rotation will serve for the protection of corn against 
 this species. According to the scattered observations hitherto 
 reported sweet corn seems to be much more liable to injury than 
 the field varieties, from which fact we may surmise that the time 
 of planting has something to do with the intensity of the attack. 
 The vicinity of cucumbers, squashes, and other of the commoner 
 food plants of the beetle may, however, account for this seeming 
 preference. 
 
 c. Roots visibly penetrated and perforated scarcely at all; some- 
 times decayed at tips, but not eaten away. Principal injury 
 interior, in form of minute burrows which are commonly 
 longitudinal. 
 
 THE NORTHERN CORN ROOT WORM. 
 (Diabrotica longicornis, Say.) 
 
 (Fie. 57-6i.) 
 
 The northern or common corn root worm (Diabrotica longi- 
 cornis} is by far the most destructive corn root insect dependent 
 on that plant alone. Indeed, it now seems likely that if it were 
 not for the fact that it is highly susceptible to a measure of pre- 
 vention which farmers have very generally taken unconsciously, 
 
288 BULLETIN NO. 44. [May, 
 
 as a part of a sound agricultural routine, it would long ago have 
 seriously threatened the profitable continuance of corn culture in 
 the very part of the country best adapted to that great crop. 
 Even as it is, its injuries are undoubtedly to be reckoned by 
 millions of dollars annually*, although the essential facts concern- 
 ing its ravages and their ready and complete prevention were 
 officially and widely published nine years ago.t 
 
 FIG. 57. Northern Corn Root Worm; enlarged six diameters. 
 
 INJURIES TO CORN. 
 
 The presence of this insect first betrays itself in badly infested 
 fields when the plant is a foot or so high. If at this time patches 
 of corn are observed which seem to be standing still, so that 
 the plants adjacent leave them behind, giving the field an uneven 
 appearance, it is 'possible especially if the field has been in corn 
 two years or more preceding that this retardation of growth 
 is due to the presence of this corn root worm. In this case, if 
 the corn be pulled up, many of the larger roots will be seen to 
 be short and stubbed and rotten at the ends. On others a dead- 
 ened brown line will be found, running irregularly lengthwise, 
 while still other roots may be dead their whole length. Possibly 
 when the earth is shaken off a slender white grub will be discov- 
 ered, two-fifths of an inch long and about as thick as a pin ; but 
 more frequently the observer must carefully split or peel some of 
 the affected roots, when a slender sinuous brown burrow filled 
 with excrement will be exposed, running from one end of the root 
 to the other, usually with the root worm just mentioned some- 
 where in its course. This grub is white, except the head, the top 
 of the first segment of the body, and a little patch on the last seg- 
 ment, which are yellowish brown. The body is smooth and 
 cylindrical, the head is short, deep, and rounded, and the tip of 
 the body is also bluntly rounded off, somewhat like that of a com- 
 mon grub. These last characters will serve to distinguish it from 
 small wireworms which are often found in such situations, but 
 which are usually flattened from above, especially at the head, 
 while in them the end of the body is commonly more or less 
 toothed or notched or pointed. The grubs or larvae of several 
 
 * Webster estimates the damage to corn in twenty -four counties of Indiana in 1885 
 at $2,000.000, basing this judgment on a loss of $16,000 by one large farmer, and on his 
 personal knowledge of its distribution and abundance in that State. 
 
 fTwelfth Rep. State Ent. 111., pp. 29, 30. 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 289 
 
 small flies will often be found about the roots of corn, and careless 
 or unskilled observers have occasionally mistaken these for the 
 corn root worm, but this latter insect has six short legs on the 
 three segments just behind the head, while the grubs of flies are 
 footless. We have seen as many as fifteen or twenty to a hill, and 
 I do not doubt that in fields heavily attacked they are much more 
 numerous. As the root dies, however, it is forsaken and another 
 is attacked, until, not infrequently, almost every root will become 
 infested as fast as it puts forth. This damage may thus extend 
 to the practical destruction of the entire root growth, and the con- 
 sequent death of the plant ; or it may remain miserably dwarfed 
 six inches, perhaps, when other plants measure four or five feet. 
 If the stem is perforated above the roots, the injury is probably 
 due to the southern root worm or to some of the species of wire- 
 worms, which one can only be told by finding the insect itself. 
 
 FIG. 58. Com root broken across to show Northern 
 
 Corn Root Worm within. Fl - 59- Pupa of Northern 
 
 Lorn Root Worm; enlarged. 
 8^ diameters. 
 
 Attention may perhaps be first attracted when the corn is 
 putting forth the silk, by the extraordinary number of barren 
 stalks upon which no ear is forming, or stalks may be seen which 
 have scarcely life enough to tassel. It may also be observed that 
 the corn is unaccountably late, looking evidently greener and 
 younger than other fields which had no advantage at the start. Or 
 injury may be first suspected during a period of drouth, patches here 
 and there, or the entire field, suffering unduly from this cause.. 
 The most conspicuous evidence of this injury, however, at this 
 stage of growth, is the prostration of the corn after a soaking rain 
 with wind, and the evident inability of the plant to right itself. 
 If one of the worst affected stalks be pulled up, the observer will 
 notice that the roots are few in number, that many of them are 
 withered and brown, and that others are rotted away to stubs. In 
 these discolored roots the minute brown burrow of the insect may 
 usually be detected, and the corn root worm itself may often be 
 exposed. A minor attack frequently has the effect so to retard 
 
2QO BULLETIN NO. 44. [May, 
 
 the ripening of the corn that it is not ready for the earliest frosts, 
 and the ear consequently remains soft and unfit for use ; or the 
 loss of roots may have diminished the size of the stalk and ear, 
 leaving a small nubbin where a full ear might have been expected. 
 
 The injury continues from about the first or the middle of June 
 to the last of August. As some of the larvae mature and cease 
 their work in the latter half of June, and others not for two 
 months later, plants once infested may be freed of the attack, at 
 least in part, by the pupation of the root worms, and others, 
 spared at the beginning of the season, may become infested later. 
 It has sometimes been observed that large, rank stalks which did 
 not ear out had evidently been injured after the corn had begun 
 to tassel ; while others, which leaned over at the root and then 
 grew erect, had been infested earlier in the season, but had thrown 
 out new roots after the root worms had matured. 
 
 It is a matter of common observation that injuries by this 
 insect are most noticeable during dry years and upon the higher 
 parts of the field. We have no evidence, however, that the corn 
 root worms themselves are more numerous at such times or in 
 such situations, and the greater injury may be due simply to the 
 diminished ability of the plant to withstand attack. I have, in fact, 
 seen vigorous and flourishing hills of corn badly infested during 
 wet seasons with no visible effect upon their growth, even the 
 larger, burrowed roots remaining fresh and efficient, notwith- 
 standing the injury. 
 
 In case no retardation of growth or damage to the crop has 
 been observed, less conspicuous mischief may often be indicated 
 by the great abundance in the field, late in July and in August, of 
 a small grass-green beetle about a fifth of an inch in length, 
 resembling in shape and general aspect the common small striped 
 squash beetle, to which, indeed, it is closely allied. These beetles 
 are most likely to be seen clustered at the tip of the ear and feed- 
 ing upon the young silk, or lurking at the base of the leaf where it 
 joins the stalk, feeding there upon the fallen pollen of the plant. 
 They should also be looked for upon the blossoms of ragweed, 
 smartweed, and other plants in bloom among the corn. This is 
 the adult insect to which the corn root worm, so-called, has given 
 origin, and its presence in extraordinary numbers in any field of 
 corn is presumptive evidence that the plant has suffered earlier 
 considerable root injury of the character above described. 
 
 It is very rarely that these phenomena are to be observed on 
 ground not previously in corn, although sorghum and broom corn 
 have been found somewhat favorable to the development of this 
 insect. It is only where through neglect it has become enormously 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 2QI 
 
 abundant in a f ild that we may anticipate its escape from the corn 
 in very large numbers before it has laid its eggs, in which event, 
 corn not succeeding corn may possibly suffer the following year.* 
 The general damage to a field is in the worst cases sufficient to 
 destroy the crop so far that the disgusted farmer turns his pigs 
 into his corn to get what they can, and makes no attempt to 
 harvest his crop. A badly infested field was described to me by 
 Dr. Boardman in 1882, which is worthy of mention as illustrating 
 one of the common effects of root injury by this beetle. "I should 
 say," he writes, " that one-fourth of the corn in this field was 
 rotting or beginning to rot. I found, on cutting an ear open, that 
 I could slice the cob as easily as if it were a turnip. The infested 
 corn [in Stark county] is yielding from ten to fifteen bushels per 
 acre." 
 
 Although the corn root worm beetle is distributed throughout 
 the Mississippi Valley, and south even to Central America, it 
 clearly becomes comparatively rare southward, and has never 
 been taken by us in Southern Illinois in any numbers, nor found 
 injurious in the larval stage except in the northern two-thirds of 
 the State. 
 
 This root worm has not heretofore been certainly found 
 infesting any other plant than corn, and the amount of skilled 
 attention which has been given to this point by entomologists and 
 other accurate observers, makes it practically sure that it is so 
 closely limited to corn at the present time in Illinois that we may 
 base our economic methods upon the supposition that it infests no 
 other plant. 
 
 FOOD OF THE BEETLE. 
 
 The beetles, beginning to appear in June and continuing until 
 November, feed entirely during this whole period upon the softer 
 and more delicate parts of the vegetation present at the time. 
 They collect the pollen from the tassels of the corn, or gather that 
 which has sifted down among the leaves and collected at their 
 bases, where these join the stalk. They also gnaw away the fresh 
 silk from the tip of the ear (where they may often be found con- 
 gregated in numbers of a dozen to twenty, or more), probably 
 thus doing a considerable amount of mischief by destroying the 
 silk before it has served for the fertilization of the grain, and 
 causing thus a partial blasting of the ear. They often eat the 
 pollen of smartweed and ragweed among the corn, and outside the 
 
 * As an example of this tendency to spread from the infested field, I may note the 
 not uncommon occurrence at Rankin, 111., July i, iSSy, of this corn root worm in a field 
 of corn following oats, but only on that part of it which bordered an infested field in 
 corn the previous year. It is possible that other instances of this kind reported previous 
 to 1891 may have related to the southern corn root worm, Diabrotica i2-pimctata. 
 
BULLETIN NO. 44. 
 
 [May, 
 
 fields are very abundant upon thistle blossoms, and likewise upon 
 heads of red clover, the pollen and petals of which they feed upon. 
 By Professor French, of Carbondale, 111., they are said sometimes 
 to infest the bean plant ; Dr. Boardman, of Stark county, reported 
 them- as abundant on cucumber and squash vines ; and we have 
 repeatedly seen them late in the year (October nth to December 
 i6th) gnawing into ripe pumpkins in the field, eating through the 
 outer hard coat, and burying themselves in the pulp to a depth of 
 nearly half an inch. We have found them feeding on flowers of 
 Helianthus, goldenrod, and other Compositae, and on the pollen of 
 sorghum and of squash ; and Professor Webster has seen them on 
 the blossoms of the cotton plant. A farmer in DeKalb county 
 asserts that they eat the pulp of apples where the skin has been 
 broken from some other cause, enlarging such injuries so as seri- 
 ously to damage the fruit. This same fact was reported to me 
 some years ago from Grundy county, by Mr. O. B. Galusha, then 
 Secretary of the State Horticultural Society, thin-skinned apples 
 apparently suffering worst and, according to the judgment of my 
 informant, being thus injured without the assistance of other 
 insects. They have been repeatedly detected by us beneath the 
 husks of ears of corn, where the tips had been exposed or injured 
 by birds or grasshoppers, feeding here on the broken grains. In 
 one instance the beetle had apparently made its way through the 
 husk itself, and was feeding upon the soft grains beneath. By 
 Professor Burrill, of the University of Illinois, it was found in 1889 
 (September 30th) feeding upon a fungus belonging to the genus 
 
 Fig. 60. Beetle of Northern Corn Root 
 Worm ; enlarged ten diameters. 
 
 FIG. 61. Egg of this species; 
 enlarged eighty diameters. 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 293 
 
 Phallus ; and I demonstrated by dissections in 1882 the fact that it 
 sometimes feeds largely on the smaller fungi blights, rusts, etc.* 
 
 LIFE HISTORY. 
 
 This species is single-brooded, as far as known. Although a 
 few beetles may occasionally linger late in open winters, to 
 December i6th of the present year (1892) for example, and as a 
 rare exception may even pass the winter alive, the species hiber- 
 nates almost invariably as an egg in the earth. t As a rule, which 
 is, so far as known, practically without exception, these eggs are 
 deposited in fields of corn and hatch there the following spring 
 at just what date has not been precisely ascertained. The larvae 
 have first been detected in Central Illinois June loth. They were 
 found by me less than half grown near Polo, in Northern Illinois, 
 June 14, 1883. As the beetle was reported by an excellent ob- 
 server (Dr. E. R. Boardman) to have occurred one season in 
 southeastern Iowa as early as June 25th, some larvae must hatch 
 by the beginning of that month. Pupation can scarcely begin 
 later than June 2Oth if Dr. Boardman's date for the beetle is correct, 
 and the same observer reports the finding of the pupa itself in the 
 earth June 29th. On the other hand, larvae ready for pupation 
 have occurred in our collections as late as August 26th giving a 
 period of something over two months for the pupation of an 
 entire generation. 
 
 The extreme dates definitely fixed for the next transforma- 
 tion the emergence of the beetle are June 25th for the earliest 
 and not earlier than August 3ist for the last again a period of 
 something more than two months. We have seen the beetles 
 copulating at various dates from July I9th to September 25th, an 
 interval of two months and six days, observations which probably 
 fix approximately the beginning and the end of oviposition. The 
 eggs, however, were not all laid by October I, 1882, as I deter- 
 mined by dissecting females at the time. For the present we may 
 assign August 1st and October 5th as the average dates for the 
 first and last deposit of eggs. 
 
 The recognition of this eight or nine weeks' period for the 
 passage of the whole of a brood from one stage to another, enables 
 us to say with some assurance that the eggs laid during this long 
 interval in one year will hatch through a corresponding interval 
 
 "Twelfth Rep. State Ent. 111., p. 23. 
 
 fl have in my office collection two specimens (one male and one female) obtained 
 March 14, 1883, at Normal, 111., with a quantity of miscellaneous insects collected from 
 their hibernating quarters. On the other hand, beetles collected from pumpkins at 
 Urbana, November 2, 1892, and placed in breeding cages with pieces of pumpkin as 
 food, had died in large numbers by November 2oth ; a very few were still alive Decem- 
 ber 4th ; two remained December i7th ; but December 28th all were dead. 
 
294 BULLETIN NO. 44. \May, 
 
 the year following approximately from May igth to July 1 5th, 
 or a little later. While these dates are, some of them, inferred,, 
 there is no doubt of the extension of each stage of the develop- 
 ment over as long a period as that here given ; namely, two 
 months to nine weeks. We have no precise observations concern- 
 ing the length of life of any individual in any one stage ; neither 
 do we know the number of eggs laid by each female, except as 
 an inference from dissections. I have counted as many as fifty 
 well-formed eggs of nearly full size in the ovaries of a single 
 female beetle. 
 
 HABITS OF BEETLE AND LARVA. 
 
 The growing larvae remain concealed from view within the 
 roots, burrowing, not through the middle but nearer the surface, 
 in a slightly sinuous longitudinal direction, sometimes from the 
 stalk outwards, but more frequently mining inwards from the outer 
 end of the root. They have considerable power of locomotion 
 when removed from their burrows, and seem capable of going 
 from one root to another. Indeed, the fact that they must con- 
 centrate in hills of corn after hatching, demonstrates their power 
 of locomotion when still very young. It is altogether likely, con- 
 sequently, that if a hill of corn is killed by them before they have 
 reached maturity, they will be entirely able to search out another. 
 
 When full grown they leave the root preliminary to pupation, 
 shortening up and changing to the pupa stage in the dirt close by. 
 At this time they may often be found in considerable numbers by 
 pulling up infested corn and shaking out the dirt from the roots. 
 The beetles emerge from the pupa under ground, and, coming to 
 the surface, most commonly crawl up the stalk of corn adjacent. 
 When recently transformed they are of a pale yellowish color, with 
 scarcely a tinge of green. Their first food consists, as already 
 mentioned, of the softer tissues of the corn plant itself, especially 
 of the silk at the tip of the ear, or the pollen from the tassel, or 
 sometimes of the soft kernels, especially if these have been 
 exposed by any injury to the husks. They also spread to 
 various blossoming weeds in the field, and after a time begin to 
 desert the corn field, scattering elsewhere for food. It is com- 
 monly towards the last of August that they are first noticeably 
 frequent on thistle blossoms, heads of clover, and other outside 
 blooming plants. They do not, however, leave the corn fields 
 generally for some time thereafter, but may be found there in 
 greatly diminished numbers at least as late as the middle of 
 October. 
 
1896.] INSECT INJURIES TO SEED AND ROOT OF CORN. 295 
 
 How soon after pairing their eggs are laid we do not now 
 know; neither has the process of oviposition ever been directly 
 witnessed. The frequent occurrence of dead female beetles (in 
 October and November) in the earth in corn fields in the midst of 
 the eggs, and the distribution of the eggs themselves, is, however, 
 sufficient evidence that the beetle enters the earth to lay her eggs, 
 and that she may perish there after her ovaries are spent. .Al- 
 though the eggs of this beetle have never been found outside of 
 corn fields, notwithstanding extensive search in many other situa- 
 tions, it is certain that the eggs are not necessarily all laid before 
 the female leaves the field in which she emerged. I have, on the 
 contrary, frequently proven by dissection of beetles taken from 
 flowers by roadsides, in meadows, and the like, that females thus 
 dispersed may still contain eggs in large numbers. A considerable 
 part of the beetles, and apparently the greater part, do, however, 
 lay their eggs under ordinary circumstances before they leave the 
 field of corn; and it is also highly probable on general grounds 
 that those which go elsewhere in search of food return to corn 
 fields for oviposition. Since the larva is not known to infest any 
 other plant than corn, or, indeed, to be capable of living upon any 
 other, it is altogether likely that the female instinctively searches 
 out the corn plant when seeking a place of deposit for her eggs. 
 
 As this is a surmise or inference, however, and not a matter of 
 observation, it remains possible that if the corn root worm is neg- 
 lected it may in time accumulate in such numbers as no longer to 
 confine its chief injuries to fields previously in corn, but that the 
 beetles, forced to scatter early, in search of food, from the fields in 
 which they emerge will deposit their eggs freely everywhere in the 
 ground, instead of being confined as now chiefly to corn fields. It 
 is probably in fields of clover that this is most likely to occur, 
 since the beetles sometimes become abundant there, feeding upon 
 the pollen of the second growth. 
 
 The depth at which the eggs are laid varies from an inch to 
 five or six inches, the greater part of them being near the surface 
 of the ground. They are usually deposited in bunches of three or 
 four to eight or ten, within a space of half an inch across, not in 
 contact with each other, nor in any cell or cavity, but always 
 simply scattered in the earth. Most careful examinations made in 
 1882, and many times repeated, of the earth between the rows, and 
 of the roots of all the weeds growing in the field, have failed to 
 discover so much as a single egg outside a space a few inches 
 across, around each hill. A similar careful search of the roots of 
 thistles, ragweeds, and goldenrod outside the fields, upon the 
 flowers of which the beetles were feeding in great numbers, had a 
 
296 BULLETIN NO. 44. [May, 
 
 similar result; and we have found no evidence in the roots of 
 these plants, either in the corn fields or elsewhere, that they have 
 ever been infested by the larvae. In short, not the slightest direct 
 proof has thus far been found that the beetle breeds anywhere 
 except in fields of corn. It. is very probable that a few develop in 
 other situations; but the number seems to be so small as to defy 
 discovery, except by accident. 
 
 PREVENTION AND REMEDY. 
 
 A judicious rotation of crops is so simple and complete a pre- 
 ventive measure, that remedies for injury to corn by the northern 
 corn root worm are practically unnecessary. The eggs being laid 
 in corn ground in the fall and the larvae hatching the following 
 spring, feeding so far as known upon nothing else but corn, the 
 planting of such infested land to any other grain must inevitably 
 lead to the starvation of the young when they hatch in spring. 
 This is not an inference from the life history of the insect merely, 
 but even before the time and place of oviposition were known, it 
 had been commonly noticed that corn was rarely if ever liable to 
 injury by this insect if planted on ground which had borne any 
 other kind of crop the preceding year. I have, however, some 
 reason to suppose that sorghum and broom corn are not good 
 crops to follow with corn when this root worm is present. 
 
 The frequency of the rotation must depend upon oircum- 
 stances, and especially upon the general abundance of the insect 
 at the time. I know of no part of Illinois in which corn is not safe 
 for at least two years, and in many situations another year may 
 be added to this period. No field on which the crop has already 
 suffered to any noticeable extent should be planted to corn the 
 following year ; and it will likewise be prudent to avoid continuing 
 in corn any field in which the grass-green beetle of this species is 
 seen to be abundant in September and October. 
 
 The only other preventive measure worthy of mention is one 
 equally to be commended as a general agricultural practice ; 
 namely, the maintenance of the fertility of the soil by the use of 
 manures, etc. This will not, so far as known, diminish in any way 
 the amount of insect attack, but it will enable the plant to stand a 
 minor injury with relatively little loss. It is possible that experi- 
 ments with various kinds of fertilizers will show that some of them, 
 the potash salts for instance, may have an immediate deleterious 
 effect upon the-larvae in the earth, but we have at present only a 
 speculative basis for this supposition. 
 
 S. A. FORBES, PH. D., 
 
 Consulting Entomologist. 
 
r<Se ^,~.4 t & \C. 
 
 
 

 
 
UNIVERSITY OP ILLINOIS-URBANE