CHINCH BUG. lIficropus leucopterus. This bug, when favorable seasons allow it to increase largely, is one of the most destructive of noxious insects. The Wheat Midge, the Grain Plant Louse, the Hessian Fly, destructive as they are in particular seasons, are, all combined, not to be so dreaded as this pest of the cereal crops. In significant as this minute scourge may seem, being little more than an eighth of an inch long, yet when they appear in countless millions, covering fields black, and sucking the life of the plants with their myriad beaks, the hopes of the farmer may well cease. Fortunately, they are assailed by nu merous foes, and by fun gus enemies. They may also be successfully destroyed by persistent effort. The illustrations give this insect in all its stages of transformation, the hair lines at the bottom of the perfect insect and at the sides of other figures showing the natural size.
Explanation: a, b, eggs; c, newly hatched larva; d, its tarsus (part of the foot to which the leg is. . joined); e, larva of the first moult; f, larva after second moult; g, pupa; le, leg of perfect insect; j, being the same still more highly magnified; i, proboscis in beak. Dr. Riley gives the natural history of this pest, including some observation& on insects in general, which is so terse and com prehensive that we quote it nearly entire: In the four great and extensive Orders of Insects, namely, the Beetles (Coleoptera), the Clear-winged Flies (Hymenoptera), the Scaly-winged Flies (Lep idoptera), and the Two-winged Flies (Dipte ra), and in one of the four small orders in its restricted sense, namely, the Net-winged Flies, (Neuroptera) the insect usually lies still through out the pupa state, and is always so far from being able to eat or to evacuate, that both mouth and anus are closed up by membrane. In the three small orders, on the contrary, namely, that of the Straight-winged Flies in its most extensive sense (Orthoptera including the Half-winged Bugs (Heteroptera) and the Whole-winged Bugs (Hom,optera), the pupa is just as active and just as ravenous as either the larva or the perfectly developed and busy insect, and the little creature never quits eating as long as the warm weather lasts, except for a day or so while it is accomplishing each of its successive three, four or five moults. As the Chinch Bug belongs to the Half-winged Bugs, it therefore continues to take food, with a few short intermissions, from the day when it batches out. from the egg to the day of its unlamented death. Most insects—irrespective of the Order to which they belong—require twelve months to go through. the complete circle of their changes, from the day that the egg is laid to the day when the per fect insect perishes of old age and decrepitude. A few require three years, as for example the Round-headed Apple-tree Borer (Saperda bicit tata, Say) and the White Grub which produce& the (Lachnosterna guercina, Knoch). One species, the Thirteen-year Locust (Cicada tredecim, Riley) actually requires thirteen years to pass from the egg to the winged state; and another, the Seventeen-year Locust (Cicada sep temdecim, Linn.) the still longer period of seven teen years. On the other hand there are not a few who pass through all their three states in a few months, or even in a few weeks; so that in one and the same year there may be two, three or even four or five broods, one generated by the other and one succeeding another. For example, the Hessian Fly (Cecidomyia destructor, Say) the common Slug-worm of the Pear (Selandria cerasi, Peck) the Slug-worm of the Rose (Selandria row, Harris) the Apple-worm and a few others, produce exactly two generations in one year, and hence may be termed two-brooded. Again, the Colorado Potato-beetle in Central Missouri is three-brooded, and not improbably in more southerly regions is four-brooded. _Lastly, the common House-tly, the Cheese-fly, the various species of Blow-flies and Meat-flies, and the mul tifarious species of Plant-lice (Aphis) produce an indefinite number of successive broods in a single year, sometimes amounting in the case of the last-named genus, as has been proved by actual experiment, to as many as nine. The Chinch Bug is two-brooded in North Illinois, and I find that it is likewise two-brooded in Missouri, and most probably in all the Middle states. Yet it is quite agreeable to analogy that in the more Southern states, it may be three-brooded. For instance, the large Polyphemus Moth is single brooded in the Northern and Middle states, and yet, two broods are sometimes produced in this state, while in the South it is habitually two brooded. Again, the moth known as the Poplar Spinner (Clostera Americana, Harris) is stated by Dr. Harris and Dr. Fitch to be only single brooded in Massachusetts and New York, the insect spinning up in September or October, passing the winter in the pupa state, and coming out in the vvinged form in the following June. But Dr. Harris—no doubt on the authority of Abbott—states that in Georgia this insect breeds twice a year; and I have proven that it does so breed in Missouri, having bred a number of cocoons which were formed by a second brood of larv. It is quite reasonable, there fore, to infer that the Chinch Bug may produce even more than two broods in the rnore Southern states. It is-these two peculiarities in the habits -of the Chinch Bug, namely, first, its continuing to take food from the day of its birth to the day of its death and, secondly, its being either two brooded or many brooded, that renders it so .destructive and so difficult to combat. Such as survive the autumn, when the plants, on the sap of which they feed, are mostly dried up so as to afford them little or no nourishment, pass the winter in the usual torpid state, and always in the perfect or winged form, under dead leaves, under sticks of wood, under flat stones, in moss, in bunches of old dead grass or weeds or straw, and often in corn-stalks and corn-shucks. In the fall and winter of 1868, I repeatedly received -corn-stalks that were crowded with them, and it was difficult to find a stalk in any field that did not reveal some of them, upon stripping off the leaves. I have even found them wintering in the gall made by the Solidago Gall-moth (Ode chiagalke solidaginis,) described in the first report. In the winter all kinds of insect-devouring ani mals, such as birds, shrew-mice, etc., are hard put to it for food, and have to search every hole and corner for their appropriate prey. But. no matter how closely they may thin out the Chinch Bugs, or how generally these insects may have been starved out by the autumnal droughts, there will always be a few left for seed next year. Suppose that there are only 2,000 Chinch Bugs remaining in the spring in a certain field, a.nd that each female of the 2,000, as vegetation _starts, raises a family of only 200, which is a low calculation. Then—allowing the sexes to be equal in number, whereas in reality the females are always far more numerous than the males— the first or spring brood will consist of 200,000, of which number 100,000 will be females. Here, if the species were single-brooded, the process would stop for the current year and 200,000 Chinch Bugs, in one field, would be thought nothing of by the Western farmer. But the species is not single-brooded and the process does not stop here. Each successive brood increases in numbers in geometrical progression, unless there be something to check their increase, until the second brood amounts to twenty mil lions, and the third brood to two thousand mil lions. We may form some idea of the meaning of two thousand millions of Chinch Bugs, when it is stated that that number of them, placed in a straight line, head and tail together, would just about reach from the surface of the earth to its central point—a distance of 4,000 miles. Dr.
Shimer, of Mt. Carroll, Ill., a careful observer, held that the insect only takes wing during the impulse of the sexual season. Dr. Riley, in relation to this matter, says : It is a notori ous fact that Chinch Bugs do not all mature at once, and if they took wing only when making their courtships, some of them would be flying during a period of several weeks and, as will be shown presently, there exists a dimorphous short winged form of the Chinch Bug, which cannot possibly make any such aerial love trips. It seems more agreeable to analogy that they take wing only when they have become so unduly numerous that they are instinctively aware that they must either einigrate or starve. Be this however as it may, the fact of their being as a general rule, unwilling to use their wings, is well known to every practical farmer. It has long been known that the Chinch Bug deposits its eggs underground and upon the roots of the plants which it infests, and that the young larv remain underground for some considerable time after they hatch out, sucking the sap from the roots. If, in the spring of the year, you pull up a wheat plant in a field badly infested with this insect, you will find hundreds of the eggs attached to the roots; and at a somewhat later peiiod, the young larv naay be found cluster ing upon the roots, and looking like so many moving little red atoms. The egg is so small as to be scarcely- visible to the naked eye, of an oval shape, about four times as long as wide, of a pale amber-white color when first laid, but sub sequently assuming a reddish color, from the young larva showing through the transparent shell. As the mother Chinch Bug has to work her way underground in the spring of the year, in order to get at the roots upon which she pro poses to lay her eggs, it hecomes evident at once, that the looser the soil is at this time of the year, the greater the facilities which are offered for the operation. Hence the great advantage of plowing land for spring grain in the preceding autumn, or, if plowed in the spring, rolling it repeatedly with a heavy roller after seeding. And hence the remark frequently made by far mers, that wheat harrowed in upon old corn ground, witliout any plowing at all, is far less infested with Chinch Rug than wheat put in upon land that has been plowed. There is another fact which has been repeatedly noticed by prac tical men.' This insect can not live and thrive and multiply in land that is sopping with water; and it generally commences its operations in early spring upon those particular parts of every field where the soil is the loosest and the driest. The female occupies about three weeks in depos iting her eggs and, according to Dr. Shimer's estimate, she deposits about 500. The egg requires about two weeks to hatch, and the bug becomes full-grown and acquires its wings in from forty to fifty clays after hatching. There are, as is well-known to entomologists, many genera of the half-winged bugs which, in Europe, occur in two distinct dimorphous forms, with no intermediate grades between the two; namely, a short-winged, or sometimes even a completely wingless type and a long-winged type Fre quently the two occur promiscuously together, and are found promiscuously copulating so that they can not possibly be distinct species. Some times the long-winged type occurs in particular seasons, and especially in very hot seasons. More rarely the short-winged type occurs in a different locality from the long-winged type, and usually in that case in a more northerly locality. We have a good illustration of this latter peculi arity in the case of the Chinch Bug, for a dimor phous short-winged form occurs in Canada, and Dr. Fitch describes it, from specimens received, as being a variety, under the name of apterus. Besides the cannibal foes of the Chinch Bug, and disease, heavy rains are destructive, sometimes killing them over large extents of country. In fact it is only in hot, dry seasons that they fairly swarm. So, also, they cannot hybernate in cold, damp ground, their natural home being in the dryest soils. The methods and agencies for the destruction of the Chinch Bug will be pretty much included in the following: Their natural enemies. The plan of anticipating their ravages by sowing grain so early, in the spring, as to get in advance of their depredations. The attempt to save a part of our crops by preventing the migration of the bugs from one field to another. The method of destroying them by burning corn stalks and other rubbish, in the fall of the year. The attempt to prevent their breeding, to any serious extent, by abstaining from the cultivation of those grains upon which they chiefly subsist. Among the important natural enemies of the chinch-bug, are the Spotted Lady-bird, (Hippo dm-Ida maculata); the Trim (Coccinella munda); a Lace Wing Fly (Chrysopa plorabunda) and the Insidious Flower Bug (Anthocoris instdi osus). This last resembles the Chinch Bug, and and has often been mistaken for it. Quail also eat the Chinch Bug, The second plan is the early sowing of grain. A modification of this plan has been practiced as follows: With twelve bushels of spring wheat raiX one bushel of winter rye, and sow in the usual manner. The rye not heading out, but spreading out close to the ground, the bugs will content themselves with eating it, until the wheat is too far advanced to be injured by them. There will, of course, be no danger of the winter rye mixing with the spring wheat. Take common fence-boards, six inches or less wide, and run them around the piece, set edgewise, and so that the bugs cannot get under them or between the joints, and then spread either pine or coal tar on the upper edge, and they will not cross it. The tar needs renew ing till the edge gets saturated, so that it will keep wet and not dry in any more, and either kind of tar is effectual. Then dig holes close to the boards, about like a post-hole, once in four or five rods, and run a strip of tar from the top. of the board to the bottom on the outside oppo site the hole, and they will leave the board, and in trying to get around the tarred stripe will slide' iuto the hole, where they will be obliged to remain till they can be buried at leisure, and new holes opened for more insects to drop into. In relation to the management of crops, etc., in the case of Chinch Bugs, Dr. Cyrus Thomas draws the following conclusions: That it is useless to• attempt to raise spring wheat or barley where Chinch Bugs have been present in any consider ahle numbers the preceding year, unless we have reason to believe that they have been killed off by heavy rains. That in case the season should be favorable to the propagation of the Chinch Bug we always have it in our power to get rid of these pests by the abandonment of these two kinds of grain for one or two years. But to make this course effective there must be a concert of action by farmers over a considerable section of the country. That the presence of Chinch Bugs the preceding year will not prevent the raising of corn or any of the winter grains. -With regard to oats the testimony thus far is that if this grain be sown where Chinch Bugs abound, and especially if it be sown exclusively, it will be damaged to a greater or less extent the first year, but that the bugs probably will not continue to breed in it to any great extent in succeeding years.