ah i iy i i i ii ivi 1 am St i" Ui ved Tyivy i ui tr { ; 7 i i i mi } i { i { i ilk i 1 ea j i i Tit 7 v i : 1 ion Te 1 nh a i T t ‘eae ) a Pun 3 ite nN ‘i i r i 1 1 i ; il mn Li iti ‘A F i foi at i i é i wu ; ey” “ile r ; » 1 hy { i : 1 i x i ; f fy coe vl i i, Heraine ) nl ia ito i nit il 1 i oot iF ry 6 i ii i 7 iL i eee i i i i yn i i — at oT ! i ant i ao a Tot i fq = ianey at = aie SB 818 C576 ENT CIRCULAR No. 84. Issued April 6, 1907. United States Department of Agriculture, BUREAU OF ENTOMOLOGY, L. O. HOWARD, Entomologist and Chief of Bureau. THE GRASSHOPPER PROBLEM AND ALFALFA CULTURE. 3y EF. M. WEBSTER, In charge of Cereal and Forage-Plant Insect Investigations. SPECIES RESPONSIBLE FOR DEPREDATIONS. While specimens of the species of grasshoppers actually engaged in devastating alfalfa fields have not always accompanied complaints of their ravages, it is nevertheless possible, taking the data secured by Government and State officials in connection with informa- tion from correspondents, accompanied by specimens of the insects actually committing these depredations, to fix the responsibility— largely at least—upon two species. One of these is known as the differential grasshopper (J/elanoplus differentialis Thos., fig. 1) and the other as the two-striped grasshopper (J/elanoplus bivittatus Say., fio, 2). ? Other species of grasshoppers have probably at times been more or less involved, as it is rarely that material submitted with a complaint of damages does not include more than one species; on the other hand, species depredating on other crops on the same farm or ranch are often submitted under the supposition that they are like those seen at work in alfalfa. A notable case in point is that of the yellow- winged or pellucid grasshopper (Camnula pellucida Scudd.), which, while very destructive to grain and grass crops, is said to work but little injury to alfalfa. However, as all grasshoppers likely to be- come involved in this or similar depredations have much the same habits and all are probably susceptible to the same treatment, the question of species is not one to interest the farmer particularly, be- yond the matter of his ability to determine for himself which one is the worst pest and to apply his measures of suppression more espe- cially with reference thereto. 25264—No. 84—07 mM 2 THE MEASURES HEREIN DESCRIBED ARE APPLICABLE ALSO TO CLOVER CROPS. While this circular is primarily for the benefit of the alfalfa grower, the measures of suppression recommended may be applied in the clover fields of the eastern section of this country with equally good results. Indeed, the two species here discussed are at times destructively abundant in the red-clover fields of the Middle West, and the writer has there used the “ hopperdozer ” to advantage. EARLY DEPREDATIONS. With the rapid increase in the culture of alfalfa throughout the country west of the Mississippi River there has come the problem of protecting this crop from attacks of several species of grasshoppers or locusts. The reason for this state of affairs is not at all obscure, as in order to breed freely and in destructive numbers these grass- hoppers require two conditions: First, an undisturbed soil for the protection of their eggs after these have been deposited, and, second, an early food supply for the young in spring. No other crop comes so near supplying these conditions to an ideal degree as does alfalfa. Thus it is that the farmer in this section of the country has from the beginning of alfalfa culture been sorely beset by these pests, whose destructive hordes might even now be said to follow closely in the footprints of the reclamation engineer. SERIOUSNESS OF INJURIES. Hardly a season passes during which more or less serious outbreaks are not reported in different localities, and the aid of this Bureau is frequently invoked in destroying these grasshoppers or otherwise lessening their ravages. Thus during the year 1905 1 such out- break was reported from California, 7 from Colorado, 1 from Idaho, 10 from Kansas, 3 from New Mexico, 2 from Utah, and 1 from Texas. It is in no wise likely that these numbers indicate more than a minor portion of the destructive outbreaks of these pests that actually occurred over this territory, and the seriousness of some of these outbreaks is indicated by the fact that as many as 12 complaints were received from a single locality. In fact, the probabilities are that, as this agricultural industry increases, the amount of injury in- flicted by these insects will greatly increase in future unless measures are taken to control them. DESCRIPTIONS OF THE TWO PRINCIPAL ALFALFA-AFFECTING SPECIES. The differential grasshopper (fig. 1) 1s about 14 inches long, its wings expand about 2$ inches, and it is of a general bright yellowish- green color. There is, however, a nearly black melanic form that does [Cir. 84] 3 not seem to differ otherwise from the normal. The head and thorax are olive-brown, and the front wings are of very much the same color, without other markings but with a brownish shade at the base; the hind wings are tinged with green; the hind thighs are bright yellow, especially below, with four black marks; the hind shanks are yellow, with black spines and a ring of the same color near the base. The two-striped grasshopper (fig. 2) varies in color from a dull green to a dull brown, with a distinct yellow stripe extend- ing on each side from the upper _ part of the eye to the end of the wing. The male is about 14 inches long and the female . ~ about one-fourth of an inch Fic. 2.—T wo-striped grasshopper (Melanoplus bivitta- longer. This grasshopper may tus) Natural size (after Riley). : : be so easily recognized from the accompanying figure that further description is unnecessary. The young are very much like those of the Rocky Mountain grass- hopper or locust (Jelanoplus spretus Thos.), shown in figure 3. Fic. 1.—Differential grasshopper (Melanoplus differentialis). Natural size (after Riley). DISTRIBUTION OF THE TWO SPECIES, Although both these grasshoppers seem to be generally distributed over the country, the differential grasshopper rarely becomes destructively abundant east of the Missis- sipp1 River. It is very decidedly so, and with great frequency, however, to the west of the Mississippi, while, though extending from Maine to California, the two-striped seadahe Gh aoe ate grasshopper is sometimes disastrously abun- — larve; 6, full-grown larva; ¢, pu- dant, locallyiat least, as far east as Ohio. '* “e's Gute In the red-clover-growing sections of the country the two-striped species is probably very much the more destructive of the two, though even as far east as Indiana the differential grasshopper does considerable injury to fruit trees by gnawing the bark from the twigs. LIFE HISTORIES AND HABITS. The eggs are deposited in the ground in masses, inclosed in more or less kidney-shaped pods, in late summer and fall, after the manner [Cir. 84] 4 shown in figure 4, which illustrates the oviposition of the Rocky Mountain grasshopper or locust. The females seem to prefer a mod- erately compact, rather damp but not wet soil which is rarely dis- turbed by the plow or other cultivating implement. It will thus be seen that the alfalfa fields throughout the irrigated sections consti- tute an ideal breeding ground. Winter is passed in the egg state, the young hatching in spring and reaching maturity in summer, and there is but one annual generation. Neither of the two species is migratory. Their flight is rather clumsy, and they do not remain long on the wing before alighting. NATURAL ENEMIES. Upward of 100 species of birds are known to feed to a greater or less extent upon grasshoppers, but probably the most useful in this direction are quails, prai- rie chickens, the sparrow hawk and Swainson hawk, the loggerhead shrike, all cuckoos. the cowbird, all blackbirds and meadowlarks, the eatbird, and red-headed woodpecker. That do- mestic fowls are espe- cially fond of these in- oe Sa \————___ sects goes without saying. Se a : Fia. 4.—Roecky Mountain grasshopper or locust (Melanoplus Skunks are VAY fond of spretus): a, a, a, female in different positions, ovipositing; grasshoppers, and akeses= paseo iced fom pod, Wit te od SEM teerned by Cie) Hames earth partially removed, to illustrate an egg mass already Biological Survey as the in place and one being placed; f shows where such a mass most useful of mammals : has been coveredup. (After Riley.) they therefore deserve protection rather than destruction by the farmer. Toads and prob- ably some of the snakes add these insects to their bill of fare. Of the insect enemies, the grasshopper mite (7rombidium locus- tarum Riley) is often found infesting grasshoppers in great numbers. It collects under the base of the wings, sometimes causing them to stand out from the body. While these mites probably destroy many grasshoppers, it is possible that their value to the farmer has been overestimated. There are several species of parasitic flies that fre- quently destroy immense numbers of these grasshoppers. Of these Sarcophaga cimbicis Towns., S. huntert Hough, and 8S. georgina Wied. (fig. 5) sometimes sweep these locusts off in myriads. Under date of August 7, 1906, Mr. John Hunton, of Fort Laramie, Wyo., forwarded to the Department a quantity of dead differential grass- hoppers that he had found on different weeds and grasses over an atl a [Cir. 84] 5 area of about 6 acres, mostly in alfalfa. He stated that although the live grasshoppers were yet very thick, many appeared weak and in a dying condition. When received the material was simply a mass of decaying bodies of grasshoppers and among them were both maggots and pupe of Sarcophaga georgina. These flies deposit ninute, elongated, ivory-white eggs on the surface of the bodies of the grasshoppers. The young maggots hatching from these make their way directly into the body of their host, and as they grow and develop there they feed upon the living insect. When full grown the maggots go into the ground and within a brown case transform to flies. While all of these natural enemies do much to hold the pests in check, there are two or three vegetable parasites that also kill off myriads of them, the dead bodies of the grasshoppers destroyed thereby often being conspicuous objects as they cling to the weeds and grass where death overtook them (see fig. 6). One of these fun- gous parasites is the same as that attacking the chinch bug, and is known to science as Sporotrichum globuli- ferum.