GRASSHOPPERS AND LOCUST PLAGUES. Insects of comparatively large size of the orthopterous families Acridiide and Locustide, or short-horned and long-horned grasshoppers respectively. In Great Britain and her colonies the former are the °locusts° of popular speech and only the Locustidce are called °grasshoppers.° (For the allied family of crickets, see GRYLLIDdE). The Acridiidce have the antenna shorter than the body and blunt, the ovipositor short and its parts divergent at the tip and the sound-producing organs (see ORTHOPTERA) on the hind thighs and outer edge of the forewings. In the Locustide the antenna are long and tapering, the ovipositor long and sword-like and the sound-organs are at the inner base of the forewings. This latter family embraces the katydids, tree-crickets, green meadow-grasshoppers and certain West ern species erroneously called °crickets° and the group is more particularly treated under KATYDID. In both families the hinder legs are greatly enlarged, enabling the insects to make the long leaps so characteristic of them; their wings are also capable of carrying them in some cases many hundreds of miles.
The short-horned grasshoppers are those of greatest interest economically and those re sponsible for the °locust° plagues of Africa, Arabia and southern Asia, as also in our West. From time to time vast bodies of certain species sweep from one region to another in swarms many square miles in area and so dense as to darker. the sun, feeding on grasses and herbage and consuming not only crops and pasturage as if by fire, but stripping bushes and trees of foliage and even of the bark. In the ancient world such visitations, which frequently ex tended into central Europe, caused extensive local famines, sometimes resulting in the loss of hundreds of thousands of human beings and vast numbers of grazing animals. Such °plagues* lasted for two or three years, the hosts breed ing numerously at first, but gradually dying out and ceasing to reproduce outside the limits of their permanent breeding-grounds. The repro duction of grasshoppers consists in the deposit in autumn of eggs laid in bunches, covered with a secretion which hardens into a case or °pod,'" beneath the surface of the ground, into which the ovipositor is deeply thrust and where the eggs remain to be hatched the following spring; in warm countries, however, two generations may take place annually. The locusts referred to in Scripture belonged probably to the species now named Schiztocerca peregrina, of North Africa and Arabia. The swarms which from time to appear in South Africa are of Pachytylus nugratoroides; while P. migratorsus is the best-known one of southern Europe and Asia. Similar species inhabit the open interior
regions of both North and South America, a species of Acridium afflicting Argentina.
Of the many species in the United States those of the genus Melanoplus are of greatest interest because frequently destructive of crops. The most conspicuous is M. spretus, the Rocky Mountain locust, which has been a scourge of agriculture west of the Mississippi River ever since settlements began there. Among the more recent great plagues were those of 1856 and 1874, the latter enduring three years and causing widespread ruin throughout the whole region between the Mississippi River and the Rocky Mountains. The Federal government appointed a commission of entomologists to investigate the habits of the insect and its three 'Reports' (1877, 1879 and 1882) arc exhaustive essays on the subject. It was found that these and other destructive locusts bred throughout the whole plains region in the river bottoms and sunny depressions and that little could be hoped for in defense except the gradual effect of culti vation in destroying the eggs and young by late and early plowing. This effect has been gained with unexpected celerity; and troublesome grasshoppers now breed in considerable num bers only in northern Idaho and central British Columbia. Swarms occasionally migrate and do damage, but the extensive plagues of the past will probably not recur. Nevertheless, grass. hoppers are likely often to be locally harmful in the West and must be combated intelligently. The most valuable preventives are the burning over or deep plowing of breeding grounds, so as to turn the eggs out and kill them in the fall or before they can hatch in the spring. The grasshoppers themselves may be captured by means of or kerosene pans. A cheap destroyer consisting of one part of Paris green thoroughly mixed in 60 parts of fresh horse-dung, two pounds of salt to half a barrel of the mixture being added, after being dis solved in water. This mixture is scattered broadcast along the edges of crops where in festation is feared and the locusts, Wring and eating the poison, die a few days later. The ordinary bran-arsenic mixture for cut-worms may also be used and in some regions wheat fields are protected by a trap-crop of rye sown in a strip around the fields and poisoned by spraying with Paris green.
Bibliography.— Sharp, 'Insects' (Vol. VI, Cambridge Natural History 1900) ; Howard, 'The Insect Book) (1901) ; Hyatt and Arms, 'Insecta' (Boston 1890); Kellogg, 'American Insects) (New York 1908) ; Fabre, J. Henri, 'The Life of the Grasshopper' (1916), and publications of the United States Department of Agriculture, especially Bulletin 25, Division of Entomology.