The grasshopper is a member of either of two distinct families of orthopterous insects, the Tettigoniidae, including the long-horned grasshoppers, and the Locustidae, comprising the short-horned grasshoppers or locusts. These familiar green or brown colored insects have two pairs of wings, chewing mouth parts, and a distinctly segmented abdomen. The Locustidae have short antennae and a short ovipositor in the female, while the Tettigoniidae have long antennae and a long sword-shaped ovipositor.
In both families the hind legs are long and strong, giving the insects their jumping power; both are vegetarian in diet, feeding chiefly on grasses and weeds. The characteristic chirping sound of the grasshopper is made only by the male. It is produced either by rubbing the hind wings against the fore wings or by scraping the femur of the leg, which is equipped with bead-like protuberances, against the fore wing. Grasshoppers also produce supersonic sounds, inaudible to the human ear. When measured with a special meter, these sounds were found to reach frequencies of about 40,000 vibrations per second. Egg deposition varies with the species. The eggs may be laid either in masses or singly, in the ground, or on leaves, stems, and twigs. The young grasshopper, upon emerging from the egg, is wingless and resembles but is somewhat smaller than the adult. It undergoes a period of gradual metamorphosis, involving a number of molts, and finally reaches the adult stage.
Grasshoppers are found in the temperate and tropical parts of the world. In China they are kept as pets and placed in ornamental cages made of bamboo or gourds. In other parts of the world grasshoppers are serious agricultural pests. They attack such crops as small grains, cotton, corn, and alfalfa, sometimes devouring them entirely and at other times reducing crop yields. In the United States five species are of agricultural importance: the migratory grasshopper, Melanoplus mexicanus; the differential grasshopper, M. differentialis; the two-striped grasshopper, M. bivittatus; the red-legged grasshopper, M. femurrubrum; and the clear-winged grasshopper, Camnula pellucida. Migratory grasshoppers are strong fliers and often migrate in large swarms; differential grasshoppers are weak fliers, seldom migrating. The clear-winged grasshopper also migrates but generally marches in bands from one field to another.
The causes of grasshopper outbreaks are dependent upon environmental conditions. There is usually a gradual increase in numbers over a period of several years, followed by an especially favorable year with ideal weather conditions for the grasshopper, an abundant food supply, and a minimum of predators. It is during this year that the increase in population is marked. With the appearance of less favorable conditions, the outbreak gradually subsides. Control measures for grasshopper infestation should be started as soon as the increase in their numbers becomes evident. Although the grasshopper has many natural enemies, such as various kinds of flies, beetles, spiders, birds, and rodents, man-made controls are usually necessary. These involve the spreading of poison baits over areas occupied by the grasshoppers and the use of proper tilling and seeding methods to destroy the developing insects.