DIVISION II.—SALTATORIA Legs of unequal size, the hind pair with enlarged femora and adapted for leaping. Tarsi with fewer than five joints, stridula tory organs usually present, ovipositor well developed and evident.
Three families belong here and included in the Acridiidae are the short-horned grasshoppers (see GRASSHOPPER) and the true lo custs (q.v.). The antennae are shorter than the body, the tarsi are 3-jointed and the ovipositor short. Stridulation takes place by the insect rubbing the inner side of its hind femur, which bears a row of minute pegs, against a hard ened area of the tegmen of the same side. Auditory organs are represented by a pair of drums at the base of the abdomen. The Tet tigoniidae (Locustidae) include the long-horned grasshoppers (see GRASSHOPPER) which have the antennae usually longer than the body, 4-jointed tarsi and a long broad ovipositor. Stridulation is effected by the insect rubbing its right tegmen against a filelike area of the left tegmen and auditory organs are present on the fore tibiae. The Gryllidae include the crickets (q.v.) and their allies. The antennae are generally long and threadlike, the tarsi are usually 3-jointed and the ovipositor is commonly long and slender (fig. 4). Stridulation takes place by rubbing the tegmina together and the auditory organs are on the fore tibiae, but unlike the Tettigoniidae the outer organ is larger than the inner one of the same side. The tegmina differ from those of other Saltatoria in that they are bent downwards along the sides of the body when in repose.
The eggs of Orthoptera are more or less cylindrical and in cock roaches (fig. 2) and mantids they are laid in protective capsules or oothecae, each containing 16 or more eggs. On hatching the young nymphs bear a close miniature resemblance to the adults except for the absence of wings. After a period of gradual growth, accom panied by a very variable number of moults, the adult condition is assumed. As previously men tioned, the saltatory forms are capable of stridulation, a fea ture that is almost confined to the males; auditory organs, on the other hand, are present in both sexes. Some of the most notorious stridulators are the katydids (see GRASSHOPPER) and the crickets, and in some cases the strident notes can be heard nearly a mile away.
Many Orthoptera are wingless (fig. 3), while among the stridu lating forms the wings are sometimes reduced to the sound producing portions of the teg mina only. The majority of the Orthoptera are herbivorous, and many of the grasshoppers and all the locusts are highly injurious insects—voracious devourers of all kinds of vegetation. Some of the cockroaches are omnivorous, the domestic species injuring or fouling a great variety of materials, while the mantids are pred ators devouring various insects and other creatures. Although Orthoptera are predominantly terrestrial in habit, a few species are aquatic, the curious cricket Hydropedeticus, for example, skates actively over streams in Fiji. Many of the Tettigoniidae frequent trees and bushes, while some of the Gryllidae, notably the mole crickets and their allies, are subterranean. The curious small wing less crickets of the genus Myrmecophila live in close association with ants.
Geographically the largest families are world-wide in range. The leaf insects, however, are restricted to the oriental region and the Grylloblattidae are confined to North America and Japan. The Mantidae and Phasmidae are corn mon in the warmer regions of the world, but are absent from more northern latitudes. Among indi vidual species the oriental cock roach (Blatta orientalis) and some of its allies have become practically cosmopolitan. In the fossil condition cockroaches are abundant, and form the greater part of the insect remains in cer tain of the Upper Carboniferous rocks of western Europe. They persisted until Permian times, after which their pre-eminence gradually declined until at the present day they form an insignificant part of the world's insects.