These insects belong among the orthoptera--an order including species whose transformations are less complete than in other groups, and whose larval and pupal forms are very active, and closely resemble the imago. Two pairs of large wings characterize the adult state, the first pair of which are somewhat thickened to protect the broad, net-veined hinder pair, which fold up like a fan upon the abdomen. The hind legs are large and adapted for leaping. The raptorial group called _Mantidæ_, which forms the subject of this article, includes species that maybe easily recognized by their large size, their enormous, spinous fore legs, which are adapted for seizing other insects, and from their devotional attitude when watching their prey. These insects exhibit in general the phenomenon of mimicry, or adaptation for protection, through their color and form, some being green, like the plants upon which they live, others yellowish or grayish, and others brownish like dead leaves. In the best known species, _Mantis religiosa_, the head is triangular, the eyes large, the prothorax very long, and the body narrowed and lengthened; the anterior feet are armed with hooks and spines, and the shanks are capable of being doubled up on the under side of the thighs. When at rest it sits upon the four posterior legs, with the head and prothorax nearly erect, and the anterior feet folded backward. The female insect attains a length of 54 millimeters, and the male only 40. The color is of a handsome green, sometimes yellow, or of a yellowish red. The insects are slow in their motions, waiting on the branches of trees and shrubs for some other insect to pass within their reach, when they seize and hold it with the anterior feet, and tear it to pieces. They are very voracious, and sometimes prey upon each other. Their eggs are deposited in two long rows, protected by a parchment-like envelope, and attached to the stalk of a plant. The nymph is as voracious as the perfect insect, from which it differs principally in the less developed wings.