Page:Jardine Naturalist's library Entomology.djvu/221

Rh is technically called semi-complete—that is to say, the changes in external form, which they undergo in their transition from one state to another, are only half so considerahle as those which take place in some other instances—the Lepidoptera for example. In fact, it is difficult, in many instances, from inspecting an individual to say what stage of its progress it has reached. The final state, however, may usually be determined by the full development of the wings and tegmina; these members exist in the pupa only in a rudimentary condition. The pupa is never quiescent, but moves about and takes food. Not only do the larva and pupa resemble the perfect insect in external appearance, but it is likewise found on dissection that their internal organisation is similar. In the penultimate and antepenultimate states, the sexes are likewise distinct, and copulation sometimes takes place, but it is improbable that this premature union ever proves productive. The transformations in question, therefore, must be considered as merely a series of gradual approaches to perfection, none of the transitions being marked by any decided change of general form, the only consequences resulting from ecdysis, or casting of the external crust, being increase of size, slight development of certain parts, and an aptitude to continue the species.

This order is one of the least numerous in species. But its poverty in this respect is in some measure compensated for by the great amount of individuals of the same species, the swarms of locusts, grasshoppers, and cockroaches, which sometimes