Page:Jardine Naturalist's library Entomology.djvu/94

88 or of taking food. But although this is the general condition of pupa, it is by no means universally so; many scarcely differ in appearance from their larvæ, and are equally capable of moving about, and equally voracious. This affords a convenient means of separating them into two great divisions, the one comprehending such as resemble their larvæ, the other those which bear no resemblance to their larvæ. To the first of these divisions belong all those pupæ which Linnæus called complete, viz. the Orthoptera, Hemiptera, (with some exceptions,) and certain tribes among the Neuroptera. The principal perceptible difference between these pupæ and the perfect insects consists in the wings not being fully developed; but these organs approach gradually to a state of greater maturity with the age of the pupa, although without breaking through the case that contains them. The general form of the body, and the organization of the mouth, are similar in both states, the other differences besides the one indicated, when such exist, being confined to the legs or certain other parts of structure which are of utility to the pupa when it differs in its economy, as sometimes happens, from the imago. Thus the pupa of Cicada has the forelegs greatly thickened and adapted for digging, because in that stage of its life it lives beneath the ground; after undergoing its final change, it frequents trees, and the fossorial legs, being no longer useful, disappear. The respective states of larvæ and pupa in the tribes in question being not indicated by any marked character, it is often