Page:Insects - Their Ways and Means of Living.djvu/43

 into the solid capsule of the cranium. Thus we see that the entire body of an insect is composed of a series of segments which have become grouped into the three body regions. Note that the insect does not have a “nose” or any breathing apertures on its head. It has, however, many nostrils, called spiracles (Fig. 70, Sp), distributed along each side of the thorax and the abdomen, its breathing system is quite different from ours, but will be described in another chapter treating of the internal organization (page 114).

Most young insects grow rapidly because they must compress their entire lives within the limits of a single season. Generally a few weeks suffice for them to reach maturity, or at least the mature growth of the form in which they leave the egg, for, as we shall see, many insects complicate their lives by having several different stages, in each of which they present quite a different form. The grasshopper, however, is an insect that grows by a direct course from its form at hatching to that of the adult, and at all stages it is recognizable as a grasshopper (Fig. 9). A young moth, on the other hand, hatching in the