The life-history exhibits a very typical and familiar metamorphosis.
From the egg, which is often very beautifully sculptured, a larva known
as a caterpillar hatches out, possessing not only the three pairs of
jointed legs characteristic of the class, but also a varying number of
unjointed pro-legs terminating in suckers. After feeding voraciously for
some time by means of its powerful biting first jaws, and undergoing a
number of moults, the caterpillar passes into the motionless pupa stage,
here called a chrysalis, which may or may not be invested in a
protective cocoon. The skin of the chrysalis ultimately splits, and the
perfect insect makes it way out.