In one stage of life or another, all insects shed their skin. In class Insecta, there are two subclasses: Apterygota and Pterygota, the wingless and winged insects.
The former is the smallest subclass, containing only bristletails and silverfish. Like some of their pterygotan counterparts, these go through a process called ametaboly, or incomplete metamorphosis. In this process, there are three stages of life for the insect: the egg, nymph, and adult. Nymphs often resemble miniatures of the adult, but are unable to produce offspring. After hatching from the egg, nymphs will then grow until their exoskeleton becomes too small and subsequently shed it, entering into its next instar.
They will continue to repeat this cycle until adulthood, when all molting ceases.Complete metamorphosis is similar to this, but molting occurs only in the larval and pupae stages. In the pupa state, the insect only molts once to escape its cocoon, a process known as eclosing. Complete metamorphosis only occurs in the more developed Endopterygotan subdivision.
Complete metamorphosis in a fly.
Footnotes