 Larvae of the question mark butterfly, like all lepidopteran larvae, mature through a series of stages called instars.Near the end of each instar, the larva undergoes a process called apolysis, in which the cuticle, a tough outer layer made of a mixture of chitin and specialized proteins, is released from the softer epidermis beneath, and the epidermis begins to form a new cuticle beneath.At the end of each instar, the larva moults the old cuticle, and the new cuticle expands, before rapidly hardening and developing pigment.