(a) The larva (caterpillar) spends its time eating and growing, molting as it grows. (b) After several molts, the larva develops into a pupa. (c) Within the pupa, the larval tissues are broken down, and the adult is built by the division and differentiation of cells that were quiescent in the larva. (d) Eventually, the adult begins to emerge from the pupal cuticle. (e) Hemolymph is pumped into veins of the wings and then withdrawn, leaving the hardened veins as struts supporting the wings. The insect will fly off and reproduce, deriving much of its nourishment from the food reserves stored by the feeding larva.
Urry, Lisa A.. Campbell Biology (p. 709). Pearson Education. Kindle Edition.