Insects that have complete metamorphosis have four life stages. These insects start as eggs, which are very small. The egg hatches and a larva comes out. The larva looks like a worm and eats and eats so that it can grow much bigger. When the larva has grown it changes into a pupa. The pupa usually can not move or eat. The pupa is a special time when the insect is changing into an adult that will look very different from the larva or the pupa. Moth pupae (plural of pupa) are inside cocoons. When the pupa opens, the adult insect comes out.