other insects have complete metamorphosis, which means that the small larva which comes out of the egg looks very different from the adult insect. insects that have complete metamorphosis usually come out of the egg as a larva, which usually looks like a worm. the larva eats food and gets bigger until it turns into a pupa. butterfly pupae (plural for pupa) are often inside cocoons. inside the cocoon the insect changes the way it looks and often grows wings. when the cocoon opens, the adult insect comes out. many insects have complete metamorphosis, for example beetles, butterflies and moths, and flies. the adult stage of development is called the imago.