Scientists use the term life cycle to describe the different stages in the life of an animal. During their life cycles, most invertebrates produce new young animals like themselves. This process is called reproduction. Most invertebrates need a male and a female of the same species to reproduce.
Most insects lay eggs. The eggs of moths, butterflies, flies, beetles, ants, and wasps hatch into young called larvae. Caterpillars are the larvae of butterflies and moths. Insects, such as butterflies, pass through several stages from being an egg to becoming an adult.

This amazing change is called metamorphosis.

The larva changes into a sort of legless shell called a chrysalis, or pupa. The body of the adult insect forms inside the pupa and comes out fully grown later.