Metamorphosis is a Greek word which means 'transformation' and is the word used by biologists to describe how an insect develops from an egg into an adult. This process involves extreme physical changes in appearance and occurs in certain living things such as insects and some reptiles and amphibians. In most insect species the following stages occur in their life cycle: egg, larva, pupa, adult.
Beetles, flies, bees, wasps, ants, and many other insects exhibit complete metamorphosis. More primitive insects, such as grasshoppers and cockroaches, have only three stages: egg, nymph (larva), and adult. This type of metamorphosis, which lacks the pupal stage, is called incomplete metamorphosis.