Why does the butterfly have a cocoon stage in its life cycle?

Question

Why does the butterfly have a cocoon stage in its life cycle? It could have simply grown up within the egg/cocoon, and emerged as a butterfly. Instead it is first an egg, then a worm, then a chrysalis, and finally after some time a butterfly.

Answer 1

Butterflies like several other insect families have holometabolous development which means when they hatch they are an immature version of themselves and need to develop further in order to become sexually mature and reproduce. Other insects that are like this are beetles(Coleoptera) and flies (Diptera). On the other end of this there is hemimetabolous development which is when an insect hatches it is a tiny version of an adult and just needs to shed its exoskeleton multiple times before it becomes a mature adult an example of a hemimetabolous insect would be grasshoppers (Orthoptera) and cockroaches (Blattodea).