Caterpillar Development

When a butterfly egg hatches, a very hungry caterpillar (termed a first instar) eats its egg shell.

It will then start to feed on its larval host plant until its skin becomes so tight that it cannot grow any larger. At that point, it will be set to molt for a day or so. Caterpillars that are set to molt should not be removed from the leaf that they have attached themselves.This video demonstrates the differences between when an indra swallowtail caterpillar that is set to molt and when it is not.

After the caterpillar molts its skin, a new, larger head is formed and it becomes a second instar.

This process of feeding and molting is repeated from first through fifth instar. At fifth instar most caterpillars, instead of molting, will form a chrysalis.