The Butterfly Life Cycle

The complete life cycle of the butterfly is known as metamorphosis. The cycle encompasses four stages - egg, caterpillar, chrysalis, and butterfly.

The Egg

The cycle begins when the female butterfly lays her eggs on the appropriate plant. Caterpillars are very finicky eaters. Particular plants are food for particular caterpillars, and nothing else will do. For example, the Monarch and Queen prefer milkweed, the Black Swallowtail dill or parsley, and the Gulf Fritillary passionvine. You would never find a Monarch caterpillar feeding on passionvine or a Gulf Fritillary feeding on milkweed. Eggs come in all shapes and sizes - spherical, conical, ribbed or smooth, and are laid either singly or in clusters.

Above Left: A Monarch depositing eggs on Milkweed

The Caterpillar

From the egg emerges the caterpillar, which has one purpose in life - to eat. The caterpillar grows rapidly and will shed its skin, or molt, several times, since the skin does not stretch to accommodate new growth. The caterpillar readies itself for the next stage either by spinning a silken pad from which it hangs head down, attached by its rear legs, or by spinning a silken girdle whereby the head is upright. The final molt of the caterpillar's skin reveals the chrysalis.

Above Right: Giant Swallowtail (Heraclides cresphontes) caterpillar

The Chrysalis

Outwardly, the chrysalis stage is inactive, but there is great activity within. In a process which is not fully understood, the old caterpillar body transforms into that of the adult butterfly. Usually just prior to the time when the butterfly will emerge, the chrysalis becomes transparent so that the butterfly can be seen within.

Left: Gulf Fritillary (Agraulis vanillae) chrysalis

The Butterfly

The chrysalis splits open and the butterfly, its wings crumpled and its body bloated, crawls out. It immediately begins pumping fluid from its body into its wings. (For complete sequence, see Emerging from the Chrysalis.) In about half an hour, the wings are fully extended and the body has assumed its final, slim shape. Before it can fly, the butterfly must "dry out" for a couple of hours. It will remain inactive, its wings hanging slightly apart. When ready the butterfly will take to the wing, searching for food and a mate, and the cycle starts over again.

Right: Queen (Danaus gilippus)

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