It's called a complete metamorphosis--from an egg to a larva to a pupa to an adult. 

Metamorphosis--Greek for "transformation" or "change in shape" is spectacular.

And it's particularly spectacular when the subject is the Anise Swallowtail (Papilio zelicaon).

Adult butterflies recently laid their eggs on anise (Pimpinella anisum), also known as fennel, in a friend's backyard in Fairfield. The eggs transformed into larvae (caterpillars) with coloring reminiscent of the adults.

We didn't see the first stage, the eggs, but did see the second stage, caterpillar and remnants of the third stage, an empty chrysalis.

One more butterfly flying around in Fairfield...