As advanced insects, butterflies (and moths) have a "complete" life cycle, which means there are four separate stages of development. Each stage looks completely different from the others, and serves a different purpose in the life of the insect.

Butterflies begin their life as an egg, a tiny round, oval, or cylindrical object, usually with fine ribs and other microscopic structures. Eggs are laid either singly or in clusters, depending on the species. Female butterflies attach their eggs to leaves, stems, or other objects, usually on or near the intended caterpillar food.

Upon hatching, a larve, or tiny caterpillar emerges. Caterpillars are often stripes or colored in patches, and may have spine-like hairs. Some caterpillar species consume their eggshells, then begin feeding on the host plant. The most rapid growth happens during this stage, and a caterpillar can shed its skin four time or more to enclose its rapidly growing body.

As the transformation stage begins, the caterpillar attaches itself upside-down to a twig or leaf, and then spins a silken thread with which it attaches to itself. It then sheds its skin for the last time and forms a hard outer shell, becoming a chrysalis. During this stage, the caterpillar tissues break down and the adult insect's structures are formed. The chrysalis of most species is brown or green and blends into the background. Many species overwinter in this stage.

As the butterfly is about to emerge the chrysalis becomes transparent, revealing colors beneath. When the chrysalis splits, a limp, damp butterfly emerges. Initially, its wings are very small and shriveled, but as the butterfly pumps blood into its veins they unfurl. An enzyme is then released and the wings stiffen. A little warming in the sun, and within an hour it is ready to fly off to feed and mate.

Adult butterflies will live approximately 3 to 4 weeks, however, the entire life cycle of a butterfly can range between 2 and 8 months, depending on the species.