There are four stages in a butterfly’s life cycle: egg, larva, pupa, and adult. This sequence is an example of complete metamorphosis, in which the young insect looks and lives very differently from the mature form.
The cycle begins when an adult female lays eggs, usually on or near the particular host plant that the caterpillar will eat. The larva, or caterpillar, hatches and spends most of this stage feeding and growing. Because its soft body expands quickly, it sheds its skin several times; these intervals are called instars.
Next comes the pupa stage. In butterflies, the pupa is commonly called a chrysalis, although a chrysalis is not the same thing as a moth’s cocoon. Inside the chrysalis, the caterpillar’s body is reorganized as adult structures—including wings, antennae, and reproductive organs—develop.
The adult butterfly emerges with folded, soft wings. After its wings expand and harden, it feeds, mates, and eventually lays eggs, beginning the cycle again. Different species spend very different lengths of time in each stage.