|The amazing process of metamorphosis-the butterfly's transition from egg to caterpillar to pupa to winged adult begins with the egg laid by the adult female on or near the particular plant plants that will serve as food for the caterpillars.
The caterpillar or larva is a little eating machine, and as it grows it passes through about five stages, or instars, each one larger than the last. Because the larva's skin can stretch only so far, it sheds its skin each time it passes to the next instar. The last time it sheds its skin, it reveals not a larger larva but the next phase in its life, the pupa.
The pupa, also called the chrysalis, is the stage in which the larva is transformed into the adult butterfly. Unlike moths, butterflies do not spin a protective cocoon; their pupa is smooth but often colored for camouflage. When the development inside is complete, the pupa splits open and the adult crawls out; after an hour or two for the wings to expand and dry, the butterfly is ready for flight.