Alice Waterman, age 13, of Oriskany Falls, N.y., for her question:

How does a chrysalis differ from a cocoon?

The chrysalis and the cocoon belong to the world of insects, and both of them serve the same purpose. Many insects develop through a life cyc1e in four distinct stages. They begin as eggs that hatch into hungry caterpillars. The caterpillars become pupae and pupate through a sleeping beauty stage. Finally the pupae hatch, and the adult insects emerge into the world.

A s1eeping pupa needs shelter and protection from the world while the insect changes from a grubby caterpillar into a winged adult. This shelter may be a crusty shell called a chrysalis or a silken blanket called a cocoon. When time to pupate, the skin of the monarch butterfly becomes a tough green shell. It looks like a furled leaf of the milkweed plant on which it hangs. At pupation time, the caterpillar of the glamorous luna moth spins a long thread of silk and winds himself up in figures of eight. His silken blanket is a cocoon. Moths prefer to pupate in cocoons, while most of the butterflies favor crusty chrysalises.