If you have forgotten the biology of the butterfly, here is a brief summary of its life cycle. The adult butterfly lays eggs that hatch into caterpillars (larvae). The hungry caterpillars eat and grow until they reach a certain size, and then change into pupae (chrysalises). From this stage they transform into adult butterflies, completing metamorphosis. If you need a review, grab Eric Carle’s classic, The Very Hungry Caterpillar, from your toddler’s library.