and life cycle—Foliage-feeding caterpillars
After mating, the female moth or butterfly lays her eggs singly or in a mass on
the host plant. These eggs hatch after several days, except in those species that spend the winter in the egg
stage. The emerging larvae move singly or in groups to feeding sites on the plant.
Most caterpillars eat voraciously and grow rapidly, shedding old skins three to
five times before entering an inactive pupal stage; some species pupate within silken cocoons. Most species
pupate in a characteristic
location, such as in litter beneath the tree, on leaves, or the trunk. The adult moth or butterfly emerges
from the pupal case after several days to several months, depending on the species and season. Some common
caterpillar pests, such as the fruittree leafroller and most tussock moths, have one generation a year. Other
species have several generations annually and can cause damage throughout the growing season.
Stages of development for typical moth or butterfly