Bagworm is the common name given to the larvae of certain species of moths. Size varies depending on the species. They vary in color from black to beige. The cases or bags are composed of silk and portions of leaves and twigs from the plant on which they feed. Bagworms attack many deciduous and evergreen trees and shrubs.
Young larvae feed first on the leaf surfaces and later they eat all but the larger veins.
Trees may be almost complet- ely defoliated due to the bagworms feeding. The preferred hosts include arborvitae, juniper, willow, maple, locust, sycamore and elm. Most bagworms overwinter in the egg stage in the bags of the female moth. In late May and June, the eggs hatch and the young larvae begin to construct their cases and carry them about as they feed. They feed through most of the summer and, in August when they are full-grown, they attach the case to a twig or side of building or fence post, and pupate inside the case.