They are rarely a serious problem on deciduous trees, except when larvae move away from evergreens. Damage In urban areas, bagworms are most common on evergreen trees and shrubs. Juniper, arborvitae, pine, and spruce may be killed if completely defoliated. Less severe attacks can slow growth. Bagworms feed on shade, orchard, and forest trees of nearly every kind, as well as many ornamental shrubs and perennials.
Severe attacks are unusual.
Since deciduous plants grow new leaves, damage to them is usually not serious. The growth of small or newly planted trees, however, could be slowed by leaf feeding. Description Newly hatched larvae begin to spin silken bags around themselves shortly after hatching. As larvae grow, leaf fragments are added to the bag, which may reach a length of 2 inches by the end of summer. The adult female moth is wingless and never leaves the bag.