Eggs are found in the mother's bag inside her pupal cast skins. Biology Bagworms occur throughout North Carolina. Bagworms have a very wide host range but are usually associated with arborvitae or juniper. A single bagworm does relatively little harm as it feeds on leaves. Excessive defoliation may kill conifers within one or two seasons.
Damage is most noticeable in landscapes rather than woodlands.
Occasionally, the silk band with which the bagworms attach themselves to a twig before they pupate girdles the twig as the twig enlarges. They hatch in May and June. The newly hatched larvae spin down on silken threads and are blown about by the early spring breezes. Upon reaching a suitable host, the worm begins to spin its bag and as it grows, it incorporates some of the host plant foliage into the bag for camouflage. As the bagworms grows, it enlarges the bag and adds fresh plant material to the outside.