The male evergreen bagworm moth has a wingspan of 1.7 to 3.6 cm. Its primary function is to mate with the female. An adult female bagworm has no wings; doesn't look like a moth and never leaves her bag. She resembles a yellowish maggot and is soft-bodied. A female, after mating, lays a large mass of eggs within the bag and soon dies. The eggs are sheltered inside the bag during cold months and hatch with the coming of spring. Enjoying the warmth of springtime, bagworm larvae (caterpillars) emerge from the bags and construct their own protective bags. The bag is fashioned in such a way that a caterpillar's head and legs are free, allowing the caterpillar to move about the plant as it feeds on the foliage. When full grown, the caterpillar attaches its individual bag to a twig (sealing the bag at both ends) and the life cycle starts over again in favorable weather conditions.
Our local junipers (red cedars) and arbor vitae plants often host a population of bagworms. Picking off the individually suspended bags by hand is usually the most effective means of control.
Copyright © 2003 William T. Hathaway.