In Oklahoma the most common hosts are eastern red cedar, other junipers, and arborvitae. Other hosts sometimes damaged include pines, spruce, bald cypress, maple, boxelder, sycamore, willow, black locust, oaks, and roses. The bagworm has been recorded on 128 different plant species in various parts of the United States.
Bagworm larvae damage their hosts by feeding on the foliage. Heavy infestations can completely defoliate small plants. Defoliation usually kills hosts such as red cedar and other junipers. Broadleaf hosts are not killed but are weakened and become more susceptible to borers and diseases.
The overwintered eggs (in the year old female bags) begin to hatch in late April or early May and the young larvae begin to feed and construct bags immediately. The first evidence of an infestation is normally a small bag, about 1 /4 inch long, standing almost on end. As larvae grow, silk and fragments of the host plant foliage are added to the bag until it reaches 1 1/2 or 2 inches long. When larvae are mature they fasten the bag to a plant stem with silk. Pupation occurs in the bag in August and males emerge in late August and September. They engage in a mating flight in search of the wingless females still inside their bags. After mating the female lays several hundred white eggs inside her old pupal case, drops from the bag, and dies. There is one generation per year.
Adult males are small, clear winged moths with a black, hairy body and a wingspread of about 1 inch. Adult females are wingless, have no functional legs, eyes, or antennae, and are almost maggotlike in appearance. The females body is soft, yellowish white, and practically naked except for a circle of woolly hairs at the posterior end of the abdomen. Mature larvae have a dark brown abdomen and the head and thorax are white, spotted with black. They are about 1 inch long. Both larvae and adult females are found in silken bags on the host plants.
Please contact your local county extension office for current information.