Eastern Tent Caterpillar, Malacosoma americanum
Tent Structure and Feeding Habits
Eastern tent caterpillar, Malacosoma americanum, typically builds tents in the crotches of trees. (In contrast, fall webworm caterpillars incorporate leaves and sometimes entire branches in silken tents spun, typically, at branch tips.). Host plants include wild and cultivated species of hardwoods such as cherry, flowering crabapple, peach, plum, quince, and hawthorn. Unlike fall webworm, tents of the eastern tent caterpillar do not enclose the tree’s foliage. Instead, eastern tent caterpillars emerge from the silken tent to feed on leaves about three times per day (early morning, evening, and at night), depending on the temperature and weather. Eastern tent caterpillars may remain within the tents if the heat of the day is too high, nighttime temperatures are too cold, or it’s raining.
Caterpillar populations are, in part, regulated by a variety of natural enemies such as predators (other insects, toads, birds), diseases (viral, fungal, protozoan, or bacterial organisms, occurring alone or in combination), and parasitoids (such as braconid, ichneumonid, and chalcid wasps).
Tents may be removed via physical removal or pruning if the tents are accessible while standing firmly on ground level. Never use fire to manage tent caterpillars. Tents may be torn or broken open to expose the caterpillars within to predators and parasitoids. Larvae ¼ inch or longer and larvae beneath the webbing within the tents are difficult to kill with pesticides (an insecticide in this case). However, young caterpillars may be treated with insecticides that contain Bacillus thuringiensis kurstaki (Btk), carbaryl, spinosad, and pyrethroids. Read and follow all pesticide label directions.