USDA Forest Service Forest Health Protection, Southern Region Forest Tent Caterpillar, Malacosoma disstria Hbn. Outbreaks occur periodically on oaks, tupelo gum, and other hardwoods over wide areas of the eastern half of North America. Growth loss and dieback occur, but trees are seldom killed unless they sustain 3 or more successive years of complete defoliation. Identifying the Insect . The larvae have pale bluish lines along the sides of a brownish body, and a row of keyholeshaped white spots down the middle of the back.
Adult moths are buff-brown, with darker oblique bands on the wings.
Egg masses of 100 to 350 eggs encircle the twigs and are covered with frothy, dark brown cement. Identifying the Injury . The first noticeable signs of attack are sparse crowns and falling frass. Caterpillars often cluster on the lower trunks of infested trees. Single trees or complete stands may be completely defoliated during the spring.