Identification

Fully grown caterpillars are about 2 inches long, with a bluish head and body. There are white, keyhole-like spots running down the middle of the back, and thin orange lines along the sides.

Hosts

Black gum, sweetgum, oaks, aspen, and sugar maple are common hosts in Maryland.

Biology

Eggs hatch in early spring, about the time of bud break. Caterpillars congregate on the sides of trees, but do not construct tents. There is one generation per year.

Control

Removing caterpillars as they congregate on the sides of trees may help individual landscape trees; area-wide infestations may require large-scale insecticide treatments.