Northern Prairie Wildlife Research Center
Large, thickened robust caterpillar mottled with browns and grays. Head flat, sloping inward, vertex cleft. Each spot on head made up of 10 to 20 speckles. Thorax swollen and humped, darkened above. Dorsal paired raised warts on second and eighth abdominal segments and ventral warts on third. Subventral fringe of thickened setae between abdominal and anal prolegs. Food: many forest trees. Caterpillar: June to October; 2 generations in South, 1 principal generation in North.