Northern Prairie Wildlife Research Center
Color variable, somewhat quadrate in cross section with greenish thoracic dorsum giving way to reddish and brownish colors over abdomen; sides green. Setal warts enlarged on dorsum of second and third thoracic segments. Head yellowish, distinctively marked with 2 brown transverse rings. Warty birch caterpillar (D. bilineata) with more pronounced warting; head mottled with browns but lacking defined rings; birches, alders, and aspens. Food: birches and alders. Caterpillar: June to October; 2 generations.