Northern Prairie Wildlife Research Center
Brown, tan, or peach, strongly humped; dorsum flattened, nearly quadrate in cross-section; posterior end produced as tail. Dorsum with 3 anterior and 2 posterior tufts of stinging spines, these largest on hump. Abdominal venter edged with pink and white. Food: birches, elms, oaks, and many other trees and shrubs. Caterpillar: August to October, 1 generation.