Northern Prairie Wildlife Research Center
Somewhat flattened, mottled greenish gray with indistinct markings, dorsum with pale chevron over fourth and sixth abdominal segments. Sides corrugated, often with dark subspiracular stripe. Head pale with strong mottling. Thin black addorsal lines on thorax. Venter greenish gray and unmarked. Anal plate with 4 small posterior teeth, each bearing a seta. Rests appressed to leaf or twig. Food: both deciduous and coniferous trees and shrubs. Caterpillar: May to November; 2 generations in North.