Northern Prairie Wildlife Research Center
Pale green with purple and yellow dorsum; somewhat flattened above, sloping to tail end. Undulating purple dorsal stripe widest at second or third abdominal segment. Dorsum with 3 anterior and 1 posterior pair of enlarged orange-red warts, each armed with numerous stinging spines. Food: many forest trees and shrubs, often on oaks and cherries. Caterpillar: August to October; 1 generation in North.