Northern Prairie Wildlife Research Center
Pale green flecked with purple spots; yellow dorsal stripe often edged with red; oblique yellow lines run through abdominal spiracles. Body somewhat triangular in cross section. Head large with yellow lateral band, edged inwardly with broad, irregular, red-brown band. Dorsum of first thoracic segment with 2 small reddish warts. Last segment with "tails" (these proportionately longer in earlier instars). Food: many trees and shrubs but especially oaks. Caterpillar: June to October; 2 generations.