Northern Prairie Wildlife Research Center
Highly distinctive, head adorned with "crown of thorns," and body granulose. Spikelets on dorsal horns of head more than half length of longest spikelets along cheek. Dorsum and often sides with yellow or white stripes; middorsal stripe continuous, dark green or blue. Body often zigzagged at rest. Gregarious through third instar. In hackberry emperor (A. celtis), spikelets of dorsal horns shorter, only half length of longest along cheek, dorsal striping often inconspicuous to absent (eastern populations); and body often straight at rest. Food: hackberries. Caterpillar: July to October; 2 or more generations in South; 2 in North.