Northern Prairie Wildlife Research Center
Smoky green, smooth, cylindrical with prominent creamy spiracular stripe ending at anal proleg, this stripe sometimes edged below with yellow or red. Dorsum with thin middorsal (heart), addorsal, and subdorsal stripes variously expressed. Intersegmental areas pale. Spiracles tannish orange. Food: firs, hemlocks, larches, spruces, and pines. Caterpillar: June to September; 1 generation.