Northern Prairie Wildlife Research Center
First instar: brownish with dark setal tufts; first thoracic segment with prominent subdorsal warts bearing numerous long setae that makes face look "eared." Early instars "balloon" on threads of silk up to several hundred feet from egg mass.
Middle and late instars: dorsum of thoracic and first and second abdominal segments with paired blue knobs; dorsum of third to eighth abdominal segments with paired reddish knobs. Head tan with characteristic black mottling. Colors and mottling becoming more pronounced in successive instars. Later instars move down trunk and shelter along bole by day, then at dusk move back to feed in canopy. Hairs allergenic, especially if brought into contact with eyes or sensitive skin; hypersensitive individuals may react to single hairs and scales from adults. Food: early instars often on understory shrubs and trees, later moving into canopy. Recorded from more than 500 shrub and tree species. Asiatic races readily consume conifers unlike well-established European race. Caterpillar: May to July; 1 generation.