Identification: Upperside is orange-brown with darker wing bases and black spots; a single white spot on leading edge of each wing. Underside is mottled gray and brown, with dark bases and borders; hindwing with small white V at outer end of cell.
Life History: Eggs are laid in clumps on the host plant, and caterpillars feed together. Adults hibernate, sometimes in groups.
Wing Span: 2 1/2 - 3 1/16 inches (6.4 - 7.8 cm).
Caterpillar Hosts: Aspen and cottonwood (Populus), willows (Salix), gray birch (Betula populifolia), and paper birch (B. papyrifera).
Adult Food: Sap, rotting fruit, nectar of willow flowers.
Habitat: Upland deciduous or coniferous forests.
Range: Southeast Alaska and Canada south in the mountains to Montana and Wyoming; east across southern Canada and the northern United States to New England; south to North Carolina and Missouri. Rare migrants to Newfoundland, Nebraska, and Florida. This species is also found in temperate Eurasia.