DESCRIPTION: Large purple-brown butterfly (wingspan: 6-8 cm). The wing margins are marked with a row of blue spots bordered by a broad yellow band. The sexes are identical. LIFE CYCLE: The eggs are laid in masses, in trees such as willows (Salix spp.), poplars and aspens (Populus spp.), elms (Ulmus spp.), birches (Betula spp.) and alders (Alnus spp.). The caterpillars feed communally. The species overwinters in the adult phase. When the adults emerge early in spring, their wing margins are white. Two generations a year. ACTIVE PERIOD: The adults are active from early April to early October and the caterpillars, from July to August. ABUNDANCE: Very common. HABITAT AND DISTRIBUTION: Urban parks, deciduous forest edges and near rivers, streams, lakes and logging roads in mixed forests. Occurs throughout North America.