Wings are white with black markings including a black crescent-shaped cell spot on each wing.
Females lay eggs in rings around twigs of host plants. Eggs overwinter and hatch from April-June. Young caterpillars feed together while older ones feed alone. Fully-grown caterpillars overwinter in loose cocoons in the leaf litter or in burrows in soft soil. Adults emerge from July-September, but at high elevations and northern latitudes, the cocoons overwinter and adults emerge in the spring.