When deposited, the egg mass forms a protective coating that acts as a shield during overwintering. Eggs hatch in early autumn and larvae remain under the coating until early spring. Larvae, 15-20 mm long and varied in color, first burrow into leaves but later cease this activity, form the webbed tent, and begin feeding extensively. Adults are 16-20 mm long, with white forewings and grey hind wings. Upper sides of the forewing usually have 15-20 small dots arranged in 3 or 4 rows.
Adults are active at dusk and at night.
Movement of the pest is usually by artificial means. Egg masses can be easily transported on dormant nursery stock. Natural spread should not be very rapid since the adults appear to be weak fliers. Overseas, the pest is controlled effectively by insecticides and parasites.