Pre-ovipositional behavior and oviposition were investigated in a Japanese population of the gypsy moth, Lymantria dispar L. in the laboratory and field. During the days, mated females stayed motionless at the copulation sites. At dusk, the females began to walk and/ or fly actively in search of oviposition sites. Oviposition began at night and continued for several days at the same site. Females ceased oviposition every morning after covering the eggs with a thin layer of scales from their abdomens. In the field, females showed multiple mating before oviposition.