The Bruce Spanworm (Operophtera bruceata) or (in North America) "Winter Moth" is a species of moth of the family Geometridae. It is found from coast to coast in southern Canada and the northern parts of the United States. The wingspan of the males is 25–30 mm. Females have underdeveloped wings and do not fly. Adults are on wing from October to December. The larvae primarily feed on the leaves of Sugar Maple, American Beech and Trembling Aspen. They have also been recorded on willow and various other deciduous trees.