A recent study of that complex of the genus Diarsia which at present is found in collections under the name rosaria Grt. has convinced me that at least two species, easily separable on the basis of maculation and colouring, have gone under this name. One of these, the true rosaria, is confined to the more northerly portions of the California coast. The other species ranges from Alaska south through British Columbia into the Pacific Northwest of the United States, and from the coast of British Columbia east through the northern coniferous forest zone to the coast of Labrador. The latter species is divisible on the basis of well defined genitalic differences into a subspecies inhabiting the Cordilleran region and a subspecies confined to the northern coniferous forest.