Margined White (Pieris marginalis)

Note the dark vein outlines on the underside of the wing. Formerly lumped with Green-veined White (P. napi) of Europe and Mustard White (Pieris oleracea) of northeastern North America, it is now recognized as a separate species inhabiting western North America. This is the spring form which has dark wing-tips. The population in most of Western California is the subspecies "P. m. venosa" often called "Veined White." The local checklist considers it occasional here in San Mateo County.