“Melissa Blue Butterfly” by LYLE GLASS.

While photographing other insects that were on rabbitbrush blossoms, I noticed this white butterfly and at first thought it was just a cabbage white sulpher, but then I noticed the orange spots on the wings.

Photographed in Theodore Roosevelt National Park, South Unit, Medora, North Dakota on 7-11-2012 at 9:09 a.m.