From above the pink-edged and clouded sulphurs can easily be mistaken for one and other, especially the males. Both have yellow wings with a black marginal band. On the underside, which is typically how you view sulphurs, both have wings that are lined with pink but the the pink-edged sulphur only has a single central spot on the underside of the hindwing while the clouded usually has two central spots. The third type, the orange sulphur also has a double central spot on the underside of the hindwing and both wings are orange-yellow in color. I photographed this sulphur at Necedah NWR in Wisconsin in June of 2009.