Female Eastern Swallowtail - Dark Phase

Papilio glaucus female - Dark Phase

This season is bringing quite a proliferation of butterflies to my garden. The latest visitor is this Female Eastern Swallowtail in her "dark phase". It is said that it is to deter predators. This must be true because I've also seen a yellow version with a chunk of hind wing gone. I'll try to get a picture of him next.