Eastern Tiger Swallowtail (Papilio glaucus): Intermediate

September 4, 2011. When we drove up to the White Crownbeard (Verbesina virginica) plants, several butterflies were feeding on the flowers. In addition to a yellow Eastern Tiger Swallowtail (Papilio glaucus) and a Monarch (Danaus plexippus), there was a dark swallowtail. I assumed it was a black female. When I got close enough to take the photo, it was clear that this butterfly was different. I could see…

the black rib pattern of the yellow form showing through the dark colored wings.

I’d never seen a butterfly like this before but a little research revealed that the female could exist in several forms including this rare ‘intermediate’ form. A lucky find.

See other photos of the intermediate form here and here.
Click on the image to view a larger image

Identification resources:
- Micheal Beohm, West Central Georgia Butterflies: Eastern Tiger Swallowtail (Papilio glaucus)
- Butterflies and Moths of North America: Eastern Tiger Swallowtail (Papilio glaucus)