The Eastern Black Swallowtail can be found in open spaces and is seldom seen in the woods. It likes parsley and carrot plants, as well as phlox and milkweed. This particular butterfly was flitting around at Phinizy Swamp one day back in 2005 when I was walking out there. There is a similar looking butterfly called the Ozark Swallowtail, (photos of which can be seen here at this neat site called "Zipcode Zoo") that inhabits the forest; its caterpillars feed on meadow parsnip. There is another similar species, called the Kahli Swallowtail that can be found in Manitoba and Saskatchewan that likes to fly around bare hilltops where the females lay their eggs on cow parsnip.
Check out this nice slideshow of the Eastern Black Swallowtail Caterpillar., and a nice set of pictures including one of an adult just out of its chrysallis.
Update: Apparently the Kahli Swallowtail is no longer considered to be its own distinct species. From the information that I'm finding on the internet, it seems that what was formerly called the Kahli Swallowtail is actually the dark offspring of an interbreeding that frequently occurs between the Black Swallowtail and the Old World Swallowtail. Cool!
