By the way, I'm not familiar with insects such as this. This swallowtail, if my guess of P. eurymedon is correct, should not be on the east coast at all, it's a western species. If anyone knows more about this, please let me know.
I think that's an eastern tiger swallowtail, Papilio glaucus. The plant is some kind of monocot with a glaucous stem, obviously, but I haven't gotten further than that.