I found four of these black swallowtail caterpillars yesterday munching away on the parsley in the herb planter that Mary included in this post. I'm reasonably sure that the caterpillars in the other photos (taken in previous summers) are black swallowtails also. Unlike monarch caterpillars which look the same throughout their growth, swallowtails change with each instar and there's a lot of variation among individual caterpillars. This one I photographed looked like a bit of bird poop yesterday when I first spotted it.
So in addition to providing fresh herbs for our table and the bunnies' twice daily salads, my little garden herb patch feeds the next generation of flutterbies!