
Papilio polyxenes - Black Swallowtail Caterpillar
The larvae of this species changes color quite dramatically with each molt. This picture shows the last instar, which is green with black bands dotted with yellow spots on each segment. I think it was getting ready to pupate as it was really still and didn't show its osmeterium when I touched it.
Habitat: On fennel (Foeniculum sp.) in a rural garden.

The Black Swallowtail is a butterfly found throughout much of North America. It is the state butterfly of Oklahoma. An extremely similar-appearing species, "Papilio joanae", occurs in the Ozark Mountains region, but it appears to be closely related to "Papilio machaon", rather than "P. polyxenes".