Papilio polyxenes - Black Swallowtail Caterpillar
When provoked, the larvae of this species sprout eversible orange horns called osmeterium, which release a foul odor in order to deter predators. The osmeterium is a defensive, glandular organ that is coated in stinky chemicals, and is located at the base of the caterpillar's head. The osmeterial odor changes between species and within the life stages of the caterpillars.
This particular caterpillar's osmeterium smelled like apples. You can actually see bits of the stinky fluid dripping off the osmeterium in this photo!
Habitat: On fennel (Foeniculum sp.) in a rural garden
The Black Swallowtail , also called the American Swallowtail or Parsnip 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''.