The black swallowtail is the State Butterfly of Oklahoma. It’s a beautiful butterfly with a striking caterpillar. It is found throughout the state and is common in our flower and vegetable gardens from April till late fall.
Males are black with yellow spots along the margins of the wings. An orange “eyespot” with black pupil may be seen on the inner edge of the hindwing. The female is not as shiny black and yellow spots are not as bright. The margins of the hindwings are bluish. It has the same eyespots as the male.
Immature caterpillars are black with yellow spots. Mature caterpillars are green with black bands on each body segment. Yellow spots are present on each black band. When alarmed, the caterpillar will produce bright yellow antennae or “horns” on its head. The appendage is called an osmeterium. It is a defensive response that resembles the forked tongue of a snake and acts as a deterrent to a predator. All swallowtail caterpillars have osmeteria.
The chrysalis is brown and appears wooden. The butterflies can be attracted to the garden by planting the caterpillar’s food plants, dill, fennel or parsley.