The Black Swallowtail also called the American or parsnip
swallowtail, is found throughout much of North America and is
the state butterfly of Oklahoma.
After mating, small, yellow eggs are laid, typically on garden plants from the carrot family, including dill, fennel and parsley. First instar larvae grow to about 0.6 inch long, resemble bird droppings and are dark purple-brown with a white band, a light brown-orange ring at the base of each of the spikes in the dark region. Later instars grow to about 2 inches and are yellow-white and black banded with yellow spots around every second black band. They have short, black spikes around some of the black bands, although these tend to disappear as the larva nears pupation.
The Black Swallowtail Caterpillar has an orange "forked gland", called the osmeterium. When in danger the osmeterium everts and releases a foul smell to repel predators.
The chrysalis is either brown or green in color, depending upon what the caterpillar attaches itself to. This feature provides excellent camouflage to protect it.