Eastern Black Swallowtail

The Black Swallowtail has a wingspan of 3.1 to 4.3 in. The upper surface of the wings is mostly black. On the inner edge of the hindwing is a black spot centered in larger orange spot. A male of this species has a yellow band near edge of wings; a female has row of yellow spots. The hindwing of the female has an iridescent blue band. After mating, small, yellow eggs are laid, typically on garden plants from the carrot family, Apiaceae, including dill, fennel, Queen Anne's lace, and parsley. They are also found eating bishop's weed. First instar larvae grow to about 1.5 cm (0.59 in) long and resemble bird droppings. They are dark black with a white band in the middle and have spikes, with a light brown-orange ring at the base of each of the spikes in the dark region (spikes are white on the white band). Later instars grow to about 5 cm (2.0 in) 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, which looks like a snake's tongue, everts and releases a foul smell to repel predators.