The Black Swallowtail (Papilio polyxenes), is a butterfly found throughout much of North America. It has a wingspan of 3.25 to 4.25 inches. The upper surface of the wings is mostly black. On the inner edge of hind wing is a black spot centered in larger orange spot. A male of this species has a yellow band near the edge of the wings. The female has a row of yellow spots. The hind wing of the female has an iridescent blue band. In the Southwest USA, yellow forms predominate in the subspecies.
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 inches long, resemble bird droppings and are dark purple-brown 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 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, which looks like a snake’s tongue, ejects and releases a foul smell to repel predators.
The Black Swallowtail chrysalis is either brown or green in color, depending upon what the caterpillar attaches itself to. This feature provides excellent camouflage to protect it. It is the state butterfly of Oklahoma.
Photo (c)2007 Derek Ramsey