The black swallowtail butterﬂy has a wingspan of about three and one-eighth to four and one-half inches. The upper surface of the wings is basically black. The male has a yellow band near the edge of the wings, while the female has a row of yellow dots in the same position but lacks the band of color. The hindwing of the female shows a blue band of color. The hindwing has an orange spot with a black dot centered in it. The abdomen has rows of yellow spots. The black swallowtail caterpillar is green with black bands and rows of orange dots.
The black swallowtail butterﬂy may be found statewide in Illinois, living in open areas, such as ﬁelds and gardens. It feeds on plants of the parsley family, for example, wild carrot, parsley and dill. It is active from April through October. The life cycle includes egg, larva, pupa and adult stages. It overwinters in the pupal stage. The larva has a defensive gland which it may stick out from behind its head when disturbed. The adult female looks very much like the pipevine swallowtail butterﬂy, one that tastes bad to predators when they attempt to eat it. The predators learn from trying to eat the pipevine swallowtail to avoid anything that looks like it. The female black swallowtail gains some protection in this manner.