2 5/8-3 1/2" (67-89 mm). Black to blue-black above with blue cloud on outer HW (more blue on female). Small cream-yellow spots and chevrons rim wings above and below (larger on male). Bright orange eyespot with round, black-centered pupil at corner of HW toward body. Sometimes band of yellow spots across outer third of wings inside row of blue patches, more commonly present or enlarged on male. No yellow stripes on thorax.
Western Black Swallowtail has yellow bars along thorax and irregular off-center pupil in eyespot. Short-tailed Swallowtail and Short-tailed Black Swallowtail have stubby tails; Short-tailed Swallowtail also has orange in bands of dorsal spots. Spicebush Swallowtail has 2 orange spots on HW above. Pipevine Swallowtail has no orange spots on HW above.
Egg yellow. Mature caterpillar, to 2" (51 mm), white to leaf-green with black bands on each segment broken by yellow or red-orange spots. Chrysalis woodlike brown or leaf-green; overwinters. Host plants
are Queen Anne's lace (Daucus carota) and other members of carrot family (Apiaceae), as well as some members of the citrus family (Rutaceae), including rue (Ruta graveolens) and Texas turpentine broom (Thamnosma texana).
2 or 3 broods; February-November, depending on latitude. Late spring, midsummer, and early autumn flights in mid-continent.
Open spaces including gardens, farmland, meadows, and banks of watercourses; seldom in woodlands.
S. Canada along E. Rockies into Arizona and Mexico, and east to Atlantic.
Eastern Black Swallowtails may be attracted to gardens by parsley or carrot plants, and nectar sources such as phlox and milkweed. Less blue and less rapid than the Pipevine Swallowtail, the Eastern Black likes to flit among the vegetation, drifting and stalling again and again, until disturbed; then it takes off in a direct line, making it most difficult to pursue. A similar-looking species of the Missouri Ozarks, known as the Ozark Swallowtail (Papilio joanae) has dramatically different habits. It dwells in forests, where caterpillars feed on meadow parsnip (Heracleum). Another related black swallowtail, the Kahli Swallowtail (Papilio kahli), flies in Manitoba and Saskatchewan and may be a hybrid of the Old World Swallowtail. It frequents bare hilltops, where females lay their eggs on cow parsnip (Heracleum lanatum).