There are several swallowtail butterflies in the Midwest, but the black swallowtail (Papilio polyxenes) is the only one in our region that features a black-dot-in-orange-circle eyespot on the inner edge of the hindwing. Both males and females feature this distinctive spot, making the species fairly easy to identify with close examination. Other distinctive features include the body, which is black with two rows of yellow dots, and the orange spots on the underwings. Although black swallowtails can be found fluttering around a wide variety of flowers, the caterpillars are particularly fond of plants in the carrot family and similar plants (for example poison hemlock). The caterpillars are generally hospital-green, with bands of yellow and black spots between green sections. The closest Midwestern look-alike for the black swallowtail is the giant swallowtail (Papilio cresphontes), which is much larger and features a yellow body.

Upperwings of a male; in females the large central band of yellow spots is smaller or missing, and the blue areas can be larger

A caterpillar enjoying dill plants in our garden

Male feeding on dame's rocket (Hesperis matronalis)

Underwing: note orange spots and dot-in-circle eyespot

References: Bland & Jaques 1978, Milne & Milne 1980, Scott 1986, Arnett 2000, Lotts & Naberhaus 2018.

Kuo, Michael & Melissa Kuo (July, 2018). Papilio polyxenes (black swallowtail). Retrieved from the midwestnaturalist.com website: www.midwestnaturalist.com/papilio_polyxenes.html

All text and images © , midwestnaturalist.com.