Creature Feature: Black Swallowtail (Papilio polyxenes)
By Emma Dean, CG Science Editor
As winter falls on Ohio University and the rest of southeast Ohio, its residents hide indoors and brave the chilly weather huddled in peacoats and North Face jackets. The black swallowtail spends its winter in its chrysalis stage. Hanging by a thin web-like structure, the black swallowtail caterpillar hangs from its host plant encased in its cocoon.
During its larvae stage, the creature feasts on its host plant which includes members of the parsley family such as carrot, parsley, dill, fennel and Queen Anne’s Lace as well as members of the Rutaceae family. Its diet gives the caterpillar an unpleasant taste which helps to protect it from birds and other predators so that in the spring, a full grown butterfly emerges from its cocoon. As an adult, the black swallowtail’s diet consists of nectar from flowers such as red clover, milkweed and thistles.
Males will perch on moist areas and survey its surroundings for interested females. The females will then lay yellow eggs on the leaves of the host plants. When first emerging from its egg, the caterpillar is black with a white saddle. After several molts, its color changes to green with black bands and yellow spots.
- Males can be identified by a yellow band near the edge of their wings while females have a row of yellow spots.
- The wingspan of a black swallowtail can range between three and a half to four and a half inches.
- Except for the yellow and blue markings, the black swallowtail mimes the appearance of the pipevine swallowtail.
- When disturbed, the larvae reveals a defensive structure called a osmerterium behind the head which emits a strong, distasteful scent which helps to ward off predators.
- The black swallowtail prefers open areas such as meadows, fields and gardens.
- To attract the beautiful black swallowtail to your garden, simply plant any of its host plants such as parsley or carrots.
Check out the black swallowtail’s complete transformation here.