Black Swallowtail Butterfly
Common Name: Black swallowtail
Scientific Name: Papilio polyxenes asterius Stoll
Order: Lepidoptera
Description: The black swallowtail is a black butterfly with yellow markings near the margins of the forewings and hindwings and more limited blue and red markings on the hindwings. Its wing span can reach 4 ½ inches. Full grown parselyworms or caterpillars can reach 2 inches in length and are smooth and green, marked with black bands and yellow spots.
The Black Swallowtail Caterpillar changes dramatically in appearance as it develops.
After it hatches, it is a tiny black caterpillar with a white spot (Picture 2). It is suppose to look like a bird dropping to divert its predators. As the caterpillar molts, it eats the skin.
The caterpillar continues to grow and as it sheds its skin new patterns and colors appear (Picture 3).
One interesting fact about the Swallowtail Caterpillars is they have 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......all to repel predators! (Picture 4)
Black Swallowtail Host Plant
There are several host plants or caterpillar food for the black swallowtail. I have used parsley, bronze fennel, Queen Anne's Lace and Rue Ruta. Their favorite is Rue. Rue can irritate the skin when touched (I haven't had a problem with this) and can make you sick if eaten, so be aware of this before planting it.