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What is a Black Swallowtail Butterfly (Papilio polyxenes)

What is a black swallowtail butterfly
What is a Black Swallowtail Butterfly (Papilio polyxenes)

Black Swallowtail Butterfly Overview

Black Swallowtail Butterflies are large butterfly that is found in most places around the United States, but mostly in the central and eastern states. Found in fields, parks, meadows, wetlands, and even in backyards, these butterflies are known for their beauty and known by other names such as the American Swallowtail or Parsnip Swallowtail Butterfly. As caterpillars, they are often referred to as Parsley Worms because they like to feed on parsley.


  • Kingdom: Animalia
  • Phylum: Arthropoda
  • Class: Insecta
  • Order: Lepidoptera
  • Family: Papilionidae
  • Genus: Papilio
  • Species: P. polyxenes

Size and Body Description

Black Swallowtail Butterfly has large, distinct wings that have what can be described as a tail at the end of both wings. The upper wings are black in color with white-yellow or cream-colored spots that run along the outside edge of the wing in two rows. The back pair of wings are also black and only has one row of the same colored spots along the outside edge. There is another, sometimes dull or hard to see, row of spots but it’s separated by an iridescent blue patch or spots. The Black Swallowtail Butterfly will also have two red “eyes” on the lower portion of its rear wings, near the inside edge of the wing.  Males will have brighter yellow spots and not as much blue whereas the females will have less pronounced spots but a more pronounced blue section on their rear wings.

The underside of the Black Swallowtail Butterflies’ wings is black in color with yellow spots along the edges with a row of orange spots next to them. They will have the same blue color from the topside of the wing separating the row of orange spots from another row of orange spots. 


Black Swallowtail Butterfly can grow to have a wing length of around 3 to 4 inches long.


Black Swallowtail Butterflies will eat nectar from plants such as thistle and milkweeds.

As caterpillars, they tend to feed on leaves from plants that are in the parsley family like dill, celery, Queen Anne’s Lace, and parsley.

What is a Black Swallowtail Butterfly (Papilio polyxenes)

Eastern Black Swallowtail Caterpillar (Papilio Polyxenes) close up


Black Swallowtail Butterflies pick their mates through a process called lekking which means that male butterflies will not care for the eggs, male butterflies gather at a specific area to display themselves, male butterflies are the only resource in the area for female butterflies, and female butterflies get to pick their mate. From there, mating occurs with males only being able to mate a couple of times a day whereas females can mate multiple times to replenish sperm that may have gone bad over time.  

Female Black Swallowtail Butterflies will lay eggs on their preferred host plant with eggs taking around 3 to 9 days to hatch. Caterpillars can grow to be around 2 inches in length and live up to 30 days before starting their metamorphosis. 


Black Swallowtail Butterflies are found in most states in the United States except for Oregon, South Dakota, Idaho, Montana, Hawaii, and Alaska. As stated before, these butterflies tend to live mostly in central and eastern states.


As of writing this, the Black Swallowtail Butterfly is not a federally protected species.


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What is a Black Swallowtail Butterfly (Papilio polyxenes)