Papilio polyxenes

The range of black swallowtails (also known as American swallowtails) extends from Southern Canada, through North America, and down to South America. Included in the South American range are the West Indies. In North America, black swallowtails are not commonly found west of the Rocky Mountains. (Ehrlich, 1961; Neck, 1996)

Black swallowtails tend to be found in open areas such as meadows, fields, parks, gardens, lowlands, marshes, and deserts. (Jackman, 1998)

Adult black swallowtails range in length from seven to nine cm, and can reach a wingspan of 11.5 cm. Older larva vary from green to yellow and most often each segment is crossed by a black band. Pupae of this species can vary from green and yellow, to brown and white, to a black form.

The upper surface of an adult is black with two rows of yellow spots past the middle or median of the wing. In females these yellow spots are narrow and lighter, or nonexistent as is the case in North America where they can mimic Battus philenor (pipevine swallowtails). On the upper surface of the adults' hind wing, there are irridescent blue spots on males and an irridescent blue band on females. On the upperside of the hindwing there is a large red spot that has a black center towards the tail. Under the forewing there are yellow spots, and on the underside of the hindwing there are a row of orange-red spots, in front of blue caps, followed by black centered red spots towards the tail. (Douglas, 1986; Ehrlich, 1961; Neck, 1996; Scott, 1986)

The nocturnal behavior of seeking a nightly sleeping perch occurs in several frenzied flights. Once the butterfly finds a good stalk or tip of an herbaceous plant, it will rest for a few minutes. While resting, it raises its abdomen with wings outstretched, giving the appearance that it is ready to quickly change its perch. When finally settled, it closes its wings and lowers its abdomen into the sleeping position where it will remain all night. In the morning the butterfly wakes up and positions itself again with its wings open, but this time it turns around to catch the morning light.

It has been discovered that black swallowtails mimic pipevine swallowtails, a distasteful species. Pipevine swallowtails are similar in appearance with a black-blue color on their upper wings, just lacking the yellow and blue markings of black swallowtails. While black swallowtails are distasteful as a larva, they are palatable as adults. By mimicking distasteful pipevine swallowtails, adult black swallowtails gain some protection where their ranges overlap. (Bordoni and Forestiero, 1998; Douglas, 1986; Jackman, 1998)

In Costa Rica, black swallowtails feed on food plants that exist in habitat patches. They have adapted to this patchiness by having females with a great dispersal abiblity. The females lay eggs before leaving a food patch so that the species can continue to thrive there, but then it will leave to find and lay eggs in new habitat patches. This movement to new food patches provides protection from predators and parasites, and also limits competition from other populations of butterflies. (New, 1991)

The larvae of American swallowtails are attracted to Umbelliferae (or Apiaceae) oils. Umbelliferae plants include dill, parsley, celery, carraway and carrots. These plants have adapted to insects herbivores by producing specific chemicals known as psoralins that repel the insects that try to eat them. American swallowtail larvae are resistant to these psoralens because their intestine and body detoxify and eliminate the toxins quickly. Psoralens make the caterpillar bad-tasting to avian predators. Some plants from the Umbelliferae family make psoralens that reduce growth rate and fertility in American swallowtails. The larva are most often found at the small umbelliferae flowers. Adults feed on flower nectar and mud. (Douglas, 1986; Jackman, 1998; Neck, 1996; Scott, 1986)

The larvae of American swallowtails are attracted to the oils of plants such as dill, parsley, celery, carraway and carrots. These plants have adapted to insects herbivores by producing specific chemicals that repel the insects that try to eat them. American swallowtail larvae are resistant to these chemicals and make the caterpillar bad-tasting to bird predators. Some plants from the Umbelliferae family make psoralens that reduce growth rate and fertility in American swallowtails. The larva are most often found at small flowers. Adults feed on flower nectar and mud. (Douglas, 1986; Jackman, 1998; Neck, 1996; Scott, 1986)

These butterflies pollinate many plants. Their larvae eat many plant species. They also may provide food for many predator species.

The caterpillar of this species is occasionally a pest in gardens and farms. (Jackman, 1998)

These butterflies have no positive economic effect on humans.

These butterflies are widespread and do not seem to be threatened.

Black swallowtail pupae have color polymorphisms. Their colors vary from green and yellow, to brown and white, to a black form. It is interesting that by controlling the wavelength of light that the pupae is exposed to in the instar larvae stage, one can determine the color they will express. This allows the larvae to match the background color of the pupal site. (Douglas, 1986)