Papilio polyxenes

Geographic Range

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)

Physical Description

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)

  • Sexual Dimorphism
  • sexes colored or patterned differently
  • Range length
    7 to 9 cm
    2.76 to 3.54 in
  • Range wingspan
    11.5 (high) cm
    4.53 (high) in


To find a female black swallowtail, males alternately perch on the tops of hills and then patrol in flat areas. Males defend territories of about 70 square meters where they perch and patrol. It has been found that about 67% of their day is spent perching, 25% patrolling, 6% feeding, and lastly 2% interacting with other butterflies. The location chosen by a male can and most often does change daily. Black swallowtails mate on hilltops. Courtship lasts for about 45 seconds. The male and female will flutter near each other momentarily, fly an approximate distance of 20 meters away from where courtship started and mate after landing. The coupling lasts from 30 to 45 minutes. After a successful mating, a female must survive, temporarily avoid, and reject other courting males. Many times, if the female survives, she will mate more than once to ensure fertilization of her eggs.

Females lay round, cream-colored eggs on the leaves of Umbelliferae plants. A female black swallowtail lays on average 200 - 440 eggs, 30 - 50 per day, starting at two days after emergence from the pupal stage. (Jackman, 1998; Scott, 1986)

  • Range eggs per season
    200 to 440

Once eggs are fertilized and laid, there is no longer any parental care.

  • Parental Investment
  • pre-fertilization
    • provisioning


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)

  • Average territory size
    70 m^2

Food Habits

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)

  • Plant Foods
  • leaves
  • nectar
  • flowers

Ecosystem Roles

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

  • Ecosystem Impact
  • pollinates

Economic Importance for Humans: Positive

These butterflies have no positive economic effect on humans.

Economic Importance for Humans: Negative

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

Conservation Status

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

Other Comments

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)


Matthew Wund (editor), University of Michigan-Ann Arbor.

Katy Eby (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.



living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map


living in the southern part of the New World. In other words, Central and South America.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

  1. active during the day, 2. lasting for one day.

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature


union of egg and spermatozoan


an animal that mainly eats leaves.


An animal that eats mainly plants or parts of plants.


having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

internal fertilization

fertilization takes place within the female's body


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


marshes are wetland areas often dominated by grasses and reeds.


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


an animal that mainly eats nectar from flowers


reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

seasonal breeding

breeding is confined to a particular season


reproduction that includes combining the genetic contribution of two individuals, a male and a female


that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).


defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement


the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.


A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.


Bordoni, S., Forestiero. 1998. Butterflies of the World. Ontario, Canada: Firefly Book.

Douglas, M. 1986. The Lives of Butterflies. Rexdale, Canada: The University of Michigan Press.

Ehrlich, P. 1961. How to Know Butterflies. Dubuque, Iowa: WM. C. Brown Company Publishers.

Jackman, 1998. A Field Guide to Common Texas Insects. Houston, Texas: Gulf Publishing.

Neck, R. 1996. Butterflies of Texas. Houston, Texas: Gulf Publishing Company.

New, T. 1991. Butterfly Conservation. New York, New York: Oxford University Press.

Scott, J. 1986. Butterflies of North America. Stanford, California: Stanford Press.