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Eastern Black Swallowtail (Papilio polyxenes asterius)


Eastern Black Swallowtail

Eastern Black Swallowtail

Scientific Classification

  • Family: Papilionidae
  • Genus: Papilio
  • Scientific Name: Papilio polyxenes asterius

The eastern black swallowtail, a subspecies of the black swallowtail is an attractive butterfly known for its immense beauty, though occasionally considered as a pest.


Description and Identification


Eastern Black Swallowtail Caterpillar
Eastern Black Swallowtail Larvae

The young caterpillars are mostly black, having a white saddle which is due to the deposit of uric acid that ensures protection to the larvae from the phototoxic chemicals. As they get older the larvae attains a green color having black transverse bands with yellow spots.


Eastern Black Swallowtail Pupa

Pupae belonging to the overwintering generations attain a brown color, while those from other generations might be brown or even green with markings of yellow.

Adult Butterfly

Sexual Dimorphism: Present

Color and Appearance: When opened, the wings are black with yellow spots arranged in two rows with blue markings present below. The yellow spots are big and bright in males, while in females they are small and light.  Red spots with a black-bull eye are seen in the inner hind margins. When closed, bright orange spots separated by powdery blue patches can be seen.

Eastern Black Swallowtail Male
Female Eastern Black Swallowtail

Average wingspan: 6.9 cm to 8.4 cm

Flight pattern: Fast


Eastern Black Swallowtail Eggs

They are pale yellow in color often laid upon host plants.

Distribution Southern parts of Canada, eastern as mid-western and Southern United States up to Arizona, and the northern parts of Mexico

Quick Facts

Habitat Uplands and wet areas like fields, weedy areas, flat-woods, gardens and roadsides
Predators Mostly birds
Lifespan of adults 6-14 days
Host plants Mock bishopweed, Spotted water hemlock, Canby’s dropwort, Queen Anne’s lace, Water cowbane
Adult diet Nectar form plants like milkweed, clover,  phlox and thistles,

Did You Know

  • The term Papilio means butterfly in Latin while the name polyxenes stems from Polyxena, who according to Greek mythology was the Trojan king Priam’s youngest daughter.
Papilio Polyxenes Asterius
Eastern Black Swallowtail Pictures
Eastern Black Swallowtail Butterfly

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