A medium-sized black swallowtail with yellow spot bands and blue dust on hindwings. Caterpillars are famous garden visitors — feed on dill, fennel, parsley.

Also called: Black Swallowtail, Parsley Worm (caterpillar reference), American Swallowtail

Native status: Native to North America

§ Quick facts

SizeWingspan 6.9–10.4 cm (2.7–4.1 in)
Weight~0.4 g
LifespanAdults 6–14 days; multiple generations per year
OrderLepidoptera
FamilyPapilionidae

§ Encyclopedia

Papilio polyxenes, the (eastern) black swallowtail, American swallowtail or parsnip swallowtail, is a butterfly found throughout much of North America. An extremely similar-appearing species, Papilio joanae, occurs in the Ozark Mountains region, but it appears to be closely related to Papilio machaon, rather than P. polyxenes. The species is named after the figure in Greek mythology, Polyxena, who was the youngest daughter of King Priam of Troy. Its caterpillar is often called the "parsleyworm" because the caterpillar feeds on parsley.

Source: Wikipedia — Papilio polyxenes Licensed under CC BY-SA 4.0

§ Identification

Field marks. Large black butterfly with yellow spot band across both wings; bright iridescent blue dusting on hindwings (especially females); two distinct "tails" off hindwings; row of orange/red eyespots near tail.

Similar species. Pipevine Swallowtail (iridescent blue throughout). Spicebush Swallowtail (different markings). Female Tiger Swallowtail dark morph (no orange spots; mimics Pipevine).

Voice. N/A

§ Diet & behavior

Diet. Adults: nectar (especially clover, milkweed, phlox). Caterpillars: members of the carrot family — parsley, dill, fennel, Queen Anne's lace, golden alexander.

Behavior. Among the most common large butterflies in eastern gardens, where caterpillars often eat planted herbs (the "parsley worm"). Caterpillars start out black with white "saddle" — mimicking bird droppings — then transform to brilliant green with black bands and yellow spots as they grow. When threatened, caterpillars evert bright orange-yellow "osmeterium" horns from behind the head and release foul-smelling defensive chemicals. State butterfly of Oklahoma.

§ Range

Eastern + central US

§ Habitat

Open areas, gardens, meadows

§ Threats

Habitat loss, garden pesticides.

§ Conservation status

According to the IUCN Red List, the black swallowtail is currently classified as Least Concern.

§ What helps

Plant native parsley relatives. Skip pesticides. Tolerate caterpillars on dill/fennel.

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§ Further reading

§ Sources cited

  • Butterflies and Moths of North America
  • Xerces Society
  • iNaturalist
  • BugGuide