Pipevine Swallowtail

Battus philenor

Pipevine Swallowtail

Battus philenor

Harmless

Not dangerous

Harmless to people. It is toxic to eat, from the aristolochic acids its caterpillars take up from pipevine, but there is no sting, no bite and nothing that affects skin.

SizeWingspan 70–115 mm

MarkingsBrilliant iridescent blue-green sheen across the hindwings, strongest in males · Underside carries a single arc of large orange spots on a blue field

WhereWoodland edge, meadow and garden wherever pipevine grows.

SeasonSpring through autumn, in two or three broods

How to tell it apart

Brilliant iridescent blue-green sheen across the hindwings, strongest in males
Underside carries a single arc of large orange spots on a blue field
Fewer, fainter yellow marks on the upperside than a black swallowtail
Wingspan 70–115 mm, with a tail on each hindwing
Caterpillar is dark red-black with rows of fleshy orange tubercles

Where you’ll find it

The southern and eastern United States, north into the Great Lakes and west through the southwest into California.

Woodland edge, meadow and garden wherever pipevine grows.

Spring through autumn, in two or three broods.

How it behaves

The caterpillars feed only on pipevine and sequester aristolochic acids from it, which makes both the larva and the adult genuinely poisonous to predators. That toxicity supports one of the largest mimicry complexes on the continent: female black swallowtails, spicebush swallowtails, red-spotted purples and dark female tiger swallowtails all converge on its appearance. Adults flutter constantly while feeding rather than settling, which is itself a useful field mark.

You’ve found one indoors

Nothing needed. Planting native pipevine is the only reliable way to get them, and it is worth knowing that the caterpillars will strip a vine — that is the plant doing its job rather than a problem.

Common questions

How do I tell it from a black swallowtail?

The blue. A pipevine swallowtail has a strong iridescent blue-green wash across the hindwing and only faint yellow marks; a black swallowtail has two clear rows of yellow spots. The underside orange spots form one arc rather than two rows.

Is it really poisonous?

To eat. It carries aristolochic acids from its foodplant, which is why so many other butterflies have evolved to look like it. It is entirely safe to handle.

Which butterflies mimic it?

Female black swallowtails, spicebush swallowtails, red-spotted purples and the dark form of the female tiger swallowtail, among others. It is one of the largest mimicry complexes in North America.

Commonly confused with

Black Swallowtail Harmless

Keep identifying

Identify another animal from a photo or return to the Butterflies guide.

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Where this was checked

iNaturalist — Battus philenor checked 2026-07-30

Last reviewed 2026-07-30. We identify, we don’t diagnose — what we can and can’t tell you.