Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada

Species Papilio polyxenes - Black Swallowtail - Hodges#4159

Black Swallowtail Emerging - Papilio polyxenes - female Black Swallowtail (polyxenes)  - Papilio polyxenes - male Desert Black Swallowtail in LA County - Papilio polyxenes papilionid - Papilio polyxenes - female butterfly - Papilio polyxenes - female Which swallowtail is this? view 3 - Papilio polyxenes Papilio polyxenes Papilio polyxenes eclosion series, 8:34am - Papilio polyxenes
Show images of: caterpillars · adults · both
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Lepidoptera (Butterflies and Moths)
Superfamily Papilionoidea (Butterflies and Skippers)
Family Papilionidae (Swallowtails, Parnassians)
Subfamily Papilioninae
Tribe Papilionini (Fluted Swallowtails)
Genus Papilio
Species polyxenes (Black Swallowtail - Hodges#4159)
Hodges Number
Other Common Names
Eastern Black Swallowtail
Parsely Swallowtail
Dill Worm, Parsley Worm, Celery Worm
Carrot Worm, Fennel Worm
Explanation of Names
Papilio polyxenes Fabricius, 1775
The common names for the caterpillars vary because they can be found on many important cultivated plants in the Carrot Family. Pick the host plant, add the word "worm", and you have another common name that has probably been used and published somewhere.
Wingspan 8-11 cm
Adult: a common member of the "blue-and-black" swallowtail complex. Female, with its large blue patches on hindwings, is a mimic of the Pipevine Swallowtail. Some female Black Swallowtails have little yellow on wings above. Males have more extensive broken yellow band. Note orange and black spot on inner margin of hindwings (Palamedes Swallowtail is otherwise very similar, above, but has no black center in the orange spot).
Female (below left) Male ( below right)

Underneath, the median orange spot-band varies in thickness.

Larva changes color quite dramatically with each molt. Last instar is green with black bands dotted with orange or yellow spots on each segment; pupa has two forms - brown and green.

e NA to s. CA / Mex. to S. Amer. - Map (MPG)
Open areas, meadows, fields, gardens
April-October in north, 2 broods. Longer flight, with three broods in southern US.
Larvae feed primarily on plants of the carrot family (Apiaceae = Umbelliferae), and some in the Rue Family (Rutaceae). Commonly found on Dill, Parsley, Fennel, Carrot, and Rue in gardens, and Queen-Anne's-Lace, Poison Hemlock, and Lovage in the wild. They will occasionally be found on Citrus trees.
Adults take nectar and frequently visit moist ground.
Life Cycle
overwinters as a pupa
This composite image shows several larval instars, pupa/chrysalis and adult butterfly

The Black Swallowtail appears to interbreed fairly regularly with its close relative the Old World Swallowtail (P. machaon) in Manitoba and Saskatchewan. The dark offspring, formerly thought to be a distinct species (Papilio kahli), are widespread in Manitoba, but scarce; they feed as larvae mainly on Heart-leaved Alexander (Zizia aptera)
[from Butterflies of Canada; CBIF]
Larvae and pupae are parasitized by members of the following families: Phoridae, Tachinidae, Ichneumonidae, and Braconidae (Ecological monographs)
See Also
In eastern US, compare Pipevine Swallowtail, Spicebush Swallowtail, Palamedes Swallowtail and Red-spotted Purple (which has no tails). A comparison of the underside of the hindwings is helpful for ID:

Pipevine - single row of orange spots which do not touch

Spicebush - missing one orange spot in the median row

Palamedes Swallowtail - stripes on body and front part of wing

Red-spotted Purple - no tails, single row of orange spots

Eastern Tiger Swallowtail, dark female form - faint darker tiger striping visible, no median spot-band. Orange spots are at edge of wing, with blue band above them.
Print References
Glassberg (1)
Brock and Kaufman (2)
Scott (3)
Allen (4)
Feeny et al. 1985. Larval growth and survivorship of the black swallowtail butterfly in Central New York. Ecological Monographs 55(2): 167-187.
Works Cited
1.Butterflies Through Binoculars: The East
Jeffrey Glassberg. 1999. Oxford University Press.
2.Butterflies of North America (Kaufman Focus Guides)
Jim P. Brock, Kenn Kaufman. 2003. Houghton Mifflin Co.
3.The Butterflies of North America: A Natural History and Field Guide
James A. Scott. 1992. Stanford University Press.
4.The Butterflies of West Virginia and Their Caterpillars
Thomas J. Allen. 1998. University of Pittsburgh Press.