Black Swallowtail
Papilio polyxenes Fabricius, 1775

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Diagnosis: The wings are black with a row of submarginal yellow spots. There is also a row of yellow crescent-shaped spots on the margins of the hindwing. The female differs from the male in having the submarginal band of spots small or non-existent and in having the blue submarginal band of the hindwing larger; females, with their black and blue pattern, appear to mimic the Pipevine Swallowtail (Battus philenor). The Black Swallowtail has distinct orange eye-spots with black-centred pupils on the hindwings close to the tails. Wingspan: 52 to 94 mm.

Subspecies: Only subspecies asterius is found in Canada.

Range: The Black Swallowtail is at home in most areas of the eastern U.S. and ranges all the way to South America with several named subspecies. It reaches into Canada in three areas. In the west it can be found in southern Manitoba (one record from Saskatchewan), and in northwestern Ontario around Lake of the Woods, with three isolated records from the north shore of Lake Superior. It is common in southern Ontario and southern Quebec. The third area is the Maritimes, with records from all provinces except Newfoundland, from which no authenticated specimens are known, although it has mistakenly been reported in the literature.

Similar Species: The predominance of black on the wings and the orange spot on the lower corner of the hindwing with a black spot in the centre make this species easy to identify in most of eastern Canada. Identification is more difficult in the eastern Great Plains, where it hybridizes with machaon, and in the Maritime Provinces, where its range approaches that of brevicauda. [compare images]

Early Stages: The green larva has black bands dotted with orange or yellow spots on each segment. The pupa has both brown and green forms. Larvae feed on a wide variety of members of the parsley family (Apiaceae = Umbelliferae), including wild (Queen Anne's Lace) and cultivated Carrot (Daucus carota), Parsley, Dill, and Celery.

Abundance: The Black Swallowtail is fairly common in most parts of southern Ontario and Quebec, especially in abandoned farmland where its food plants grow wild; it is generally less common towards the edges of its range in the eastern Great Plains and in the Maritimes.

Flight Season: There are two broods annually. In most parts of its Canadian range, the first-generation adults emerge from the overwintering pupae in mid- to late May and fly until late June. The next brood emerges in mid-July and flies throughout August.

Habits: This handsome swallowtail is often found in and around gardens because of its larval foodplants and its fondness for flowers as an adult. In wilder areas it is usually seen near damp meadows and can be found occasionally sipping at wet sand.

Remarks: 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) (Klassen et al., 1989).

© 2002. This material is reproduced with permission from The Butterflies of Canada by Ross A. Layberry, Peter W. Hall, and J. Donald Lafontaine. University of Toronto Press; 1998. Specimen photos courtesy of John T. Fowler.

The Toronto Entomologists' Association thanks Agriculture and Agri-Food Canada for providing the content and computer code for this web page.