Diagnosis: The Short-tailed Swallowtail is medium-sized (wingspan: 57 to 73 mm), with black, rounded wings crossed by a double row of yellow spots, often with an orange wash. On the hindwing, it has a red-orange eye-spot with a black centre. The tails, as indicated by the common name, are generally quite short.
Subspecies: There are three described subspecies. These, however, are not discrete, but form a cline from east to west. Subspecies brevicauda occurs in Newfoundland and Anticosti Island, and has the most orange in the upperside bands; subspecies bretonensis occurs on Cape Breton Island and the north shore of New Brunswick; and subspecies gaspeensis, found in Quebec, has the least amount of orange on the upperside.
Range: This swallowtail is found only in the Maritime Provinces and those parts of Quebec surrounding the Gulf of St. Lawrence west to St. Fulgence, Quebec. The occurence of the species at Cartwright, Labrador, which was questioned for many years, has recently been confirmed by two sources and there is another Labrador record at Northwest River Post. Brevicauda has never been recorded from Prince Edward Island, although it is regularly seen on the New Brunswick coast close to the island.
Similar Species: The only other similar species in its range is the Black Swallowtail (P. polyxenes). In most specimens, the Short-tailed Swallowtail can be recognized by its stubbier, less-pointed wings, the shorter tails, and the orange coloration often present in the yellow bands. The two species fly together on Cape Breton Island, but Ferguson (1954) found few hybrids. [compare images]
Early Stages: Young larvae are brown with a white saddle, resembling a bird dropping as a form of protective coloration. Later instars are green- and black-banded with yellow dots in the black, appearing paler than most polyxenes larvae. The pupae can be green or brown but are more often found in the green form. The larvae feed on members of the parsley family (Apiaceae), including cow-parsnip (Heracleum spp.), Angelica (Angelica atropurpurea), and Scotch Lovage (Ligusticum scoticum).
Abundance: The Short-tailed Swallowtail is widespread and commonly encountered in Newfoundland, particularly in gardens near its food plants. In the other parts of its range it tends to be local and uncommon.
Flight Season: Adults are on the wing from mid-June to the end of July in most of its range.
Habits: In addition to gardens, this butterfly is often found in coastal areas, where it can be seen flying over grassy clifftops and rocky beaches. It can also be found in inland meadows and mountainous areas close to the treeline, as on the slopes of Mont-Albert in the Gaspé Peninsula, and even above treeline at the summit of Gros Morne Mountain in Newfoundland.
Remarks: At one time brevicauda was considered a subspecies of Papilio polyxenes. Recent molecular studies by Felix Sperling have shown that it is a close relative of the Old World Swallowtail (P. machaon), and some authors (Tyler et al., 1994) have treated it as a subspecies of machaon.
© 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.
Contact Us |
Coming Events | About CBIF | Links | Reports and Publications | Home
Date Modified: 2010-05-31