Anise Swallowtails can be distinguished from Old World and Baird's swallowtails by the shape and position of the black pupil of the red eyespot on the dorsal hindwing. The black pupil forms a black spot centred in the red eyespot, and is completely surrounded by red. Adults of interior populations tend to be smaller and darker than those of coastal populations. Occasional hybrids with Old World and Baird's swallowtails occur, and they are intermediate in appearance.
Eggs are spherical and pale yellow. The micropylar area turns red, and a red ring develops around the middle of the egg as it matures. The first to third instar larvae resemble bird droppings, being black with a white splotch in the middle of the back and, in instars 2 and 3, orange spots down the sides. In mature larvae, black and green rings alternate around the body, with yellow or orange spots in the black rings. The spots are usually yellow on the coast and orange in the Peace River and eastern interior, and yellow and orange in equal frequency in the Southern Interior (Sperling 1987). Pupae are long and cylindrical, tapering posteriorly. Each side of the thorax has a lateral protuberance, and down each side of the back is a row of small protuberances. Pupal colour is highly variable, ranging from very dark brown through green to green yellow.
The Anise Swallowtail type locality has been restricted to San Francisco, CA (Emmel et al. 1998b), and there are no recognized subspecies. Within California there is no significant genetic differentiation (Tong and Shapiro 1989), but the unpublished electrophoretic data of Wehling (1994) suggest the possibility of a California subspecies separate from the rest of western North America. There are also some isolated, genetically distinct populations along the coast of Washington and Oregon that may have resulted from postglacial colonization patterns as the sea level rose and climate changed.
Linnaeus divided butterflies into several groups. The first group was the swallowtails, which were called equites or knights. Those with red on the thorax were Greek heroes, those with no red on the thorax were Roman heroes (Emmet 1991). Papilio, which is Latin for butterfly, was the original generic name that Linnaeus used for all butterflies. The common name was first used in Britain in 1766 for "The Swallowtail," P. machaon (Bretherton 1990b), in reference to the resemblance of the tails on the hindwings to the tails of swallows. The name was later extended to include the entire genus. Gosse (1840) was the first to use the common name "swallowtails" in North America.
Swallowtails found in North America are large, brightly coloured butterflies with tails on their hindwings. Six of the eight species in BC are yellow with black stripes. In addition, Pale Swallowtails are white to very pale yellow with black stripes, and Indra Swallowtails are mostly black. Swallowtails also have an orange eyespot at the base of each hindwing tail, and orange and blue spots on the ventral hindwings.
Eggs are smooth and hemispherical, and are cream, yellow, yellow green, or green when laid. The egg colour darkens, and a red ring develops around the top before hatching. Young larvae are black with a white saddle, and resemble bird droppings. Larvae of all ages have well-developed osmeteria, extrusible Y-shaped glands on the top of the thorax that produce defensive chemicals in response to attack. Pupae have two small horns on the head and a point at the top of the thorax. A silk girdle holds them head up against a stem.
The eggs are laid on the leaves of the larval foodplants. On plants with large flat leaves, the eggs are laid on the top or occasionally just under the leaf edge. Both the top and bottom of small leaves are used. The pupae overwinter. In BC two species have more than one generation each year in some populations; the other six are univoltine.
Hancock (1983) split the genus Papilio into six genera, two of which (Papilio and Pterourus) are in BC. We treat Hancock's genera as subgenera of a single large genus, Papilio, as do most recent authors.
Higgins (1975) suggested that the North American populations of Old World Swallowtails may not be the same species as Papilio machaon. Eitschberger (1993) found that the rings of plates surrounding the egg micropyle are significantly different between one European machaon subspecies and subspecies aliaska, the North American subspecies closest to European machaon. European P. machaon has 3 rings with about 112 plates around the micropyle, while aliaska has 5 rings with about 142 plates. A second character used by Eitschberger to separate P. machaon from aliaska, the number of teeth on the harpe of the male genitalia, is not useful in separating species in North America. The difference in egg structure is insufficient to split the species without additional data, hence we continue to treat the North American populations as subspecies of Papilio machaon.
All the tiger swallowtails (subgenus Pterourus) hybridize in the wild to some extent. In southern BC there is a broad zone of hybridization between Canadian Tiger Swallowtails and Western Tiger Swallowtails from Manning Provincial Park east to Creston. In the areas where their ranges overlap, Western Tiger Swallowtails prefer low-elevation deciduous forest habitats whereas
Canadian Tiger Swallowtails prefer higher-elevation boreal forest habitats. Hybridization between Pale Swallowtails and Western Tiger Swallowtails is rare, but Wagner (1978) collected a perfectly intermediate male hybrid in the wild in Idaho. Jon and Sigrid Shepard found a male hybrid of the Pale Swallowtail and the Canadian Swallowtail 10 km south of Galloway, BC. lt is intermediate in appearance between the two species.
Similarly all the Old World swallowtails (subgenus Papilio) occasionally hybridize in the wild. The Old World swallowtail species are most easily distinguished by the overall coloration of the hindwing and by the colour of the eyespot at the base of the tail on the hindwing.
Anise Swallowtails are univoltine east of the Coast Range. Adults are in flight in April and May at low elevations, and until August and September above the timberline. In subalpine and alpine habitats west of the Coast Range, they are also univoltine. At low elevations on the coast, they are univoltine (April and May) in dry areas around Victoria, and trivoltine (April to September) along the wetter coastal areas. In dry summers occasional adults occur in the "univoltine" areas of southeastern Vancouver Island throughout the summer, due to either immigration from the west coast of Vancouver Island or a partial second and/or third brood. In years with a wet May and June, there is definitely a partial second brood. In general, populations using Lomatium species as their primary larval foodplant (such as those on southeastern Vancouver Island) are univoltine, because the foodplants dry up by midsummer. Females from different populations prefer to lay eggs on different foodplant species among those available. The differences in oviposition preference do not result from genetic differences, and change between seasons in some populations (Wehling 1994), including the one at Boundary Bay, Delta (R. Ashton, pers. comm.).
Many different plants in the family Apiaceae are used as larval foodplants, including garden parsley, parsnips, and carrots. Wehling (1994) recorded 69 foodplant species in 39 genera of Apiaceae and Rutaceae, with 70% of the host species in the genera Lomatium, Angelica, Foeniculum, and Heracleum. In BC Lomatium species (spring gold, chocolate tip) are commonly used in dry areas, both on southern Vancouver Island and in the Southern Interior. Cow parsnip (Heracleum maximum) is used in wet meadows and ditches at all elevations. Cow parsnip and angelica are used along beach tops. Females straying into urban and suburban areas frequently lay eggs in vegetable gardens on carrots, parsley, anise, parsnips, and dill (Jones 1933; RA Cannings, pers. comm.; CSG). Most of the resulting larvae are eliminated as pests, unless the gardener recognizes them as Anise Swallowtail larvae.
Anise Swallowtails inhabit forest edges, stream banks, beach tops, hilltops, open rocky knolls, moderately dry grasslands, and subalpine meadows both on the coast and in the interior. Males are frequently found hilltopping.
Anise Swallowtails occur only in North America, from the central coast of BC east to SK and south to CA, AZ, and NM.
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2021. E-Fauna BC:
Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab
for Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
2021-12-04 5:25:50 PM]
The information contained in an
E-Fauna BC atlas pages is derived from expert sources as cited (with permission) in each section.
This information is scientifically based. E-Fauna BC also acts as a
portal to other sites via deep links. As always, users should refer to
the original sources for complete information. E-Fauna BC is not
responsible for the accuracy or completeness of the original information.