E-Fauna BC: Electronic Atlas of the Wildlife of British Columbia

Colias canadensis Fabricius, 1807
Canadian Sulphur; Sulphurs
Family: Pieridae (Whites, Marbles, and Sulphurs)
Species account authors: Crispin Guppy and Jon Shepard.
Extracted from Butterflies of British Columbia
The Families of Lepidoptera of BC
Introduction to the Butterflies of BC
Photo of species

© Norbert Kondla  Email the photographer   (Photo ID #6184)

E-Fauna BC Static Map
Distribution of Colias canadensis in British Columbia
Details about map content are available here.

Species Information


Adult

Canadian Sulphur males are orange or yellow orange, with a black wing border of variable width. Females have white or pale orange dorsal wings. The ventral hindwings are yellow green and the red ring of the ventral discal cell spot is seldom smeared towards the outer margin of the wing. There are no ventral submarginal spots. Canadian Sulphurs were recently shown to be a distinct species from Hecla Sulphurs by Ferris (1988). The two species fly together in some areas of Alaska, and in northwestern BC along the Haines Highway.

Immature Stages

Mature larvae are dark green. They have numerous black slightly raised points, with a short black hair arising from each black point, and a darker green dorsal line. The upper half of the lateral line is white and the lower half pink red (CSG).

Subspecies

None. The type locality of the species is Mile 209, Alaska Highway, BC.

Genus Description


Colias is the name of a promontory on the coast of Attica where there was a tem pie of Aphrodite. There is no obvious relationship to the butterfly, but the name may be a pun (Emmet 1991). An alternative explanation is suggested under Pontia. The common name "sulphurs" is derived from the yellow "sulphur" colour of most species.

Sulphurs in BC are generally medium-sized butterflies that are yellow, orange, white, or (one species) yellow green with black markings. The wings of males always have a solid black border, with the exception of the Arctic Sulphur. The black borders of females contain extensive pale areas, or may be greatly reduced or absent. There are several multivoltine species that show considerable seasonal variation in wing colour.

There are about 70 species of Colias in the world. The centre of distribution in North America is BC, with more species (13) than any other province or state. Colias species may all be inter-fertile, with natural hybrids known for most species combinations where they occur together in the wild. The species have behavioural, ecological, and physiological differences that maintain separation of the species in the wild (Hovanitz 1963).

Eggs are laid singly on the leaves of the foodplants, and are pale yellow green to cream, later turning orange. Young larvae are slender, yellowish or green, and smooth-skinned with a thin coat of fine hairs. Mature larvae are yellow green or green with fine black dots all over, and stripes of various colours running along the back and sides. Sulphurs hibernate as second to fourth instar larvae (except Canadian Sulphurs, which hibernate as fifth instar larvae), and then complete development in the spring. There are five larval instars in all Colias (Ae 1958a). Pupae are fastened head up with a girdle around the middle.

Members of the genus utilize a wide range of foodplants, although each species specializes to a greater or lesser extent. Larvae of sulphurs feed on plants in three groups: legumes (Fabaceae), Vaccinium (Ericaceae), and Salix (Salicaceae). Sulphurs occur in a wide range of habitats, including arid sagebrush areas, alfalfa fields, meadows, alpine tundra, and forest bogs.

Sulphurs always rest with their wings folded over their backs, and bask in the sun by leaning to the side to allow the sun to warm the underside of their wings. It has been demonstrated for several species (C. meadii, C. nastes, C. philodice, and C. eurytheme) that the darker the pigmentation on the underside of the wings, the more heat can be absorbed from the sun while basking, permitting greater flight activity in cold environments (Kingsolver 1985).

There is relatively little variation in wing pattern between many species, making identification difficult. The key characters mentioned in the species discussions are shown in the figure.

Biology


Canadian Sulphurs are univoltine, and fly in June and July. Mature larvae hibernate (CSG). Larval foodplants are probably Fabaceae such as Hedysarum (Ferris 1988). In captivity a Canadian Sulphur from Atlin oviposited on Hedysarum and larvae were reared on red clover (CSG).

Habitat


Canadian Sulphurs occur in boreal forest openings in northern BC, with most known populations occurring along the Alaska Highway. Populations commonly occur at Second World War emergency airstrips, now overgrown with low vegetation (Ferris 1982). Both Canadian and Hecla Sulphurs occur along the Haines Highway in extreme northwestern BC.

Distribution

Distribution

Canadian Sulphurs occur from northern AK and YT south to northern BC and AB.

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)
COSEWIC
NativeS5YellowNot Listed
BC Ministry of Environment: BC Species and Ecosystems Explorer--the authoritative source for conservation information in British Columbia.

Additional Photo Sources

General References


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: 2024-12-11 6:13:42 PM]
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