Pelidne Sulphur (Colias pelidne) (Boisduval and Le Conte, 1830)

Diagnosis: One of the smaller sulphurs (wingspan: 33 to 44 mm), this species is pale yellow with medium to narrow black borders and dark scales at the wing base on the upperside. Females can be white or yellow with the black borders reduced or almost absent. The spot in the centre of the hindwing above is faint. There are pink fringes to the wings. The hindwing underside is dark olive-coloured with a pink-rimmed spot; the pink shading often extends over the white spot.

Subspecies: The eastern and western arctic populations are the nominate subspecies pelidne. Subspecies skinneri is smaller and occurs in the Rocky Mountains.

Range: The Pelidne Sulphur has three widely separated populations. In the east it is found in Newfoundland, Labrador, Ungava, southern Baffin Island (Iqaluit on Frobisher Bay), and around the eastern and southern shores of Hudson Bay and James Bay. The northwestern population is known from Atlin, in northwestern British Columbia, the southern Dempster Highway and the British Mountains in Yukon, and from a few locations between Great Bear Lake and Port Epworth, on the arctic coast of Nunavut. The third population occurs in the Rocky Mountains from Wyoming and Idaho in the U.S. north in southeastern British Columbia and western Alberta as far as Horn Ridge, Alberta.

Similar Species: The Heath Sulphur (C. chippewa) lacks the red rim around the underside spot in the centre of the hindwings. The Pink-edged Sulphur (C. interior) has an orange rather than a yellow spot in the centre of the hindwing above, the hindwing underside is yellow rather than olive, and the spot in the centre of the wing is white without the pink suffusion of pelidne. [compare images]

Early Stages: These are undescribed, but the larva feeds on blueberry (Vaccinium spp.).

Abundance: This species is fairly common in northeastern Canada and in alpine habitats in the Rocky Mountains. It is rare and local in northwestern Canada.

Flight Season: Adults occur from late June to early August in most of its range.

Habits: In the north the Pelidne Sulphur is found on the arctic tundra, and in the Rocky Mountains in alpine meadows just above tree line. However, on the northern part of the James Bay Highway in Quebec it flies with Pink-edged Sulphur (C. interior) in bogs and even along roadsides well south of treeline, and in Newfoundland it is found along low-elevation roadsides and on mountain summits above treeline.

© 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.