Queen Alexandra's Sulphur (Colias alexandra) (W.H. Edwards, 1863)
Diagnosis: This is one of the larger (wingspan: 38 to 57 mm) sulphurs, with a bright yellow upperside and narrow black borders. The fringes of the wings are yellow, with the silver spot on the hindwing beneath lacking a darker rim (subspecies alexandra) or there may be pink on the fringes and around the silver discal spot (subspecies columbiensis). Females of subspecies alexandra have some dark shading on the margin, but those of subspecies columbiensis have little if any. White females are common, especially in subspecies columbiensis. This species has ultraviolet reflectance on the hindwing between the central pale yellow spot and the black border. This area can frequently be seen as a darker yellow patch compared to the paler colour of the wing base and the forewing.
Subspecies: There are two subspecies found in Canada, the nominate subspecies alexandra in the prairie regions of Saskatchewan and Alberta and subspecies columbiensis in southern British Columbia.
Range: A western U.S. species occurring from New Mexico north into southern Saskatchewan, southern Alberta, and southern British Columbia. In British Columbia it is most common in the Okanagan and Kootenay Valleys and in the dry interior between the Cariboo Mountains and the Fraser River.
Early Stages: The green larva has alternating light and dark stripes running its length. It feeds on a wide variety of legumes, including milk-vetch (Astragalus spp.).
Abundance: Queen Alexandra's Sulphur is fairly common in its range.
Flight Season: This species is on the wing in Canada from mid-May to August.
Habits: Subspecies alexandra prefers high prairies, while subspecies columbiensis flies in open coniferous forests. Both subspecies frequently visit flowers in meadows and along roadsides and are regular mudpuddlers.
Remarks: This species and Christina Sulphur (Colias christina), have been considered to be one species for the last 30 years. However, based on geographic distribution, habitat preferences, female wing pattern, and male ultraviolet wing patterns, Ferris (1993) recognizes them as separate species. See also Remarks under Western Sulphur (Colias occidentalis).
© 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.
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