Hecla Sulphur (Colias hecla) (Lefèvbre, 1836)
Diagnosis: This truly arctic butterfly is dark orange above with black borders and dark scaling near the body. There is also a smeared brighter orange spot in the centre of the hindwing. The underside is greenish yellow with a pink-rimmed silver spot in the hindwing that extends as a red streak towards the outer margin of the wing. The female has orange spots in the dark borders and more dark scaling than the male. Wingspan: 33 to 45 mm.
Subspecies: In Canada, the nominate subspecies hecla is found throughout most of the range. Subspecies hela, which is a bright, more yellowish orange, occurs in northern Manitoba near Churchill.
Range: The Hecla Sulphur is a true holarctic species found around the northern part of the Northern Hemisphere. In Canada, it flies from coastal Labrador and northern Quebec through the Arctic Islands to northern Ellesmere Island, and from the western side of Hudson Bay (Churchill, Manitoba) through Nunavut, the Northwest Territories and Yukon to Alaska.
Similar Species: The other orange northern sulphurs are similar. Mead's Sulphur (C. meadii) is more orange above and greener below. The range of the Orange Sulphur (C. eurytheme) overlaps in northern Alberta; it has brown spots on the forewings below. See also Johansen's Sulphur (C. johanseni), and Booth's Sulphur (C. tyche). [compare images]
Early Stages: Like most sulphur larvae, those of hecla are slender and green with lateral stripes and tiny black points. They feed on a number of northern legumes, but Alpine Milk-vetch (Astragalus alpinus) appears to be the most common foodplant.
Abundance: This butterfly can be common in the far north, but becomes less common farther south, where it can be local and rare.
Flight Season: It is recorded flying from late June into early August. It probably takes two years to develop into an adult (Howe, 195).
Habits: This is mainly a wet-tundra species. Like most arctic species, it is low flying but can be very swift.
Remarks: The evidence of possible hybridization between this and several other arctic sulphurs has caused a great deal of confusion (see Booth's Sulphur).
© 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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