California Hairstreak (Satyrium californicum) (W.H. Edwards, 1862)

Diagnosis: The California Hairstreak is very similar to the previous species. The underside is more brownish in colour, dark blackish brown towards the wing base. The orange cap over the blue spot is small and is not connected to the orange crescents on each side of it. Wingspan: 27 to 32 mm.

Subspecies: Subspecies californicum occurs in Canada.

Range: A widespread species of the western U.S., it occurs in Canada in southern British Columbia, mainly in the Okanagan Valley and in the Lillooet area.

Specimen collection data

Similar Species: The Acadian Hairstreak (S. acadicum) is pale grey underneath and the orange cap over the blue spot is prominent and fused with the orange crescents on each side of it. The Sylvan Hairstreak (S. sylvinum) has virtually no orange cap over the blue spot, the orange marginal band is reduced to one or two crescents, and the underside is pale grey; see also Remarks below. [compares images]

Early Stages: The larvae are grey brown, with light grey spots on the back and white chevrons on the sides. They have been recorded as feeding on buckbrush (Ceanothus spp.), Antelope-brush (Purshia tridentata) oaks (Quercus spp.), cherry (Prunus spp.), and Saskatoon (Amelanchier alnifolia). Reports on willow (Salix spp.) may be in error owing to confusion with the Acadian and Sylvan Hairstreaks.

Description of this image follows
California Hairstreak
(Satyrium californicum californicum).
Osoyoos, BC. G.J. Hilchie.

Abundance: It is fairly common throughout most of its range, but in British Columbia it is uncommon and local.

Flight Season: In British Columbia it has been recorded in the months of June, July, and August (Jones, 1951).

Habits: Unlike the similar Acadian and Sylvan Hairstreaks, which favour moist areas, this butterfly inhabits dry foothills, canyons, and chaparral. Like the others, it is fond of sipping nectar from roadside flowers.

Remarks: This is considered a threatened species in its localized British Columbia range (Guppy et al., 1994). Specimens in the Canadian National Collection from the Squamish area include specimens typical of both californicum and sylvinum, as well as others that fill in the range of variation between these two species, so we treat these specimens as possible hybrids.

© 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.