Sylvan Hairstreak
Satyrium sylvinum (Boisduval, 1852)

Click on image for larger view

Diagnosis: More greyish above than the other similar species, the Sylvan Hairstreak is also lighter grey below. The black spots are small but still distinct, and the orange spots are indistinct or even absent. Wingspan: 25 to 30 mm.

Subspecies: There are at least five variable subspecies named from throughout its range depending on habitat. Subspecies putnami, which is pale grey beneath, occurs in British Columbia.

Range: The Sylvan Hairstreak occurs from Baja California north into southern British Columbia and east into Colorado and Wyoming. It is widely distributed across southern BC from the Columbia River Valley (Cranbrook) to Vancouver Island, and as far north as 51° N, with isolated records further north as far as Endako. It has been recorded at Crowsnest near the BC/Alberta border, but has not yet been reported in Alberta.

Similar Species: The California Hairstreak (S. californicum). [compare images]

Early Stages: The larva is pale green, with two cream lines and oblique pale dashes on the sides. It feeds on willows (Salix spp.).

Abundance: The Sylvan Hairstreak is very local, never straying far from the willow foodplants.

Flight Season: The adults are on the wing in July and August.

Habits: The Sylvan Hairstreak is rarely found away from moist wooded areas. It is often found nectaring on milkweeds in woods and clearings and along streamsides.

© 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.

The Toronto Entomologists' Association thanks Agriculture and Agri-Food Canada for providing the content and computer code for this web page.