Grey Hairstreak (Strymon melinus) (Hübner, 1818)

Diagnosis: This distinctive hairstreak has a uniform slate-grey colour above and a bright orange spot above the tails. The underside is a lighter grey with a red and black median band. There are bright orange and black spots above the tails. It is our only hairstreak that is a uniform grey on the upperside. Wingspan: 23 to 29 mm.

Subspecies: There are four subspecies in Canada. Subspecies melinus (=humuli) is found in eastern Canada; subspecies franki occurs in the Prairies; subspecies setonia is found in the dry interior of British Columbia; and subspecies atrofasciatus occurs on Vancouver Island and the lower mainland.

Range: This widespread butterfly occurs from northern South America to southern Canada. It is rare in southern Nova Scotia and New Brunswick. It is uncommon to rare in southern Quebec, with one northern record from Neuville (Portneuf County) near Quebec City. It occurs through southern Ontario north to Matatchewan and was recently discovered in the Rainy River District in northwestern Ontario. From there, it ranges across the southern Prairies as far north as Lloydminster and across southern British Columbia.

Similar Species: None in Canada.

Early Stages: The larvae are variable green with white to purple diagonal lateral stripes. They feed on many plant species from up to 20 families, although in eastern Canada probably only on Sweetfern (Comptonia peregrina) in the Myricaceae; see Remarks below. The Grey Hairstreak has been a major pest of crops such as beans, cotton, and hops in the U.S.

Abundance: Despite being so widespread, this hairstreak is rare or sporadic in most of its Canadian range. At some locations, it disappears for years, then seems to reappear. It can be fairly common in southern Ontario and in western Canada.

Flight Season: There are two overlapping broods in most of its Canadian range, from April to the end of September. It has only been recorded in August in Manitoba (Klassen et al., 1989).

Habits: This butterfly is a fast erratic flyer, often seen feeding at flowers. In the west it occupies a wide variety of habitats from clearings in woods to vacant lots in cities.

Remarks: From at least Nova Scotia to northwestern Ontario, almost all records of Strymon melinus are from extremely dry, sandy, Jack Pine areas where Sweetfern thrives. It was reared once from Sweetfern in Nova Scotia (Ferguson, 1954) and has been seen alighting on this plant in Nova Scotia and Ontario. In several locations it has been seen in numbers over a period of years, so these records are clearly not of strays. In southern Ontario it is a seasonal migrant, appearing in the spring and breeding, but these populations feed on weedy plants of roadsides and waste places. Why it is so restricted in food plant choice at its northern limits is a mystery.

© 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.