Satyrium sylvinus desertorum

Sylvan Hairstreak

This subspecies flies from approximately May to August in a single brood in habitats where the host willows thrive. In Jim Brock's Caterpillars in the Field and Garden, he says (p.56) the larvae can be found from April to July, and the eggs hatch as the willow buds appear. According to Ken Davenport, nominate sylvinus reaches into southern California in the Greenhorn Mountains; the subspecies dryope is found from the Frazier Park vicinity west and southwest into SLO, Santa Barbara, Ventura, and western L.A. counties. The rest of southern California down to San Diego County should be this subspecies: desertorum. That includes a blend zone with dryope in the San Gabriels. These are said to be lighter than the nominate subspecies, and a bit darker than dryope, and unlike the latter it has tails.

The type locality - Oak Creek - is in the Tehachapis a few miles west of the town of Mojave. The Pacific Crest Trail runs along Oak Creek for several miles. It would have looked very different in 1905 when the types were collected; today the ridgeline is dominated by wind turbines.

Photograph of Satyrium sylvinus desertorum - Sylvan Hairstreak
A Sylvan Hairstreak along the West Fork trail in the San Gabriel Mountains. June 1, 2007.
Photograph of Satyrium sylvinus desertorum - a Sylvan Hairstreak butterfly
Satyrium sylvinus desertorum at Upper Newport Bay, Orange Co. June 18, 2007.
Photograph of Satyrium sylvinus desertorum - a Sylvan Hairstreak butterfly
This is the original description by Fordyce Grinnell of Satyrium sylvinus desertorum. It was published in 1917 in a journal from the University of Toronto called The Canadian Entomologist. Grinnell was president of the Entomological Club in Pasadena, and he organized the Lorquin Club, which in 1927 changed its name to the Lorquin Entomological Society.

©Dennis Walker