Satyrium sylvinus desertorum
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.