Glaucopsyche lygdamus australis

'Southern' Silvery Blue

If you encounter a Silvery Blue butterfly in southern California, chances are good it is subspecies australis. Exceptions are populations in San Luis Obispo Co. (sabulosa, incognitus); on Santa Rosa Island (pseudoxerces); in the eastern Mojave desert ranges (deserticola), or on the Palos Verdes Peninsula (palosverdesensis). If you're in the southern Sierra Nevada mountains, there are populations that may merit naming in the future. So this means that what I've seen in the mountains of Santa Barbara Co., in the Santa Monica and San Gabriel Mountains, down into Riverside and San Diego counties, are all australis.

The Silvery Blue is single-brooded, with an early flight (usually February to April). The usual host is deerweed - Acmispon glaber (formerly Lotus scoparius) - which is common in cismontane southern California. Larvae - which may be ant-attended - feed on the plant and then leave it to overwinter as pupae. Along the coast, butterflies may emerge surprisingly early if conditions are right: I photographed a fresh male in Pt. Mugu State Park in Ventura Co. on January 12, 2006.

Glaucopsyche lygdamus australis - 'Southern' Silvery Blue
Male 'Southern' Silvery Blue, Glaucopsyche lygdamus australis, West Fork Trail, San Gabriel Mountains, March 16, 2006.
Glaucopsyche lygdamus australis - 'Southern' Silvery Blue
Females have blue scaling against a dark ground color. When you explore the different subspecies, the ground color and extent of blue in females can be an important trait. This was along Barrett-Stoddard Truck Trail, San Gabriel Mtns, April 1, 2007.
Glaucopsyche lygdamus australis - 'Southern' Silvery Blue
Ventral of australis, West Fork Trail, San Gabriel Mountains, March 16, 2006.
Original description of Glaucopsyche lygdamus australis
This is Grinnell's original description of what is now G. lygdamus australis, from the journal Canadian Entomologist in 1917. Grinnell, living in Pasadena, founded the Lorquin Entomological Society (then the Lorquin Natural History Club) in the summer of 1913.

©Dennis Walker