Silvery Blue
Glaucopsyche lygdamus
Description
1-1 1/4" (25-32 mm). Above, male silver-blue with narrow black margins; female dark with diffuse, wide dark margins, sometimes blue restricted to base, or wings totally brown. Both sexes pale gray to dark brownish-gray below, usually with 1 bold, crooked row of black rounded dots, each ringed with white (missing in northern populations); very few other dots, and sometimes a bluish cast to wing bases.
Endangered Status
The Palos Verdes Blue, a subspecies of the Silvery Blue, is on the U.S.
Endangered Species List. It is classified as endangered in California. This butterfly relies on a single plant species, called the Southern California Locoweed. After a critical coastal sage scrub habitat in Palos Verdes Peninsula containing its food plant was turned into a baseball diamond, the butterfly disappeared and was presumed extinct. Eleven years later a population of Palos Verdes Blues was spotted in a small stand of its host locoweed. The butterfly now survives on Department of Defense property. Efforts are being made to save critical habitat and reestablish the locoweed in its native range.
Similar Species
Common Blue lighter beneath, spots less contrasting with rims, usually with a marginal row of spots. Reakirt's Blue much smaller, with prominent spots at HW outer angle (tornus).
Life Cycle
Egg laid on various hosts in legume family (Fabaceae): deer weed (Lotus scoparius), lupine (Lupinus), wild pea (Lathyrus), vetch (Vicia), locoweed (Astragalus), and others. Mature caterpillars variable: green to tan with darker (often reddish) back stripe and lighter, oblique dashes on sides. Pale brown chrysalis marked with small black dots; overwinters.
Flight
1 brood; about 1 month, precise time varying with altitude and latitude - March-July depending on location.
Habitat
Widespread from sea level to above timberline: mountain meadows, open woodlands, brush, disturbed or burned areas, canyons, seeps, and streamsides.
Range
E. Alaska and Nova Scotia south to Baja California, central Arizona, New Mexico, Oklahoma, Alabama, and Georgia.
Discussion
The slow-flying Silvery Blue is among the first species to appear in spring. It is easily recognized by the small number of dots on the underside. Over 10 geographic races are identified; the shade of blue, depth of iridescence, and size of spots very dramatically from area to areas. These blues can stand chilly, windy weather in the early spring but never linger into late summer.
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