This is a tentative ID on a brown hairstreak I photographed on the blooms of our native buckwheat (Eriogonum fasciculatum) here on the property. Per Kenn Kaufman's Butterflies of North America, Hedgerow Hairstreaks are "the most common brown hairstreak in the west, and a regular visitor to flowers...Most common in lower foothills, but ranges from coastal dunes to lower mountains. Flies in late spring or summer...Distinct post median line may or may not be edged with white."
5/31/10 Hedgerow Hairstreak (Satyrium saepium).
FAMILY: Lycaenidae (Gossamer-Winged Butterflies)