Bad photo. Wind wouldn't let me focus...
One of the great "mud-puddling" species. These are all males, extracting sodium/minerals for the production of spermatophores.
Western Morning Glory (Calystegia occidentalis), Mitchell Canyon, Mount Diablo State Park, Contra Costa County, California - 4 July 2012. Corrections welcome. A bee fly (Bombyliidae, possibly Hemipenthes sinuosa) is visiting the lower flower.
Eating Asclepias californica