Residence near Rosebowl, Pasadena, Los Angeles County, California, USA May 10, 2012 Size: 10 mm
Taken on Sisyrinchium bellum, where the females appear to obtain most of their pollen load, at least in my garden. I also see them on the Sage.
Photos for convenience on Eriogonum crocatum after cooling the bee; worked out better than the Sisyrinchium.
Looks like A. californica may be a good candidate. Or?