This particular plant is covered with these beauties.  I gave identification a shot, but realized quickly that I’m not very good at butterfly ID, so I wrote to fellow MG Kathy, who is a butterfly enthusiast and expert.  She identified it, and forwarded her ID to Dr. Shapiro at UC Davis, the primary force behind Art Shapiro’s Butterfly Site.

Dr. Shaprio confirmed that Kathy was correct in identifying this as Mitoura gryneus nelsoni, commonly known as Nelson’s Hairstreak.  Dr. Shapiro says it’s a female, and I’ll take his word on that.  Thanks Kathy and Dr. Shapiro!