At ~3860' on Sawmill Creek, Clear Creek Management Area (BLM), San Benito County, California, USA
September 9, 2007
I think this is
Toxomerus marginatus from searching through BugGuide photos/comments (and a "semi-reinforcing" experience working through the key to Syrphidae in Cole
(1)). If it is, I 'm guessing it's a female from the black stripe on the frons (compare with the gravid member of this pair

). Please let me know if you think I've erred!
It was photographed on an uncommon Goldenrod species
Solidago guiradonis along a creek in the unusual "chaparral/conifer woodland" habitat of the large, arid, serpentine area of Clear Creek near San Benito Mountain.