Seen here on a flowering stem of the shrub Psorothamnus schotti.

Note the "flag" of long, densely-packed, scales along dorsal edge of hind tibia; entirely orange abdomen; and tri-color wings (tawny-to-black-to-hyaline, from front to rear)...the last two characters indicate a male here (per references cited below).

The catalog entry for Trichopoda from O'Hara & Wood(2004) lists 3 spp. occurring in CA: pennipes, indivisa, and subdivisa.

This goes to Trichopoda pennipes using the key at the bottom of pg. 47 in Coquillet(1897)...but that key does not includes Townsend's species indivisa and subdivisa. However, both those species are in the nominate subgenus Trichopoda, whereas the individual in my photo is in subgenus Galactomyia per the characterization on pg. 135 of Townsend(1908) that males therein have "abdomen flattened" (see 2nd to last image in this series)...whereas in the nominate subgenus (described under "Polystomyia" on pg. 132) the "abdomen is subcylindric in both sexes".

[BTW, the original description of T. subdivisa (as Polystomyia subdivisa) appears on pg. 133 of Townsend(1908); and that of T. indivisa (as T. histrio var. indivisa) appears here in Townsend(1897)...but be forewarned that I often find his descriptions significantly wanting for additional detail.]

A detailed description of male & female T. pennipes and its biology appears in Worthley(1923).