Full-size 960 x 962 image here.

Seen here nectaring on the gigantic flowers of Chorizanthe diffusa. (Just kidding...though actually, the flowers are quite large compared to those of the congener barely visible at the bottom of the image...the newly described Chorizanthe minutiflora. Way to go Randy & David!! :-).

[Note: Hartmut corrected by initial mis-ID of Conophorus here in the comments thread...my original remarks appear below for context.]

Keyed to Bombyliidae, then Conophorus in the MND(1), then to C. collini in Hall & Evenhuis(2). There are only two species of Conophorus with pictured wings (among 18 nearctic taxa in total). C. collini can be distinguished from the other one, C. fenestratus, by its bilobed scutellum...with the lobes shining black and the median suture filled with yellowish tomemtum, well-illustrated in Hartmut, Alice, and my photos:



This one is a female...they have very well-separated eyes in Conophorus, while males have eyes contiguous.

These have interesting wing venation too...with the cross vein between R2+3 and R4+5. Neat creatures!

It's interesting that Hartmut's and Alice's posts (in thumbnails above) are from sandy coastal adjacent habitats (Pt. Mugu, Oso Flaco Dunes, and Burton Mesa). The Conophorus and Chorizanthe here were also growing on sandy substrate...part of the remains of the extensive past dunes widely occupying the southern Monterey embayment, that have since been pioneered and colonized by maritime chaparral and the distinctive oak woodlands of the Fort Ord area.