That's a great find! Rhaphiomidas are impressively large flies and remarkable wasp-mimics. They're also not commonly encountered, and when seen are typically found in fairly wild habitat...so the perforated metal grate here is somewhat curious.

BTW, could you please give the date when this photo was taken? That might help place this (some species fly early in spring, others in late summer, etc.).

It would also be helpful if you could provide more precise location info beyond county (i.e. nearest town or geographic landmark. And perhaps some habitat info (i.e. was it by a sandy field in the Central Valley, or near a desert wash on the east side of the Sierras, or a mountain canyon, or...??).

Thanks for your post.

Moved from ID Request.

Thank you!