Subject: Robber Fly?
Location: Baldwin Hills in Los Angeles, CA
July 20, 2012 11:56 am
Found this guy last week on a backyard window sill. S/he seemed a bit worn down. I’d guess length to be 3/4”.
I’ve pics of a larger yellow/black robber fly in the same area from last year, if you’re interested.
This brown one is smaller but reminiscent of other robber flies I’ve seen on your site.
Thanks for all your great work and insights.
This is not a Horse Fly. It is a Tachinid Fly, a member of a family of flies that parasitize other insects and arthropods. This is a large, diverse and confusing family, and we did not know if we would have much luck with a genus or species identity, but the white face seems rather distinctive. Upon doing a web search, we found this very similar photo on Bugguide, and we suspect your fly is probably in the same genus, Gonia. BugGuide has this photo of a genus member from California.