I spotted this little fly on the underside of a large leaf. I was really thrilled to find something so unusual. I probably spent about a half hour chasing it around from one perch to another. Luckily, it always flew just a short distance.
I had heard of antler flies before, and I figured this was a good candidate to be one. Initial internet searches using that phrase didn’t turn up anything though. On a whim I tried searching for “hammerhead fly” since that seemed like an obvious common name for this fly. That turned out to be a good guess, and I found lots of similar looking images of Richardia telescopica in the family Richardiidae. I’ve been unable to eliminate the possibility of similar looking species. If not for that uncertainty, I’d have made this into an identification challenge.
This “species of the day” page has some excellent illustrations and a bit of info on Richardia telescopica. The length mentioned there (15mm) seems off though. The same illustration appears in one of my references and it includes a scale which is consistent with the size I measured for this specimen.
Here’s a nice YouTube video of a similar species, Plagiocephalus latifrons.