Between about May 12th and May 27th, I was quite regularly finding these wonderful therevids floating in the pool. Sadly, they were quite delicate and many of them did not survive their ordeal. Some lived to fly another day though and I documented them all as best as I could. I have already determined that these belong somewhere in Genus Nebritus. I have come to this conclusion based on these other images in the guide, this online key, and most notably via personal communication with Dr. Hauser.

By far, the most fascinating part about these flies was the extremely unusual way that they moved their antennae and proboscis together, in a sort of snapping jaw kind of motion. (To me, it looked rather comically like a silent dog barking! Possibly best seen in this image.) I have no idea what purpose this action serves and would love to hear if anyone has ever seen something similar.

Please also see these other posts showing different specimens of the same species:

Specimen 2: Specimen 3: Specimen 4:
Specimen 5: Specimen 6:

Mixed oak & chaparral habitat.