A truly lovely pool rescue which was off and flying again within minutes of being removed from the water. I did my best to follow the fantastic key, The Bee Flies of Ontario, with a Key to the Species of Eastern Cananda (created by Kits, Marshall, and Evenhuis), and have paraphrased below the characteristic traits which seemed to apply to my specimen:

* Wings at least as long as abdomen
* Proboscis short to medium length, extending beyond oral margin by less than length of antennae
* Antennae shorter than head length, basal segments with short pile or bare
* Hind margin of eye strongly indented; usually with dense pile or tomentum
* Shape and colour variable, but not with conspicuous white pile on both face and end of abdomen. Vein R2+3 arising from R4+5 at a right angle near crossvein r‑m. (NOTE: It was extremely difficult for me to see the intersection of vein R2+3 with R4+5, but it definitely did not have noticeable white pile at either end, so I made the assumption that the intersection of the veins must indeed be perpendicular.)
* Antenna with one or two antennal flagellomeres and an apical stylus but without a terminal tuft of hair. Basicosta sharply pointed and narrow, laterotergite and mediotergite with pile. (NOTE: I couldn't see either of the characteristics pertaining to the shape of the basicosta or the appearance of pile on the tergites.)
* Veins R2+3 and R4 not connected by a crossvein
* Face projecting, usually conical
* Face with only thin, mostly erect hairs; wings extensively smoky brown with or without clear spots; basal antennal segment strongly expanded at apex in dorsal view, wider than 2nd segment. (NOTE: I couldn't see the basal antennal segment clearly enough to determine how strongly it was expanded.)

Following these characteristics, it ended up keying to the genus Poecilanthrax. There is a further key provided for that genus, but as it is region-specific, I didn't know how helpful that would be. (For example, the only species of Poecilanthrax currently identified in BugGuide from CA is P. arethusa, which is not included in the aforementioned key.) Confirmation of genus and ID help to species would be greatly appreciated!

Mixed oak & chaparral habitat.