At base of Chalk Bluffs, near Pleasant Valley Campground, Bishop area, Inyo County, California, USA
August 8, 2017
Found in late afternoon resting in the shade on a large chunk of volcanic rock (welded tuff), a bit above the base of Chalk Bluffs just north of the Owens River. This mating pair stayed absolutely motionless for quite some time while I walked back to the vehicle to get my camera, and also for many minutes more after I returned. Then all of a sudden it darted off in a flash, spooked by some relatively minor movement compared to our proceeding movements while positioning to get photos.
Appeared to be a therevid in the field, and though I couldn't positively verify all the characters in keying it to family in the MND(1)
, it did seem to go best to Therevidae.
Similarly, in the MND(1)
key for family Therevidae, I don't have enough detail in my photos to navigate all the detailed character couplets...but going "both ways" at unclear junctures, the best candidate I got was Ammonaios
. And consulting:
Hauser, Martin & Michael E. Irwin (2003). The Nearctic Genus Ammonaios Irwin and Lyneborg 1981 (Diptera: Therevidae). Ann. Entomol. Soc. Am. 96(6): 738-765. (Full Text)
...my best guess would be A. confusus
, which also has nearby records (e.g. at Fish Slough
Alice Abela also got some photos of the pair before it darted off, perhaps hers may show more diagnostic characters.