This bee fly is perched on a flower of the rare Eremalche parryi ssp. kernensis, and is dusted with the pollen of the flower on tarsi, scutum, and wing-tips.

It keys to subfamily Phthiriinae in Hull(1), Cole(2), and the Manual of Nearctic Diptera(3). The radial vein R2+3 appears to originate proximal to the base of the discal cell, so couplet 31 on pg 598 of Manual of Nearctic Diptera(3) goes to genus Phthiria. But Joel Kits has pointed out on other BugGuide posts that no Nearctic taxa are placed in that genus anymore. Maybe it's in the genus Neacreotrichus?

This female bee fly was found at the same time and place as this male. Perhaps they're the same species? That male has "palpus extending at least as far as antennae", which the Manual of Nearctic Diptera(3) key lists as a key character for genus Poecilognathus. However, it also has vein R2+3 originating proximal to the discal cell, like this female, which contradicts the other character in the couplet leading to Poecilognathus, namely that R2+3 should originate opposite or distal to the base of the discal cell. So I don't know what to make of the situation. Perhaps this reference (mentioned by Joel in another post) would help:

Hall, J.C., and Evenhuis, N.L. 2004. Bombyliidae. In Flies of the Nearctic Region. Edited by G.C.D. Griffiths. E. Schweizerbart, Stuttgart. Vol. V, pt. 13, no. 7, pp 657–716.