While there are 120 different species of bee fly in this genus worldwide, there are only 5 species in North America. While that gives us pretty good odds at a guess, based on geography and appearance we believe this might be Systoechus oreas (found along the west coast and Rocky Mountain region). They are parasitoids of grasshoppers.

Photo by: Kristi DuBois on 7/17/21 in Missoula, MT