I compared the wing venation with the genera key on the Canadian Journal of Arthropod Identification and it seems to match P. tegminipennis. The wings were smoky brown but in certain llght the lower half looked clear. I'm not at all confident with this i.d. though so any comments or corrections would be appreciated. I found these beeflies mating in a weedy field in the middle of a very hot (29C) day. I'm not sure which one is the female but the fly on the bottom was being dragged around through the weeds by the bigger fly on the top.