I think there were two males and a female in this bunch, but I never got a good look in the field, I mistook them for wasps. They were about the size of a paperwasp. Now Eric already told me that they are mydas flies - and looking at the photos I can only imagine that I thought they were hymenoptera because they also made a noise like trapped wasps do. (excuses...it was also more than 100 F, humid, and swarming with real wasps)