On September 15, 2006 I photographed these bees (or flies that mimmick bees) on a goldenrod. It was late in the afternoon and the bright sun gave color to the field. Jennifer found this large cluster of white and black bees that were only slightly smaller than honey bees. Their eyes were noticeably green and they were thickly covered in hair. All were congregated on a single goldenrod.
I did not count them, but there seemed to be around a dozen. I could not tell what was keeping their attention focused. I would like to identify these bees (or flies), but I have not been able to find information on them yet.