There were 6 of these in close proximity in the garden. At one point, one was next to a smaller "smiley face" triepolus. None were attempting to mate. When I checked again in about 2 hours, they were still in the same area. I looked at the triepolus ID page, but none had the same markings on the thorax, although one was similar. I thought the points under the abdomen might also be diagnostic. There are very large numbers of bees in the garden, and I worry that in my attempt to make a bee-friendly garden, I have made it too easy for bee parasites.