Just spotted this today and luckily got an ID right away since it’s so distinctive. (Thanks to bugguide.net for the image.)
This is the four-toothed mason wasp, a solitary wasp that uses existing holes for its nest. Mine was eating the pollen on the clethra. It’s looking a little weedy here, but the scent is divine. You will just have to imagine the wasp cradling one of these blossoms.
Find out more at this informative site.
Caroline's Garden and Travel Record 