I finally found the bees! In fact, it’s been Buzzapaloosa around here. The honeybees have been hiding in the bladder campion. Nice to see I was remembering correctly that it’s a popular flower with them. The bumblebees are a lot easier to spot, naturally.
Some of the most beautiful bees are these tiny metallic green sweat bees. I can just see them as little glints of color flitting between the smallest flowers. Now I think I know what this is: Agapostemon virescens among the other little bees on the daisy fleabane.
Update: It’s a small carpenter bee of genus Ceratina.