There again today
My theory is the bee goes to sleep in a female flower, and wakes up in a male flower the next morning. I think the flower it's on supports this. It looks like it has just become male or is not quite there. It's hard to get a good picture with the lighting issues, and the bee inside still. It looks like the ball/sphere is mostly covered in yellow/amber honeycombs, with a bit of green near the tip. The bee I saw in the morning on Monday was on top of a male flower that was partially fallen apart. I'm not sure if they fall apart that quickly after turning male, though he could have just been there by chance.
Maybe the bees check out male flowers to sleep in, in the early evening, but the petals fall off making them unsuitable shelters, so they move on to female flowers. The petals and sepals fall off easily in male stage. If they slept in a female the night before, which was a male when they woke up, they might still have some pollen on them (or if they just tried to sleep in a male flower). If they get up around 9:30 and go to bed somewhere around 5, that's only 8 hours the pollen would need to stay on them and viable.
If the pawpaw is evolved to be pollinated by these bees, a few features of their anatomy would make sense: flowers that turn from female to male, turning to male quickly after pollination, and the petals falling off very easily in male stage.
