Only today I had a similar experience. Inside a flower on a pumpkin plant there were 4 BBs going round and round. It was impossible to decide which BB they were as they were smothered in pollen. They must have been working this flower for at least half and hour.
Sparrow - Sue
Liatris are quite tall and I have seen several bees contentedly browsing on one flower spike. Often there are different species on the same plant too…solitary bees, bumbles, butterflies and hoverflies all together.