Bees bugging each other

I hope that thistle counts for Flower Friday.  I was looking for bees on this once again very hot humid day, so was delighted to find one on this lovely purple color.  Then these other little bees of some sort (obviously I didn't learn enough in my Entomology class at Grandparents University to distinguish between the two) started bugging the bigger bee. He was flying around, so not in focus, but can still be seen!