This fellow spends a good portion of his time patrolling his flower patch. I have seen him run off both bumblebees and honey bees. He lets female carder bees stay to feed (but ambushes them for a quickie). I watched him drive off a honey bee the other day and the poor mellifera did not fare well. She staggered about the grass and had to rest a good while. I bent close to try to see any visible damage but she took to wing and landed nearby on the plum tree. She hung about there, still recovering, until a paper wasp decided she was an easy target and drifted in for lunch. This caused the honeybee to suck up whatever energy she had and leave this yard of hoodlums.