With the reading that Mickey has done, I am sure he will have found the physical and management techniques that can be used to reduce the robbing.
The robbers don't sound like honeybees.
In New Zealand, there is a big problem with wasps. In parts of Europe it can be Asian Hornets. In both these parts, insecticidal paths are used. In NZ, a bait called "Vespex" is used. In Europe, an insecticidal "Dear John" is attached to stunned foraging hornets.