To stop robber bees empty and DRY comb can be put close to the hive entrance of the attacked colony. The entrance itself should be a bit reduced stil allowing desired ventilation. The comb MUST NOT contain any drop of honey. A large portion of robber bees, especially those not well informed about the real target, will search for the honey in the pretty smelling but empty comb. After some time they return to the maternal colony and probably inform it that the source was exhausted. The attack ceases than rapidly. This workes well if the robbed colony has some endeavour to defence. Vladimir Ptacek, Brno, Czech Republic ([log in to unmask])