Nucleus, weak, and queenless colonies may be quickly destroyed and robbed of all their honey stores. Strong colonies may lose many workers in robbing or in fighting robbers to protect their own stores. The frenzy reaches its height when the honey supply is exhausted, but it may be some time before the colony returns to routine activities. Robbers are easily recognized as they eventually become smooth, shiny, and almost black. Robbing is a bad habit that is difficult to break.
Careful beekeepers know that the best way to combat robbing is through prevention.
If you notice robbing in the apiary, you immediately should reduce the entrances of all hives according to colony strength. You also should close off all cracks or openings in the equipment through which robbers might gain entrance. In addition to reducing the entrance, it may help if you lay a board from one side of the bottom board to the other. This forms a tunnel through which the robber must pass and in which the hive bees congregate and defend themselves. A large bunch of weeds or grass thrown in front of the entrance will also hinder the robbers.