Robbing is a term used by beekeepers to describe bees that raid another hive and take all of the honey back to their own hive. Robbing is particularly prevalent during nectar dearths that occur in the warm months of summer or early fall.
The robbing bees may come from within an apiary or from neighboring areas. At first glance the cloud of robbers may look like a small swarm or a group orientation flight but, on closer inspection, the beekeeper will see that the robbing bees are all older foragers. They are in a frenzy, and there may be fighting at the entrance. Although fighting is a sure sign of robbing, if the bees in the invaded hive have already surrendered or the guards have been killed, fighting may be absent.
Robbing is triggered by the smell of honey. It often starts just after a beekeeper has opened a hive for inspection, for feeding, or to remove honey supers. In less than an hour after opening, a hive may be engulfed in a black cloud of invaders.
Robbers are not at all gentle or neat. They rip cells open, leaving waxy shards on the bottom board and jagged, rough edges on the comb. They may kill many bees, including the queen, to get what they want. Although they leave at nightfall, they will be back bright and early the next morning. Robbing is always a case of the strong preying on the weak.
It is difficult to stop robbing once it starts, but here are some things you can try:
- Completely cover the hive with a wet sheet to keep the invaders from getting in.
- Close up the hive completely for several days until the robbers give up. Be sure to provide feed, pollen, water, and ventilation for the confined colony.
- If you don’t have screens, reduce entrances and fill remaining openings with grass.
It is much more effective to anticipate robbing and take preventive measures than to try to stop it once it starts. Here are some strategies that may work—at least some of the time.
- Reduce entrances at the first sign of a nectar dearth. Bees can successfully defend their hive if they have a large enough population and a small enough entrance.
- Many beekeepers have observed that Italian bees rob more often than other sub-species. If you keep Italians, you should be more vigilant.
- It appears that queenless hives are more vulnerable to robbing than queenright hives. Make sure all your hives are queenright as robbing season approaches.
- Entrance feeders seem to promote robbing more than other feeders, probably because the food source is so near the hive opening. Use some other type of feeder during nectar dearths.
- Small or weak hives are particularly vulnerable. Consider combining such hives before a nectar dearth.
- Commercial robbing screens are highly effective devices that allow the resident bees to get in and out while discouraging the robbers. These can be especially valuable for use on weaker hives that you do not want to combine.