"Swarm Prevention" is the term used for the steps taken by the beekeeper to reduce the chances of swarming before the visual signs a colony is preparing to swarm are seen. "Swarm Control" is the action taken after the visible signs of the colony intending to swarm are seen. Some beekeepers think they mean the same thing, but they don't. I think swarm prevention is misleading and "Swarm Reduction" might be a more accurate term, but I won't try to change established terminology.

In my view, swarm prevention should be a major part of all management methods and I include some below:-

The Bees.

• Some bees are much more prone to swarming than others. It is universally known that Carniolans(Apis mellifera carnica) are heavy swarmers and this is accepted by beekeepers in countries where carniolans are the bee of choice. My own experience, based on helping others, is they are more swarmy than most. I haven't used any myself for a very long time, but I once helped a new beekeeper who bought a nucleus headed by a carniolan queen. The next year they swarmed and later in the season, both the parent colony and the swarm swarmed again. Four colonies for the price of one, but little honey! The message here is if you use carniolans, then expect heavier swarming than you may be used to and inspect regularly.
• The higher the number of swarm cells that are built by a colony, the more swarmy it will be - see Peak Queencell Number (PQN). When using swarm cells to raise queens, e.g. when artificial swarming, only use those from colonies that produce relatively small numbers, say no more than 10-12. This of course is at the point of swarming.

The above points are relevant to the types of bees that are kept. The good beekeeper will cull any colonies that show strong tendencies to swarm. In my opinion Bee Improvement should be a major part of all beekeeping management systems and selecting for lower swarming tendencies could be one characteristic.

Colony Management.

• Understand the life cycle of the queen and the swarming procedure.
• Inspect your colonies regularly.
• Congestion is often a problem. There are two issues you need to think about, firstly the amount of room there is for honey and nectar, secondly the room for the brood. In the wild, a swarm has already chosen the cavity it uses and it is known they take size into account. There are usually no restrictions, as they use the comb for storing honey and raising brood. They can't do that with managed colonies, where the beekeeper is constantly changing the capacity and confining the queen by the use of a queen excluder. It will reduce the chance of swarming if the brood box and queen are matched. Putting a colony with a prolific queen in a small brood box is likely to result in early swarming. Supers should be added in advance of requirements.
• Overheating is often said to cause swarming, but I think this is quite a complex issue. When everyone used solid floors, bees would often cling to the outside of the hive in full sun, presumably to shield it. When open mesh floors (OMFs) are used this rarely happens, presumably because ventilation is better. I use solid and OMFs in equal quantities and in my experience swarming is still at about the same level. Having said that I put my hives in shade, as I think it causes less stress to a colony.
• It is often said that colonies are less likely to swarm if they have a young queen. With prolific queens I will agree with that, but in my experience not with non-prolific ones, where colonies will usually give good account of themselves irrespective of the age of the queen and not show any greater inclination to swarm.

If you attend to the details above you have done as much as you can to reduce swarming. Regular inspections will still be needed and as soon as eggs appear in queen cells you will need to use some method of swarm control.

With the current queen problems, it has become common for a colony to swarm on supersedure cells if they are built during the summer. Similarly it is also likely that colonies will swarm on emergency cells. Swarm prevention will not prevent swarming in either situation, because the queen cells were not built under the swarming impulse.

Roger Patterson.

Page updated 17/11/2022