Swarm control, have we been doing it wrong?
I think we could all benefit from discussion of the elements that lead up to a swarm issuing from a colony. I will post some thoughts about the behaviors of bees that lead to swarming. This is about reproductive swarming, not absconding. Swarming is the honey bee's natural method of reproduction so trying to prevent it is going against basic bee biology.
Genetics is a huge part of swarming. Some races and types of bees are hard wired to swarm every spring. Only extreme measures can normally prevent swarming with these bees. Carniolans and AMM black bees are examples of this biological imperative in strongest form. There remains a huge amount of variation that can be exploited to breed bees with reduced swarming tendency.
Bees will rarely swarm unless they have an abundance of drones in the hive, but if drone brood is removed from the hive, they will still swarm. I think the drones are a step in swarm preparation, but not a step that can be interrupted to effectively prevent swarming.
Bees won't swarm unless there is an abundance of nectar available. We had an unusual spring in 2007 with a freeze of -7C on April 7th which is during apple bloom in this area. This killed most of the spring flowers including fruit bloom and chinese privet. That year, there were no swarms. There also was no honey crop to harvest.
Bees in small hives become congested and swarm. I always heard that giving bees plenty of room to store honey was a huge part of swarm prevention. Well, there is a lot of truth to this statement, but it is not the entire story. A hive with volume of 1500 to 2000 cubic inches will almost always trigger swarming. A volume of 17,000 cubic inches will strongly suppress swarming.
The age of the queen is a huge factor in swarming. Older queens lay fewer eggs on average than young queens. A huge part of this gets down to formation of a honey dome, reduced queen pheromones, and supersedures that turn into swarms. Keep young queens that lay an abundance of eggs in your colonies and this swarm trigger can be prevented.
Bees will not swarm until they have "provisioned" the parent colony. This takes the form of constructing a honey dome above the brood nest. Break the honey dome - and keep it broken - and the bees will discontinue swarm preparation most of the time. Walt Wright documented this method of swarm prevention about 10 years ago. I've used it and it is highly effective.
The honey dome can be prevented from forming in the first place with management steps. This is common practice with "Brother Adam" square Dadant hives. The brood nest is constrained with follower boards so the queen has only enough combs to lay eggs. This forces the bees to store all surplus honey above the excluder which prevents formation of a honey dome except in exceptional circumstances. A prolific queen can keep about 7 modified Dadant frames filled with brood. Give her 8 combs to lay in and now there is room to form a honey dome and the bees will swarm.
Queen cells must be present before bees will produce a reproductive swarm. Swarms will usually issue sometime around the 10th day of the queen production cycle when the cell is sealed. It is possible to remove queen cells and prevent swarming. Miss just one cell and the bees will be in the air. This method is relied on by many beekeepers. Combining queen cell removal with other steps can be effective but is labor intensive and time consuming.
There must be an abundance of bees of all ages present in the hive. Swarms rarely issue from colonies with all old bees and no young bees or vice versa. Many beekeepers control swarming by removing the queen for 10 days shortly before normal swarm season, then giving a new young queen. This forced brood break disrupts the brood cycle so that either young or old bees are not present in quantities to enable swarming. Unless carefully timed, removing the queen can limit honey production because bees of the appropriate age to forage won't be present when needed.
Please add your thoughts about what constitutes effective swarm control. Do you encourage swarming to get more colonies of bees?
NW Alabama, 50 years, 20 colonies and growing, sideliner, treatment free since 2005, 14 frame square Dadant broodnest