Guide to bee swarming
Useful information about the reproduction of bee colonies
What is swarming and why do bees do that?
Have you ever seen something similar like in the picture? Looks scary, right?
The sight of swarming bees can certainly cause anxiety in some people.
However, you should know that swarming is a fundamental and almost magical part of the bee’s life cycle.
Let’s think about bee reproduction. During the year the queen bee lays lots of eggs, the worker bees are born and form the colony. We call it the “individual bee reproduction“. Keep in mind that a worker bee only lives few months. If bees would reproduce only in this way, bees would have difficulties to reproduce as a species1.
So, what about the colony itself? How does an entire colony reproduce?
Imagine a hive in spring and summer.
During this time a colony can grow massively, both in terms of number of worker bees and needed space. The available space becomes smaller and smaller. How would you feel if your home is packed with so many people? You would probably split up and find a new place to live. This is what bees do when they swarm2.
When bees swarm, it means that one colony just became two colonies. We call it the “reproduction at the colony level”.
With swarming, bees try to solve a very apparent space problem and in the same time they follow their instinct of survival and reproduction.
Are bee swarms dangerous for people?
As we learned previously, swarming bees are on their way to find a new home. If you are not a beekeeper who wants to catch the swarm, you should keep a natural distance and avoid threatening the bees. If they feel threatened, they sting and you probably don’t want that to happen. Even if the swarm is placed in inconvenient interim locations: Do not try to move or destroy the swarm at all cost, as this move could have serious consequences3.
How does swarming exactly work?
We can break down the swarming process to the following 9 phases:
1) Usually in spring and early summer, the “collective wisdom” of the colony decides to swarm (for space and reproduction reasons);
2) The colony prepares several future queens in so-called “queen cups”. Queen cups are regularly created by worker bees, but the existing (old) queen lays only eggs in it when swarming is imminent. When she does it, she clearly plans to leave and let another queen bee take over the existing hive;
3) At this point, the old queen is heavy. Her latest task was to produce a lot of eggs. She isn’t able to fly well and needs to lose weight. Worker bees reduce her feedings and she stops laying eggs, becoming lighter. Immediately before swarming, the bees that intend to leave the colony gorge themselves with honey (like packing a box lunch before a long trip).
4) Before any new queens emerges, the existing queen and about half of the bees of the colony (called the “split”) leave the hive, searching for another home. Right before they abandon the hive, they gorge themselves with honey to get ready for the trip. Then, thousands of bees stream out of the hive;
5) The split (or swarm) temporarily moves to an interim location, not very far away from the original hive, where it rests for a while. The queen is still not able to fly long distances;
6) The split sends out “scout bees” to check the area for suitable final locations. This process might take from one to a few days, so don’t worry if you see a swarm hanging on a tree for more than a day. It doesn’t mean that it will stay there forever;
Don’t worry if you see a swarm hanging on a tree for more than a day. It doesn’t mean that it will stay there forever
7) Scout bees then “debate” and “vote” for the new final location. When the democratic decision is taken, the split flies off and moves to the final location, where it begins its new colony life.
8) Meanwhile in the old hive: The queen bee that emerges first from the queen cups will hunt down her as-yet-unborn sister queens and kill them while they remain in their queen cups. Worker bees will help her removing the wax capping and give her access to the unborn. Once made sure that she is the only queen bee left, she becomes the new queen;
9) The worker bees accept her and consider her their new queen of the old hive. The colony in the old hive begins its life.
Result: Two out of one! Two colonies are now about half the size of the original colony and they just continue living in different locations.
Why do beekeepers consider swarming as a problem?
When searching for a new location, the splitting part of the colony could basically be gone forever. Nobody exactly knows where the swarm will end up. A beekeeper apparently loses 50 % of its bees if he can’t find the swarm again. Some beekeepers then fear that they won’t collect any surplus of honey. Plus, a colony that loses half of its population and honey production will have a difficult time regaining its population and productivity and might have a tough time making it through the winter.
Again, the most obvious reason for swarming is to resolve a space issue. This is particularly true for the small, wooden boxes, in which beekeepers domesticated their bees, called hives.
Those hives usually can be expanded and sort of “grow” with the colony, but not always beekeepers can anticipate the potential moment of swarming and extend the space to prevent it.
What can you as a beekeeper do to prevent swarming?
Let’s come back for a moment to the primary reasons for swarming: Reproduction and space problems. A poor performing queen might contribute to the urge of swarming, but the most pressing reasons are space issues and overcrowding leading to congestion and poor ventilation.
=>You should avoid congestion and provide the right ventilation4.
How to avoid congestion?
- Anticipate the needs of the colony and provide them with more room before the need it.
- Add honey supers before the first nectar flow in early spring.
How to help bees to have a good ventilation?
- Keep the ventilation hole in the front of the inner cover open
- Drill some holes in the upper deep and in the honey supers
- In case of hot weather:
- Make sure to have a nearby water source, where bees can easily access water. Bees need water to monitor the temperature in the hive.
- If the hive is completely exposed to sunlight, help bees to get some shadow on hot days by providing a shield.
Here are a few additional recommendations to prevent swarming:
- If you don’t rely on local bees and want to choose a particular bee race, then you can choose a race that is less inclined to swarming. Keep in mind the downsides of these races, though. Read also our Guide to bee races.
- Create new appealing homes close to the original hive by placing for example empty hives in the surrounding environment. In this way, swarming colonies might just move to another hive and you don’t lose them.
- Make a split yourself. Leave the queen cells in the original hive and put the old queen and half of the colony in a new hive5.
- Do not cut the internal wings of the queen bee. The queen, when walking out of the hive to start the swarm, falls on the ground and dies as she is unable to fly. Some beekeepers do this to keep the colony in the hive. We don’t consider it an ethical solution for queen bees.
- If possible try to avoid crush barriers. These are grids made of metal or plastic with holes that allow only the smaller worker bees to pass through. Drones and queens cannot pass these grids. This significantly restricts the queen’s movements and leads to unnatural behaviour that can be harmful to the whole colony.
- If possible due to local and personal conditions, try not to destroy the queen cells. We know that this sounds like a simple way to prevent swarming, but it does not reduce the urge to swarm in general. Bees just build more queen cells and sooner or later you might miss one and the bees swarm out.
When deciding whether to destroy queen cells or not it is important to consider where the colonies are located. If they are standing in a meadow where there are only a few low trees nearby where the swarm flies to, it is quite easy to catch the swarm at these trees. However, if the bees are in a forest, it is very difficult. Also, when keeping colonies in residential areas, it can be very critical to let colonies swarm because of the danger for the neighbors. In addition, depending on the climatic region and breed, it must also be taken into account that colonies that cannot be recaptured are very likely to die.
Are there bee races that are more inclined to swarming than others?
Some bee races are more likely to swarm than others. In our Guide to bee races you will find useful information about the different swarming attitudes of bee races and an overview about the pros of cons of the most common bee races.
We list here the bee races that are more or less inclined to swarming:
Races with low inclination to swarming: Caucasian and Buckfast
Races with medium inclination to swarming: Italian, German, Cordovan and Russian
Races with excessive inclination to swarming: Carniolan, African and Africanized.