Why do bees swarm?

Bees swarm because it is how they reproduce. In their quest for propagation, the existing queen leaves the hive with approximately half of the colony and establishes a new hive in another location. The bees left behind in the original hive raise a new queen from fresh larvae, and continue on with business.


When do bees swarm in Australia?

In the south-west of Western Australia swarming usually occurs between September and December. Bees will typically coincide their swarming with a period of nectar flow, such as when many plants flower in Spring and early Summer.

A hive can swarm multiple times a year, however, they generally send out their biggest swarm in Spring once they have begun building up their colony strength both in bee population and stored nectar (honey). Subsequent swarms are known as ‘after-swarms’ and contain minimal bee numbers and sometimes no queen at all.

swarm-cell-300x300-2788050 Swarm cells such as these are a sure sign that a colony is about to swarm

How many bees in a swarm?

Bee swarms can contain anywhere from a few hundred bees, right up to forty or fifty thousand bees. The actual size of these swarm clusters can vary from the size of a tennis ball, up to the size of a basketball. In terms of beehive size, these swarms may occupy just a frame or two, or require housing in a double box with 20 frames.

62be61_a528e0fd180f4aae9bd7d2f63ace3ed6-mv2-1309694 A swarm of bees about to be recovered into a nucleus hive box

Are bee swarms aggressive?

You may ask whether a swarm of bees is dangerous. While they may appear threatening and daunting to most people, bees are actually at their least aggressive while they are in a swarm. Therefore, swarms of bees are generally not dangerous until they have settled into a new location and the queen has begun to lay.

During the phase from when the bees have left their hive up until when the colony has established itself and started raising larvae (young bees), the bees do not really have anything to defend so are therefore very unlikely to sting. We certainly do not recommend members of the public to approach bee swarms, but so long as they do not directly interfere with the bees physically, the bees pose very little risk to people at all.

Do all beehives swarm?

No, not all beehives will swarm. A beehive will only swarm if they are in a position to do so, both in terms of colony strength, and the environmental conditions that they are in.

As mentioned, swarming occurs when beehives are at their peak, so weak colonies will tend not to swarm. A weak colony that is subject to poor conditions may decide to ‘abscond’, but this is entirely different.

Absconding is when an entire colony of bees leave their hive and move to a new location. They may leave behind capped brood and young larvae, but all the flying age bees will leave with the colony, essentially abandoning their home in search of a better location.


How do beekeepers prevent swarming?

Swarm prevention is an important part of beehive management for a beekeeper. There are a number of ways in which beekeepers prevent swarming, but typically they all involve reducing the colonies urge to swarm.

One way that beekeepers can prevent bees from swarming is by giving the colony more space. This can be done by adding additional super boxes to hives, which has the effect of allowing the bees more room to build honeycomb into and store more pollen, honey and raise new bees in. The new space allows the colony the space it needs to grow and may reduce their urge to swarm.

Another important swarm prevention measure beekeepers can implement is to remove any ‘swarm cells’ that they find in the hive. These swarm cells are new unmatched queens that the bees raise in order to replace their old queen when she leaves with the swarm.

Identifying these swarm cells is a key part of observing when a hive is considering swarming, and the removal of these swarm cells can also help prevent the bees from swarming, particularly when used in conjunction with providing them more space, as discussed above.

62be61_98ed5dcb870c428ea7588971a0e0f270-mv2-9057615 Beekeepers can rehome swarms of bees and allow them to prosper.

Where do bee swarms go to?

Traditionally bees will go for tree hollows, logs or natural caverns. Bees like to live in dark cavities that are insulated and protected from the weather. Many man-made structures also provide the characteristics that bees look for too.

We have recovered bees from car boots, compost bins, wall cavities, cupboards and even a swag.

Most experienced beekeepers have a tale or two about the random and often odd places that they have removed bee swarms from.

They can often show up in the most unusual places, and can eventually be quite difficult to remove if not gotten to soon enough.

If you’d like to learn more about how to catch bee swarms, this article may interest you.

62be61_9c2a47ba8a144a26a252a43c8054eda9-mv2-4894871 Swarms of bees often end up in places where they are unwelcome, such as this possum box.


While this has just been an overview, in future blogs we will endeavour to cover some of what was mentioned above in more detail.

Whether you are a beekeeper, aspiring beekeeper or just someone interested in learning about bees, we hope the above information on bee swarms has been useful for you!

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