Pest Control
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A dense, humming cluster of bees hanging from a branch, fence or wall is almost always a honeybee swarm. It looks dramatic, but a swarm is usually calm, and most move on within a day or two. What matters is whether it stays a swarm or turns into a colony inside your building.
Why honeybees swarm
When a honeybee colony grows too big for its home, it raises new queens. Before they emerge, the old queen leaves with a large part of the workers, often around half the colony, to find somewhere new. The bees that stay behind carry on with one of the new queens.
The departing swarm flies out as a noisy cloud, then settles in a temporary cluster on a branch, a fence post, a hedge or the side of a building. Scout bees go out looking for a permanent home, usually a sheltered cavity such as a hollow tree, and when they agree on one, the whole swarm leaves for it.
Is a swarm dangerous?
Not usually. Bees in a swarm have filled up on honey before leaving the hive and have no comb, brood or stores to protect. They are about as docile as honeybees get. They will still sting if the cluster is knocked, sprayed or poked, and anyone allergic to stings should keep well away.
Keep children and pets indoors or at a distance, close nearby windows, and do not spray the bees with water or insecticide. Spraying a swarm can break it up into smaller clusters and makes collection harder.
Swarm or colony?
The difference decides what happens next.
- A swarm is a visible cluster of bees in the open, with no comb. It is temporary, and often gone within hours or a few days.
- A colony is bees that have moved in somewhere and started building comb. You see a steady stream of bees going in and out of one point, such as a gap in brickwork, a chimney pot or an air brick, often with a hum from inside. A colony can stay for years.
If you only see bees going in and out of a hole and no cluster, you probably have a colony. Our guide to bees in chimneys, walls and lofts covers that.
What to do about a swarm
If the swarm is in the open and nobody needs to go near it, the simplest option is to leave it and let it move on. If it is in an awkward spot, or it has hung around for more than a couple of days, a local beekeeper may be able to collect it. Swarms are valuable to beekeepers, and the British Beekeepers Association runs a swarm collector finder that lists volunteers by postcode.
A beekeeper will want to know that it is honeybees, so a photo helps. Bumblebees and wasps do not swarm, and beekeepers will not collect them.
Stopping a swarm moving in
The real risk is scout bees choosing your house. Chimneys that are no longer used, gaps in soffits and fascias, and wall cavities with an open air brick or a missing brick are typical choices. Fitting a cowl or mesh to unused chimney pots, keeping soffits in good repair and covering open vents with fine mesh all make a building less attractive. Do this when there are no bees present, not once a swarm is already moving in.
When to call us
Call us if a swarm has settled somewhere it cannot be left, if you are not sure it is honeybees, or if bees have started going in and out of the building. We try to relocate honeybee swarms and colonies rather than destroy them, because one of our technicians is a working beekeeper. Send us a photo first. Our bees page explains how we work, or call 01926 632 929.