Why do honey bees swarm in the UK?

A swarm of bees in a tree in a garden in Sussex UK

Buzzin’ bees

Swarms of bees look pretty dangerous but the first thing to say is don’t worry! They’re pretty docile and if you treat them with respect you’ll have nothing to worry about. Watch them and admire them – when bees swarm it’s one of nature’s little miracles!

If you’re looking for information about having a bee swarm removed please click here to find a swarm collector.

So why do bees swarm?

Honey bees live in colonies, and at the beginning of the year a colony might number 20,000 bees. A colony has just one Queen Bee. She’s very important to the 19,999 other bees, and they spend an awful lot time looking after her. During the summer months the colony gets bigger and bigger, with numbers increasing to as many as 50,000 bees. That’s a lot of honey! Out of the 50,000 bees there will be just one Queen, 200–300 male bees (known as Drones) and the rest will be female (Worker) bees.

Still with me? Ok here’s where it gets complicated.

Bees talk to each other using ‘pheromones’. Pheromones are chemicals that bees release to tell each other what’s going on. The Queen Bee has her own pheromones which she uses to tell her Workers to go out and look for food, to protect the nest, look after the youngsters, etc. But her success is also her downfall. By the height of summer our Queen Bee is trying to talk to 50,000 bees using chemical smells, and frankly it’s asking a bit too much! Her pheromones can’t reach all of the Workers and the bees that don’t hear from her start to get confused. With no pheromones reaching them, they think there’s no Queen Bee. So they do what’s natural. They produce a new Queen. Which is bad news for the existing Queen because the colony can only survive with one Queen Bee.

Sensing the arrival of a new Queen, the existing Queen leaves the nest with about 20,000 bees. They’re homeless at this stage – which is when you might see a swarm like this one, hanging in a tree like a great big lump of buzzing buzziness. The Queen Bee will be right in the middle of this swarm – kept safe and warm by her army of Workers.

Bee swarm in the garden
A different Honey Bee swarm in our garden in 2015 – on a rose bush

The swarm on the tree will only be there for a day or two while a new, permanent home is found. Scout bees leave the swarm and look for holes in the ground, or in trees or walls – possibly in your roof if you’re (un)lucky! When the Scouts find a new home they send a pheromone message back to the swarm that’s waiting in the tree. The Queen then flies off to the new nest site followed by a whirling cloud of bees – it’s one of nature’s most incredible sights as 20,000 bees take to the air. It’s just like the cartoons (well almost)!

Cartoon bee swarm in the shape of a plane
Swarms of bees are famous for flying in the shape of aeroplanes, anvils and bows-and-arrows!

When the swarm in our garden moved from the tree to their new home, the whole thing was over in less than 10 minutes. The sky was filled with bees and the noise was fearsome; yet almost as quick as it started the swarm disappeared into a hole in our neighbour’s roof. And apart from some buzzing and some coming and going of bees, you’d hardly know they were there.

Bee swarm in the garden
A swarm of Honey Bees – this was as close as I wanted to get for a photo!

Please look after our bees

Honey Bees are just one type of about 250+ species of bees that we have in the UK. They will sting you if they see you as a threat. For example, it’s not a good idea to squirt hairspray at a swarm of 20,000 bees or to blast them with water from your garden hose… If you leave them alone, they will leave you alone too.

Bees and other pollinators are vital to food production but they are in serious decline. Studies show that we’re losing huge numbers of Honey Bees through the widespread (yet currently legal) use of pesticides that contain harmful neonicotinoids.

It’s tough being a bee. If you have honey bees in your garden please look after them, they need all the help they can get!

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