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What Is Honey Bee Swarming? 2024 Guide

A bee swarm in a tree temporarily resting

As spring arrives, bees get busy collecting pollen and building comb. The colony can grow fast during this time, resulting in a crowded beehive. Part of the hive may swarm to a new location to make space.

This guide looks at what is honey bee swarming and how beekeepers can stop it happening.

What is a honey bee swarm?

Honey bee swarming occurs when around half the bees in a colony leave to establish a new colony. It is a natural process usually resulting from a crowded hive.

Swarming isn’t ideal for beekeepers who will lose bee stocks. It is essential to create favorable conditions for the colony to encourage them to stay. Understanding why bees swarm will help the beekeeper remain on top of potential hive issues.

Check out the bee swarming video below:

What causes bees to swarm?

While there are various reasons for swarming, the most common one is congestion within the hive. An overcrowded hive can reduce the availability of queen pheromones, stimulating worker bees to build queen cups and cells in anticipation of leaving.

Other triggers for swarming include:

  • A sub-standard queen: As the queen bee ages, her ability to lay fertile eggs reduces. Once worker bees detect a problem, they’ll raise a new queen and eventually leave the hive.
  • Rise in temperature: The arrival of spring usually brings warmer weather which triggers bees to seek out new space.
  • Unfavorable food sources: A colony may have access to lots of pollen but limited nectar in some areas. This results in idle worker bees overcrowding brood boxes instead of making honey. Be sure to check out our article on honey bee washboarding, which often occurs during a nectar dearth.
  • Genetics: Beekeepers may provide the perfect environment for bees, and they still leave. This could be a bee strain that loves to swarm.

When do bees swarm?

Bees often swarm on warm, fine days in spring and early summer. They will usually set off any time between mid-morning and late afternoon. If they don’t find a new home by nightfall, they’ll cluster at a temporary resting point like a tree branch until morning.

Bees may swarm in the fall if there is a desperate need. It will leave them little time to establish a new hive with honey stocks to last through winter. Most late swarms tend to fail.

A cluster of bees on a tree branch during swarming
Swarming bees temporarily wait for scouts to confirm their new home.

Swarming vs. absconding – what’s the difference?

Swarming events result in about half the bees leaving for a new hive while the other half stay where they are. Absconding occurs when the entire colony leaves, often because of an intrusive beekeeper, pests, disease, and other threats.

Swarming is generally considered a positive activity for bees, a sign that they are thriving. Absconding is always a bad sign for bees and may result in the demise of the whole colony.

An infographic explaining the definition of bee swarming with a picture of a swarm on a branch included

The stages of swarming

  1. Once a hive decides to swarm, they begin initial preparations by building queen cups and queen cells. They are often found on the frame bottoms and contain a fertilized egg from the current queen bee. You can learn more about how a bee becomes a queen here.
  2. During the queen-rearing process, scout bees leave the hive and search for a suitable new home. It needs to have water, pollen, and nectar sources nearby; a safe location, away from pests, predators, and the elements, is also essential.
  3. In the week building up to departure, the queen is selected. She will eat less, enabling her to slim down and fly easier.
  4. The bees will set off in a swarm when a fine day arrives. Along the way, they often find a temporary resting location, such as a bush, tree, or building. Finally, when the scouts give the signal, they head off together and begin building their new beehive.

Common signs that a colony is looking to swarm

If the hive has a large population and all the frames are fully drawn, then there’s a good chance you’re about to lose bees.

Other cues may include a high drone population, forager bees using the entire entrance width, queen cells, festooning bees, and large amounts of honey stored above and in the brood.

How can beekeepers prevent swarming?

While many beekeepers love swarms from another hive, none want their own bees to leave. It takes time to rebuild the colony, and the season’s honey production will take a severe hit.

Most beekeepers will eventually lose bees, as swarm prevention is almost impossible. However, they can reduce the chance of swarming by identifying warning signs early and making quick changes.

An open hand that is holding comb with queen cells.
Queen cells are a sign that a colony is going to swarm.

Hive splitting is the most common tactic, involving transferring some of the existing frames to a new hive.

Before splitting a hive, try to give the new home a running start by adding a super. This step creates a platform for the colony to build on. Don’t add supers too quickly; it may have the opposite effect.

Consider creating room for agitated bees by harvesting some honey. This is a good idea if your colony is increasingly storing honey in brood frames.

For disease and pest-free apiaries with more than one hive, the beekeeper can remove some bees from a thriving hive and use it to bolster weaker ones. Use young nurse bees as forager bees will likely return to their old home. 

No swarm-stopping tactic will work every time. Bees can be unpredictable, and their urge to swarm may be too great to control. If that happens, move on and help the remaining bees rebuild.

How do I trap a swarm?

Beekeepers can attract a swarm into one of their hives using a swarm lure. You can learn how to lure a swarm here.

A bee swarm bait trap full of bees.
Beekeepers love to lure swarming bees.

The 3 types of bee swarms

1. Prime bee swarm

A primary swarm is the most common variety, as it is the first of the season for a hive. At this stage, the colony could have reached a population of 50,000, meaning the swarm would be roughly 25,000.

2. Secondary swarm

A secondary swarm occurs when an additional virgin queen swarms from the primary. If the original colony contained 50,000 bees, the second group might have a population as low as 12,500.

3. Absconding swarm

An absconding swarm occurs when a colony leaves its hive due to problems like disease, pests, and starvation. Scientists often refer to this as Colony Collapse Disorder.

Abandoned honeycomb
Pests and diseases are common reasons for absconding.

Commonly asked questions

Are swarms dangerous?

Although honey bees seem terrifying in a swarm, they are docile and unlikely to sting. This clump of bees is rarely aggressive as they have no honey, young ones, or home to protect. However, bees are wild insects and may choose to defend themselves if threatened.  

Can bees swarm without a queen?

A colony won’t swarm without a queen as she is needed to lay fertilized eggs which develop into worker bees. Nurse bees will always raise a queen in the existing hive before leaving.

What do I do if a swarm attacks me?

Swarms are highly unlikely to attack unless they are threatened or provoked. If they defend their location, run to a nearby building or vehicle and seek shelter. Although a few bees may get inside, it’s better than dealing with thousands outside.

What should I do if I spot a swarm?

Always leave a bee swarm alone unless you’re a beekeeper or professional. It will usually move on within a day or two, but often quicker. Call your local beekeeper’s association or an experienced beekeeper to remove the swarm.

Never try to move a swarm, as you could get severely stung. It may be tempting to kill the bees or call pest control, but keep in mind bee numbers are reducing drastically around the world. We recommend not being part of the problem.

Am I allowed to kill a honey bee swarm?

It may not be illegal to destroy an unwanted swarm, but we strongly recommend against it. You’ll put yourself in a dangerous situation and end the lives of harmless bees that greatly benefit our ecosystem. 

What should I do if the bees move into a building?

Swarms entering a chimney or wall space inside a building have found their new home and are beginning to build the hive. Act quickly and call a beekeeper to remove the bees before the colony establishes itself. If you know how to deal with bees, consider investing in a bee vacuum to make them easier to catch.

A beekeeper in protective clothing removing a bee swarm
Call an experienced beekeeper if you need bees removed.

Can beehives swarm more than once?

Bees may decide to swarm a second time in a matter of days, depending on factors like season, sources of food, and queen availability. “After swarms” may divide three or more times in a short space of time. This activity reduces the hive’s chance of survival due to reduced numbers. 

What types of bees swarm?

Honey bees are the most common type of bee to swarm. They will generally take one queen bee, tens of drones, and thousands of worker bees. The swarm size in one clump could be as small as an apple or as large as a big watermelon. 

What can I use to repel a bee swarm without harming them?

If you’re concerned that a swarm will settle around your home, discourage them without using harmful chemicals. Instead, spray an equal mix of bitter almond essence and water in areas that scout bees are likely to visit. They dislike the fragrance and should move on to another location.

Summing up

A bee swarm is a natural event in the lifecycle of a honey bee and usually signifies a thriving colony. Beekeepers should stay vigilant and maintain regular beehive inspections in the warm seasons. This work will ensure the bees have sufficient space and problems like pests can be dealt with.

A resting swarm is best left alone as it will soon move on to a new home. If there is a chance people may get stung, contact a local beekeeper and get it removed humanely. Many beekeepers love adding diverse new bee stocks to their apiaries. 

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