Why Do Bees Swarm? A Beekeeper Explains

Bees are fascinating creatures with complex behaviors, and one of their most intriguing actions is swarming. But why do bees swarm? Swarming is a natural process that honey bees use to reproduce and maintain the long-term survival of their colony. It plays an essential role in the honey bee’s life cycle and it's important to understand it if you want to keep bees.

David Horstmann

— 14 min read

Swarming is remarkable event. If you happen to be witness to it, it’s a spectacle you won’t soon forget. A large group of bees leaves the hive together, filling the air with thousands of bees and a buzzing sound that can be heard far and wide. The bees are searching for a new home to create a healthy and sustainable environment for their future generations.

Why do bees swarm is a very valid question. There are many reasons why a bee colony can decide to do so. Let me try to shed some light on bee swarms for you.

Why do Bees swarm? Understanding the Swarming Process

The Start of the Swarming Process

Most commonly, swarming occurs when a colony outgrows its hive and decides to split into two distinct colonies. This behavior is most common in the spring and summer, but can occasionally happen throughout the entire producing season. I’ve had colonies swarm in the very early (too early) spring months.

As often, queen bees are the key factor in why bees swarm. When the colony is at the height of their capacity the queen bee’s pheromones sometimes are not enough to reach the far corners of the colony anymore. This is one possibility why bees swarm—the colony is getting too large for one queen. She might decide to leave the hive with a part of the bees to give way to a new sovereign.

Preparations for Swarming

Before swarming, the worker bees in the colony create special «queen cells» to develop new queen bees. Mostly, the old queen leaves the hive with her workers before the new queens emerges. Sometimes they wait for the new queen to emerge before doing so. And when they do, it’s a spectacle. I was at the right spot at the right time only a couple of times. It was always a spectacle to say the least.

A cloud of thousands of bees leaves their colony filling the air with a hum. When you’re standing in a cloud of swarming bees, there’s no need to be worried. The swarming bees have everything else to worry about apart from stinging you. They are stuffed with provisions for the voyage to their new home and are busy with the swarming process entirely. They will fly around in a zigzag pattern for about 15 minutes.

Forming a Swarm Cluster

Eventually, the queen will land somewhere nearby and signal her position to the swarm with pheromones. The bee swarm will cluster up around her, where they will remain for several hours. Thousands of bees gather around the queen tightly packed together. The bees in the cluster can even regulate the temperature of the cluster adjusting their heat production. The cluster will often hang from a tree branch or a similar object. The clusters look intimidating, but are harmless.

Bees are clustering up on a tree branch
The clusters can be very impressive in size

Scouting out a new Home

While the cluster is resting, scouting bees will look for a suitable nesting ground for the swarm to move into.  Once a target location has been identified, the scout bees will return to the swarm cluster and perform a dance to inform the others about the location they’ve discovered.

This dance also provides information about the distance and direction of the new home. After receiving this information, the rest of the honey bee colony will prepare to move, led by the scout bees. In their new hideout, they will build new comb, start breeding and eventually turn into a strong new bee colony. But why do bees swarm in the first place? Upon what factors do the bees base their decision to swarm?

The bee swarm clusters are not always in reach. Sometimes they form way up in the trees

Why Do Bees Swarm? Factors influencing Swarming

There are many factors that influence why bees swarm. Finding the issue can be hard. A lot of times I stood before a swarming hive having no idea why the bees have swarmed in the first place. Here is a list of some of the most common ones:

Colony reproduction

Swarming is an essential process for bees to survive and maintain their population, as it allows the colony to reproduce and multiply. Each time a swarm occurs, a single colony effectively becomes two or more colonies, ensuring the survival of their species.


As a colony grows, it may become too congested, with not enough space and resources for the bees to thrive. In such cases, swarming helps alleviate the overcrowding issue by dividing the population. By doing so, both the bees that leave with the old queen and the ones that remain with the new queen can have a better chance of survival.

Tiny clusters of bees hanging from the hive entrancec can be a sign of overcrowing

Poor queen quality

If the queen bee is old or unhealthy, the colony may swarm in an attempt to replace her. A new queen will be more likely to lay more eggs and produce a stronger colony. This is not only achieved by swarming. The worker bees can also requeen by themselves without splitting the hive.

Seasonal Factors

In the spring and summer, swarming is a frequent bee behavior primarily because these seasons offer an abundance of resources such as nectar and pollen. During these warmer months, worker bees collect more food, leading to an increase in the hive population.

Colony Health and Resources

The health and resources of a bee colony play a significant role in swarming. When the hive becomes overcrowded, resources like food and water become scarce, affecting the colony’s health. A colony being pestered by too many varroa mites might or other sicknesses might be another reason why bees swarm. In this case swarming is a desperate try to keep the colony alive. No bueno. I’ve had it happen.

One of my hives that was super strong but suffering from overcrowing. Not a good situation that needed adressing.

Hive Conditions

Hive conditions, such as ventilation and space, impact bees› swarming behavior. Proper ventilation helps maintain a suitable temperature inside the hive, ensuring the comfort and wellbeing of the bees. However, if a hive is poorly ventilated or becomes too cramped due to overcrowding, it can initiate a swarm. Addressing issues related to hive conditions helps curb swarming and supports a healthy bee colony. If you can identify the issue at all.

Why Do Bees Swarm? Signs of Swarming

Queen and Brood Patterns

One of the key indicators of an impending swarm is shifts in queen and brood patterns. I have noticed that the presence of queen cells. Queen cells are specialized cells created by worker bees for the development of a new queen. They are a strong sign that the hive is preparing to swarm. In addition to queen cells, alterations in brood patterns can also signal swarming behavior.

For instance, the rate at which the queen bee lays eggs may slow down, or the distribution of eggs within the brood comb might become more erratic. These changes will lead to a situation where the old queen departs the hive with a swarm of worker bees, paving the way for a new, young queen to take charge.

Changes in Hive Behavior

In times leading up to a swarm, I sometimes observe changes in the behavior of the hive as a whole. The colony seems more nervous, more busy than usual. Worker bees may become more energetic, making more noise within the hive and sometimes spilling out of the entrance. This heightened activity level is a sign that the bees are preparing to leave their current location and establish a new colony.

There are even more changes one could observe. It’s helpful to visualize them in a table:

BehaviorNormal HiveSwarming Hive
Queen cellsAbsentPresent
Egg layingSteady rateSlows down
Brood patternRegularIrregular
Waggle danceOccasionalFrequent
Worker bee activityModerateHigh

By keeping an eye out for these signs, I can identify the potential for swarming in my beehives and take appropriate measures to manage the situation in a way that benefits both the bees and myself as a beekeeper. It’s always helpful if you can bee “ahead” of your bees by closely observing their behavious.

Preventing and Managing Swarms as a Beekeeper

Failing to prevent them from doing so is the main reasons why bees swarm. If you want to harvest honey from your colonies, you want to keep the hives at their maximum capacity. This can be a balancing act as the bees would likely want to swarm, but you need to keep them from doing so. Here are the techniques I use to keep my bees from swarming.

Beekeeping Techniques

As a beekeeper, I’ve learned that preventing and managing swarms is crucial for maintaining the health of my honey bee colonies. Overcrowding can lead to swarming, so providing ample space is important.

The most important “technique” I use is to regularly inspect the hive and look for signs of swarm preparation. When I find queen cells, this could indicate that the colony is preparing to swarm.

My response to that is that I remove the emerging queen bee cells. But more importantly I need to check if there is actually a queen bee. You can cause heaps of trouble for your hive if they’re actually requeening and you are removing their queen bee cells to “keep them from swarming”. Make sure you have located the queen bee and eggs before starting to remove cells.

A simple Trick to spot Queen Cells in your Hives

It’s hard to spot all the queen cells. In the swarming season there will be loads of them. And they’re not always easy to spot. I guess it’s not the nicest and stress free of things for the bees, but here’s what I do: I grab a comb from the hive and remove as many bees as possible with one big shake.

It’s also critical to pay attention to the type of honey bees you’re working with. Carniolan, Caucasian, and Buckfast bees are some of the various bee subspecies, and each has its unique swarming tendencies. Choosing a less swarm-prone bee and adapting your beekeeping techniques accordingly can help you manage swarms more effectively.

How to retrieve a Bee Swarm

Despite taking preventive measures, sometimes swarms still occur. I can rarely keep all my hives from swarming. In these cases, I need to be prepared to retrieve the swarm and integrate it back into my hive management. It’s not hard at all actually. Here are the steps I take when retrieving a swarm:

1. Locate the swarm

Swarming bees usually form a cluster around the queen, which could be on a tree branch, a fence, or in other unexpected places. You can spray them with a bit of water to simulate rain. When it rains, swarms are less likely to go flying out.

A beekeeper friend has located a swarm and I went to help her

2. Use a suitable container

I have a dedicated “swarm box” ready to collect swarms. It has a couple of different entries for the bees to enter. Also, it has a connection for a bottle of sugar water so you can store the swarm for a couple of days.

3. Shake the swarm into the box

Once the cluster is reachable, I shake the branch or support, allowing the bees to all into the container. This should be done with caution to avoid agitating the bees. Stay with the bees a bit to see if they are gathering in and around the box. This was you can see if the queen is in the box or not.

4. Wait for the queen

If the queen is in container, the rest of the bees will follow. Sometimes they may release a pheromone to call the other bees, making the process easier. Give them a couple of hours’ time. They will all enter the box eventually.

5. Reintegrate the swarm

Once the swarm is in the container, I put them in a cool and dark spot for two days. This will calm down the swarm. Also, the queen will “reconnect” the bees as a colony with her pheromones. This takes a bit of time. I then return them to an empty hive or integrate them with an existing colony, ensuring the proper space and resources are available.

It will take a while for the swarm to settle in their new home. But once they did you have yourself an additional bee colony.

In Conclusion: Bee Swarms are a great Pleasure

For me as a beekeeper, collecting a bee swarm is a great pleasure. Not only is it a fascinating and awe-inspiring sight, but it also presents a valuable opportunity to expand my colonies without spending a dime. If you´re not a beekeeper I hope I could give you a glance into a true wonder of bee nature. There´s no need to be afraid of bee swarms. If you are one – remember to view it as an exciting chance to enhance your beekeeping journey and contribute to the thriving world of these remarkable pollinators.

Why do Bees swarm? Frequently Asked Questions

What triggers a Bee Swarm?

A bee swarm is triggered when a honey bee colony outgrows its home, becomes too congested, or too populated for the queen’s pheromones to control the entire workforce. This causes the workers to signal that it’s time to swarm, and they begin building swarm cells for new queens.

How are swarming Bees different from regular Bee behavior?

During a swarm, bees exhibit different behavior compared to their regular activities. Swarming bees become focused on finding a new home and protecting their queen while they search for a suitable location. Additionally, bees in a swarm are generally less aggressive than those defending their established colony, as they have no honey or larvae to protect.

What Factors influence the swarming behavior of Bees?

Several factors influence the swarming behavior of bees, including population size, available resources, environmental conditions, and the age of the queen bee. When the hive becomes overcrowded, resources become scarce, and the colony’s health may decline; these factors contribute to the decision to swarm.

Do Bee swarms pose any risks to Humans?

While the sight of a large bee swarm may be intimidating, they usually do not pose any significant risks to humans. Swarming bees are typically preoccupied with finding a new home and are less likely to attack. However, it’s essential to give them space and not disturb the swarm, as they may become aggressive if they feel threatened.

How long does a Bee swarm typically last?

The duration of a bee swarm can vary, but it’s often a temporary situation, as bees work together to find a new home quickly. Once an appropriate location is found, the swarm will typically disperse and begin setting up their new colony within a few hours to a few days.

What should you do if you encounter a Bee Swarm?

If you encounter a bee swarm, it’s important to stay calm and give the bees plenty of space. There´s no need to panic! Avoid approaching or disturbing the swarm, as this may provoke them into becoming defensive. If the swarm is on your property, it’s advisable to contact a local beekeeper or bee removal service to safely relocate the bees without harming them. Or you just wait, stay calm, let them do their thing and eventually, they`ll disappear.