Bee swarming is a natural part of honey bee behaviour, but for many, it can be surprising or even worrying. Whether you're a beekeeper or simply curious, knowing what swarming is and why it happens is essential. This guide covers everything you need to know about bee swarming in the UK, including when it happens, why it occurs, and how to handle it if you encounter one.

What is Swarming?

Swarming is the process by which a large group of bees, typically including a queen, leaves an existing colony to form a new one. 

When a swarm leaves a hive, it looks like a large, buzzing cloud of bees flying in unison. They typically settle on a nearby tree branch or structure, forming a tight cluster. Contrary to common belief, swarming bees are not usually aggressive since they are full of honey and focused on finding a new home, not defending their old one.

Why Do Bees Swarm?

Swarming occurs mainly for reproductive reasons. When a colony becomes too large for its hive, the queen, along with a portion of the bees, will leave to establish a new colony elsewhere. Several factors can contribute to swarming:

Overcrowding: 

When a hive becomes overcrowded, it can no longer accommodate the growing colony. In an overcrowded hive, resources such as food and space for new eggs becomes limited, which can stress the colony and prompt them to swarm. The bees will go in search of a new location with more space to thrive and expand in better conditions.

Healthy colony growth: 

A strong, healthy colony is more likely to swarm as it rapidly reproduces, ensuring the survival and spread of the species. This natural growth, driven by an abundance of resources like nectar and pollen, signals to the bees that they have enough strength and numbers to successfully divide into multiple colonies. It’s a sign of vitality but also a sign that they’re outgrowing their current environment.

Old Queen: 

A colony with an ageing queen is also more prone to swarming. As the queen's ability to lay eggs diminishes, the bees may start preparing to swarm by raising a new queen. Younger queens are typically more productive, and the introduction of a new queen ensures the future of the colony. The old queen, often accompanied by half the worker bees, will leave to form a new hive, while the new queen takes over the original colony, continuing the cycle of reproduction.

When Do Bees Swarm in the UK?

Timing is key. Having a good knowledge of when bees are likely to swarm and the conditions that lead to swarming can make a big difference in how you manage or respond to the situation. 

Swarming Season: 

In the UK, swarming typically happens between April and June, during the warmer months. Spring marks a time of rapid growth for bee colonies, as warmer temperatures and abundant food sources, such as blooming flowers, support the hive's expansion. This is when bees have the best chance of establishing a new home before winter. 

During this period, it’s important for beekeepers to keep a close eye on their hives, especially as the colony’s population peaks. A swarm can mean the loss of thousands of bees and can significantly reduce honey production if not managed. 

Time of Day: 

Swarms usually occur in the late morning or early afternoon, on warm and sunny days. Bees are more active during these times because the weather is favourable for finding a new nesting site. Rain, cold, or wind can delay swarming, as these conditions make it more difficult for bees to fly and find a secure location.

By being mindful of the swarming season and the specific times of day when bees are most likely to swarm, you can better identify swarming behaviour and take steps to manage or avoid it. For beekeepers, this knowledge can differentiate between losing a massive number of bees or keeping your colony intact, helping you stay prepared during the busy bee season.

What is the Process of Swarming?

Swarming is an organised event, which may appear sudden for humans but has been well planned by a sequence of events for the bees. Let’s dive deeper into the stages of this phenomenon: 

Preparation: 

Swarming typically starts when the colony becomes overcrowded with too many bees. The bees recognize the need for a new space to avoid competition and ensure their survival. If not addressed, overcrowding can lead to stress, disease, or a shortage of food and space.

During this time, the bees focus on the queen, preparing her for flight by reducing her food intake so she can lose weight. This makes her light enough to lead the swarm. Meanwhile, they raise a new queen to take over the original hive, a process that can take several days or weeks as the bees carefully plan the transition.

Queen Cells:

Once the decision to swarm has been made, the colony starts constructing special chambers known as queen cells. These are larger than regular cells, and they are designed to house the developing larvae of potential new queens. The bees feed the chosen larvae royal jelly, a nutrient-rich substance, which helps them grow into queens.

The Swarm:

When the big moment comes to swarm, the old queen, now lighter and prepared to fly, departs the hive with about half of the worker bees, including foragers and nurse bees. As they all exit the hive at once, they form a massive cloud of buzzing bees, and this represents the swarm itself.

Despite the massive cloud,  the bees are highly organised, rather than flying off aimlessly.  The swarm typically travels a short distance from the hive and clusters at a temporary spot, often a tree branch, fence post, or the side of a building.

This cluster of bees will stay in place while scout bees leave the group to search for a more permanent home. These scouts can venture out in all directions, investigating potential nesting sites, such as hollow trees, cavities in walls, or other protected spaces.

Relocation:

When scout bees find a suitable place, they return to the cluster and communicate their new location and the quality of the site through a series of ‘dances’. After a decision has been made about which location to use, the swarm flies directly to the new site, where they start building their combs for the queen to lay eggs and store food. Throughout this process, the bees must work swiftly to gather resources before winter. Meanwhile, the old hive, led by a new queen, continues functioning and rebuilding its strength. 

Why is Swarming a Problem?

While swarming is a natural part of a colony's lifecycle, it can present significant challenges for both beekeepers and the public. Though beneficial for bees, it can create difficulties that range from loss of hive strength to public safety concerns. 

Loss of Bees:  

When a large portion of the colony, including the queen, leaves, it significantly reduces the hive’s population. This loss of bees directly impacts honey production, as fewer bees remain to forage, process nectar, and maintain the hive. 


In some cases, if the remaining colony is too small, it may struggle to survive, especially during the colder months. Additionally, sourcing and nurturing a new queen for the original hive can be a time-consuming and resource-intensive process for both bees and beekeepers. 

Public Safety Concerns: 

While swarming bees are generally calm and less likely to sting, the sight of thousands of bees clustered together can be intimidating or alarming for those unfamiliar with bee behaviours. When a swarm appears in public spaces such as parks, schools, or busy streets, it often causes concern. In urban areas, local authorities or beekeepers are sometimes called upon to safely relocate the swarm. 

Can You Prevent Swarming?

Preventing swarming can be a challenge, but with regular hive maintenance and close monitoring, it's possible to minimise the likelihood of a swarm. Bees often give clear signals before swarming, and by intervening early, you are more likely to be able keep your colonies intact.

Signs of Swarming: 

One of the first indicators that bees are preparing to swarm is the appearance of queen cells in the hive. Beekeepers should inspect their hives regularly during the swarming season (typically from April to June) to check for these cells. 


Increased bee activity at the hive entrance and the formation of a cluster of bees on the outside of the hive are additional signs that the bees may be preparing to swarm. Monitoring these behaviours can help you take preventive actions before the swarm leaves the hive.

Bearding Vs Swarming: 

It is so easy to confuse bearding with swarming, however they are different bee behaviours. Bearding occurs when bees gather in a dense, beard-like cluster outside the hive, usually in hot weather. This happens as a way for the bees to cool down the hive, reducing the temperature inside by spreading out. 

Bearding is temporary and harmless, while swarming involves bees permanently leaving the hive to start a new colony. Being able to distinguish between the two can save you unnecessary worry and allow you to focus on genuine signs of swarming.

To tell them apart, observe the bees' behaviour closely: if they are calm and clustered near the hive, it’s likely bearding. If you see large groups of bees in flight and a cluster forming away from the hive, you’re likely witnessing swarming. Recognizing these differences will help you address the right issues, avoiding unnecessary interventions during bearding.

Splitting the Hive: 

One of the most effective methods to prevent swarming is to transfer some bees, along with frames of brood and resources, into a new hive, providing the original colony with more space, easing overcrowding.

By adding a second hive, beekeepers simulate the natural swarming process without losing bees. This hive-splitting technique also offers a chance to expand the number of hives in an apiary, boosting overall productivity.

Regular Inspections: 

During swarming season, it’s crucial to conduct regular hive inspections, ideally once a week. Keeping a close eye on the hive’s population and resources will allow you to spot early signs of overcrowding or queen cells. By managing space within the hive, such as adding extra frames or expanding the hive itself with additional brood boxes or supers, you can provide the bees with the room they need, reducing the impulse to swarm. 

Summary

Bee swarming is a natural, essential part of how honey bee colonies grow, but it can also be disruptive, particularly for beekeepers. By understanding why bees swarm, when it happens, and how to prevent it, you can better manage your hives or handle any swarms you might come across.

As a beekeeper, having the right equipment can make all the difference in managing your colony and preventing swarming. Check out our collection of beehives and polycotton bee suits to help keep your bees safe and productive.

Hillary Gassongo