As the first signs of warmth ripple across the UK countryside and blossom scents drift through hedgerows, something ancient and awe-inspiring begins to stir in the hive. It’s called swarming, and it’s a perfectly natural, essential part of bee life. Yet for many people — especially gardeners, homeowners, and new beekeepers — a cloud of bees appearing out of nowhere can feel alarming. In this blog post, we’ll explore why bees swarm, when they are most likely to do so in the UK, how to recognise the signs, and what you can do if you come across one.
If you’re based in or near the Brecon Beacons, remember: Roger from Brecon Beecombs is on hand to help with swarm removal — safely and responsibly.
🐝 What is Swarming?
Swarming is how honeybee colonies reproduce. Unlike most species that reproduce by individuals giving birth, a honeybee colony reproduces as a whole. When conditions are just right, the queen bee will leave the hive with thousands of her workers to form a new colony. This mass migration of bees is what we call a swarm.
The remaining bees in the original hive will rear a new queen, ensuring the survival and growth of both the old and new colonies. It’s a dazzling, natural phenomenon — and entirely essential to the health of the species.
Understanding why bees swarm helps us appreciate not only the beauty of bee behaviour but also how we can work with nature, especially as responsible beekeepers or landowners in the UK.
🌼 When is Swarm Season in the UK?
In the UK, swarm season generally occurs between late April and early July, with a peak around May and June. However, timing can vary depending on weather, regional conditions, and colony health.
Key triggers include:
- Rising temperatures after winter
- Plenty of nectar and pollen from spring flowers
- Overcrowding inside the hive
- Presence of a strong, mature queen
- Lack of ventilation or space
Swarming can happen earlier in southern England or parts of Wales, such as the Brecon Beacons, where spring often arrives a little sooner than further north. Mild winters and early warmth (as we’ve increasingly seen with climate change) can cause colonies to build up faster — prompting an earlier swarm season.
🐝 Why Bees Swarm: The 5 Key Reasons
1. Reproduction of the Colony
The most fundamental reason why bees swarm is to reproduce the colony. A thriving hive with a good queen, ample forage, and lots of worker bees reaches a natural point where splitting into two is the healthiest path forward.
Swarming allows for:
- Spreading genetics
- Reducing competition for resources
- Occupying new territories
In this sense, a swarm is a sign that the colony is doing well — not that it’s in trouble.
2. Overcrowding in the Hive
As spring flowers bloom and nectar flows, colonies build up rapidly. If the beekeeper hasn’t added space or performed inspections, the hive can become too crowded, leading to poor ventilation, stress, and an urge to leave.
This kind of swarm due to overcrowding is one of the most common reasons why bees swarm — and something that proactive hive management can help prevent.
3. Aging or Tired Queen
Sometimes a colony will choose to replace an older queen. When they do, the existing queen may sense it’s time to go. She’ll leave with a portion of the workforce before the new queen emerges. It’s not personal — just nature’s way of planning succession.
4. Strong Environmental Conditions
A warm, dry spring with abundant blossom is a classic swarm trigger. Bees are opportunists. When food is plentiful and the weather is ideal, they act fast to ensure their survival and spread.
This is why bees swarm most frequently in May and June — a time when apple blossoms, hawthorn, dandelions, and clover are all flowering profusely across the UK.
5. Lack of Management (for kept hives)
In unmanaged hives — such as wild colonies or abandoned apiaries — swarming is inevitable. But even in kept hives, if weekly inspections and swarm prevention measures aren’t taken during peak season, swarming is likely.
So another big reason why bees swarm comes down to beekeeper intervention (or lack thereof).
🐝 What Does a Swarm Look Like?
A swarm begins with an explosive, dramatic take-off. Thousands of bees pour from the hive entrance, spiralling into the sky in a loud, buzzing cloud. This spectacle typically lasts 5 to 15 minutes, after which the swarm settles somewhere nearby — often in a tree, fence post, or even a garden shed.
The cluster of bees that forms is usually the size of a rugby ball (sometimes much bigger) and appears to be just “hanging there,” calmly waiting. This is the resting stage, while scout bees fly off in search of a new permanent home.
This behaviour may look scary, but the bees are at their most docile during a swarm. They’ve gorged on honey and have no hive to defend — making them relatively passive unless provoked.
🌍 Why Bees Swarm – And Why It’s Vital to Protect Them
In recent decades, honeybee populations have suffered due to habitat loss, pesticide use, and disease. Swarming is a natural act of renewal — one that keeps colonies alive and contributes to pollination, ecosystem diversity, and local food production.
Removing swarms without harming bees is crucial. And that’s where local beekeepers like Roger from Brecon Beecombs come in. Based in the Brecon Beacons, Roger provides a safe swarm collection service and rehives bees into new, suitable homes where they can continue to thrive.
If you find a swarm in your garden or nearby woodland, don’t spray it or panic. Instead, call a registered beekeeper — preferably someone like Roger who understands why bees swarm and how to manage it responsibly.
📅 Timeline: What Happens During a Swarm?
- Pre-swarm build-up (April–May): Bees start making swarm preparations, including raising new queens.
- Queen cells are built: Multiple special cells are created to rear a replacement queen.
- Old queen leaves: The existing queen departs with 5,000–20,000 bees.
- Swarm cluster forms: Bees gather in a temporary location.
- Scout bees explore: Over several hours (or days), scouts find a new nesting site.
- Swarm relocates: Once a decision is made, the entire swarm flies to their new home.
Knowing this timeline helps explain why bees swarm and how we, as beekeepers or members of the public, can respond calmly and responsibly.
🔍 Signs a Hive is About to Swarm
If you’re a beekeeper in the UK, or even just interested in bees, it’s helpful to know the signs a colony is preparing to swarm:
- Presence of queen cells
- Increased drone population
- Bees “bearding” outside the hive
- Restlessness inside the hive
- Sudden drop in egg-laying
Catching swarms early can mean the difference between managing your apiary well and losing half your bees unexpectedly.
📢 What to Do If You See a Swarm
If you encounter a swarm of bees in your garden or local area:
- Keep calm – Bees in a swarm are not aggressive.
- Don’t disturb the swarm – Don’t try to move or spray them.
- Call a local beekeeper – If you’re in or near Brecon, Roger from Brecon Beecombs can help.
- Note the location and height – This helps with safe collection.
- Keep pets and children away – Just until the swarm is removed.
Roger is passionate about bee welfare and community education. He’ll relocate the bees to one of his natural beekeeping hives and ensure they have a safe place to rebuild.
🌿 Why Bees Swarm – A Gift, Not a Nuisance
To the untrained eye, a swarm might look like trouble. But it’s really a sign that nature is doing exactly what it should. Bees swarming means the colony is alive, strong, and fulfilling its natural cycle.
With rising awareness around sustainable beekeeping, wildlife conservation, and back-to-nature living, understanding why bees swarm helps us make informed choices. Whether that means contacting a beekeeper for help or simply standing back to observe a mesmerising natural process, knowledge brings peace of mind.
🐝 Need Help with a Swarm in Brecon?
If you’re in Brecon, the Brecon Beacons, or surrounding areas and you spot a swarm of bees, get in touch with Roger from Brecon Beecombs. With years of experience in natural beekeeping, Roger safely collects and relocates swarms, giving them a new lease on life while protecting public spaces and gardens.
📞 07719 146662
📧 info@breconbeecombs.wales
🌐 www.breconbeecombs.wales
🔑 Key Takeaways
- Swarming is natural reproduction for honeybee colonies.
- In the UK, May and June are peak swarm months.
- The primary reason why bees swarm is overcrowding and colony growth.
- Swarms are docile, not dangerous — don’t panic.
- Beekeepers like Roger can help with safe removal in the Brecon area.
🐝 Final Notes
Swarm season in the UK is a spectacular time. Knowing why bees swarm, how to spot the signs, and who to contact helps protect our pollinators and keeps communities safe. Let’s embrace the wonder of bees — and support the vital work they do.
If you’re lucky enough to witness a swarm, consider it a glimpse into the incredible intelligence and coordination of one of nature’s most important creatures.