Why Do Bees Swarm?
In the world of beekeeping, there is nothing more frustrating than opening up your colony of bees are realising they have swarmed. In this blog, I am going to help you answer the question, why do bees swarm?
What Is Swarming?
Swarming is the reproductive cycle of the honey bee. The colony produces swarm cells within the colony and once the swarm cells are mature, the prime swarm leaves the hive accompanied by the old queen bee. The prime swarm (first swarm of the season) can contain thousands to tens of thousands of bees. Swarms exit the hive and settle 20–30 m away from the hive for a few hours/days. The swarm then departs for a new nest site after getting information from scout bees. They are looking for a safe, permanent home such as a chimney or rotten tree hollow.
You can find out more about the process of swarming from the BBKA website - https://www.bbka.org.uk/honeybee-swarms
When Do Bees Swarm?
To answer the question, why do bees swarm? It's good to question, when do bees swarm? Bees generally swarm towards the beginning of the beekeeping season as the days get longer and the weather is suitable. In the UK, the main swarming season is between April – June; however, swarms can be triggered at any point throughout the season, often by poor beekeeping practises.
Why Did My Bees Swarm?
If your bee have already swarmed, it's probably too late to answer the question, why do bees swarm?! But if your bees have already swarmed you are probably thinking, what next? Check out my dedicated blog post that answers this question – HERE
But in this blog post, we are going to forensically analyse, why your bees swarmed and hopefully help you reduce the risk of it happening again too many times in the future.
Size of Colony
The size of the colony is probably the most important variable that impacts the bees desire to swarm. The single aim of the beekeeper is to attempt to keep every single bee within the colony in the beehive for the duration of the season. By doing this, it maximises the honey crop and stops your bees becoming a nuisance. However, when a colony of bees becomes too large, this triggers a response from the bees to commence their reproductive cycle, through swarming and splitting.
It's quite a simple formula. The bigger the colony, the more likely the colony is to swarm. But this aligns closely to another formula, which is, more bees = more honey. Ideally, as beekeepers we want both. We want as many bees as possible, to create a decent honey crop, but we want to avoid swarming wherever possible.
Colony is size is only one of the factors that can trigger swarming but what’s arguably more important is the colony size relative to the space within the beehive.
Space – Brood Box
The brood box is the most critical area of the beehive in terms of ensuring the bees have enough space. Once the bees are covering all the frames in the brood box they are in a position to swarm. It’s up the beekeeper at this point do they split the colony? Do they create an artificial swarm? Do they do a Demaree? Do they run the risk of the bees swarming? Do they add another brood box to create more space? There is no right or wrong answer and it depends on what your beekeeping goals are. All of the above come with positives and negatives but the simple fact is this. If you restrict the available space for the bees in the brood nest, the colony is far more likely to swarm. My personal preference is to double brood and take the slight hit on the honey production as it generally means the bees aren’t crammed into the brood box during the period where swarming is most likely.
When the colony is building up, it’s unlikely the bees will swarm if all of the frames are not covered in bees. However, there is an exception to this rule when it comes to frames with foundation. Bees can sometimes perceive a frame with foundation as the hive wall and they determine that once they reach the foundation frame, they will swarm due to lack of space. This is one of the most frustrating swarms. The way to mitigate this is to constantly take the outside foundation frame and checkerboard the brood area with a single frame of foundation. You only need to do it with a single frame at a time and once they have drawn out the central frame, you can replace with another foundation frame. Keep on doing this until the brood box is full of bees and all frames are drawn.
Space – Beehive
Why do bees swarm? It's because they haven't got enough space in the beehive. That's probably the answer 90% of the time! The space in the total beehive needs to be treated differently to the space in the brood box, when it comes to triggering the swarming response and it’s a much simpler formula. You have to ensure the bees never, ever hit the ceiling of the hive. If the bees hit the ceiling of the hive, this means they have nowhere to store nectar (which takes up a lot of space) and what they then do with the nectar is to start backfilling any available space in the brood nest. This instantly triggers to the colony that they have reached maximum capacity in their current hive and they commence swarm preparation. This is the easiest way to get your bees to swarm.
I ensure I always have between 4-5 supers available for each and every colony that I own. I also ensure that I extract my honey twice per season as this means there is always plenty of available space for the bees to store nectar at any point throughout the year.
If you are interested in starting beekeeping and want a calm, placid colony of bees for your garden, our F1 Buckfast Nucs make a great starter hive - https://www.blackmountainhoney.co.uk/bee-nucs-for-sale
Age of Queen
A young queen is far less likely to swarm. The older the queen gets, the more likely the colony is to swarm. It’s a pretty simple formula this one. I am not entirely sure of the logic behind it but from my anecdotal experience, it seems to be true. It’s probably something to do with a colony trying to ensure they spread their genetics before it’s too late and the queen starts to fail or become a drone laying queen. If you have a drone laying queen and need to fix it, check out the video below:
We ensure that we keep no queens for any longer than 2 full season and when they enter their third year, we requeen with a new F1 Buckfast queen, that you can buy – HERE
Genetics of Queen
The genetics of a queen plays a huge importance in the colony’s propensity to swarm. Buckfast bees for example are bred specifically to reduce the propensity to swarm. This doesn’t mean they will never swarm but it does mean that if you ensure you follow all the guidance in this blog, you at least have half a chance of the bees staying put in their beehive throughout the season.
Mongrel bees on the other hand have naturally evolved to swarm regularly. Even worse, if you go out catching swarms and then bring them on as colonies, you are effectively rewarding that colony’s decision to swarm through your own selection. Swarmy bees breed swarmy bees. It’s a simple fact and one that I have personal experience of. What is the point in keeping swarmy bees that decide to swarm when they hit 5 frames in the brood box and haven’t even made it up into the supers?
If you catch a swarm and want to eliminate the swarmy genetics, you can requeen straight away and within 8-12 weeks, the genetics of the colony of bees will be transformed. You get the added bonus of increased honey production and calm, placid bees that are a pleasure to work with. You can buy our queen bees for sale HERE
Age of Combs
When a colony swarms and finds a new home, they fill their stomachs full of honey to ensure they have a source of food when they arrive at their destination. This food is used to keep the colony alive but it’s also used to convert to wax to build the colony’s new home. I may have gone a little off topic there, but there is a reason for the digression. Bees are much less likely to swarm when they are in the process of building new combs. It seems to give the bees something to do and it means that incoming nectar doesn’t cause a dramatic drop in the available space in the beehive. The building of new combs also increases the available space within the beehive.
Therefore, as brood frames need to be replaced every 2-3 years anyway, it makes perfect sense to combine this comb replacement process to align with the swarming season as it’s a very good mechanism to help reduce the swarming propensity, whilst also completing a valuable task along the way.
The best way I have found of doing this is to remove the outer frames (generally stores) towards the end of April/early May and replace with frames of foundation. However, you want to place these frames of foundation into the middle of the brood nest. This means the bees will work them straight away and by putting them in the middle, the bees are more likely to create worker brood combs as opposed to drone brood. Give it a go, it’s a good method and it really does help.
Weekly Inspections
I often have people call me up and ask for advice. They say ‘why did my bees swarm? What did I do wrong’? My response is always to ask, ‘was there any signs of swarming on the previous week’s inspection’? More often than not, people say they either don’t do regular inspections or they missed the last inspection due to X, Y or Z.
During the beekeeping season, you must inspect your bees EVERY 7 days. Pick a time and regular day and stick to it. You have to complete your regular weekly inspections to ensure your bees do not swarm. If you don’t do your inspections, your bees WILL swarm. It’s that simple!
When you inspect your bees, you are looking for signs of swarming such as swarm cells, backfilling of brood box with nectar, lack of space in the supers etc. Ensure you shake the bees off every frame in the brood box. Swarm cells are nearly impossible to see when the frame is covered in bees. Inspections don’t need to take hours. Have a look at this video which shows how to complete an inspection in less than 5 mins – HERE. Hopefully you won't be asking the question, why did my bees swarm?
Absconding
Absconding is different to swarming. Sometimes you have to ask the question, where have my bees gone as opposed to why do bees swarm? When a colony swarms, it leaves behind everything required for the colony to survive in that location. When a colony absconds, they leave food and brood behind, but every single bee in the colony leaves and the colony can no longer continue. Absconding bees is more rare than swarming but it does happen. Detailed below are a couple of tips to ensure your bees don’t abscond throughout the season.
Temperature and Humidity
A colony of bees is perfectly able to regulate the temperature within the hive and its imperative that it’s kept at an optimum temperature of around 37c – similar to the temperature of human blood. The bees need to maintain this temperature to ensure the eggs, larvae and bees are able to function properly and also to ensure the wax remains stable and the honey stores remain in the wax combs.
Bees are very proficient in managing cold temperatures. They have developed clustering as an effective and efficient way of ensuring the centre of the cluster and brood area remains at the optimum hive temperature. Bees in a well maintain, insulated and draft free beehive can easily cope with winter temperatures down to minus 20 or even minus 30 degrees Celsius.
Bees aren’t as well adapted to be able to cope with high extremes of temperature. As the temperature in the beehive rises, bees collect water and release this into the hive. Combined with a unified fanning effect from the bees, they effectively create an air conditioning system where the collected water is evaporated off to create a cooling effect. This generally works well in most conditions but when extremely high temperatures are incurred, the colony can no longer tolerate the temperature as the hive mechanics start to fail. The wax melts, the honey combs collapse and this sticky mess means the bees can no longer fan to keep themselves cool. It results in a dramatic failure of the colony if they cannot escape. Have a look at what happened to this colony in the post without a ventilated screen! An expensive and very sad lesson for us.
However, if the bees can escape, this is the point when they are likely to abscond and what this means is that the bees will completely abandon the hive, the brood and the stores. Not a single bee will remain.
To give your bees the best chance of not absconding, ensure the hive is well insulated as this enables them create the conditions they need to thrive. Ensure the bees have a well ventilated floor so they can suck sufficient air into the hive to help with cooling. If your bees don’t have natural access to it, make sure you give them plenty of accessible water as this what they will use to help themselves stay nice and cool.
Varroa
Another mechanism for absconding is a high varroa load. When the mite load in a colony builds up to an intolerable level to the bees, they will abscond, leaving behind the majority of the varroa mites in the capped brood cells. This helps the colony survive against the degrading viral impacts of the varroa mite. To ensure your bees don’t abscond due to varroa ensure you follow you integrated pest management plan and regularly treat your bees for varroa.
Robbing
The final mechanism for absconding is when the colony is under threat of robbing from either wasps or other bees. If a colony feels that it can no longer protect itself from the threat of robbing, its only option is to abscond and attempt to set up home elsewhere. However this rarely works and the colonies tend to fail relatively quickly after leaving the hive.
Set your colonies up so they are strong at the right times of the year and ensure that the entrances are reduced to so the colony can effectively defend itself from robbing bees. The underfloor entrance is a useful tool in this battle. See the video HERE and the related blog post HERE.
How To Stop Your Bees Swarming - LINK
I talk about the Demaree split a lot on my channel but it really is the best method I have found help stop your bees from swarming. Check out the video below for instructions on how to complete this swarm management procedure. Why do bees swarm? They don't if you do a vertical split before they start making swarm cells!
Conclusion - So, why do bees swarm?
Hopefully this blog has helped answer the question, why do bees swarm? If bees didn’t swarm, they wouldn’t have survived for hundreds of millions of years, but by knowing and understanding why bees swarm, you are better prepared to mitigate the risk of your bees swarming and ending up in your neighbours chimney. If you don’t manage your bees properly, they will swarm. If you manage your bees well, you have every chance of them staying put and you won't have to ask yourself the question, why do bees swarm?
