Principles of swarm control

Having introduced swarm prevention last week it’s probably timely to now consider the basic principles of swarm control.

This is going to be relatively high level overview of why swarm control works (which it usually does if implemented properly), rather than a detailed ‘how to’ guide.

That’s because knowing what to do and when to do it is so much easier if you understand why you’re doing it.

That way, when faced with a colony clearly committed to swarming, you can manipulate the colony to avert disaster.

Which it isn’t … though losing a swarm might feel like that to a new beekeeper.

Welcome to the club

All beekeepers lose swarms, even those who rigorously and carefully employ swarm prevention methods. I lost one last year and would have lost another two were it not for a clipped queen in one 1 and some particularly unobservant and cackhanded beekeeping with another.

Mea culpa.

However, it’s called swarm prevention because it usually delays and sometimes prevents swarming.

But at some point the enthusiasm of the bees to reproduce often outstrips the possible interventions that can be applied by the beekeeper to the intact colony.

At that point, swarm control becomes necessary.

How do you know when that point has been reached?

Typically, if you carefully inspect the colony on a regular seven day cycle you will easily identify the preliminary stages of swarming. You will then have ample time to take the necessary steps to avoid losing the majority of your bees.

When is swarm control needed?

At some point in late spring 2 a colony is likely to make preparations to swarm.

Triggers for this are many and varied.

The colony may be running out of space because the foragers have backfilled the brood box with nectar during a strong spring flow.

Pheromone levels produced by the ageing queen are reducing. These usually act to suppress the formation of queen cells.

Alternatively, although mechanistically similar, the colony may be so populous that the queen mandibular pheromone concentration is – by being distributed to many more workers – effectively reduced. As described last week, in such strong colonies the queen rarely visits the bottom edges of the comb. Consequently, the levels of queen footprint pheromone – another suppressor of queen cell formation – in this region of the nest is reduced.

Whatever the trigger – and there are probably others – the colony starts producing queen cells.

Sometimes these are very obvious, decorating the lower edges of the drawn comb.

Sealed queen cells

At other times they are hidden in plain sight … in the middle of the comb, with a moving, wiggling, shifting, dancing curtain of bees covering them 3.

Queen cells ...

Queen cells …

The production of queen cells indicates that swarm prevention has not been successful and that swarm control is now needed.

More specifically, it is the production of charged queen cells with a larva sitting in a deep bed of Royal Jelly, that indicates prompt swarm control is required.

Charged queen cell ...

Charged queen cell …

And remember, there may well be more than one queen cell and they are not always on the same frame.

Unsealed and sealed queen cells

With experience you can ‘age’ queen cells by their size and appearance. The larva in the queen cell in the photo above hatched from the egg about 3-4 days ago.

When the larva is five days old the cell will be sealed and the larva pupates 4.

Queen development

Queen development …

In a further 8 days i.e. 16 days after the egg was originally laid in the cell, the new virgin queen will emerge.

But the colony will have already swarmed.

That is because, under normal circumstances, a colony usually swarms on the day that the queen cell is sealed

There are two events that often delay swarming beyond the day that the queen cell is sealed.

The first you have no control over. It’s the weather. Colonies usually swarm on lovely warm, sunny days. If it’s cold and wet, or blowin’ a hoolie, the swarm will wisely wait for a day with better weather. Wouldn’t you?

If you have a week of poor weather in mid/late May (the peak swarming season around here at least) then the first day of good weather is often chaos with swarms all over the place 🙂


The second thing that delays swarming is if the old queen has a clipped wing. In this instance the swarm usually waits until the new queen emerges before trying to leaving the colony.

The other event, less routine in my experience, that stops swarming 5 is supercedure. In this, the queen is replaced in situ, without the colony swarming. Queen cells are still produced, usually rather few in number 6. I’ll discuss supercedure at some point in the future.

Destroying queen cells is not swarm control

If you simply destroy developing queen cells the colony will eventually swarm.

Either you’ll miss a queen cell – and they can be very hard to spot in a busy colony – or the bees will start one from an older larva and the colony will swarm before your next 7 day inspection.

Beekeeping is full of uncertainties. That’s why these pages are littered with caveats or adverbs like ‘usually’. However, ‘the colony will eventually swarm’ needs no such qualification. If all you do is knock back queen cells you will lose a swarm. 

I said in the opening section that losing a swarm is not a disaster, though it might feel that way to a beginner.

In reality, for a beekeeper who thinks destroying queen cells is a form of swarm control, losing a swarm can be a disaster 7.

When is ‘not a disaster’ actually a disaster?

Here’s the scenario … on one of your regular inspections (delayed a week because of a long weekend in Rome 8) you open the hive and find half a dozen fat, sealed queen cells decorating the lower edges of a couple of frames.

Using your trusty hive tool you swiftly obliterate them.

Job done 😀

But wait … under normal circumstances when does the colony usually swarm?

On the day the queen cell is sealed.

That colony had already swarmed 😥 

She’s gone …

What’s more, it may well have swarmed several days ago. Therefore there will no longer be any eggs or very young larvae in the hive that could be reared as new queens. Without acquiring a new queen (or a frame of eggs and young larvae) from elsewhere that colony is doomed 😥

So … repeat after medestroying queen cells is not swarm control.

If they are sealed, the colony has probably swarmed already and destroying all that are there jeopardises the viability of the colony.

If they are not sealed, then destroying them will not stop them making more and you will miss one tucked away in the corner of a frame.

And the colony will swarm anyway.

Generally, destroying all the queen cells in a colony is a lose-lose situation 🙁

The principles of swarm control

Disappointingly, almost none of the above has been about the principles of swarm control 9. However, the point I make about colony viability allows me to get back on topic in a rather contrived manner 😉

When a colony swarms, ~75% of the adult bees and the mated, laying queen fly away.

They leave behind a much depleted hive containing lots of stores, some sealed brood, some larvae, some eggs and one or more sealed queen cells.

Swarming is colony reproduction. Therefore, both the swarm and the swarmed colony (the bits that are left behind) have the potential to form a new fully viable colony.

The swarm needs to find a new nest site, draw comb, lay eggs and rear foragers. The swarmed colony needs to let the new queen(s) emerge, for one queen to get mated and return to the hive and start laying eggs.

A small swarm

A small swarm …

But importantly these events take time. Therefore, neither the swarm nor the swarmed colony are likely to swarm again in the same season.

And that, in a nutshell, describes the two defining features of many types of swarm control:

  • the colony is manipulated in a way to retain its potential to form a viable colony
  • the colony is unlikely to swarm again until the following season

So, which parts of the hive population have the potential to form a viable colony?

The bees in the colony

A colony contains a mated, laying queen. The thousands of eggs she lays are part of the developing workforce of larvae and pupae, all of which are cared for by the very youngest adult workers in the hive, the nurse bees. Finally, the third component of the colony are the so-called flying bees 10, the foragers responsible for collecting pollen and nectar.

The principles of swarm control

Of those three components – the queen, flying bees, and the combination of developing bees and nurse bees – only the latter has the potential to form a new colony alone. 

The queen cannot, she needs worker bees to do all the work for her.

The flying bees cannot as they’re unmated and cannot therefore lay fertilised eggs.

But if the combination of nurse bees and developing brood contains either eggs or very young larvae they do have the potential to rear a new queen and so create a viable colony.

Furthermore, thanks to their flexible temporal polyethism 11 the combination of the queen and the flying bees also has the potential to create a viable colony.

Divide and conquer

The general principle of many swarm control methods 12 is therefore to divide the colony into two viable parts:

  1. The queen and flying bees – recapitulating, though not entirely, the swarm 13. We’ll call this the artificial swarm.
  2. The developing brood and nurse bees. This component must contain eggs and/or very young larvae from which a new queen can be reared 14. We’ll call this the artificially swarmed colony.

I’ve described two very standard swarm control methods in detail that fit this general principle.

  • The Pagden artificial swarm, probably the standard method taught to beginners up and down the country. 
  • The vertical split, which is a less resource-intensive variant but involves more heavy lifting.

Both initially separate the queen on a single frame and then exploit the exquisite homing ability of the flying bees to separate them from the nurse bees/brood combination that have been moved a short distance away. 

Both methods are effective. Neither is foolproof. 

The artificially swarmed colony almost always raises multiple new queen cells once it realises that the original queen has gone. If the initial colony was very strong there’s a good chance several queens will emerge and that the colony will produce casts – swarms headed by virgin queens.

To avoid this situation (which resembles natural cast production by very strong colonies) a second move of the artificially swarmed colony is often used to reduce further the number of flying bees 15, and so weaken the colony sufficiently that they only produce a single queen.

Alternatively, the beekeeper does this manually, by removing all but one queen cell in the artificially swarmed colony

And the nucleus method?

Astute readers will realise that the nucleus method of swarm control is similar but different.

Here's one I prepared earlier

Here’s one I prepared earlier

It separates the colony into two viable parts but there is no attempt to separate the majority of the flying bees from the brood/nurse bees.

I like the nucleus method of swarm control. It’s easy to understand, very simple to implement and – done properly – very effective.

In particular, I think it is an easier method for beginners to grasp … in a “remove the queen and the colony cannot swarm” sort of way 16.

However, the queenless part of the split colony is inevitably left relatively strong, with brood, nurse bees and a lot of the flying bees. As a consequence there’s a good chance it will produce cast swarms if it’s allowed to rear multiple queens to maturity.

Which is why you must inspect the queenless part of the split colony one week later. As I said in my original post on this method:

The timing and thoroughness of this inspection is important. Don’t do it earlier. Or later. Don’t rush it and don’t leave more than one queen cell.

Which neatly introduces nucleus colonies which is the topic for next week 😉



  1. So I’d perhaps argue that my prevention and control worked, though only because the swarm ended clustered under the open mesh floor and was successfully re-hived.
  2. Like all things in beekeeping it’s not possible to be precise about dates – it varies depending upon geography, season, climate and weather.
  3. This one is also pretty obvious – slightly right of the centre of the photograph. Now look again. There’s another one as well. If you look very carefully you’ll also see that the uncapped cells are filled with nectar – this colony has run out of room as the foragers have been backfilling the centre of the broodnest.
  4. Queen cell development is very fast – 3 days as an egg, 5 days as a larva, 7-8 days as a pupa, with emergence on day 16 after egg laying.
  5. Pedantically it doesn’t start in the first place.
  6. I’m not convinced you can dependaby differentiate supercedure queen cells from swarm queen cells by their appearance or position. If you find queen cells you have to consider swarm control.
  7. I’m using the term disaster in the context of beekeeping, not global viral Armageddon. These things are relative.
  8. Or a family wedding, or a conference … or one of any number of things that used to happen before Covid-19.
  9. Other than to emphasise that destroying queen cells is not swarm control.
  10. These are workers usually from about 2-3 weeks old – effectively middle age for a bee in midsummer.
  11. Bees of different ages have different roles and responsibilities in the hive. However, there is some flexibility in this. Older workers can revert back to fulfill the duties in of younger bees if needed.
  12. Like smoker fuel or hive tools, there are many, many methods of swarm control, most of which work. Many work on the principles defined here. Some do not.
  13. A natural swarm contains worker bees of all ages, and is not just predominantly the older workers.
  14. Which is why knocking back all the sealed queen cells in a colony with no eggs or young larvae is usually a disaster.
  15. This move is done a week after the initial division of the hive, after which time there are no more young larvae or eggs to be reared to make new queens.
  16. Though that’s not actually correct …

16 thoughts on “Principles of swarm control

  1. Lincoln

    Your posts are clearly explained and helpful to beekeepers of varying experiences and skills.

    1. David Post author

      Thanks Lincoln … always difficult to get the balance. I just about remember starting as a beekeeper and being aware of the enormity of my ignorance. Now, after a few years, I’m just as aware of the enormity of my ignorance … but of a much wider range of endlessly fascinating topics.

      I hope you’re having a good season.

  2. Jane

    Thanks for the post David.
    At least partly thanks to your advice about emergency varroa control in the early winter after autumn treatment failed, I do still have a colony of bees to care for. I am now facing my first full season but without the practical assistance and teaching I was expecting due to coronavirus restrictions.
    From my reading, I have got the message that weekly checks for queen cells are important for colonies with unclipped queens. You mention the issue of going on holiday in your post, which won’t be a problem this season! But what about the weather? If there is a spell of cold/wet/windy weather, is it better for me to open up to check for queen cells, or wait until the first day when they are flying in decent numbers? Or possibly do two checks in less than a week if the forecast is bad?
    When I have a queen cell, my aim is to follow your nucleus method to “make an increase” because being dependent on just one queen is quite stressful!
    Thanks again for providing such a great resource, especially for those of us without BKA meetings at this time.

    1. David Post author

      Hi Jane

      It’s not unusual to be thwarted by the weather in the UK.

      Even for my colonies with clipped queens I try and check on a weekly basis. Opening hives in really bad weather is a miserable experience for you and the bees – I’d not recommend it. I’ve done it in a thunderstorm several times but it’s not something I’d choose to do.

      If the weather is really bad I usually delay the inspection. If it’s just ‘not ideal’ then I’d probably go for it. The bees carry on ignoring the odd day of poor weather, though an extended spell can delay their swarm preparations. If there’s been a period of bad weather and you’ve missed/delayed an inspection it might be best not to wait for a balmy shirtsleeves afternoon as the bees can swarm right in front of your eyes. This has happened to me and it’s a spectacular sight. If I can I try and inspect after the weather improves, but before it’s lovely flying weather again. It doesn’t always work out, but it’s worth a try.

      You can also sometimes open the hive to find half a dozen new virgin queens running around inside – the bees can ‘trap’ virgins in their cells and I suspect the inspection disrupts them, so releasing the queens. It can get pretty chaotic.


      1. Jane

        Thanks for the advice. It has just become very pertinent as I found multiple queen cups this morning! I’ve given them more space as, for reasons I needn’t explain, I think they didn’t like the super I gave them, but I will now be itching to check whether they create queen cells.

        1. David Post author

          Hi Jane

          They can make queen cups for two or three weeks before deciding what they’re going to do. Sometimes they decide to “Go for it” and other times they just quietly give up and get on with collecting the nectar. It goes without saying that the lovely calm colony you want to produce queen cells doesn’t, whereas the one you want to keep strong for honey production does everything possible to swarm.

          All part of the fun 😉

  3. Mark

    Find your updates very interesting. I assist in teaching beginners and the nucleus method of swarm control was a big success last year after reading about the method here. It is so simple and it just makes sense instead of shuffling boxes and asking beginners to remember the process when they need it.


    1. David Post author

      Hi Mark

      As long as you revisit the original colony at the right time and make sure you leave just one QC it’s very dependable. As you say, for beginners it’s simplicity itself to explain and understand.


  4. Mark Riches

    Thanks David for well explained Information on what I think is the most difficult procedure in my beekeeping to try and carry out .
    I have many books and much information on the swarming subject, written by very knowledgable and experienced beeks but the way you explain the workings of the hive iworks very well for me.
    Sitting in the sun here in Norfolk, the bees busily foraging and going about their business, and I suspect all sorts of challenges await me later in the day when I open the buggers up…but oh I do love apiculture.
    Thank you for another great post.
    With regards Mark Riches. Norfolk beekeeper.

    1. David Post author

      Thanks Mark

      I’m pleased you found it useful. It’s always worth remembering that the bees haven’t read any of the books and sometimes decide to do something completely contrary. Nevertheless, understanding the principles always helps and means that, when faced with a new situation, you can make an informed guess about what’s happening or how to rescue the situation.


  5. Keith

    Hi David
    One thing always has puzzled me…hives swarming with a dearth of drones. I’ve found congested over wintered nucs especially that have grown fabulously in a great early spring and during inspections they are primed and ready for the off but not a drone in sight. Is that not a consideration if I can give bees that particular attribute ? Thanks, really enjoy the blogs !

    1. David Post author

      Hello Keith

      An interesting question. I’m not sure that the presence of drones in the about-to-swarm colony influences the process or timing of swarming. Nucs tend to be a bit short of drones at the best of times, almost as though the colony never gets strong enough to trigger the production of drone brood (I’ve got a paper on this somewhere – I’ll look it out). I’m only too aware that they can swarm if overcrowded 🙁

      In one of the studies quoted last week (about queen footprint pheromone I think) they were able to induce play cup formation in the winter in very crowded colonies. This suggests that the triggers for swarming may be sufficient to induce it even if the conditions are unsuitable i.e. the absence of drones (and therefore the ability of the new queen to mate) does not ‘overrule’ the influence of overcrowding.

      The other point of course is that there should be selection against a queen mating with her own sons as this would decrease genetic diversity. Therefore it’s possibly irrelevant whether the nuc has drones in it as the queen ‘wants’ to mate with drones from another colony anyway.

      More research needed I suspect 🙂

      PS … the middle paragraph, about the absence of drones not overruling the induction of swarming applies irrespective of the source of the drones. How would the nuc ‘know’ there were drones about other than a) generating them in the first place or, b) incoming drones arriving through ‘drifting‘. You might be able to test this by looking at swarming in a single very isolated nuc (so no drifters). I suspect they’d still go … they usually do 🙁

  6. John Markey

    This year , my two hives having taken the two Queens out to prevent them from swarming, and as result they failed to raise their own Queens, I gave them frame after frame of eggs for them to raise queens, they used seal the queen cells but they never emerged, it was like that the Queen cells had not enough food in the cells for them to emerge, it was like as if the cell was starved of food, In August I introduced their own Queens back to the hives using the newspaper method, with the result they both swarmed, why so late in the year did they swarm.
    regards John

    1. David Post author

      Hello John

      I don’t understand how they couldn’t rear their own queens after you removed the originals. Surely there were eggs and young larvae present? I presume the original queens built up strongly in their new boxes and, when united with the originals, resulted in strong colonies that then swarmed. With only limited information it’s impossible to diagnose what went wrong. However, it’s certainly not too late for colonies to swarm – a friend had a swarm a couple of days ago at 57oN which is even further north than me.

      The nucleus method is usually a very reliable method of swarm control (because there’s so little to go wrong). I used it on almost all my colonies this year and the only ‘failure’ was those in which the new queen failed to get mated or disappeared on a mating flight.

      If the colony failed to generate a new queen an alternative solution would have been to unite them back together earlier in the season … though they still might have tried to swarm later if the colonies were very strong. Doing it this way would have save you the frames of eggs and young brood.


  7. John Markey

    I think myself there are some aspects of beekeeping that is hard to understand, when my two hives swarmed in August they were facing the autumn and would want fairly strong hives to face the Autumn and the Winter, they are now trying to raise Queens with difficulty.
    With regards 2020 in Ireland it was a bad year weather wise, and I am told by the experts that the weather being so bad, the bees were not able to go out to collect the food necessary for raising the Queens so literary the larvae in the Queen cell hadn’t sufficient food to emerge so they starved.
    regards John

    1. David Post author

      I hope they make it John … getting queens mated this late in the season is really hit and miss. Could you unite them with other colonies? Even colonies belonging to a friend, with the understanding you could split a nuc off next season? If they don’t get a new queen they’re doomed. Which, of course, you know.

      Good luck

Comments are closed.