Category Archives: Swarm prevention

The nucleus option

The definition of the word nucleus is the central and most important part of an object, movement, or group, forming the basis for its activity and growth”.

Therefore a nucleus colony of honey bees is something smaller than a full colony, but that has inherent capability to grow into a full and active colony.

A nucleus colony is usually abbreviated to nuc (pronounced nuke), often prefixed by an indication of its size e.g. five frame nuc or 2-frame nuc. The very fact that the size of the nuc is often included is an indication that they can exist in a range of different sizes. 

If the size is not defined a nuc is likely to have 5 brood frames. In this post I’ll stick to that convention; unless otherwise specified I’ll use the term nuc to mean a 5-frame nuc. 

What’s in a nuc … ?

A nuc is a fully functional colony of honey bees, just on a smaller scale than a full colony. Therefore it will contain stores, adult bees, brood in all stages and a queen.

5 frame nuc colony

5 frame nuc colony …

Of course, when first prepared it may be missing some of these components. However, to be fully functional, and to have the capacity to grow into a full colony, it must contain everything that would be expected in a full hive, just less.

Other than queens. To be functional a nuc, like a full colony, needs no less than one queen 😉

And, of course, no more than one 🙂

Part of the skill in preparing good quality nucs – for whatever purpose – is to ensure they are a balanced and functional mini-colony. They need enough adult bees to rear brood, to defend the colony and to forage effectively. They need sufficient stores to avoid starvation during a bout of bad weather, and they need a mated, laying queen to help the mini-colony expand.

… and what’s it in?

A nuc is usually housed in an appropriately sized nucleus hive, but actually doesn’t need to be. Commercially-purchased nucleus hives almost always take 5 brood frames 1, though there are exceptions. Paynes Beekeeping sell a very widely used 6 frame National nuc. Paradise Honey polystyrene Langstroth nucs also take 6 frames and, to add further confusion, can be divided easily longitudinally into two 3-frame nucs. 

Here's three I prepared earlier ...

Everynuc poly nucs

Of course, if you make your own – or butcher commercial offerings – a nucleus hive can be any size you want. As the need arises 2 I use two, three, five and eight frame nucs.

Two frame nuc box

Two frame nuc box … a bit too small for the nucleus method of swarm control (but usable at a pinch)

But the nucleus colony does not have to occupy the entire hive.

A well-prepared nuc can expand in size quite quickly. One of the biggest problems in working with nucs is their tendency to get overcrowded. As I discussed a fortnight ago, overcrowding is a well-established trigger for swarming, and a nuc is perfectly capable of swarming … thereby undoing all your efforts in establishing it in the first place.

Therefore, bearing in mind the necessity to produce a functional and balanced mini-colony, it is not unusual to create the nucleus colony smaller than the hive it is housed in, so providing some space for future expansion.

National hive dummy boards DIY

Dummy boards …

As described below, three frames in a five frame hive hive can start a new nucleus colony. You can even put the frames into a full brood box. In both cases the unoccupied space needs to be reduced or at least separated from the developing colony. With the frames pushed against the sidewall of the hive the addition of a dummy board against the ‘open’ face of the colony is usually sufficient.

Warmth and weighty matters

Being smaller than a full colony, and containing fewer bees, a nuc is less able to keep the cluster warm if the weather turns cold. This isn’t usually an issue during the late spring and summer, but is a major concern if you want to overwinter nucleus colonies.

To make things a bit easier for the bees many commercial nucleus hives are made out of expanded polystyrene. These are mass produced from moulds and sometimes include integral feeders or other design ‘features’. Some of the features included are better than others … and some are pretty useless. In my experience 3 none of the poly nucleus hives sold are perfect, but some are very good and almost all are perfectly usable.

MB poly nuc

MB poly nuc …

I’ve discussed several – now rather ageing – commercially-sold poly nucs previously. I may mention them again in passing, but will focus on the contents of the nuc for most of this post.

The low weight of polystyrene nucleus hives is an additional bonus. Less weight to carry when moving them between apiaries, when selling them or when stacking them up empty for the winter.

But nucleus hives don’t have to be made of polystyrene. For summer use only (or when preparing nuc colonies for sale) you can get nucleus hives made of folded Correx for a few pounds. I’ve also got a few lovely cedar nucleus hives built by Peter Little of Exmoor Bees. These have separate open mesh floors, tightly-fitting removable Varroa trays and deep roofs. They’re beautifully made but usually languish unused in the shed in favour of the poly Everynuc’s I routinely use.

Why prepare a nuc?

There are all sorts of reasons to prepare a nucleus colony, but – at least in my beekeeping – the three main ones are:

  • swarm control – the nucleus colony houses the old queen while the original colony requeens. If this is successful the nuc can either be expanded to a full colony or, after removal of the old queen, united with the original colony so strengthening the hive to exploit the summer nectar flows. I wrote about a nucleus method of swarm control last year.
  • making (limited) increase – a strong colony can almost always be used to prepare a nuc without jeopardising the chance of getting a good honey crop. Depending when the nuc is prepared it will either be strong enough to fill a full hive by the season’s end, or can be overwintered as a nuc. Splitting a nuc off a strong colony can also help delay swarming.
  • much greater increase – a variant of the above is to completely split a strong colony into 4 – 8 nucs. The final number depends upon the strength of the original colony 4. Remember that you need a queen or queen cell for each prepared nuc. I’ve discussed this approach previously when queen rearing using a Cloake board and in doing circle splits.

Whatever the reason, the basic mechanics of preparing nucleus colonies is the same. The important point to remember is that the goal is to produce a fully functional colony, just on a smaller scale. Unless it has sufficient stores, enough bees of the right type or a functional (or soon to be functional) queen it will struggle, and it may not survive.

Stores

I start all my nucs with a frame of largely or completely sealed stores pushed up against the sidewall of the box in which I’m going to house them.

During the first or second inspection of the season I am usually able to remove at least one frame of stores from every full colony. This is leftover from the winter and, with the spring nectar flows underway, no longer needed.

Spreading the brood nest

I replace the removed frame(s) with either drawn comb or, more usually, a new foundationless frame. These are inserted at the edges of the brood nest – effectively spreading the brood nest – rather in the space directly occupied by the frame of stores.

The colony benefits from the additional space to draw new comb for the queen to lay, so delaying the urge to swarm. And I benefit from ~2kg (5lb) of stores in the removed brood frames which I carefully hoard until I need them 🙂

Make sure you store them somewhere safe where wasps, bees and rodents cannot get at them.

Bees

This is where things start to get a little more complicated. The amount of bees – both brood and workers – added to the nuc depends upon a number of things, most important of which are:

  • where the nuc is going to be located after it has been made up. If it being moved to an out apiary more than a couple of miles away then you can usually add fewer bees. Conversely, if it is staying in the same apiary (or being moved nearby) you have to expect many of the flying bees will return to the original hive and make allowances for this by adding more at the start.
  • whether the nuc will be started with a laying queen, a virgin queen or a queen cell. A laying queen can and will start laying eggs immediately, with the resulting workers emerging in ~21 days from making up the nuc. A virgin will have to go out and mate and start laying, so adding several days to this period. If you start the nuc with a queen cell there may be a few more days to be added as well.

Remember that the flying worker bees you add as you create the nuc will all likely have died before any new bees emerge from eggs laid in the nuc. Therefore, to ensure there is a continuity of foragers you need to prime the nuc with sealed brood and plenty of young bees.

So, the next thing to add to the nucleus hive, adjacent to the frame of stores is a frame of sealed brood together with all the bees on the frame. Unless you also intend to place the queen from the original hive into the nuc make sure the queen is not on this frame.

If there is also some emerging brood on this frame as well, all the better. These will help bolster the young bee population you add, enabling them to help rear more brood and get established faster.

If the original colony is particularly strong or you want to create a strong nuc you can add a second frame of brood (and adhering bees), but this is not necessary. What is necessary is to ensure there are enough bees to compensate for ageing foragers and the loss of bees back to the original hive.

Flying bees and hive bees

When you remove a brood frame from the hive it has two general sorts of workers on it – the so-called ‘flying’ bees and the ‘hive’ bees. The former are the foragers, the latter the younger nurse bees. You can crudely separate them by deftly shaking the frame once 5. The flying bees are dislodged, the hive bees hang on tight.

Nurse bees will, as they age, mature into guards and foragers. These will be needed before adult workers emerge from any new eggs laid in the nuc. 

Therefore, I almost always shake in a frame or two of nurse bees into the nuc that is being setup. 

Doing this takes just a few moments … 

  • Lift a brood frame from the original colony and check that the queen is not on it 6
  • Shake the frame once over the original hive to displace the flying bees
  • Shake the remaining adhering ‘hive’ bees into the empty gap in the nucleus hive between the frame of brood and the sidewall
  • Return the brood frame to the original hive

Space to expand

The nucleus hive now probably contains two frames (one of stores and one of brood) and, assuming it’s in a 5-frame box, the bees have space to expand as the colony builds up.

But they also need frames to occupy.

Therefore, add a single foundationless frame, or a frame with foundation or – the 5 star deluxe treatment – a frame of drawn comb to the nucleus hive. The last is a real luxury and means the queen will have somewhere to start laying immediately.

Go on … spoil them 😉

My precious …

With the exception of a queen (see below), the nuc is now complete for the moment. Since I predominantly use foundationless frames I usually add a dummy board to isolate the colony from the echoing space in the 5-frame nuc box. For convenience I’ll usually place the two foundationless frames on the far side of the dummy board so I don’t need to remember them when the colony expands.

The arrangement of frames is therefore:

  • Stores
  • Brood (sealed and emerging), plus adhering bees
  • Drawn comb, or undrawn foundation or foundationless frame
  • Dummy board
  • Foundationless frame
  • Foundationless frame
Foam block ...

Foam block …

If the nuc is to be moved to a remote apiary I’ll also add a closed cell foam block to stop the frames moving about during transport.

Queen

When first created nucs are too small and unbalanced (in terms of the composition of bees in the box) to successfully rear a good quality queen from an egg or young larva.

They will try, but it is not a recipe for success. You’ll often end up with an undersized and underperforming scrub queen. 

Don’t let them.

Why bother putting all those valuable stores, brood and bees into a box without giving them the very best chance of flourishing?

Instead, you need to provide them with a queen – either mated and laying, a virgin or as a mature queen cell. I don’t want to cover the sometimes tricky subject of queen introduction here, so will restrict myself to the two most common scenarios:

  • using the mated queen from the hive you split the nuc off
  • making up a nuc with a ripe queen cells 

The first instance is straightforward. Either make sure the frame(s) transferred to the nucleus hive include the queen or find her in the original hive and transfer her to the nuc.

Transferring her on a frame is easy. Adding her subsequently means picking her up and gently placing her on the top bar of the transferred brood frame in the nucleus hive. Do this carefully and quickly and she will be accepted without any issues 7.

Queen cells

Although also needing care, starting a nuc with a mature, ripe queen cell is even easier.

You can make up the nuc with a frame already containing a sealed queen cell. This is simplicity itself. Just ensure you do not bump, jar or bruise the queen cell during the transfer process.

Sealed queen cell ...

Sealed queen cell …

Alternatively you can add a queen cell from another frame. This can be from the original hive, or from another colony altogether 8

  • Cut around the queen cell  to leave a wide margin of comb. A couple of centimeters isn’t too much.
  • Choose a space on the face of the brood frame in the nucleus hive. If there isn’t one, make one by pushing the comb down with your thumb.
  • Place the sealed queen cell vertically in the gap and use the wide margin of wax to fix it in place by squeezing the wax together. 

You want the queen to emerge onto brood, not stores, and you want the cell roughly central in the cluster of bees to ensure it’s well looked after until she emerges. I usually fix the cell under the top bar.

All gone ...

All gone …

Of course, if you rear your own queens (or have a friend/mentor who does), the queen cells are usually attached to small plastic cups which can simply be hung in place between the top bars.

Location and relocation of nucs

If the new nuc is to remain in the original apiary you should expect that many of the flying bees will return to the original hive. Help discourage them by stuffing the nuc entrance with grass for 48-72 hours.

By the time the grass has dried and the bees have pushed their way out they’ll realise things have changed and will reorientate to their new home.

Stuffed

Stuffed …

It’s also worth checking the population of bees a few days after making up the nuc. If your nucleus hive has a perspex crownboard this can be done with minimal disturbance to the bees. If the nuc looks sparsely populated you can shake in more nurse bees from the original colony (see above).

5 frame nuc ...

5 frame poly nuc …

If you move your nuc a few miles from the apiary it was prepared in the bees will be forced to reorientate to the new location. You’ll therefore lose far fewer of the flying bees, so maintaining a reasonable foraging force during the initial establishment of the new colony.

When transporting nucs take all the normal precautions. Seal the entrance, strap the box up tightly and orientate them with the frames in line with the direction of travel.

Maintenance of nucs

Nucs need a little more TLC 9 than full colonies. Particularly when first set up they are less able to defend themselves as the population of bees is unbalanced.

This is a very good reason not to feed nucs syrup from the start. Workers returning to their original hive may take back news of a readily-available source of ‘nectar’ and induce robbing.

Later in the season, once a nuc is established it may still benefit from a reduced size entrance to give the bees less to defend. 

Being smaller than a full hive they have less space for stores and less space for expansion. Unsurprisingly the two major problems are starvation and overcrowding. Both are readily avoided by regular inspection.

Requeening a nuc ...

Requeening a nuc …

Finally, if you start a nuc with a queen cell it makes sense to find and mark 10 her before moving the colony to a larger hive. Queens are always easier to find in nucs than in full colonies.

There are far too many additional tips and tricks to preparing nucs than I have space for here, but at least it’s a start. The key point to remember is that nucs are far more likely to be successful if set up and managed with a balanced population of bees and ample resources.


Colophon

The title of this post is a modified version of the nuclear option. Formally this is a parliamentary procedure in the US senate. More generally, by analogy to nuclear warfare, it means the most drastic or extreme response possible to a particular situation.

Preparing nucleus colonies is nothing like this. Indeed, it is one of the most useful things to do in beekeeping.

I’ve no idea how this post grew to over 3000 words … my version of filibustering which the nuclear option can be used to defeat. Next week we return to science with an exciting new study 11 on the rise and rise of chronic bee paralysis virus as a threat to beekeeping in general, and beefarming in particular.

 

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 🙂

Swarmtastic!

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 😉


 

Swarm prevention

Swarm prevention and control are distinct phases in the management of colonies during the next few weeks of the beekeeping season 1.

Not all beekeepers practice them and not all colonies need them.

But most should and will … respectively 😉

Swarm prevention involves strategies to delay or stop the colony from initiating events that lead to swarming.

Swarm control strategies are more direct interventions that are used to prevent the loss of a swarm.

Why do colonies swarm?

Without swarming there would be no honey bees.

Swarming is honey bee colony reproduction. Without management (e.g. splitting colonies) colony numbers would remain static. And, since bees have only been managed for a few thousand years, they must have been successfully reproducing – by swarming – for millions of years before then.

So one of the major drivers of swarming is the innate need to reproduce.

Bees also swarm if their current environment is unable to accommodate further colony expansion. Therefore, another driver of swarming is overcrowding.

And, of course, there is some overlap in these two drivers of swarming.

You can therefore expect that strong, healthy, populous colonies will probably try to swarm on an annual basis.

The mechanics of swarming

When a colony swarms about 75% of the worker bees – of all age groups – leave with the queen. They set up a temporary bivouac near the original hive and subsequently relocate to a new nest site identified by the scout bees.

The original colony is left with all the brood (eggs, larvae and sealed brood), a significantly-depleted adult bee workforce and almost 2 all of the honey stores.

What they lack is a queen.

But what the swarm also leaves behind, amongst the brood, is one – or more often several – newly developing queens. These occupy specially enlarged cells that are located vertically on the edges or face of the comb.

Queen cells ...

Queen cells …

Queen cells look distinctive and their initial appearance – before the swarm leaves – is a clear indication that the time for swarm prevention has gone and swarm control is now urgently needed 3.

This is one of the reasons why regular colony inspections are essential, particularly during mid/late Spring and early summer which is the time of the season when swarming is most likely.

Colony fate and the risks of swarming

But back to the recently swarmed colony. In a few days the new queen(s) emerges. If there’s more than one they usually fight it out to leave just one. She goes on one or more mating flights and a few days later starts laying eggs.

This colony should survive and thrive. They have time to build up strength (and collect more stores) before the end of the season. Under natural conditions 87% of swarmed colonies overwinter successfully 4.

Alternatively, the swarmed colony may swarm again (and again), each with a virgin queen and each further depleting the worker population. Colonies can swarm themselves to destruction like this.

Swarms headed by virgin queens are termed casts. I’m not sure what determines whether a swarmed colony also produces one or more casts. Colony strength is a determinant, but clearly not the only one as some casts contain little more than a cup full of bees.

Under natural conditions swarming is a very risky business. Swarm survival is less than 25% 5 – many will not collect sufficient stores to overwinter – and the survival of casts will be even lower because of their size and the risks associated with queen mating.

But ‘our’ bees don’t live under natural conditions

For beekeeping the ‘risks’ associated with swarming are somewhat different.

When a colony swarms you lose the majority of the workforce. Therefore honey production will be significantly reduced. You’re unlikely to get a surplus from the swarmed colony.

Of course, honey might not interest you but propolis and wax production are also reduced, as is the strength of the colony to provide efficient ecosystem services (pollination).

Secondly, despite swarms being one of the most captivating sights in beekeeping, not everyone appreciates them. Non-beekeepers may be scared and – extraordinary as it may seem – resent the swarm establishing a new nest in the eaves of their house.

Incoming! from The Apiarist on Vimeo.

Inevitably some beekeepers will claim they’ve never met anyone scared of bees, or swarms are always welcomed in the gardens that abut their apiary.

Unfortunately, that does not alter the reality that – to many – swarms are a nuisance, a potential threat and (to a small number of people 6 ) a very real danger.

Therefore, as beekeepers, we have a responsibility to practice both swarm prevention and control. This prevents our hobby/obsession irritating other people and means we have more bees to make delicious honey for family, friends and customers.

Overcrowding

I’ve already defined the event that separates swarm prevention from swarm control. It is the appearance of queen cells during the weekly colony inspection.

Swarm prevention involves managing the colony to delay the appearance of queen cells. Once queen cells are produced, swarm control is required 7

I’ve also defined the two major drivers of swarming – overcrowding and the need to reproduce 8.

How does a colony determine that it is overcrowded? As beekeepers, how can we monitor and prevent overcrowding?

As a colony expands during the spring the queen lays concentric rings of eggs from the centre of the brood nest. Imagine this initially as a kiwi fruit-sized ball, then an orange, then a grapefruit, until it is the size of a large football.

Brood frame

Perhaps a slightly squashed football, but you get the general idea.

Running out of storage space

It takes bees to make bees. The initial brood reared helps feed subsequent larvae and keeps the maturing brood warm.

As the season develops more sources of nectar and pollen become available. These are collected in increasing amounts by the expanding numbers of foragers.

This all needs to be stored somewhere.

One possibility is that the stores are loaded into the cells recently vacated by emerging workers within the brood nest. This is often termed “backfilling”. Sometimes you find a frame in which the central concentric rings of brood have emerged and, before the queen has had a chance to re-lay the frame with new eggs, workers have backfilled the cells with nectar (or, less frequently, pollen).

But, at the same time as the space available for the queen to lay is reducing, the colony population is increasing. Very fast. There are larger numbers of unemployed young bees. Unemployed because there are reduced amounts of brood to rear because the queen is running out of space.

Pheromones

And the increased number of workers means that the pheromones produced by the queen, in particular the queen mandibular pheromone, are effectively diluted. Studies by Mark Winston and colleagues 9 investigated the relationship between queen mandibular pheromone (an inhibitor of queen cell production) and colony congestion. In it he concluded that overcrowding inhibits the transmission of this pheromone, so favouring queen cell production.

Play cup or queen cell?

Play cup or are they planning their escape …?

The distribution of other pheromones is also reduced in overcrowded colonies. Lensky and Slabezki 10 showed that the queen rarely visited the bottom edges of comb in overcrowded colonies. Consequently, the levels of queen footprint pheromone was reduced. This pheromone is an inhibitor of queen cup production, the very earliest stages of queen cell development.

So, overcrowded colonies start to prepare queen cells … and swarm control is needed.

Make space

If the colony is overcrowded then you have to provide more space for colony expansion.

Just piling supers on top may not be sufficient, though it may temporarily ease congestion and partially help. Leaving a colony with no supers during a strong nectar flow is a surefire way to fill the brood box with nectar and trigger swarm preparation.

If the colony is backfilling the brood nest with nectar then the addition of supers is likely to encourage them to move the stores up, providing more space for the queen.

It will additionally have the beneficial effect of moving some bees ‘up’, to store and process the nectar, again reducing congestion in the brood nest.

However, you probably also need to encourage the bees to expand the brood nest by providing frames for them to draw out as comb. Essentially you’re spreading the brood nest by inserting one or two empty frames within it.

Expanding or spreading the brood nest

I routinely do this by removing the outer frames, which often contain stores, and adding new foundationless frames on one or both sides of the centre of the brood nest. Usually I would place these about three to four frames apart 13.

You can routinely replace queens by purchasing new ones, by rearing your own, or through colony manipulation during swarm control e.g. by reuniting a vertical split.

Of these, I’d strongly recommend one of the last two approaches. It’s more interesting, it’s a whole lot more satisfying and it is a lot easier than many beekeepers realise.

Locally bred queen ...

Locally bred queen …

You have the additional advantage that the queens produced in your own apiary will – by definition – be local and there is good evidence that local queens are better adapted to local conditions.

Robbing brood and making nucs

There are at least two additional, and related, ways of increasing the space available so helping swarm prevention in a rapidly expanding colony.

The first is stealing a frame of brood 14 and using it to boost a weaker colony.

Take care when doing this.

If the recipient colony is weak due to disease or a failing queen then you’re just wasting the donated brood. However, if the colony is healthy but small it can be a good investment of resources and may help delay swarming in the donor colony as well.

More drastically, it may be possible to remove a frame (or perhaps even two) of brood and adhering bees to make up a nucleus colony. In my experience, a strong donor colony can almost always be used to produce a nuc without compromising honey production, and with the added benefit of delaying swarm preparations.

I’m going to write about nuc production in more detail in a few weeks as it deserves a full post of its own. It’s worth noting here that the nuc should also be provided with sufficient bees and stores to survive and you will need a queen for it (or at least a queen cell).

Do not just dump a couple of brood frames and bees into a box and expect them to rear a half-decent queen on their own.

However, if you have a queen (or mature queen cell) then splitting a nuc off a strong colony is usually a win-win solution for swarm prevention.