Queenright … or not?

A brief follow-up to the (ridiculously long) post last week about leaving queen cells in the colony after a) it swarms, or b) implementing swarm control 1.

How long does it take for the new queen to emerge, mate and start laying? 

And what if she doesn’t?

How did we get here?

We are approaching the peak of the beekeeping season. Colonies have built up strongly and should now be topped by comfortingly heavy supers of spring honey. 

Mind your back 😯 

The box you inspected in early April and found three frames of brood in is now bursting at the seams with bees and brood. Everything is getting busier and bigger. You may have already run out of supers or – lucky you – are frantically extracting to free-up supers to return to the colonies.

Depending upon your location you may already have discovered that your swarm prevention efforts, whilst temporarily effective, were soon treated with disdain as the colonies started to build queen cells.

Sealed queen cell ...

Sealed queen cell …

You are now using some form of swarm control and the colony now contains a mature queen cell.

Or they swarmed … leaving a mature queen cell 🙁

Queenless colonies

Is a colony with a charged, capped, queen cell queenless? 

A philosophical question 🙂

I guess the answer is technically no, but practically yes.

There’s clearly a queen in the hive, but she’s really a potential queen. To be useful to the colony (and the beekeeper) she has to emerge, mature, mate and start laying.

It’s at that stage that the colony can be described as queenright.

All of this takes time and all of which significantly changes the tempo of the season.

Colonies that are requeening should generally not be disturbed and the change from full-on to full-off can feel strange.

Doubly so, because the lack of reassuring inspections can make the wait seem interminable. 

It’s tempting to have a quick peek … after all, what harm could it do?

Tick tock

The development of a queen takes 16 days from egg to eclosed virgin. The first three days as an egg, then six days as a larva before a further week as a developing pupa. The rapid development is due to the very rich diet that queens are fed in the first couple of days. This triggers a host of changes in gene expression 2 which dramatically alters the morphology, behaviour and longevity of the queen from the genetically identical worker.

After a virgin queen emerges she needs to mature sexually which takes 5-6 days. During this period they don’t look or behave much like queens. They tend to be quite small and, if disturbed, rush about the frame skittishly. They are also a lot more willing to fly than a mature laying queen – you have been warned! 3

Where have all my young girls gone?

What a beauty

Virgin queens are not lavished with attention by a retinue of workers, all of which often makes them more difficult to find in the hive.

The queen goes on one or more mating flights which usually take place on warm, calm, sunny early afternoons.

She then returns to the hive and, 2-3 days later, starts laying eggs. A queen that has just started laying sometimes lays more than one egg per cell. However, she settles down fast and will usually lay in a reasonably tight pattern in the centre of one of the middle frames in the brood nest.

Have patience

Add all those timings up and you have a minimum of two weeks between the capping of the queen cell and the day when she starts laying.

To be sure, you need to know when the queen cell was capped which is difficult if you’re dealing with a colony that swarmed. Was the cell capped on the day the colony swarmed (not unusual), or was it capped during the lousy weather a few days earlier that then delayed the emergence of the swarm?

It is unwise to disturb a virgin queen.

All sorts of things can go wrong. You might inadvertently crush her during an inspection 4 or scare her into taking flight and getting lost in the long grass.

Equally calamitous would be inspecting the colony on the nice, calm, warm mid-afternoon when she decides to go off on her mating flight. She’ll be off consorting with the local drones for about 10 – 30 minutes, and may go on more than one flight on subsequent days. If she returns to find the roof and supers off, the brood frames out and smoke being puffed everywhere she may never find the hive entrance.

Inspecting a colony

None of the above ends well.

Minima and maxima

The two weeks detailed above is the absolute minimum. I don’t check these things routinely but think the only time I’ve really seen it taking that short a period (from cell sealing to a mated laying queen) is when queen rearing using mini-mating nucs.

Mini-nucs …

Queens tend to get mated in these very fast if the weather is suitable. I don’t know why 5.

But, if the weather is unsuitable, irrespective of the hive type, mating will be delayed.

By ‘unsuitable’ I mean lousy. If it’s raining persistently or blowing a hoolie the queen will not venture forth.

If it’s cool (16 – 18°C) and cloudy she might, particularly if she’s of the darker Apis mellifera mellifera strain. 

But then again, she might not 🙁 

All of which means that the two weeks quoted really is a minimum.

What if it rains for a month? The virgin queen has a ‘shelf life’. If she does not get mated within ~26-33 days of emergence she is unlikely to get successfully mated at all.

Here we go again ...

No queen mating today …

To summarise, it will take a minimum of two weeks from queen cell capping to having a laying queen in the hive. If 40 days elapse before the queen is mated (again from cell capping) it is likely that she will be a dud.

Three weeks

Assuming the weather has been OK for queen mating I usually leave a minimum of three weeks between closing the hive up with a capped queen cell and looking for the mated queen. 

There’s little to be gained by rummaging around the hive before then … and a whole lot to be potentially lost.

If you do open the hive up too early – assuming none of the nightmare scenarios above occur – what can you expect to see?

Lift the dummy board out, prise out the last frame and then split the hive somewhere in the middle of the remaining frames i.e. don’t work through frame by frame, this isn’t a routine inspection, it’s a Royal Checkup.

If you look around the middle of the face of the central frames you can often see polished cells. These have been cleaned and prepared by the workers for the queen to lay in. They’re particularly obvious if the comb is a bit old and dark – then they really do look polished and shiny.

If there are polished cells present, but no eggs, I’m then reasonably confident that there’s a queen in the hive but that she’s not started laying yet (but is probably mated).

There’s no point in looking for her. Close the hive up and leave it another week.

Brood frame with a good laying pattern

If she is laying, leave her be. Wait until she’s laid up a few frames and you can tell she has a good laying pattern of worker brood i.e. look at the appearance of the sealed brood, then find her and mark her 6.

Breathe a sigh of relief … your colony is again queenright.

Five weeks

If five weeks 7 have elapsed between leaving a freshly capped cell in the hive and the non-appearance of eggs I start to fear the worst.

The colony will now have no brood – it all emerged about two and half weeks ago – and the lack of brood pheromone means there’s a possibility that the colony will develop laying workers

Laying workers ...

Laying workers …

There may be a queen present, but she’s rapidly becoming an ageing spinster

In this situation it is probably wise to decide what Plan B is … how will you ‘rescue’ the colony?

If you leave the colony for another week or fortnight you might find a laying queen, but you probably won’t. During this period the colony will dwindle further in size and strength 8

Plan B

You effectively have four choices:

  1. Unite the colony with a known queenright colony.
  2. Requeen the colony with a mated, laying queen 9.
  3. Add a mature capped queen cell to the colony. Start nervously pacing the apiary again waiting for her to emerge, mature, mate and start laying.
  4. Allow the colony to rear their own queen by providing a frame of eggs (see below).

It is important to find and dispatch the ‘failed’ queen if you are going to do 1, 2 or 3. The queen may have failed to get mated but she might still be able to kill a challenger queen in the hive. 

Uniting the colony is often the best and safest option. It’s quick. It uses the bees remaining in the colony immediately and it strengthens another hive. It’s my preferred option … but I have quite a few colonies to work with. If you have just one (and you shouldn’t have) it’s clearly a non-starter. 

An Abelo/Swienty hybrid hive ...

An Abelo/Swienty hybrid hive …

Adding an expensive purchased mated laying queen (or a cheap one) can be risky. Terminally queenless and broodless colonies are often tricky to requeen. The most successful way I’ve found to do this 10 is to use a large cage pinned over a frame of emerging brood. And even then it doesn’t always work 🙁 

If you already have laying workers it is not worth trying to requeen the colony – they’ll almost certainly kill her. I usually try once to ‘rescue’ a laying worker hive (details here), but then shake them out.

Adding a capped queen cells can work if the colony is queenless but you will have another long wait ahead of you … and all the time the colony is dwindling in size.

She emerges into a population of geriatric workers. Far from ideal.

But what if you can’t find the queen?

Is the colony really queenless?

Perhaps she mated quite late because of poor weather and is about to get started?

Perhaps she failed to mate and is just lurking in there waiting to slaughter the £40 Buckfast queen you’re about to add 🙁 

Frame of eggs

Most of these questions can be answered by adding a ‘frame of eggs’.

A queenless colony will start to rear a new queen if presented with eggs and larvae.

A queenright colony will not.

If you are unsure whether a colony is queenright add a frame containing a good number of eggs. I usually like to use a full brood frame also containing some larvae and sealed brood. The brood pheromone will help hold back laying worker development. The new young bees that emerge will bolster the hive population and will be there to help the new queen when she returns from getting mated.

If you have the luxury of choosing a frame of eggs on relatively new fresh comb the bees will find it easier to draw queen cells. However, don’t worry if you don’t … if they’re queenless they’ll be thankful for anything.

Check the colony a few days after adding the frame of eggs. If they’ve started queen cells 11 then I just let them get on with it and check again in about a month or so for a laying queen. They won’t swarm or generate casts as – by this time – bee numbers are significantly depleted. 

However, if they don’t start queen cells it means there’s a queen somewhere in the hive. Check the other frames in the hive for eggs. It’s not at all unusual to find the original queen has now started laying. Again, leave her to get on with it.

But if there are no eggs on other frames and no queen cells (on the frame you added) you need to find the non-functioning queen … and we’ll deal with that sometime in the future 😉

Good luck


Colophon

The usual dictionary definition of queenright just references a colony of bees that contains a queen. The OED has references going back to 1911 (When a colony is found that is not queen-right, it is remorselessly broken up, and distributed among other colonies, or united with a weak colony having a good queen, C.C. Miller in Fifty Years among Bees) including some from Wedmore and E.O Wilson.  

However, none specifically state whether the queen is laying. Or what she’s laying. A queenless colony is easy to define. But what about a colony containing a virgin queen? Or a drone laying queen? 

I’d argue that in these situations the colony contains a queen, but things aren’t really ‘right’ (as in correct). In my view, queenright means a mated, laying queen. 

Please, no pedantic questions or comments about a colony containing a well mated queen that, because there’s a nectar dearth, has stopped laying … 😉

Queen cells … quantity and quality

How many queen cells should I leave in my hive?

This question pops up year after year at this time of the season.

Up and down the country we’re all busy implementing swarm control because our swarm prevention, er, didn’t 🙁

The majority of swarm control methods leave part of the colony to rear a new queen. Once she has emerged, matured, mated and proved her worth by laying up a frame or two you can then decide what to do with the old queen. 

Irrespective of the swarm control method you use – e.g. Pagden, nucleus method or a vertical split – the colony often produces quite a few queen cells. 

Similarly, if both your swarm prevention and swarm control failed and a prime swarm disappeared over the fence, there are likely to be several (or possibly lots of) queen cells left in the colony.

Queen cells – the good, the bad and the ugly

How many of these queen cells should you leave in the hive? 

Which one(s) should you leave?

Assumptions

I’m in the middle of my own swarm control at the moment and so intend to keep this relatively short and simple 1.

I am going to assume you start with one hive and you want to finish with one hive at the end of the process (i.e. you do not want to make increase). I’ll briefly mention rescuing queenless colonies and stock improvement as it’s relevant.

I’m also going to keep this as generic as possible. It’s not going to depend upon the method of swarm control employed or – with some caveats to be discussed later – whether the colony has naturally swarmed.

Here’s the starting position.

Your hive is making preparations to swarm. You apply a swarm control method that removes the old queen from the original brood box 2. This box therefore contains brood in all stages (BIAS) – eggs, larvae and sealed brood. This brood probably occupies most of the frames in the brood box. 

Also in the box are a very large number of adult bees, both workers and drones 3

And there will probably be one, several or lots of unsealed queen cells 4 present as well 🙂

Why do anything? or What’s the worst thing that could happen?

When a colony swarms naturally about 75% of the adult bees leave with the old queen. This figure is similar whether the colony is large or small. 

If you start with a large double brood colony it might contain 60,000 bees. Let’s assume a large swarm leaves as the first queen cells are capped (which is when the swarm usually scarpers).

There are still 15,000 bees and perhaps 15-18 frames of brood, several frames of which are close to emerging. The queen laying rate 3 weeks prior to the swarm was probably 1,000 to 2,000 eggs per day, meaning that number of adult workers are now emerging per day. 

Honey bee development

Honey bee development

About eight days after the queen cells were capped and the swarm left the new virgin queens emerge (see the bottom row in the picture above). By this time the worker population in the hive might well be over 20,000 again (some adult worker will have died of old age in the intervening period).

20,000 bees is more than enough to swarm again if several queens emerge 5.

These secondary swarms are called casts. They are headed by a virgin queen. They can be quite large if the original colony was very strong. 

However, with a lot of virgin queens emerging around the same time a strong colony can produce several casts, one after another. These are usually successively smaller and smaller 6. Not only are these casts too small to form an effective colony, but the originating colony can be weakened sufficiently to make its survival doubtful.

What’s the alternative?

Imagine the same double-brood colony. The old queen heads for the hills with 75% of the workforce. A week later the colony strength has been boosted by the emergence of a further 7 – 10 thousand workers … but this time there is only one capped queen cell developing.

The queen emerges.

If this queen also disappeared in a cast swarm the original colony would inevitably perish.

Why?

Because a week after the original swarm leaves there are no eggs or larvae in the colony young enough to be reared as new queens. 

She’s gone …

Swarming is reproduction of the honey bee ‘superorganism’. The survival of natural swarms is low (~25%) whereas the survival of swarmed colonies is reasonably high (>75%).

From an evolutionary perspective it makes no sense for the only queen to also leave, heading a cast swarm. The colony would have ‘traded’ a ~1:5 chance of producing two viable colonies for a 1:16 chance 7

It’s a no brainer as they say 8.

So, you can probably see where this is going now …

Swarm control

The three relatively generic and representative swarm control methods –  Pagden, a nucleus method or a vertical split – all involve manipulation of the hives one week after the initial intervention.

In the ‘classic’ Pagden method the original hive is moved from one side of the artificial swarm to the other. This has the effect of ‘bleeding off’ some of the workforce, so weakening the hive. The resulting reduced worker population often tear down all but a small number of queen cells. The reduced bee numbers also make the production of casts less likely as the colony is weaker.

Pagdens' artificial swarm ...

Pagdens’ artificial swarm …

In a vertical split the hive is reversed on the stand after 7 days, achieving exactly the same outcome on a much smaller footprint with less equipment 🙂 9

In both these methods the flying bees that have reoriented to the initial new position of the queenless hive return to find the hive moved. They then enter the nearest hive, which is the queenright component (i.e. the artificial swarm). 

I’ll get to the nucleus method in a moment.

Sometimes you will see it recommended that you also check the queenless colony at this one week timepoint to ensure that there are not large numbers of queen cells still present 10. It’s not usually necessary but – assuming you are careful – it does not cause any harm. As I explain below, it can help give you confidence.

If you don’t perform the one week hive manoeuvre you really should check for queen cells and reduce the number present.

In the nucleus method I describe the beekeeper must manage queen cell numbers in the queenless hive. Not doing so almost certainly risks losing multiple casts when the queens emerge together.

How many queen cells should you leave?

The queenless component of your swarm control only needs one queen cell

Any less than that and the colony will be non-viable without further intervention from the beekeeper.

Any more and there’s a risk that the colony will generate one or more casts. 

A very strong queenless colony with large numbers of queen cells is a recipe for disaster … or, if not a disaster, then a lot of frustration as you scurry around trying to catch the casts and/or rescue the colony from swarming itself to destruction.

Workers in very strong colonies can ‘hold back’ queens, effectively trapping them in the cell, so that emergence is more-or-less simultaneous. Should you chance to open a colony in this situation all hell breaks loose, with virgin queens dashing about all over the place.

Been there, got the T-shirt 🙂

Although entertaining – at least is retrospect – it’s better to avoid this sort of situation by restricting queen cell numbers.

All your eggs in one basket

And this is where the beginner starts to experience some trepidation.

They have to reduce queen cell numbers … to one.

That queen will head the colony for the next year or three. She’ll mother tens of thousands of workers who will make countless foraging trips and collect tens or (hopefully) hundreds of pounds of honey.

Choosing that one queen cell feels like a lot of responsibility.

The consequences of choosing a dud feel very serious indeed.

Surely leaving two or three would be a ‘safer’ bet? 

Backups, if you will … just in case the first one turns out to be a dud.

How do you know which one to pick?

Trust the bees

And this is where you need to trust the bees. They’ve been doing this pretty well for several million years.

You don’t need to choose a single egg from the thousands possibly present in the colony. The one egg that will be cared for, fed copious amounts of royal jelly and eventually emerge to head the colony.

The bees have already made those decisions 11.

They’ve started several queen cells, the majority of which are likely to be suitable. You just need to choose one of those queen cells to leave in the hive. 

It’s not a one in thousands chance of choosing a ‘winner’, it’s more like one in ten … in which any of the ten would probably be OK.

With a few caveats …

What are the features of a good queen cell?

You open the hive and find a number of sealed and unsealed queen cells.

Which to choose?

What are the features you are looking for?

What are the features you can see?

Sealed queen cell ...

Sealed queen cell …

Size, shape and appearance are the obvious ones. Position on the comb might also influence your choice.

What are the features you cannot see?

Is is a charged cell i.e. does it contain a developing pupa? Has that pupa been well fed as a larva?

Size, shape, appearance and position

Mature queen cells are large, about 3 cm long. The position on the comb – whether on the face or edge can influence the apparent size. They are generally conical, more or less evenly tapering to a neatly rounded tip. Queen cells that have been well-tended by the bees are often heavily sculpted on the outside. This is generally taken to be a “good thing”, but note that this doesn’t happen until after the queen cell is capped (see the photo above). Uncapped cells are usually smooth (see the next photo).

I think the position on the frame is irrelevant in terms of queen cell quality, but it does influence which I choose. The cell should be drawn from worker comb (!) 12 and – particularly if I’m likely to be either cutting the cell out or moving the entire frame – I like it to be in a position unlikely to get damaged as I manipulate the frames in the hive.

The edge of drawn comb, with space below and to the side, makes things easy. The central face of the comb, especially if it’s on fresh comb and not near a wire in the foundation, is also a good bet. 

The position is more important if you’re going to do something with the cell or frame other than let it emerge in situ.

Charged cells

How do you know there’s a well-fed pupa in the cell?

Ted Hooper (in his Guide to Bees and Honey) describes gently prising the cap off a sealed queen cell to check it is occupied, then re-sealing it to let development run its course. He finishes discussing how to re-seal the cell with the words “you have to do a good job or the bees will tear it down.”

I bet 😉

There are easier ways.

Firstly you can be pretty sure that any well-shaped sealed cell with a good, well sculpted appearance is likely to be occupied. Alternatively, you can identify these cells in advance and only allow those you know contain a developing larva sitting on a thick bed of royal jelly to mature.

A practical example

A few days ago I used the nucleus method for swarm control in all my colonies in one apiary. Due to work constraints and lockdown some colonies were only just starting to make preparations to swarm. None of the colonies had well developed, charged queen cells. Some had ‘play cups’ with eggs present.

Three days after making up the nucs I checked the queenless parent colonies. All had a few developing queen cells.

Here is the same photograph as above, with some cells numbered on the frame.

Queen cells – capped, open and just plain dodgy

Which do you choose?

Here is the view from below of the same frame.

Queen cells – practical example

  1. A sealed cell, perhaps a bit small 13
  2. Is a nice looking unsealed cell with a thick bed of royal jelly supporting a larva inside.
  3. Also unsealed and with a good space underneath for the cell to be drawn out as it develops.
  4. Is very similar to #2. Smooth exterior as it’s only 3 days old and unsealed.
  5. A thickened play cup from a previous season. There is no egg, larva or royal jelly inside it.

Remember that this is only 3 days after implementing swarm control.

I destroyed the sealed cell #1. Since it was already sealed it was probably made from an older larva. Cells are sealed on the eighth day after the egg is laid. Since this was only 72 hours after removing the queen the larva was probably two days old before being reared as a queen – i.e. 8 minus 3 days since queen removal minus the three days it would have already spent as an egg. Alternatively, it might have been present when I removed the queen, though I did check reasonably thoroughly.

I couldn’t be sure of the contents of this cell and I suspected that it may not have been fed on copious amounts of royal jelly during the very early days after hatching from the egg.

Cell #3 was also squidged. If you look closely from below you can clearly see the larva but no thick bed of royal jelly. I doubted it had been fed well enough in the early days. Here’s an enlargement …

Cells #1 to #4 enlarged.

Why risk it? There are better cells on the frame.

I ignored #5. It’s not a queen cell and never will be.

Uncapped cells #2 and #4 were retained. They are the right size, have a good appearance and are well placed on the frame.

I marked the top of the frame with a queen marking pen to remind me where to check, and more importantly where to be careful, when I inspect the colony a week after making up the nuc.

X marks the spot

Note that the photo above is a different hive to the numbered photo of queen cells (which I forgot to photograph).

Hold on … not so fast

Go back and look again at the numbered photo of queen cells.

There is another cell, uncapped and filled with royal jelly, to the left and a little higher than the sealed queen cell #1.

This cell is actually pretty obvious. There are relatively few bees on the frame and it is not particularly well ‘hidden’. 

Miss a couple more like that in a very strong hive and there’s a chance the colony will throw off several casts when the queen emerge. The unlabelled cell, and cells #2 and #4 are all very similar in age and appearance and would likely emerge within hours of each other.

Seven days after implementing swarm control

The hives are checked again 14.

I know which frames have good, charged developing queen cells. They are the ones that are marked. I therefore :

  • treat these frames very carefully. Do not shake the bees off the frame!
  • make sure the cells are now capped and starting to be sculpted by the bees.
  • gently inspect the remainder of the frame for other queen cells.
  • destroy any new cells that I find

I choose one of the queen cells and destroy any others on the frame. If there is more than one marked frame and I don’t need the cell for another colony (see below) then I destroy the cells on the other marked frame as well.

I then thoroughly inspect every frame in the brood box, shaking all the bees off the frames and checking for any queen cells I may have missed previously. There will be some.

All I find are destroyed.

I close the hive up and leave it undisturbed for the queen to emerge, mate and start laying. I’ll discuss this – apparently interminable – period in the future sometime.

I’m confident the cell contains a well fed pupae. It was the the bees that really selected the queen … all I did was whittle down their selection to the final choice.

Using ‘spare’ queen cells

In the photo above there are two marked frames. This is a good colony. Frugal, productive, well behaved etc. 15

There is another colony in the apiary which is poorly tempered. They are also requeening and are at the same stage.

Assuming the cells on both marked frames are good I’ll transfer one to the badly behaved colony when I conduct the seven day inspection. You can transfer the entire frame or you can gently cut the queen cell out and use it directly 16

All of the developing queen cells in the badly behaved colony will first be destroyed. Since there are no eggs or young larvae in that colony (and no queen as she was removed a week ago) they cannot rear another from their own genetic material.

The new queen will be better quality.

Similarly, you can use a ‘spare’ queen from a good hive to rescue a terminally queenless colony, or to replace an underperforming or substandard queen.

A really dodgy queen cell

I wanted to squeeze in a picture of what not to choose. 

Bride of Frankenstein queen cell

There are so many things wrong with this.

Where to start?

It’s drawn from drone comb and is not neatly tapering and conical. It’s poorly sculpted considering its age and size, which is far too big.

Whatever emerges from this cell, if anything, will not be any use to me or the bees 🙁

Seven day only inspection

The process described above involves an additional inspection 3-4 days after implementing swarm control. I think this is a modest amount of additional work for:

  • the peace of mind it gives when selecting the final cell to leave
  • the time saved when going through the colony at the seven day inspection

However, often it’s not possible. In that case I refer you back to the description of what a good sealed queen cell looks like.

Choose one of those.

Just one 😉


Notes

With gale force winds predicted for the next 2-3 days I ended up checking the ‘example’ colony (above) on day 6 after implementing swarm control measures. Here is the same frame:

Just one!

I removed two less convincing queen cells on either side of the one selected (#2 in the labelled photograph further up the page). There were a small number of queen cells elsewhere in the colony. All were removed. I’m leaving just one cell sealed, I know it contains a well fed larva. She’ll emerge in about a week and should be mated – weather permitting – a week or so after that.

And now the wait begins … 😉

 

The memory of swarms

I’m writing this waiting for the drizzle to clear so I can go to the apiary and make up some nucs for swarm control. Without implementing some form of swarm control it’s inevitable that my large colonies will swarm 1.

Swarming is an inherently risky process for a colony. Over 75% of natural swarms perish, often because they do not build up strongly enough to overwinter successfully.

As a mechanism for reproduction swarming is somewhat unusual in that the intact colony is split into two not fully functional ‘halves’ 2.

By not fully functional I mean that neither the swarmed colony, nor the swarm are guaranteed to survive.

The swarmed colony lacks a queen, but has ample stores.

The swarm has a queen but has only the stores carried in the bellies of the workers.

The swarmed colony needs to rear a new queen. The swarm needs to find a new nest site, move there, build comb, rear brood, forage etc.

That seems like the very opposite of intelligent design, but it’s the way evolution has made things work. This being the case it involves a whole range of compromises and quick fixes that make it work.

One of these involves the memory of worker bees, which is what this post is about.

Two-stage swarming

A range of events within the hive – which for reasons that will become obvious I will term the original nest site – trigger the urge to swarm. I discussed some of these when covering swarm prevention. Swarming is then essentially a two-stage process. 

The two stage process of swarming

The first stage is the swarm leaving the original nest site and establishing a bivouac nearby. This is the classic cluster of bees hanging from a branch.

The bivouac sends out scout bees to search the nearby area for potential new nest sites. After ‘discussion’ (comprehensively covered by Thomas Seeley in Honeybee Democracy) between the scouts they reach a consensus of the best site.

The second stage is the relocation of the bivouacked colony to the new nest site. For example, this could be the church tower, a hollow tree or a bait hive. This site is likely to be within a few hundred metres of the original nest site, but can be further away.

All of which should raise some questions in the minds of beekeepers who are familiar with the “less than 3 feet or more than 3 miles” rule.

Have these bees not read the rules?

If you want to move a hived colony of bees you’ll often be told, or have read, that you need to move them either less than three feet or more than 3 miles.

Worker bees have a foraging range of about 3 miles. Within this range they have an uncanny ability to return to the hive location using features of the landscape to orientate themselves. The ‘final approach’ uses scent from the hive entrance.

Therefore, if you move a colony 3 feet they’ll still find the general location using landscape features, and then orientate to the hive entrance using scent.

If you move a colony 10 miles away everything is new to them and they’ll embark on some orientation flights to learn the new landscape features.

But if you move the colony a mile they’ll use the landscape features to return to the site of the original hive … to find it gone 🙁 3

Swarms break all these rules.

The bivouac is (in my experience) always more than 3 feet from the hive entrance. If the scout bees make the choice (e.g. selecting a bait hive to occupy), the swarm always relocates to a new nest site less than three miles from the site it left 4.

And a beekeeper who drops a bivouacked colony into a skep can move it wherever she wants, even back to the same hive stand it recently vacated.

If the swarm followed the rules, the majority of the workers would return from the bivouacked swarm to the original nest site.

At least they would if they had orientated to the original nest site in the first instance.

Are the bees naive?

About half of a workers life is spent as a forager collecting water, pollen or nectar. But before they venture out of the hive, the first half of a worker bees life is spent building comb, nursing larvae or cleaning cells.

Therefore, one possibility is that the bees present in a swarm have no knowledge of the hive location because they’ve never before left the hive.

We know that the proportion of workers that leave the colony when it swarms is about 75%. This has been determined in a number of independent studies and is remarkably consistent, irrespective of the size of the colony that swarms.

If 75% of the workers leave the colony when it swarms it is mathematically impossible for the swarm not to include older foragers (assuming the laying rate of the queen is steady).

In fact, we don’t need to resort to any underhand mathematics as the age classes of bees in a swarm have been measured. I’ve discussed this before when comparing natural and artificial swarms.

Age distribution of bees in swarms

Age distribution of bees in swarms

The median age of adult bees in the hive is 19 days. The median age of bees in a swarm is 10 days. Therefore swarms do contain younger bees, but not exclusively so.

One of the reasons for this bias towards younger bees must be to do with the relatively short lifespan of foragers. Many of the older bees in the swarm will have perished long before the new brood laid by the queen emerges.

Permanent amnesia?

The bivouacked swarm doesn’t dwindle in size as the older foragers drift back to the original nest site. Other than a few hundred scout bees, the majority of the bivouacked swarm huddle together to protect the queen, buried somewhere in the centre, from the elements.

They don’t fly or forage … they’re waiting for the signal from the scout bees that a new nest site has been located.

And, once they relocate to the church tower, the hollow tree or a bait hive, the older foragers stay in the new nest location. It’s as though the bees in a swarm that previously knew where the original nest site was have amnesia.

And this makes sense. If they did return to the original nest site the swarm (whether bivouacked or relocated) would shrink in size and it’s chances of surviving would be severely diminished. Other than a full belly of honey a swarm can rely on nothing. They need as many bees as possible to take on all the roles needed to establish a new colony – comb builders, nurses, foragers etc.

But have they really forgotten the original nest site?

Temporary amnesia?

It turns out that swarms do retain a memory of their original nest site.

In 1993 Gene Robinson and colleagues demonstrated that a swarm shaken out from its new nest site preferentially returns to the original nest site, rather than to an equidistant alternate 5.

This ability must rely on the memory of the foragers in the swarm. Therefore it is likely to be lost in a relatively short time (days, not weeks) 6.

Firstly, the foragers will be busy reorienting to the new nest site, effectively overwriting the memory of the original nest location. In good weather this takes just a couple of days.

Secondly, these ageing bees don’t have long to live, so there will be ever-decreasing numbers of them to lead a shaken out swarm back to the original location.

Rain stops play

Sometimes the bivouacked colony never relocates to a new nest site. Either the scouts never achieve a consensus or – more likely – bad weather forces the swarm to hunker down.

When you hive a bivouacked swarm you will often find a small crescent or two of new wax on the branch they were clinging to. If the bees get trapped by bad weather I think the comb building continues. It’s not unusual to find comb in hedgerows near apiaries where bees that have got trapped have ended up trying to make a new nest.

Natural comb

Natural comb …

What does the memory – or lack of it – of swarms mean for practical beekeeping?

The (temporary) amnesia of swarms means you can collect a bivouacked swarm and move it wherever you want. A swarm that relocates to your bait hive can also be moved, but don’t wait too long. Within just a few days of a swarm arriving the bees will have reoriented to their new location. I always try and move bait hives to their final location within three days of a swarm appearing.


Notes

The drizzle stopped and I spent the entire day finding queens and making up nucs.

Note to self … a super-strong colony with no queen cells, wall-to-wall brood and no very young larvae or eggs probably has a faulty queen excluder 🙁

Second note to self … Sod’s law dictates that the colony with the faulty queen excluder probably has supers filled with drone comb 🙁

Aristotle’s hairless black thieves

Aristotle not in his beesuit

Almost every article or review on chronic bee paralysis virus 1 starts with a reference to Aristotle describing the small, black, hairless ‘thieves‘, which he observed in the hives of beekeepers on Lesbos over 2300 years ago 2.

Although Aristotle was a great observer of nature, he didn’t get everything right.

And when it came to bees, he got quite a bit wrong.

He appreciated the concept of a ‘ruling’ bee in the hive, but thought that the queen was actually a king 3. He also recognised different castes, though he thought that drones (which he said “is the largest of them all, has no sting and is stupid”) were a different species.

He also reported that bees stored noises in earthenware jars (!) and carried stones on windy days to avoid getting blown away 4.

However, over subsequent millenia, a disease involving black, hairless honey bees has been recognised by beekeepers around the world, so in this instance Aristotle was probably correct.

Little blacks, maladie noire, schwarzsucht

The names given to the symptomatic bees or the disease include little blacks or black robbers in the UK, mal nero in Italy, maladie noire in France or schwarzsucht (black addiction) in Germany. Sensibly, the Americans termed the disease hairless black syndrome. All describe the characteristic appearance of individual diseased bees.

Evidence that the disease had a viral aetiology came from Burnside in the 1940’s who demonstrated the symptoms could be recapitulated in caged bees by injection, feeding or spraying them with bacterial-free extracts of paralysed bees. Twenty years later, Leslie Bailey isolated and characterised the first two viruses from honey bees. One of these, chronic bee paralysis virus (CBPV), caused the characteristic symptoms described first by Aristotle 5.

CBPV causes chronic bee paralysis (CBP), the disease first described by Aristotle.

CBPV infection is reported to present with two different types of symptoms, or syndromes. The first is the hairless, black, often shiny or greasy-looking bees described above 6. The second is more typically abnormal shivering or trembling of the wings, often associated with abdominal bloating 7. These bees are often found on the top bars of the frames during an inspection. Both symptoms can occur in the same hive 8.

CBP onset appears rapid and the first thing many beekeepers know about it is a large pile (literally handfuls) of dead bees beneath the hive entrance.

It’s a distressing sight.

Despite thousands of bees often succumbing to disease, the colony often survives though it may not build up enough again to overwinter successfully.

BeeBase has photographs and videos of the typical symptoms of CBPV infection.

Until recently, CBP was a disease most beekeepers rarely actually encountered.

Emerging and re-emerging disease

I’ve got a few hundred hive year’s worth 9 of beekeeping experience but have only twice seen CBP in a normally-managed colony. One was mine, another was in my association apiary a few years later.

A beekeeper managing 2 to 3 colonies might well never see the disease.

A bee farmer running 2 to 3 hundred (or thousand) colonies is much more likely to have seen the disease.

As will become clear, it is increasingly likely for bee farmers to see CBP in their colonies.

Virologists define viral diseases as emerging if they are new in a population. Covid-19, or more correctly SARS-CoV-2 (the virus), is an emerging virus. They use the term re-emerging if they are known but increasing in incidence.

Ebola is a re-emerging disease. It was first discovered in humans in 1976 and caused a few dozen sporadic outbreaks 10 until the 2013-16 epidemic in West Africa which killed over 11,000 people.

Often the terms are used interchangeably.

Sporadic and rare … but increasing?

Notwithstanding the apparently sporadic and relatively rare incidence of CBP in the UK (and elsewhere; the virus has a global distribution) anecdotal evidence suggested that cases of disease were increasing.

In particular, bee farmers were reporting increasing numbers of hives afflicted with the disease, and academic contacts overseas involved in monitoring bee health also reported increased prevalence.

Something can be rare but definitely increasing if you’re certain about the numbers you are dealing with. If you only have anecdotal evidence to go on you cannot be certain about anything very much.

If the numbers are small but not increasing there are probably other things more important to worry about.

However, if the numbers are small but definitely increasing you might have time to develop strategies to prevent further spread.

Far better you identify and define an increasing threat before it increases too much.

With research grant support from the UKRI/BBSRC (the Biotechnology and Biological Sciences Research Council) to the Universities of Newcastle (Principle Investigator, Prof. Giles Budge) and St Andrews, and additional backing from the BFA (Bee Farmers’ Association), we set out to determine whether CBPV really was increasing and, if so, what the increase correlated with (if anything).

This component of the study, entitled Chronic bee paralysis as a serious emerging threat to honey bees, was published in Nature Communications last Friday (Budge et al., [2020] Nat. Comms. 11:2164 https://doi.org/10.1038/s41467-020-15919-0).

The paper is Open Access and can be downloaded by anyone without charge.

There are additional components of the study involving the biology of CBPV, changes in virus virulence, other factors (e.g.environmental) that contribute to disease and ways to mitigate and potentially treat disease. These are all ongoing and will be published when complete.

Is chronic bee paralysis disease increasing?

Yes.

We ‘mined’ the National Bee Units’ BeeBase database for references to CBPV, or the symptoms associated with CBP disease. The data in BeeBase reflects the thousands of apiary visits, either by call-out or at random, by dedicated (and usually overworked) bee inspectors. In total we reviewed almost 80,000 apiary visits in the period from 2006 to 2017.

There were no cases of CBPV in 2006. In the 11 years from 2007 to 2017 the CBP cases (recorded symptomatically) in BeeBase increased exponentially, with almost twice as much disease reported in commercial apiaries. The majority of this increase in commercial apiaries occured in the last 3 years of data surveyed.

Apiaries recorded with chronic bee paralysis between 2006 and 2017.

BeeBase covers England and Wales only. By 2017 CBPV was being reported in 80% of English and Welsh counties.

During the same period several other countries (the USA, several in Europe and China) have also reported increases in CBPV incidence. This looks like a global trend of increased disease.

But is this disease caused by CBPV?

It should be emphasised that BeeBase records symptoms of disease – black, hairless bees; shaking/shivering bees, piles of bees at the hive entrance etc.

How can we be sure that the reports filed by the many different bee inspectors 11 are actually caused by chronic bee paralysis virus?

Or indeed, any virus?

To do this we asked bee inspectors to collect samples of bees with CBPV-like symptoms during their 2017 apiary visits. We then screened these samples with an exquisitely sensitive and specific qPCR (quantitative polymerase chain reaction) assay.

Almost 90% of colonies that were symptomatically positive for CBP were also found to have very high levels of CBPV present. We are therefore confident that the records of symptoms in the historic BeeBase database really do reflect an exponential increase of chronic bee paralysis disease in England and Wales since 2007.

Interestingly, about 25% of the asymptomatic colonies also tested positive for CBPV. The assay used was very sensitive and specific and allowed the quantity of CBPV to be determined. The amount of virus present in symptomatic bees was 235,000 times higher than those without symptoms.

Further work will be needed to determine whether CBPV is routinely present in similar proportions of ‘healthy’ bees, and whether these go on and develop or transmit disease.

Disease clustering

Using the geospatial and temporal (where and when) data associated with the BeeBase records we investigated whether CBPV symptomatic apiaries were clustered.

For example, in any year were cases more likely to be near other cases?

They were.

Across all years of data analysed together, or for individual years, there was good evidence for spatial clustering of cases.

We also looked at whether cases in one year clustered in the same geographic region in subsequent years.

They did not.

Clustering of CBPV – spatial and temporal analysis.

This was particularly interesting. It appears as though there were increasing numbers of individual clustered outbreaks each year, but that the clusters were not necessarily in the same geographic region as those in previous or subsequent years.

The disease appears somewhere, increases locally and then disappears again.

Apiary-level disease risk factors

The metadata associated with Beebase records is relatively sparse. Details of specific colony management methods are not recorded. Local environmental factors – OSR, borage, June gap etc. – are also missing. Inevitably, some of the factors that may be associated with increased risk are not recorded.

A relatively rare disease that is spatially but not temporally clustered is a tricky problem for which to define risk factors. Steve Rushton, the senior author on the paper, did a sterling job of analysing the data that was available.

The two strongest apiary-level factors that contributed to disease risk were:

  1. Commercial beekeeping – apiaries run by bee farmers had a 1.5 times greater risk of recording CBP disease.
  2. Importing bees – apiaries which had imported bees in the two preceding years had a 1.8 times greater risk of recording CBP disease.

Bee farming is often very different from amateur beekeeping. The colony management strategies are altered for the scale of the operation and for the particular nectar sources being exploited. For example, colonies may already be booming to exploit the early season OSR. This may provide ideal conditions for CBPV transmission which is associated with very strong hives and/or confinement.

Bee imports does not mean disease imports

There are good records of honey bees imported through official channels. This includes queens, packages and nucleus colonies. Between 2007 and 2017 there were over 130,000 imports, 90% of which were queens.

An increased risk of CBP disease in apiaries with imported bees does not mean that the imported bees were the source of the disease.

With the data available it is not possible to distinguish between the following two hypotheses:

  1. imported honey bees are carriers of CBPV or the source of a new more virulent strain(s) of the virus, or
  2. imported honey bees are susceptible to CBPV strain(s) endemic in the UK which they were not exposed to in their native country.

There are ways to tease these two possibilities apart … which is obviously something we are keen to complete.

All publicity is good publicity …

… but not necessarily accurate publicity 🙁

We prepared a press release to coincide with the publication of the paper. Typically this is used verbatim by some reporters whereas others ask for an interview and then include additional quotes.

Some more accurately than others 🙁

The Times, perhaps reflecting the current zeitgeist, seemed to suggest a directionality to the disease that we certainly cannot be sure of:

The Times

Its sister publication, The Sun, “bigged it up” to indicate – again – that bees are being wiped out.

The Sun

And the comments included these references to the current Covid-19 pandemic:

  • “Guess its beevid – 19. I no shocking”
  • “It’s the radiation from 5g..google it”
  • Local honey is supposed to carry antibodies of local virus and colds – it helps humans to eat the stuff or so they say. So it could be that the bees are actually infected by covid. No joke.

All of which I found deeply worrying, on a number of levels.

The Telegraph also used the ‘wiped out’ reference (not a quote, though it looks like one). They combined it with a picture of – why am I not surprised? – a bumble bee. D’oh!

The Telegraph

The Daily Mail (online) had a well-illustrated and pretty extensive article but still slipped in “The lethal condition, which is likely spread from imports of queen bees from overseas …”. The unmoderated comments – 150 and counting – repeatedly refer to the dangers of 5G and EMFs (electric and magnetic fields).

I wonder how many of the comments were posted from a mobile phone on a cellular data or WiFi network?

😉

Conclusions

CBPV is causing increasing incidence of CBP disease in honey bees, both in the UK and abroad. In the UK the risk factors associated with CBP disease are commercial bee farming and bee imports. We do not know whether similar risk factors apply outside the UK.

Knowing that CBP disease is increasing significantly is important. It means that resources – essentially time and money – can be dedicated knowing it is a real issue. It’s felt real to some bee farmers for several years, but we now have a much better idea of the scale of the problem.

We also know that commercial bee farming and bee imports are both somehow involved. How they are involved is the subject of ongoing research.

Practical solutions to mitigate the development of CBP disease can be developed once we understand the disease better.


Full disclosure:

I am an author on the paper discussed here and am the Principle Investigator on one of the two research grants that funds the study. Discussion is restricted to the published study, without too much speculation on broader aspects of the work. I am not going to discuss unpublished or ongoing aspects of the work (including in any answers to comments or questions that are posted). To do so will compromise our ability to publish future studies and, consequently, jeopardise the prospects of the early career researchers in the Universities of St Andrews and Newcastle who are doing all the hard work.

Acknowledgements

This work was funded jointly by BBSRC grants BB/R00482X/1 (Newcastle University) and BB/R00305X/1 (University of St Andrews) in partnership with The Bee Farmers’ Association and the National Bee Unit of the Animal and Plant Health Agency.

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 11.

Effectively I’m providing the bees with the space to draw more comb and, in due course, for the queen to lay more eggs.

And all this keeps the workers gainfully employed and so helps alleviate overcrowding.

But what do you do if the box is full of full brood frames?

Brood frame with a good laying pattern

You provide another brood box.

Don’t just dump another brood box on top and expect the bees to immediately move up. It’s a big empty space. Ideally provide some drawn comb and move a frame or two up with emerging bees and the queen. She will rapidly start to lay up the vacated cells and the adjacent frames. Push the original frames together and add new empty frames to fill the box.

You are expanding the brood nest … vertically.

My colonies rarely need this as they are the less prolific, darker bees which tend to perform better overall in Scotland. However, some strains of bees readily fill two stacked brood boxes every season.

It’s worth emphasising again that these swarm prevention interventions are of little or no use for swarm control. If there are queen cells already present adding a frame or two of foundation will have no effect at all.

Young queens

Young queens produce more pheromones than ageing queens. Therefore, all other things being equal, the inhibitory effects of queen mandibular and footprint pheromones will be stronger in a colony headed by a young queen.

This is why colonies are less likely to swarm in their first full season 12.

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 13 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.


 

The scent of death

It’s late May. Outside it’s dark, so you’re trapped inside until sunrise. Inside it’s warm, dark and humid. You and your sisters are crowded together with barely enough space to turn around.

And your mother keeps laying more eggs … perhaps 2000 a day. If it wasn’t for the fact that about 2000 of your sisters perish each day you’d have no space at all.

Most of them die out in the fields. Missing in action.

I counted them all out and I didn’t count them all back, as the late Brian Hanrahan did not say in 1982 😉

But some die inside. And in the winter, or during prolonged periods of poor weather, your sisters all die inside.

Which means there’s some housekeeping to do.

Bring out your dead

Dead bees accumulating in the hive are a potential source of disease, particularly if they decompose. Unless these are removed from the colony there’s a chance the overall health of the colony will be threatened.

Not all bees die of old age. Many succumb to disease. The older bees in the colony may have a higher pathogen load, reinforcing the importance of removing their corpses before disease can spread and before the corpses decompose.

Corpses

Honey bees, like many other social insects, exhibit temporal polyethism i.e. they perform different tasks at different ages.

One of the tasks they perform is removing the corpses from the colony.

The bees that perform this task are appropriately termed the undertaker bees.

Gene Robinson in Cornell conducted observational studies on marked cohorts of bees. In these he identified the roles and activities of the undertaker bees. At any one time only 1-2% of the bees in the colony are undertakers 1.

These are ‘middle aged’ bees i.e. 2-3 weeks after eclosion, similar to guard bees. Although called undertakers, they do not exclusively remove corpses. Rather they are generalists that are more likely to remove the corpses, usually depositing them 50-100m from the hive and then returning.

They preferentially occupy the lower regions of the hive – presumably because gravity means the corpses accumulate there – where they also perform general hive cleansing roles e.g. removing debris.

Bees, like all of us, are getting older all the time. Some bees may spend only one day as undertakers before moving on to foraging duties. Presumably – I don’t think we know this yet – the time a bee remains as an undertaker is influenced by the colony’s need for this activity, the laying rate of the queen and, possibly, the numbers of other bees performing this role 2.

No no he’s not dead, he’s, he’s restin’!

Dead parrot

In Monty Python’s Dead Parrot sketch Mr. Praline (John Cleese) argues with the shop owner (Michael Palin) that the Norwegian Blue parrot he’d purchased was, in fact, dead.

The shop owner tries to persuade Mr. Praline that the parrot is resting.

Or stunned.

Or pining for the fjords.

The inference here is that it’s actually rather difficult to determine whether something is dead or not 3.

So if you struggle with an unresponsive parrot how do you determine if a bee is dead?

More specifically, how do undertaker bees in a dark, warm, humid hive determine that the body they’ve just tripped over is a corpse?

As opposed to a resting bee 4.

The scent of death

Almost forty years ago Kirk Visscher at Cornell studied necrophoresis (removal of the dead) in honey bees 5.

He noted that it had two distinct characteristics; it happened rapidly (up to 70 times faster than debris removal) and dead bees that were solvent-washed or coated in paraffin-wax were removed very much more slowly.

Kirk Visscher concluded that the undertaker bees “probably use chemical cues appearing very rapidly after the death of a bee” to identify the corpses.

Visscher studied honey bees, Apis mellifera. I’m not aware of any recent studies in A. mellifera that have better defined these ‘chemical cues’. However, a very recent preprint has been posted on bioRχiv describing how the closely related Eastern honey bee, Apis cerana, undertakers identify the dead.

As an aside, bioRχiv (pronounced bioarkive) is a preprint server for biology. Manuscripts published there have not been peer reviewed and will potentially be revised and/or withdrawn. They might even be wrong. Many scientists increasingly use bioRχiv to post completed manuscripts that have been submitted for publication elsewhere. The peer review and publication process is increasingly tortuous and long-winded. By posting preprints on bioRχiv other scientists can read and benefit from the study well before full publication elsewhere.

It’s also used as a ‘marker’ … we did this first 😉

The preprint on bioRχiv is Death recognition by undertaker bees by Wen Ping, submitted on the 5th of March 2020.

Odours and pongs

Death recognition in honey bees is rapid. Visscher demonstrated that a dead worker bee was usually removed within 30 minutes, well before it would have started producing the pong associated with the processes of decay.

Corpse recognition occurs in the dark and in the presence of lots of other bees. Logically, an odour of some sort might be used for identification. Both visual and tactile signals would be unlikely candidates.

In searching for the odour or chemical clues (the term used by Visscher), Ping made some assumptions based on prior studies in social insects. In Argentine ants a reduction in dolichodial and iridomyrmecin is associated with corpse recognition, and addition of these compounds (respectively a dialdehyde and a monoterpene) prevented necrophoresis.

Conversely, some social insects produce signals associated with death or disease. Dead termites give off a mix of 3-octanone, 3-octanol and the combination of β-ocimene and oleic acid production is a marker of diseased brood in honey bees.

What else could be assumed about the chemicals involved? Corpse removal is an individual effort. There’s only one pallbearer. Therefore the chemical, whatever it is, doesn’t need to be a recruitment signal (unlike the alarm pheromone for example).

Finally, the signal needs to operate over a very short range. There’s no point in flooding the hive with a persistent long-range chemical as that would make the detection of the corpse impossible.

Cuticular hydrocarbons

Cuticular hydrocarbons (CHC) are widely used in insect communication. They are long chain hydrocarbons (chemicals composed solely of carbon and hydrogen) that have many of the characteristics expected of a ‘death chemical’.

Nonacosane – a long chain CHC with 29 carbons and 60 hydrogen atoms

They are generally short-range, low volatility compounds. Honey bees use CHC’s for communication during the waggle dance and to distinguish colony mates by guard bees. They also have structural roles, being a major component of wax comb and, in the cuticle, they help maintain water balance in bees.

As would be expected from chemicals with a wide variety of roles, there’s a huge range of CHC’s. Taking all the above together, Wen Ping searched for CHC’s that functioned during necrophoresis.

Cool corpses and cuticular hydrocarbons

Wen studied undertakers removing segments of dead bees and determined that the chemical signal was most probably a component of the cuticle.

Living bees in his studies had a body temperature of ~44°C. In contrast, dead bees rapidly cooled to ambient temperatures. Wen demonstrated that corpse removal was significantly delayed if the corpses were warmed to ~44°C, but then occurred rapidly once they were allowed to cool. Finally, dead bees washed with hexane (which removes CHC’s) were removed even if the corpse was warm.

Taken together, these results suggest that a cuticular hydrocarbon that was produced and released from warm bees, but reduced or absent in cold bees, was a likely candidate for the necrophoresis signal.

But which one?

Gas chromatography

A gas chromatograph analyses volatile gases. Essentially gas vapour is passed through a thin coated tube and gaseous compounds of different molecular weights bind and elute at different times. It’s a very precise technique and allows all the components of a mixture to be identified by comparison with known standards.

Gas chromatography of volatiles from live (red) and dead (blue) bees.

Ping studied the volatile CHC’s in the airspace immediately surrounding dead bees or live bees using gas chromatography. There were some significant differences, shown by the absence of peaks in the blue trace of gases from the cold, dead bees. All of the peaks were identified and nine of the twelve peaks were CHC’s.

CHC’s with chain lengths of 27 or 29 carbons exhibited the greatest difference between live warm bees and cool dead bees and synthetic versions of these and the other CHC’s were tested to see which – upon addition – delayed the removal of dead bees.

Three had a significant impact in the dead bee removal assay – with chain lengths of 21, 27 and 29 carbons. These include the compounds heptacosane (C27H56)and nonacosane (C29H60).

Summary

The results section rather fizzles out in the manuscript posted to bioRχiv and I wouldn’t be surprised to see modifications to this part of the paper in a peer reviewed submission.

The overall story can be summarised like this. Live bees are warm and produce a range of CHC’s. Dead bees cool rapidly and some of the volatile CHC levels decrease in the immediate vicinity of the corpse. The undertaker bees specifically monitor the levels of (at least) heptacosane and nonacosane 6 as a means of discriminating between live and dead bees. Within 30 minutes of death local heptacosane and nonacosane levels have dropped below a level associated with life and the undertaker bee removes the corpse.

One final point worth making again. This study was conducted on Apis cerana. Our honey bees, A. mellifera, may use the same necrophoresis signals. Alternatively, they might use different chemicals in the same way.

Or they might do something else entirely.

Personally, I bet it’s a similar mechanism, potentially using different chemical.

There are mixed species colonies of A. mellifera and A. cerana. Do the undertakers only remove same-species corpses?

Global warming and hive cooling

The discussion of the bioRχiv paper raises two interesting points, both of which are perhaps a little contrived but still worth mentioning.

We’re living in a warming world.

Temperatures are rising

Dead bees cooling to ambient temperature lead to reduced CHC production. If global temperatures rise, so will the ambient temperature. Potentially this could decrease the reduction in the levels of CHC’s i.e. the dead bees might not look (er, smell!) quite so dead. This could potentially reduce corpse removal, with the concomitant potential for pathogen exposure.

I suspect that we’ll have much bigger problems to worry about than undertaker bees if the global temperatures rise that high …

But Wen also points out that the rise in global temperatures is also associated with more extreme weather, including very cold weather. Perhaps cold anaesthetised or weak bees will be prematurely removed from the hive under these conditions because their CHC levels have dropped below a critical threshold?

Finally, do dead bees lying on open mesh floors (OMFs) cool more rapidly and so trigger more efficient undertaking? Perhaps OMFs contribute more to hive hygiene than just allowing unwanted Varroa to drop through?


 

Time to deploy!

It’s early April. The weather is finally warming up and the crocus and snowdrops are long gone. Depending where you are in the UK the OSR may start flowering in the next fortnight or so.

All of which means that colonies should be expanding well and will probably start thinking of swarming in the next few weeks.

So … just like any normal season really.

Except that the Covid-19 pandemic means that this season is anything but normal.

Keep on keeping on

The clearest guidelines for good beekeeping practice during the Covid-19 pandemic are on the National Bee Unit website. Essentially it is business as usual with the caveats that good hygiene (personal and apiary) and social distancing must be maintained.

Specifically this excludes inspections with more than one person at the hive. Mentoring, at least the really useful “hands-on” mentoring, cannot continue.

A veil is no protection against aerosolised SARS-CoV-2. Don’t even think about risking it.

This means that there will be a lot of new beekeepers (those that acquired bees this year or late last season) inspecting colonies without the benefit of help and advice immediately to hand.

Mistakes will be made.

Queen cells will be missed.

Colonies will swarm 1.

Queen cells

Queen cells …

It’s too early to say whether the current restrictions on society are going to be sufficient to reduce coronavirus spread in the community. It’s clear that some are still flouting the rules. More stringent measures may be needed. For beekeepers who keep their bees in out apiaries, the most concerning would be a very restrictive movement ban. In China and (probably) Italy these measures proved to be effective, although damaging to beekeeping, so the precedent is established.

Many hives and apiaries are already poorly managed 2. I would expect that additional coronavirus-related restrictions would only increase the numbers of colonies allowed to “fend for themselves” over the coming season.

Which brings me back to swarming.

Swarmtastic

The final point of advice on the NBU website is specifically about swarms and swarm management:

You should use husbandry techniques to minimise swarming. If you have to respond to collect a swarm you need to ensure that you use the guidelines on social distancing when collecting the swarm. If that is not possible, then the swarm then should not be collected. Therefore trying to prevent swarms is the best approach. 

Collecting swarms can be difficult enough at the best of times 3. And cutouts of established colonies are even worse.

In normal years I always prefer to reduce the swarms I might be called to 4 by setting out bait hives.

Swarm recently arrived in a bait hive with a planting tray roof …

Let the bees do the work.

Then all you need do is collect them once they’re all neatly tucked away in a hive busy drawing comb.

This year, with who-knows-what happening next, I’ll be setting out more bait hives than usual with the expectation that there may well be additional swarms.

If they’re successful I’ll have more bees to deal with when the ‘old normal’ finally returns. If they remain unused then all I’ve lost is the tiny investment of time made in April to set them out.

Not just any dark box

I’ve discussed the well-established ‘design features’ of a good bait hive several times in the past. Fortunately the requirements are easy to meet.

  • A dark empty void with a volume of about 40 litres.
  • A solid floor.
  • A small entrance of about 10cm2, at the bottom of the void, ideally south facing.
  • Something that ‘smells’ of bees.
  • Ideally located well above the ground.

I ignore the last of these. I’d prefer to have an easy-to-reach bait hive to collect rather than struggle at the top of a ladder. If I wanted to do some vertically-challenging beekeeping I’d go out and collect more swarms 😉

So, ignoring the final point, what I’ve described is the nearly perfect bait hive.

Those paying attention at the back will realise that it’s also a nearly perfect description of a single brood National hive.

How convenient 🙂

All of my bait hives are either single National brood boxes or two stacked National supers. The box does need a solid floor and a crownboard and roof. If you haven’t got a spare solid floor you can easily build them from Correx 5 for a few pence.

Inside ...

Bait hive floor

Alternatively, simply tape down a piece of cardboard or Correx over the mesh of an open mesh floor 6. In some ways this is preferable as it’s convenient to be able to monitor Varroa levels after a swarm arrives.

Do not be tempted to use a nuc box as a bait hive. You can easily fit a small swarm into a brood box, but a really big prime swarm will not fit in a 5 frame nuc box.

Big swarms are better 🙂 7

More to the point, bees are genetically programmed to search for a void of about 40 litres, so many swarms will simply overlook your nuc box for a more spacious nest site.

What’s in the box?

No, this has nothing to do with Gwyneth Paltrow in Se7en.

How do you make your bait hive even more desirable to the scout bees that search out nest sites? How do you encourage those scouts to advertise the bait hive to their sister scouts? Remember, that it’s only once the scouts have reached a democratic consensus on the best local nest site that the bivouacked swarm will move in.

The brood box ideally smells of bees. If it has previously held a colony that might be sufficient.

Bait hive ...

Bait hive …

However, a single old, dark brood frame pushed up against one sidewall not only provides the necessary ‘bee smell’, but also gives the incoming queen space to immediately start laying 8.

You can increase the attractiveness by adding a couple of drops of lemongrass oil to the top bar of this dark brood frame. Lemongrass oil mimics the pheromone produced from the Nasonov gland. There’s no need to Splash it all over … just a drop or two, replenished every couple of weeks. I usually soak the end of a cotton bud, and lay it along the frame top bar.

Lemongrass oil and cotton bud

The old brood frame must not contain stores – you’re trying to attract scouts, not robbers.

The incoming swarm will be keen to draw fresh comb for the queen to lay up with eggs. Whilst you can simply provide some frames and foundation, this has two disadvantages:

  • the vertical sheets of foundation effectively make the void appear smaller than it really is. The scout bees estimate the volume by walking around the perimeter and taking short internal flights. If they crash into a sheet of foundation during the flight the box will seem smaller than it really is.
  • foundation costs money. Quite significant amounts of money if you are setting out half a dozen bait hives. Sure, they’ll use it but – like putting a new carpet into a house you’re trying to sell – it’s certainly not the deal-clincher.

No foundation for that

Rather than filling the box with about £10 worth of premium foundation, a far better idea is to use foundationless frames. Importantly these provide the bees somewhere to draw new comb whilst not reducing the apparent volume of the brood box.

If you’ve not used foundationless frames before, a bait hive is an ideal time to give them a try.

There are two things you should be on the lookout for. The first is that the bait hive is horizontal 9. Bees draw comb vertically down, so if the hive slopes there’s a good chance the comb will be drawn at an angle to the top bar.

And that’s just plain irritating … because it’s avoidable with a bit of care.

Bamboo foundationless frames

Bamboo foundationless frames

The second thing is that the colony needs checking as it starts to draw comb. Sometimes the bees ignore your helpful lollipop stick ‘starter strips’ and decide to go their own way, filling the box with cross comb.

Beautiful … but equally irritating 🙂

Final touches

For real convenience I leave my bait hives ready to move from wherever they’re sited to my quarantine apiary (I’ll deal with both these points in a second).

Wedge the frames together with a small block of expanded cell foam so that they cannot shift about when the hive is moved.

Foam block ...

Foam block …

And then strap the whole lot up tight so you can move them easily and quickly when you need to.

Bait hive location and relocation

Swarms tend to move relatively modest distances from the hives they, er, swarmed from. The initial bivouac is usually just a few metres away. The scout bees survey a wide area, certainly well over a mile in all directions. However, several studies have shown that bees generally choose to move a few hundred yards or less.

It’s therefore a good idea to have a bait hive that sort of distance from your own apiaries.

Or even tucked away in the corner of the apiary itself.

I’ve had bees move out of one box, bivouac a short distance away and then occupy a bait hive on a hive stand adjacent to the original hive.

It’s probably definitely poor form to position a bait hive a short distance from someone else’s apiary 😉

But there’s nothing stopping you putting a bait hive at the bottom of your garden or – whilst maintaining social distancing of course – in the gardens of friends and family.

If you want to move a swarm that has occupied a bait hive the usual “less than 3 feet or more than 3 miles” rule applies unless you move them within the first couple of days of arrival. Swarms have an interesting plasticity of spatial memory (which deserves a post of its own) but will have fully reorientated to the bait hive location within a few days.

So, if the bait hive is in grandma’s garden, but grandma doesn’t want bees permanently, you need to move them promptly … or move them over three miles.

Or move grandma 😉

Lucky dip

Swarms, whether dropped into a skep or attracted to a bait hive, are a bit of a lucky dip. Now and again you get a fantastic prize, but often it’s of rather low value.

The good ones are great, but even the poor ones can be used.

But there’s an additional benefit … every one that arrives self-propelled in your bait hive is one less reported to the BBKA “swarm line” or that becomes an unwelcome tenant in the eaves of a house 10.

As long as they’re healthy, even a bad tempered colony headed by a queen with a poor laying pattern, can usefully be united to create a stronger colony to exploit late season nectar.

Varroa treatment of a new swarm in a bait hive…

But they must be healthy.

Swarms will potentially have a reasonably high mite count and will probably need treating within a week of arrival in the bait hive 11. Dribbled or vaporised oxalic acid/Api-Bioxal would be my choice; it’s effective when the colony has no sealed brood 12 and requires a single treatment.

But swarms can bring even more unwelcome payloads than Varroa mites. If you keep bees in an area where foulbroods are established be extremely careful to confirm that the arriving swarm isn’t affected. This requires letting the colony rear brood while isolated in a quarantine apiary.

How do you know whether there are problems with foulbroods in your area? Register your apiary on Beebase and talk to your local bee inspector.

My bait hives go out in the second or third week of April … but I’m on the cool east coast of Scotland. When I lived in the Midlands they used to be deployed in early April. If you’re in the balmy south they should probably be out already 13.

What are you waiting for 😉 ?


 

Do bees feel pain?

Even the most careful hive manipulations sometimes result in bees getting rolled between frames, or worse, crushed when reassembling the hive. Some beekeepers clip one wing of the queen to reduce the chance of losing a swarm, or uncap drone brood in the search for Varroa.

All of these activities can cause temporary or permanent damage, or may even kill, bees. A careful beekeeper should try and minimise this damage, but have you ever considered whether these damaged bees suffer pain?

Before considering the scientific evidence it’s important to understand the distinction between the detection of, for example, tissue damage and the awareness that the damage causes is painful and causes suffering.

Detection is a physiological response that is present in most animal species, the pain associated with it may not be.

What is pain?

Tissue damage, through chemical, mechanical or thermal stimuli, triggers a signal in the sensory nervous system that travels along nerve fibres to the brain. Or to whatever the animal has that serves as the equivalent of the brain 1.

This response is termed nociception (from the Latin nocēre, meaning ‘to harm’) and has been recorded in mammals, other vertebrates and in all sorts of invertebrates including leeches, worms and fruit flies. It has presumably evolved to detect damaging stimuli and to help the animal avoid it or escape.

But nociception is not pain.

Pain is a subjective experience that may result from the nociceptive response and can be defined as ‘an aversive sensation or feeling associated with actual or potential tissue damage’.

Most humans, being sentient, experience pain following the triggering of a nociceptive response and, understandably, conflate the two.

But they are separate and distinct. How do we know? Perhaps the first hint is that different people experience different levels of pain following the same harmful experience; an excruciatingly painful experience for one might be “just a scratch’ to another.

‘Tis but a scratch

With people it’s easy to demonstrate the distinction between nociception and pain – you simply ask them.

Can you feel that?

Does that hurt?

For the same stimuli you may receive a range of answers to the second question, depending upon their subjective experience of pain.

Painkillers

But you cannot ask a leech, or a worm or a fruit fly or – for the purpose of this post – a bee, whether a particular stimulus hurts.

Well, OK, you can ask but you won’t get an answer 😉

You can determine whether they ‘feel’ the stimulus. Since this is a simply physiological response you can measure all sorts of features of the electrical signal that passes from the nociceptors (the receptors in the tissue that detect damaging events) through the nerve fibres to the brain. This involves electrophysiology, a well established experimental science.

But how can we determine whether animals feel pain?

What do you do when you have a bad headache?

You take a painkiller – an aspirin or paracetamol. You self-medicate to relieve the pain.

Actually, even before you reach for the paracetamol, your body is already self-medicating by the release of endogenous opioids which help suppress the pain.

In cases of extreme pain injection of the opiate morphine may be necessary. Morphine is a very strong painkiller, or analgesic. Opioids bind to opioid receptors and this binding is blocked by a chemical called naloxone, an opiate antagonist. I’ll come back to naloxone in a minute.

But first, back to the unhelpfully unresponsive bee that may or may not feel pain …

It is self-medication with analgesics that forms the basis of the standard experiment to determine whether an animal feels pain.

The principle is straightforward. Two identical foods are prepared, one containing a suitable analgesic (e.g. morphine) and the other a placebo. If an animal is in pain it will preferentially eat the food containing the morphine.

Conversely, if they do not feel pain they will – on average – eat both types of food equally 2.

But this experiment will only work if morphine ‘works’ in bees.

Does morphine ‘work’ in bees?

An unpleasant or harmful stimulus induces a nociceptive response which might include taking defensive action like retreating or flying away. Studies have shown that the magnitude of this defensive action in honey bees is reduced or blocked altogether by prior injection with morphine.

This is a dose-response effect. The more morphine injected the smaller the nociceptive response by the bee. Importantly we know it’s the morphine that is having the effect because it can be counteracted by injection with naloxone.

So, morphine does work in bees 3.

We can therefore test whether bees choose to self-medicate with morphine to determine whether they feel pain.

And this is precisely what Julie Groening and colleagues from the University of Queensland did, and published three years ago in Scientific Reports. The full reference is Groening, J., Venini, D. & Srinivasan, M. In search of evidence for the experience of pain in honeybees: A self-administration study. Sci Rep 7, 45825 (2017); https://doi.org/10.1038/srep45825

Ouch … or not?

The experiment was very simple. Bees were subjected to one of two different injuries; a continuous pinch to the hind leg, or the amputation of part of the middle leg. They were then offered sugar syrup alone and sugar syrup containing morphine.

The hypothesis proposed was that if bees felt pain they would be expected to consume more of the sugar syrup containing morphine.

To ensure statistically relevant results they used lots of bees. Half were injured and half were uninjured and used as controls. If syrup laced with morphine tasted unpleasant you would expect the control group to demonstrate this by eating less.

Throughout the experiments the authors were therefore looking for a difference in syrup alone or syrup with morphine consumption between the injured bee and the uninjured controls.

All of the experiments produced broadly similar results so I’ll just show one data figure.

Relative consumption of morphine (M) and pure sucrose solution (S) by injured (i; amputated) or control (c) bees.

Both groups of bees preferred the pure syrup (the two box plots on the right labelled S_c or S_i) over the morphine-laced syrup (M). However, the bees with the amputation did not consume any more of the morphine-containing syrup (M_i) than the controls (M_c).

Therefore they did not self-medicate.

Very similar results were obtained with the bees carrying the hind leg clip (recapitulating an attack by a competing forager or predator, which often target the rear legs). The injured bees consumed statistically similar amounts of plain or morphine-laced syrup as the control group.

The one significant difference observed was that bees with amputations consumed about 20% more syrup overall than those with the rear leg ‘pinch’ injury. The authors justified this as indicating that the amputation likely induced the innate immune system, necessitating the production of additional proteins (like the antimicrobial peptides that fight infection), so leading to elevated energy needs. Speculation, but it seems reasonable to me.

Feeling no pain

This study, using a pretty standard and well-accepted experimental strategy, strongly suggests that bees do not feel pain.

It does not prove that bees feel pain. It strongly supports the theory that they do not. You cannot prove things with science, you can just disprove them. Evidence either supports or refutes a hypothesis; in this case the evidence (no self-medication) supports the hypothesis that bees do not feel pain because, as has been demonstrated with several other animals, they would self-medicate if they did feel pain.

In the discussion of the paper the authors suggest that further work is necessary. Scientists often make that kind of sweeping statement to:

  • encourage funders to provide money in the future 😉
  • allow them to incorporate additional, perhaps contradictory, evidence that could be interpreted in a different way to their own results.

Skinning a cat

That is painful … but the proverb There’s more than one way to skin a cat 4 means that there is more than one way to do something.

And there are other ways of interpreting behavioural responses as an indication that animals feel pain.

For example, rather than measuring self-medication with an analgesic, you could look at avoidance learning or protective motor reactions as indicators of pain.

Protective motor reactions include things like preferential and prolonged grooming of regions of the body which have been injured 5. There is no evidence that bees do this.

Avoidance learning

However, there is evidence that bees exhibit avoidance learning. This is a behavioural trait in which they learn to avoid a harmful stimulus that might cause injury.

If a forager is attacked by a predator at a food source (and survives) it stops other bees dancing to advertise that food source when it returns to the hive 6.

Whilst avoidance learning does not indicate that bees feel pain, it does imply central processing rather than a simple nociceptive response. It shows that bees are able to weigh up the risk vs. reward of something good (a rich source of nectar) with something bad (the chance of being eaten when collecting the nectar). This type of decision making demonstrates a cognitive capacity that might make pain experience more likely.

We’re now getting into abstruse areas of neuropsychology … dangerous territory.

Let’s assume, as I do based upon the science presented here and in earlier work, that bees do not feel pain. What, if anything, does this mean for practical beekeeping.

Practical beekeeping

It certainly does not mean we should not attempt to conduct hive manipulations in a slow, gentle and controlled manner. Just because rolled bees are not hurting, or crushed bees are not feeling pain, doesn’t give us carte blanche to be heavy handed.

One of the nociceptive responses is the production of alarm pheromones (sting and mandibular) which are part of the defensive response. Alarm pheromones agitate the hive and make the colony aggressive, much more likely to sting and much more difficult to inspect carefully.

So we should conduct inspections carefully, not because we are hurting the bees, but because they might hurt us.

But there are other reasons that care is needed as well. Crushed bees are a potential source of disease in the hive. One reason undertaker bees remove the corpses is to remove the likelihood of disease spreading in the hive. If bees are crushed the heady mix of viruses, bacteria and Nosema they contain are smeared around all over the place, putting other hive members at risk.

And, as we’re all learning at the moment, good hygiene can be a life-saver.


Colophon

This is the first post written under ‘lockdown’. It’s a little bit later than usual as it has had to travel a   v  e  r  y    l  o  n  g   way along the fibre to ‘the internet’. It’s going to be a very different beekeeping season to anything that has gone before.

At least spring is on the way …

Primroses, 27-3-20, Ardnamurchan