Natural vs. artificial swarms

I’ve now covered four of the most frequently used swarm control strategies. These are:

  • Pagden’s artificial swarm – the horizontal splitting of the colony
  • The vertical split – an equipment-frugal variant of the above involving a vertical separation of the colony
  • The nucleus method – in which the queen is removed with sufficient workers to make up a small (nuc) colony, leaving the original colony to rear another queen
  • The Demaree method – which, at its simplest, relocates the queen from the brood and associated nurse bees, but does not physically split the colony

If conducted correctly all should prevent loss of a swarm. However, the individual methods – even the first three which involve the physical separation of the bees in the hive – are not the same.

In addition, these swarm control methods do not recapitulate the separation of bees that occurs when a hive naturally swarms.

The purpose of this post is to contrast the original and new colony composition of the split-based methods of swarm control (i.e. Pagden and vertical) with natural swarms.

Temporal polyethism

I introduced this term when discussing the honey bee colony as a superorganism. It means that adult worker bees have different roles depending upon their age. For the first two and a bit weeks they have duties inside the hive such as cell cleaning, brood rearing and wax production.

They then transition through a period of being guard bees before becoming foragers, flying from the hive and collecting water, nectar and pollen.

For convenience I’ll refer to these two groups of bees as young, nurse or hive bees and flying bees.

Vertical and horizontal splits

The classic Pagden artificial swarm and the vertical split are fundamentally the same process.

If unsealed queen cells are found during a colony inspection the queen, with a frame of emerging brood, is moved to a new box. This box is placed on the site of the original hive.

The remaining bees and brood are moved, either to one side in the case of the Pagden or on top of the queen-containing box (separated by a split board) in a vertical split.

Split board ...

Split board …

Critically, the new box with the brood and bees is provided with a new hive entrance, located off to one side or on the opposite side of the original hive 1.

Flying home

Over the following day or two the flying bees leave the relocated brood box with the new entrance and return to the queen-containing brood box in the original location.

As a consequence of their excellent homing navigational skill, the hive manipulation results in the separation of the bees into two populations:

  1. The flying bees i.e. those over ~3 weeks of age that had orientated to the original hive location, which are now located with the queen.
  2. The nurse bees i.e. those less than 3 weeks old, which remain in the relocated brood box, together with the brood in all stages (eggs, larvae and pupae).
Artificial swarm separation of the colony

Artificial swarm separation of the colony

How does the artificial swarm compare with the age distribution of bees in a real swarm?

Real swarms

I’ve previously discussed prime swarms and casts. The former contain a mated queen. In contrast, casts are produced from very strong colonies after the prime swarm has left. Casts are headed by a virgin queen. These are sometimes called after swarms and are usually smaller than prime swarms.

What about the workers in the swarm? What might be expected?

Perhaps they’re primarily the older flying bees? After all, these are the bees that have finished their hive duties and are now routinely foraging outside the hive. It’s the natural place for them.

Swarm of bees

Swarm of bees

Alternatively, remember that swarms have no ‘homing’ instinct for a day or two after emerging. They can be readily moved and you can safely ignore the less than three feet or more than three miles rule. Perhaps this means that they’re primarily young bees that have yet to go on their orientation flights?

Real experiments and contradictory results

Enough speculation … how do you determine this experimentally?

There have been numerous studies of the age distribution of bees in natural swarms. However, the data tends to be rather contradictory though the methods used are often broadly similar.

How do you determine the age composition of workers in a swarm?

Essentially you ‘spike’ the colony with a set number of marked bees of a known age over about 8 weeks. This is easy to do, but tedious.

Workers are allowed to emerge in an incubator. On the day of emergence (0 days old) they are marked with a colour that distinguishes them from older or younger bees. Every three days 100 identically marked i.e. same age, bees are added to the study hive(s). Over the period May to July this will accumulate red, then yellow, then blue, then mauve, then cyan, then pink etc. cohorts of workers, each representing a known age class.

It must be a nightmare spotting the queen in these hives 😉

The colony is allowed to swarm, the swarm collected and the number of bees of the different age cohorts in the swarm counted.

I missed a step out there. Have you ever tried counting the bees in a swarm? It’s much easier if they don’t move.

1002, 1003, 1004, 1005, er, where was I? Damn!

1002, 1003, 1004, 1005, er, where was I? Damn!

Perhaps it’s best that I missed that step out 🙁

What you end up with is a count of the total number of bees in the swarm and the numbers of bees of each 3 day cohort over the last several weeks. You can therefore determine the age distribution of the workers in the swarm.

Is it as simple as that?

I’ve actually oversimplified things a bit. There’s a possibility that different age cohorts of bees die within the hive at different rates, perhaps depending upon forage availability or weather or something else.

Think about it. Assume there was a dearth of nectar in late May and the blue and red labelled cohorts added during that period were underfed and died prematurely.

If there were very low numbers of blue and red bees in the swarm you might assume that these ages were ‘left behind’ by the swarm … when actually they weren’t able to swarm at all.

The real question is therefore whether the age distribution of bees in the swarm is similar to that in the parental hive.

OK, OK … is it?

No.

Swarms do contain bees of all ages.

However there are significantly more young bees and many fewer old bees than would be expected from the age distribution of workers in the parental colony.

Age distribution of bees in swarms

Age distribution of bees in swarms

The o and e in the graph above represents the position of the observed and expected median age class for the expected distributions. So, in swarm C the observed median age is ~10 days old, whereas the originating hive median age was ~19 days.

The graph above comes from a 1998 study by David Gilley 2 and supports earlier work 3 by Colin Butler 4 which is often cited as one of the definitive studies on the ages of bees in a swarm.

Additional considerations

Is it surprising that young bees predominate in natural swarms?

Swarms usually emerge from the hive late morning or early afternoon on warm, sunny days. In fact, at exactly the time most older bees aren’t in the hive anyway because they’re out and about foraging.

Remember also that swarming is a precarious activity for the colony. Most swarms do not survive 5. Natural selection will have resulted in swarm populations that maximise their chance of survival.

Once bees start foraging their life expectancy is pretty short. It has been estimated that they experience about 10% mortality per day. If only old bees left in the swarm with the queen the newly established colony would very rapidly dwindle in size, perhaps before significant numbers of new brood emerged (which takes 21 days from the first egg being laid). This would likely limit the chances of survival of the new colony.

What has this got to do with artificial swarms?

As beekeepers (or at least as responsible beekeepers) we spend May and June rushing about like headless chickens trying to control swarming in our bees.

Many of us achieve this using a variety of methods which are generically referred to as artificial swarms. I suspect that many beekeepers think that the artificiality is because of our interventions.

Where have all my young girls gone?

Where have all my young girls gone?

It is … but it’s worth remembering that the artificial swarms we generate are very different in composition to natural swarms. Our artificial swarms predominantly leave the older bees associating with the queen, with the young bees remaining with the brood.

These old bees have to draw new comb and rear the new brood. These are activities they last did weeks ago (a long time in the life of a bee).

Final thoughts

There are artificial swarm control methods that were developed to better replicate the age distribution of bees in a natural swarm. One example of these is use of a Taranov board. I’ll cover this in a future post.

It’s also worth noting that the bees of different ages in a natural swarm have different roles even before they occupy a new location. The older bees form a mantle around the bivouacked swarm that protects it from inclement weather (amongst other things) and the oldest bees are the scouts responsible for finding a new nest site.

Again, both topics for another post … I’ve got bait hives to set out 🙂


 

Demaree swarm control

I’ve covered three swarm control methods in previous posts. These are the classic Pagden artificial swarm, the vertical split that is directly comparable but requires less equipment and more lifting, and the nucleus method.

As described on this site, if successful, all achieve the same two things:

  • They prevent a swarm being lost. Don’t underestimate how important this is in terms of not irritating your neighbours, in helping your honey production and in giving you a quiet sense of satisfaction 🙂
  • They result in the generation of a second colony headed by a newly mated queen.

This doubling in colony number, or – more generally – the managed reproduction of colony numbers, is termed making increase.

Managed reproduction

Making increase is of fundamental importance in beekeeping.

Without deliberately splitting colonies, unless you buy in nucs every year (kerrching!), collect swarms or steal hives 1 your colony numbers would never increase.

Making increase is therefore critical if you want more colonies. However, it’s just as important (and a darn sight less expensive than buying nucs) if you want to make up any overwintering colony losses, thereby keeping the same number of colonies overall 2.

Not making increase

Once you’ve got bees, with good management, you can always have bees. However, at some point you reach that sweet spot where you have enough bees and don’t want more colonies.

The Goldilocks Principle is the concept of having just the right amount. Not so few colonies that a really harsh winter causes problems, and not so many that you cannot enjoy your beekeeping at the peak of the season.

When you reach that point you no longer need to make increase, you just want to keep the same number of colonies.

Which means that the swarm control methods that essentially reproduce the colony may not be ideal.

Of course, you can unite colonies having removed the unwanted queen from one of them, but this is additional work. Not a huge amount of work admittedly, but work nevertheless 3.

This is where the Demaree method of swarm control comes in useful. As practised, Demaree swarm control prevents the loss of the swarm without increasing colony numbers.

It has the additional significant advantages of keeping the entire foraging force of the colony together (even better for honey production than not losing a swarm) and needing no specialised equipment.

Demaree swarm control – in principle

George Demaree

George Demaree

The principle of the method is very straightforward.

When queen cells are found during an inspection you conduct a form of a vertical split, separating the original queen and flying bees from the nurse bees and sealed brood. You place the latter above a queen excluder.

A few days later you return and remove any new queen cells from the top box, so preventing swarming. Finally you leave all the brood to emerge from the top box.

Demaree swarm control – in practice

A cartoon diagram of the process is shown below. The only additional equipment required is a brood box with 11 frames of drawn comb or foundation and a queen excluder.

That’s it.

Demaree swarm control

Demaree swarm control

Here’s a bit more detail:

  1. If you find queen cells during an inspection gently remove the brood box and place it on an upturned roof off to one side 4.
  2. Place the new brood box on the original floor. Add 9 frames of drawn comb or foundation, leaving a gap in the middle of the box.
  3. Using minimal smoke, go through the original box and find the queen.
  4. Place the frame with the queen in the middle of the new brood box on the original floor. This frame must contain no queen cells.
  5. Push the frames in the new brood box together and add in the eleventh frame.
  6. Add a queen excluder.
  7. Add the supers above the queen excluder. If there were no supers on the original hive then it’s worth adding a couple of supers now. It will provide better separation of the new and old brood boxes and it will encourage the bees to store nectar in supers rather than the top brood box.
  8. Add a second queen excluder.
  9. Place the original brood box on top of the queen excluder.
  10. Go through the upper brood box and remove every queen cell. Shake the bees off the frames to do this. Push the frames together and add one additional frame. Add the crownboard and roof.

Leave the colony for one week. At the next inspection you should only need to check the top brood box (i.e. the original one).

  1. Carefully inspect every frame and remove every queen cell. Again, you should shake the bees off the frames to do this. If you miss any queen cells there’s a good chance the colony will swarm.
  2. Close up the hive and leave the brood in the top box to emerge.
  3. About 25 days after conducting the first inspection (1 above, where you first found QC’s) you can remove the upper brood box from which all brood will have now emerged.

Explanatory notes

If you have a reasonable understanding of the development cycle of queen and worker bees you will understand how the Demaree Method simultaneously prevents swarming and keeps the entire colony together.

Honey bee development

Honey bee development

  • By splitting the colony you separate the queen and the flying bees from the nurse bees and the brood. The queen in the new (now bottom) box has ample space to lay, particularly if you provide her with some drawn comb to use.
  • The bottom box will now be less crowded and the swarming urge will therefore be much reduced.
  • You destroy all of the queen cells in the original (now top) box when you rearrange the hive. This is to stop any new queens emerging in this box in the following week.
  • However, this top box still contains eggs and young larvae. Since it is now located a long way from the queenright box the level of queen pheromone is very low. Consequently, in the week following the hive rearrangement, the bees will create new emergency queen cells in the top box.
  • When you return a week later all the eggs in the top box will have hatched and the youngest larvae left will be about four days old i.e. too old to be reared as new queens. Therefore, when you destroy all the new queen cells in the top box, you prevent the colony swarming.
  • You can remove the top brood box as soon as all the brood has emerged i.e. 25 days after first rearranging the hive 5.

Demaree pros and cons

Pros

  • An effective method of swarm control
  • Relatively simple procedure to implement and understand
  • Only requires a single brood box, frames and a queen excluder
  • Generates big, strong colonies and keeps the entire foraging force together
  • Modifications of the process can be used for queen rearing 6

Cons

  • Necessary to find the queen
  • Critical to remove all queen cells at the start and after one week
  • Generates tall stacked boxes, so some heavy lifting may be involved
  • Drones in the top box get trapped by the queen excluder 7
  • In a strong flow the bees can backfill the top box with nectar. Add sufficient supers when you first rearrange the hive
Framed wire QE ...

Framed wire QE …

Historical notes

George Whitfield Demaree (1832–1915) was a lawyer in Kentucky, USA, and a pioneer in swarm control methods. His eponymous method was published in the American Bee Journal in 1892. The original method was subtly different from that described above:

Demaree method

Demaree method

In his description he emphasises the need to keep the colony together to maximise honey production.

I suspect Demaree used a single sized box (as broods and supers) as he describes placing brood frames above the queen excluder in the centre of the super flanked by empty frames. As described, he doesn’t mention returning after one week to destroy queen cells above the queen excluder. Don’t forget to do this!

I particularly like Demaree’s comment that any swarm prevention method that “require a divided condition of the colony, using two or more hives, is not worthy of a thought”.


 

Bait hive guide

Spring this year is developing well. Even here on the chilly east coast of Scotland colonies are looking good and flying strongly when the sun is out. Large amounts of pollen are being taken in and there’s every sign that the hives are queenright and rearing lots of brood 1.

It’s too soon 2 to open the colonies but it’s not too soon to be thinking about the consequences of the inevitable continued expansion over the next few weeks.

Most healthy colonies will make preparations to swarm, often between late April and mid-June. The timing varies depending upon a host of factors including colony strength, climate, weather, forage, build up and beekeeper interventions.

Swarm prevention and control

You, like all responsible beekeepers, will use appropriate swarm prevention methods. Supers added early, ensure the brood box has space for laying etc.

In due course, once the colony gets bigger and stronger, you’ll notice queen cells and immediately deploy your chosen swarm control method e.g. the classic Pagden artificial swarm, the nucleus method I described last week, Demaree, vertical splits or – if you’re feeling ambitious – a Taranov board 3.

Which will of course be totally successful 😉

But just in case it isn’t …

… and just in case the beekeeper a couple of fields away is forgetful, unobservant, clumsy, on holiday, in prison or has some other half-baked excuse, be prepared for swarms.

As an aside, other than just walking around the fields, you can easily find hives near you by searching on Google maps and you can get an idea of the local beekeeper density 4 using the National Bee Unit’s Beebase.

You might think you know all the local beekeepers through your association, but it’s surprising the number who just ‘do their own thing’.

Swarms

This isn’t the place to discuss swarms in much detail. Here’s a quick reminder:

  1. The colony ‘decides’ to swarm and starts to make queen cells.
  2. Almost certainly, scout bees start to check out likely sites the swarm could occupy in the future 5.
  3. The swarm leaves the hive on the first calm, warm, sunny day, usually early in the afternoon, once the queen cells are capped. The prime swarm contains the mated, laying queen and about 75% of the worker bees 6.
  4. The swarm gathers around the queen and sets up a bivouac hanging from a convenient spot (tree, gatepost, bush, fence etc.) near to the hive. They rarely move more than 50 metres. It’s worth emphasising here that the spot they choose is convenient to the bees, but may be at the top of a 60 foot cypress. It may not be particularly convenient for the beekeeper 😉
  5. Scout bees continue to check out likely final sites to establish the new colony, returning to the swarm and ‘persuading’ other scouts (by doing a version of the waggle dance) so that, finally, a consensus is reached. This consensus is essentially based upon the suitability of the sites being surveyed.
  6. The scout bees lead the swarm to the new location, they move in and establish a new colony.

If you’re lucky you will be able to recapture the swarm if the spot they choose for their bivouac is within reach, not above a stream, in a huge thorny bush or on an electricity pylon.

A small swarm ...

A small swarm …

I say ‘recapture’ because, since the bivouac is usually near the issuing hive, it’s probably come from one of your own hives (unless you are snooping around your neighbouring apiaries 7).

But what if you miss the bivouacked swarm? Or if your neighbour misses it?

Those bees are going to look for a suitable location to set up home.

If you provide a suitable location, you can get them to hive themselves without the grief of falling off a ladder, toppling into a stream, getting lacerated with thorns or electrocution

This is where the bait hive comes in. Leave a couple in suitable locations and you can lure your own and other swarms to them.

Freebees 🙂

What do scouts look for?

The scout bees look for the following:

  1. A dark empty void with a volume of about 40 litres.
  2. Ideally located reasonably high up.
  3. A solid floor.
  4. A small entrance of about 10cm2, at the bottom of the void, ideally south facing.
  5. Something that ‘smells’ of bees.

What I’ve just described is … a used beehive 8.

More specifically, it’s a single National brood box (or two stacked supers) with a solid floor and a roof, containing one old dark frame of drawn comb pushed up against the back wall.

No stores, no pollen 9, just a manky old dark comb. The sort of thing you should be turning into firelighters.

That’s all you need.

However, you can improve things by giving the bees somewhere to start drawing comb and siting the hive in a location that makes your beekeeping easier.

Des Res

The first thing swarms do when they move in is start drawing comb. You can populate the bait hive with a few foundationless frames so they’ve got somewhere to start.

Bait hive ...

Bait hive …

In my view foundationless frames are much better than frames with foundation for bait hives. The scout bees measure the size of the void by flying around randomly inside 10. If you have sheets of foundation they’ll crash into it frequently, effectively giving them the impression that the void is smaller than it really is. And therefore making it less attractive to the scouts.

You can improve the smell of the hive by adding a little lemongrass oil to the top bar of one of the frames. Don’t overdo it. A drop or two every 7-10 days is more than ample.

If you do use foundationless frames make sure the hive is level. If you don’t the comb will be drawn at an angle to the frames which makes everything harder work later in the season. Your smartphone probably contains a spirit level function that makes levelling the bait hive very easy.

Location

But not if it’s above head height, or you’re teetering on top of a ladder …

It was Tom Seeley who worked out most things about scout bees and swarms (see his excellent book Honeybee Democracy). This included the observations that they favoured bait hives situated high up.

Believe me, it’s a whole lot easier if the bait hive is on a standard hive stand. It’s easier to level, it’s easier to check and it’s easier – in due course – to retrieve.

Bait hive

Bait hive

I’ve previously discussed how far swarms prefer to move from their original hive. Contrary to popular opinion (and perhaps illogically) they tend to prefer to move shorter distances i.e. 20m >> 200m >> 400m. However, there are also studies that show swarms moving a kilometre or more.

Don’t get hung up on this detail. Stick out a bait hive or two and, if there are swarming colonies in range, they’ll find it.

I always leave a bait hive in my apiaries and one or two in odd corners of the garden. In the last few years I’ve never failed to attract swarms to the bait hives, and know for certain that some have moved in from over a mile away as the bee flies (thanks Emma 😉 ).

Mites and swarms

Assuming you don’t have the luxury of living in Varroa-free areas of the UK (or anywhere in Australia) then the incoming swarm will contain mites. Studies have shown that ~35% of the mite population of a colony leaves with the swarm.

But, for about the first week after the swarm sets up home in your bait hive, what’s missing from the new arrivals is sealed brood. Therefore the mites are all phoretic.

Do not delay. Treat the swarm with an appropriate miticide to knock back the mite population by ~95%. An oxalic acid-containing treatment is ideal. Single dose, relatively inexpensive, easy to administer (trickled or vaporised) and well tolerated by the bees.

Varroa treatment ...

Varroa treatment …

You have eight days from the swarm arriving to there being sealed brood in the colony

Far better to slaughter the mites now. In a few months their numbers will have increased exponentially and the majority will be in capped cells and more difficult to treat.


 

The nucleus method

Almost all beekeeping associations – and most books – teach Pagdens’ artificial swarm as the recommended method of swarm control. It is tried and tested and reasonably dependable. However it can be a bit tricky to grasp for inexperienced beekeepers.

At least part of the problem is you have two hives that look the same, one on the original site, one adjacent. Conducted properly, the adjacent hive is moved to the other side of the original a week or so into the process.

Teaching this in a poorly lit, draughty church hall in late January, facing the audience with the inevitable confusion over left and right, and getting ‘new’ and ‘old’ hives mixed up, often bamboozles the beginner 1. Or the instructor 😉

Here’s an alternative … the nucleus method of swarm control.

There she goes ...

There she goes …

General principles

This method is simplicity itself. When the colony looks as though it’s preparing to swarm you remove the queen, some stores and some bees into a nucleus hive.

This keeps the queen safe in case things go awry with the original colony.

You then return a week later and remove all but one queen cell in the original colony. The virgin queen emerges, mates, returns and starts laying.

A month or so after starting the original colony is headed by a new queen and you have a ‘spare’ building up in the nucleus box. You can overwinter this, sell it, give it away or – after removing the queen – unite it back with the original hive.

And that’s it … I said it was simple 🙂

Here is a more complete account.

Equipment needed

It goes without saying that the nucleus method of swarm control needs a nucleus (nuc) hive 2. Any sort of 5 frame nuc is suitable. Nucs are incredibly useful, so they are a good investment. If you’re buying one for the first time get polystyrene as they’re lighter, better insulated and much better for overwintering bees in. I’ve reviewed poly nucs a few years ago. There are even more makes to choose from now.

I’d recommend not using a two frame nuc as there’s not really enough room for stores and colony expansion 3.

Two frame nuc box

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

In addition to the nuc you’ll need five frames that are compatible with your nuc and hive. Ideally, one or two of these should be drawn comb, but don’t worry if you just have foundation. A dummy board can also be useful. Like nucs, you can almost never have too many dummy boards.

Honey bee development

To properly understand honey bee swarm control you really need to understand the timing of the development cycle of queen bees.

Honey bee development

Honey bee development

Queen cells have a characteristic appearance. Unlike the horizontally-oriented worker cells, larvae destined to become queens hatch from eggs laid in vertically-oriented queen cells. After three days as eggs and a further five days of larval development the queen cell is sealed.

A colony will usually swarm on or soon after 4 the queen cells are sealed.

~3 day old queen cell ...

~3 day old queen cell …

This is why it is recommended that colony inspections are conducted at seven day intervals. If the colony is thinking of swarming you’ll find an unsealed cell (because there were none last week when you inspected and they take 8 days to be sealed) and you can immediately start swarm control.

Day 1 – Making up the queenright nucleus colony

If you find one or more unsealed queen cells at a routine inspection … don’t panic. You’re prepared, you’ve done your homework and you have the necessary equipment.

  1. Stuff the entrance of a nucleus hive with grass and place it near the colony 5.
  2. Remove one of the outer frames from the colony (you’ve probably already done this to give yourself room for the inspection) as this should have a good amounts of sealed and unsealed stores.
  3. Check again that the queen isn’t on this frame of stores (unlikely) and that it doesn’t contain any queen cells (again unlikely).
  4. Gently transfer the frame of stores plus all the adhering bees to the nucleus box.
  5. Continue the inspection and find the queen. Be gentle, don’t rush, don’t use too much smoke.
  6. Ideally you want the queen on a frame with some sealed and emerging brood. If you are lucky you’ll find her on a suitable frame.
  7. Gently transfer the queen and the frame she is on to the nucleus box. It is very important that this frame has no queen cells on it. Check very carefully. Destroy any you find.
  8. Your nuc colony is now queenright and has two frames of bees. Push the frames against the side wall of the nuc box, leaving a wide gap.
  9. Into this gap shake a further two frames of bees. Foragers are likely to leave the nuc and return to the original hive. You do not want the box to be short of young bees. If in doubt shake a further frame of bees into the gap in the nuc 6.
  10. Add a frame of drawn comb if you have it then fill the box with foundation. Add a dummy board if needed. Gently place the crownboard and roof on the nuc, secure everything with a strap and turn your attention to the colony.

Notes

  • The purpose of this exercise is to establish a small colony with stores, a laying queen, space to lay and sufficient bees to support her and the brood being reared. Remember stores, queen, bees, space and no queen cells you won’t go wrong.
  • You will usually find the queen on a frame with eggs and young larvae. It’s very important that this frame does not have any queen cells on it.
  • Ideally you want the queen on a frame of emerging brood. This offers a number of advantages
    • The young bees will immediately strengthen the population supporting the queen
    • The vacated cells can be used by the queen to lay eggs (so reducing the need for drawn comb, or for the bees to build new comb)
    • The nuc colony will go through a period with no sealed brood and you can take advantage of this for Varroa management if needed (I’ll deal with this in another post)
    • It’s unlikely (due to the age of the other brood) to have a queen cell on it
  • One of the most common problems encountered with this method of swarm control is making up (or ending up) with a nuc that is not strong enough. A weak nuc will be unable to defend itself against robbing or wasps. There’s very little chance of weakening the original hive too much.
  • One way to avoid losing foragers from the nuc is to move it to an out apiary more than 3 miles from the original hive.
  • If you do leave the nuc in the same apiary check it a couple of days later. The bees should have chewed their way out through the dried grass. If they haven’t, pull a bit out at the corner of the entrance to encourage them to fly.

Day 1 – Preparing with the queenless colony

  1. Inspect every frame in the colony. Destroy all large queen cells 7. Anything that looks like the queen cell in the picture above should be destroyed. The idea here is to only leave queen cells containing very small larvae.
  2. Mark the frames containing these remaining selected queen cells using a drawing pin or pen.
  3. Push the frames together, add two frames of foundation, add the crownboard and close up the colony.
Here's one I prepared earlier

Here’s one I prepared earlier

One week later – Ensuring the queenless colony does not swarm

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.

  1. Inspect the colony and look for queen cells on the frames you marked a week earlier. These had very young larvae in them then and so will now be sealed 8.
  2. Select one queen cell to keep. Just one. Which one? Choose one that is large, well-shaped and has a sculptured exterior.
  3. Destroy all the other queen cells on this frame. All of them! If you need to remove the bees to see the frame better either brush them off gently or blow gently on them. Do not shake the bees off the frame as this might damage the developing queen.
  4. Gently return the frame with the selected queen cell to the box.
  5. Inspect all other frames in the colony (not just the ones you marked last week) and destroy all of the queen cells you find.
  6. You can shake the bees off these other frames to be sure of finding all other queen cells.
  7. Remember that some queen cells will be unsealed 9 … destroy them all.
  8. Return all the frames to the colony. Close it up and leave it for at least two weeks before inspecting again (see below).
Sealed queen cell ...

Sealed queen cell …

Notes

  • The purpose of this return visit is to leave the colony with only a single queen cell.
  • Because you removed the queen a week ago there are no other suitably aged young larvae or eggs for the colony to rear queens from. Therefore, the colony cannot produce multiple casts (swarms headed by virgin queens).
  • The nucleus method of swarm control often leaves the queenless colony very strong 10, if you leave more than one queen cell the colony may produce casts.
  • What if the queen gets lost on a mating flight? Shouldn’t I leave two queen cells? Just to be on the safe side? No. If there’s a problem with the queen getting mated you’ve still got the old queen tucked away safely in the nuc box.
  • Queen cells that are large, well shaped and sculptured have received a lot of attention from the workers and so presumably contain a well-fed and good quality queen 11.
  • Don’t be tempted to inspect the colony in less than two weeks. Ideally leave them for three weeks. If you inspect too early there’s a chance that the queen may not have had a chance to mate and start laying (so the point of inspecting is missed) or – worse – that she returns from her mating flight as you have the box open and is then confused or lost.
  • Don’t meddle! Look for pollen being taken into the colony.
  • Have patience. Bees have been around for a few million years. They would not be this successful if they weren’t pretty good at getting queens mated …
  • Finally, particularly if the weather is poor, check the nuc as well. Ensure that it has sufficient stores. With reduced numbers of bees there’s a chance they could starve if the bees cannot forage (in which case the queen in the main colony is going to struggle to get out and mate as well).
Everynuc

Everynuc …

Pros and cons of the nucleus method of swarm control

With the exception of vertical splits almost all of my swarm control uses this nucleus method 12. I particularly like the nucleus method because I have lots of nuc boxes ( 🙂 ) and because it leaves manageable single-entrance hives rather than double height, multiple entrance stacks.

Almost all of the foraging bees are left with the original colony so the nectar-gathering capacity is not significantly reduced.

I almost never use the Pagden artificial swarm, largely because it ties up too much equipment.

Pros

  1. Limited amount of extra equipment needed – five frames and a nuc box … both of which are useful anyway.
  2. The old queen is kept safe and out of the way.
  3. Simple to implement, with just two visits at fixed times.
  4. Reasonably easy to understand the manipulations involved.
  5. No heavy lifting.
  6. You generate a nucleus colony to give away or to build up for overwintering.

Cons

  1. You need to find the queen.
  2. You need to find all the queen cells and use your judgement as to their age and quality.
  3. Unless you remove the nuc to an out apiary there’s a good chance lots of the bees will return to the original hive. Make sure you add enough at the start and be prepared to add more if you check the nuc after a day or two and find it heavily depleted.
  4. If you don’t want to make increase the nuc is a little more difficult to unite back with the original colony 13.

Give it a go … what could possibly go wrong?


 

Superorganism potential

The term superorganism can be used to refer to a colony of honey bees. The term gained prominence in the mid/late noughties having been reintroduced by the world-renowned myrmecologist 1 E.O. Wilson.

Bees, like ants (myrmex, “ant”, from the Greek μύρμηξ), are social insects in which there are divisions of labour. Different individuals within the colony perform different tasks. Some of these roles are defined by the castes in the colony – queen, worker and drone in a colony of honey bees for example – and some are defined by physiological differences between individual members of the same caste.

The term superorganism describes the entirety of the colony and is defined as a group or association of organisms which behaves in some respect like a single organism.

Essentially, a superorganism has characteristics and behaviours that the individuals within the colony – due to caste or physiological specialisation – do not exhibit.

The superorganism operates as a unified entity, collectively working together to maintain and reproduce the colony.

Division of labour and temporal polyethism

Drones and queens have relatively straightforward roles in the colony. Drones, like teenage boys, lounge around eating and thinking about sex. The queens are egg-laying machines.

An egg laying machine

An egg laying machine

Although there’s undoubtedly work involved in laying your bodyweight in eggs at the height of the season, the real work in the colony is – appropriately – done by the workers.

Worker bees exhibit temporal polyethism i.e. they display different patterns of behaviour depending upon their age. They have a maturational schedule in which they sequentially undertake age-correlated roles in the colony:

  • Young bees work in the hive in a series of roles starting with cell cleaning (days 1-2), nursing developing larvae (nurse bees; days 3-11) and wax production (days 12-17).
  • After two to three weeks the workers undergo significant physiological changes (weight loss, changes in immune function, reduced stress resistance) which prepare them for a productive life outside the hive. During this period the bees transition through a period when they act as guard bees.
  • Older bees (the ‘flying’ bees) perform a range of foraging activities including water carrying, pollen collection and nectar gathering.

And then they die in the field 🙁

Behavioural plasticity

This behavioural maturation is controlled by a so-called negative feedback loop between vitellogenin (Vg 2) and juvenile hormone (JH).

Nurse bees have high Vg levels which are reduced at the transition to foraging. Conversely JH levels increase with the onset of foraging (I know this sounds counterintuitive). These changes are responsible for a range of physiological changes in the worker bee.

Behavioural maturation in worker bees

Behavioural maturation in worker bees

But it’s not as simple as that. High Vg levels can block JH synthesis, so delaying maturation and foraging. Similarly, JH may reciprocally inhibit Vg synthesis and induce early foraging.

Clearly that last couple of sentences indicates that worker maturation is not an invariant process. It doesn’t always occur after 2-3 weeks.

In fact, the maturation or ageing process in honey bees is a very interesting phenomenon.

Ageing exhibits seasonal variability and remarkable plasticity.

Nurse bees can survive for at least 130 days and overwintering bees may survive up to 280 days. Clearly ageing in bees is a remarkably variable process. Overwintering bees ‘mature’ into either nurse bees or foragers. Presumably this has evolved as an effective mechanism of allowing spring colony build up (by having sufficient bees for the different roles) once environmental conditions improve.

In addition, there is another striking feature of the maturation process of honey bees.

Under certain social environmental conditions maturation is reversible.

This reversible maturation can be demonstrated by removing the nurse bees from the hive. Under these conditions some of the younger foragers revert, both behaviourally and physiologically, to nursing tasks. JH levels drop and Vg levels increase.

Old foragers are unable to undergo this rejuvenation.

Reversible maturation in worker bees

Reversible maturation in worker bees

Which finally and in a round the houses way gets me to the subject I meant to cover in the first place this week …

Brood and the superorganism

The honey bee colony superorganism not only contains a queen, workers and drones. It also contains brood. In the following text I’ll use the term brood as a collective noun meaning all the eggs, unsealed larvae and sealed pupae in the colony (unless otherwise specified).

Is the brood a component of the superorganism?

It certainly is.

Laying workers ...

Laying workers …

Remember previous discussion of laying workers. These are workers that lay unfertilised eggs which develop into drones. Egg laying by workers is suppressed by pheromones produced from unsealed brood 3. Therefore brood does influence the behaviour of the colony 4.

If the complete colony – brood, workers, drones and a queen – is a superorganism, which components of the colony, individually or together, have the potential to form the superorganism?

And why should this matter?

Swarming and the superorganism

During swarming, either naturally during colony reproduction, or during manipulation by the beekeeper, the ‘superorganism’ is broken up.

During natural swarming the (old) mated queen leaves the colony with 60-75% of the workers to establish a new colony. By the time the swarm leaves, the original colony – which has all the eggs, larvae and brood (obviously) – is usually already well on the way to rearing a new queen. The (new) virgin queen emerges, gets mated, and the colony has successfully reproduced.

Many of the colony manipulation methods that are used to prevent the loss of natural swarms exploit the potential of the components in the colony to form a complete new colony.

Most ‘artificial swarms’ work by breaking the colony – the superorganism – into two parts:

  1. The queen and the ‘flying’ bees. Even young bees can fly, so the term ‘flying’ bees refers to the older bees from the colony that have matured sufficiently to leave the hive.
  2. The nurse bees and all the brood.
Swarms, splits and superorganisms

Swarms, splits and superorganisms

These two parts both have the potential to create a new colony.

The queen and the flying bees that form the swarm (or the queenright part of an artificial swarm) occupy a new site (or hive 5), draw comb in which the queen lays, the larvae are fed 6, pupate and emerge. At the same time, foragers collect the necessary nectar and pollen to maintain the new colony.

The swarmed colony (i.e. the queenless part of an artificial swarm) contains ample stores and the nurse bees. What they don’t have is a queen. But they do have eggs and young larvae. The nurse bees select and feed one or more of these young larvae with copious amounts of Royal Jelly. A few days later a virgin queen emerges, matures, mates and returns to the colony to start laying eggs.

Sealed queen cell ...

Sealed queen cell …

Therefore both natural and artificial swarms exploit the potential in both parts of the original colony to eventually reproduce the colony.

No potential

Not all components of the colony have the potential to give rise to a new colony or superorganism. A solitary queen doesn’t even have the ability to feed herself properly, let alone double up for egg laying and nursing larvae duties.

This comes as a surprise to some people. If you frequent any of the online discussion forums you’ll sometime see questions posted like this:

What sort of hive do I need to buy to put a queen bee in to make honey?

Followed by some polite, or not so polite, responses saying that there’s a little bit more to beekeeping than that 7.

The ‘flying’ bees alone, in the absence of a queen, also have no potential. They can lay eggs (as laying workers, see above), but since the eggs are unfertilised the colony will be doomed. It’s not unusual for a queen from an artificial swarm (or from a cast) to fail to return from a mating flight, so condemning the workers in the hive to oblivion.

Swarms and behavioural plasticity

The classic artificial swarm involves moving the nurse bees and the brood to a new site, leaving the queen and the flying bees in the original location.

You do this so that the flying bees that have orientated to the position of the original hive – whether out in the field actively foraging or in the moved hive – eventually return and so become separated from the nurse bees and the brood.

In doing this you remove the urge to swarm and you weaken the queenless hive.

The majority of those flying bees are foragers.

And this is where behavioural plasticity is essential. remember that the artificial swarm predominantly contains foragers, not the nurse bees needed to feed developing larvae.

Some of these foragers undergo rejuvenation to produce wax or to become nurse bees. These build new comb and, in a few days, feed larvae that have hatched from the eggs laid by the queen.

This behavioural plasticity contributes to the potential of the artificial swarm to produce a new colony or superorganism.

A small swarm ...

A small swarm …

Do the same processes happen in natural swarms?

That requires a discussion of the worker composition of swarms which is not straightforward and will have to wait for another day 😉


 

Unknown knowns

If there’s one thing that can be almost guaranteed about the beekeeping season ahead it’s that it will be unpredictably predictable. I can be pretty sure what is going to happen, but not precisely when it’s going to happen.

These are the unknown knowns.

The one thing I can be sure about is that once things get started it will go faster than I’d like … both in terms of things needing attention now (or yesterday 🙁 ) and in the overall duration of the season.

So, if you know what is coming – spring build up, early nectar flow, swarming, queen rearing, splits, summer nectar flow, robbing, uniting, wasps, Varroa control and feeding colonies up for winter – you can be prepared.

As Benjamin Franklin said …

By failing to prepare, you are preparing to fail

Preparation involves planning for the range of events that the season will (or could) produce.

It also involves ensuring you have additional equipment to cope with the events you’ve planned for.

Ideally, you’ll also have sufficient for the events you failed to include in your plans but that happened anyway 😉

Finally, it involves purchasing the food and treatments you need to manage the health and winter feeding of the colony 1 .

So what do you need to plan for?

Death and taxes 2

The two utterly dependable events in the beekeeping season are – and this is likely to be a big disappointment for new 3 beekeepers – Varroa control and feeding.

Not an outrageous early spring honey crop, not ten weeks of uninterrupted balmy days for queen rearing, not even lots of swarms in your bait hives (freebees) … and certainly not supers-full of fabulous lime or heather honey.

Sorry 😉

So … plan now how you are going to feed the colony and how you are going to monitor and manage mites during the season.

Feeding usually involves a choice between purchased syrup, homemade syrup or fondant. I almost exclusively use fondant and so always have fondant in stock. I also keep a few kilograms of sugar to make syrup if needed.

Buy it in advance because you might need it in advance. If it rains for a month in May there’s a real chance that colonies will starve and you’ll need to feed them.

Early June 2017 ...

Early June 2017 …

I’ve discussed mites a lot on this site. Plan in advance how you will treat after the summer honey comes off and again in midwinter. Buy an appropriate 4 treatment in advance 5. That way, should your regular mite-monitoring indicate that levels are alarmingly high, you can intervene immediately.

Having planned for the nailed-on certainties you can now turn your attention to the more enjoyable events in the beekeeping year … honey production and reproduction.

Honey production

Preparing for the season primarily means ensuring you have sufficient equipment, spares and space for whatever the year produces.

In a good season – long sunny days and seemingly endless nectar flows – this means having more than enough supers, each with a full complement of frames.

How many is more than enough?

More supers

More supers

Here on the east coast of Scotland I’ve not needed more than three and a bit per hive i.e. a few hives might need four in an exceptional summer (like 2018). When I lived in the Midlands it was more.

Running out of supers in the middle of the nectar-flow-to-end-all-nectar-flows is a frustrating experience. Boxes get overcrowded, the bees pack the brood box with nectar, the queen runs out of laying space and the honey takes longer to ripen 6.

Without sufficient supers 7 you’ll have to beg, borrow or steal some mid-season.

Which is necessary because … it’s exactly the time the equipment suppliers have run out of the supers, frames and foundation you desperately need.

And so will all of your beekeeping friends …

Ready to extract

Ready to extract …

Not that you’ve necessarily got the time to assemble the things anyway 😉

Don’t forget the brood frames

You’ll need more brood frames every season. A good rule of thumb is to replace a third of these every year.

There are a variety of ways of achieving this. They can be rotated out (moving the oldest, blackest frames to the edge of the box) during regular inspections, or you can remove frames following splits/uniting or through Bailey comb changes.

Irrespective of how it’s achieved, you will need more brood frames and – if you use foundation – you’ll need more of that as well.

Foundationless frames

Foundationless frames …

And the suppliers will sell out of these as well 🙁

But that’s not all …

You will also need sufficient additional brood frames for use during swarm prevention and control and – if that didn’t work – subsequent rescue of the swarm from the hedge.

Swarmtastic

In a typical year the colony will reproduce. Reproduction involves swarming. If the colony swarms you may lose the bees that would have produced your honey.

You can make bees or you can make honey, but it takes real skill and a good year to make both.

And to make both you’ll need spare equipment.

Pagdens' artificial swarm ...

Pagdens’ artificial swarm …

Knowing that the colony is likely to swarm in late spring, you need to plan in advance how you will manage the hive to control or prevent swarming. This generally means providing them with ample space (a second brood box … so yet more brood frames) and, if that doesn’t work 8, manipulating the colony so that it doesn’t swarm.

Which means an additional complete hive (floor, brood box, yet more brood frames, crownboard, roof) if you plan to use Pagdens’ artificial swarm.

Alternatively, with slightly less equipment, you can conduct a vertical split which is essentially a vertically orientated artificial swarm.

Or you can use a nucleus (nuc) box to house the old queen … a very straightforward method I’ll discuss in more detail later this season.

Bait hives and skeps

I don’t like losing swarms. I’ve previously discussed the responsibilities of beekeepers, which includes not subjecting the general public to swarms that might harm or frighten them, or establish a colony in their roof space.

But I do like both attracting swarms and re-hiving swarms of mine that ‘escaped’ (temporarily 😉 ). I always set out bait hives near my apiaries. If properly set up these efficiently attract swarms (your own or from other beekeepers) and save you the trouble of teetering at the top of a ladder to recover the swarm from an apple tree.

But if you end up doing the latter you’ll need a skep 9 or a nice, light, large poly nuc box to carefully drop the swarm into.

Paynes nuc box ...

Paynes nuc box …

Don’t forget the additional brood frames you will need in your bait hive or in the hive you eventually place the colony in the skep into 😉

Planned reproduction

You’re probably getting the idea by now … beekeeping involves a bit more than one hive tucked away in the corner of the garden.

Not least because you really need a minimum of two colonies.

A quick peek inside the shed of any beekeeper with more than 3 years experience will give you an idea of what might be needed. Probably together with a lot of stuff that isn’t needed 😉

Storage shed

Storage shed

By planned reproduction I mean ‘making increase’ i.e. deliberately increasing your colony numbers, or rearing queens for improving your own stocks (or those of others).

This can be as simple as a vertical split or as complicated as cell raising colonies, grafting and mini mating nucs.

By the time most beekeepers get involved in this aspect of the hobby 10 they will have a good idea of the additional specialised equipment needed. This need not be complicated and it certainly is not expensive.

I’ve covered some aspects of queen rearing previously and will write more about it this season.

3 day old QCs ...

3 day old QCs …

Of course, once you start increasing your colony numbers you will need additional brood boxes, supers, nuc boxes, floors, roofs, stands, crownboards, queen excluders and – of course – frames.

And a bigger shed 😉


Colophon

The title of this post is an inelegant butchering of part of a famous statement from Donald Rumsfeld, erstwhile US Secretary of Defense. While discussing evidence for Iraqi provision of weapons of mass destruction Rumsfeld made the following convoluted pronouncement:

Reports that say that something hasn’t happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns—the ones we don’t know we don’t know. And if one looks throughout the history of our country and other free countries, it is the latter category that tend to be the difficult ones.

The unknown known

The unknown known

If you can be bothered to read through that lot you’ll realise the one thing Rumsfeld didn’t mention are the unknown knowns.

However, as shown in the image, this was the title of the 2013 Errol Morris documentary on Rumsfeld’s political career. In this, Rumsfeld defined the “unknown knowns” [as] “things that you know, that you don’t know you know.”

Perhaps unsurprisingly Condoleezza Rice, Secretary of State, claimed that Rumsfeld doesn’t know what he’s talking about.” ... though she wasn’t referring to the unknown knowns.

 

Spring starvation

A very brief post this week to highlight the dangers of unseasonably warm weather early in the season. February 2019 has entered the record books as the first ‘winter’ month in which the temperature exceeded 20°C (on at least the 25th and 26th in the UK). It’s also been a record with the daily temperature (highs … we’ve had some hard frosts as well) exceeding the historic average daily temperature on almost every day of the month.

Fife temperatures, February 2019

Fife temperatures, February 2019

Even here in Fife on the East coast of Scotland, the weather has been very warm and sometimes even sunny. The graph above shows the daily maximum temperature compared to the monthly average (dashed line).

The contrast with this time last year is very striking. The big winter storm called Anticyclone Hartmut (aka the Beast from the East) arrived in the last week of February.

The Beast from the East ...

The Beast from the East …

We had six foot deep snow drifts blocking the road to the village and there wasn’t a bee to be seen.

Crocus and snowdrop

Fast forward exactly 12 months and the bees are piling in the pollen and flying well for an extended period. Around here this early pollen probably comes from crocus, snowdrop, hazel and alder, perhaps with a bit of gorse as well which flowers throughout the season.

Brood rearing will have started in earnest. The large amounts of pollen being collected is a pretty good indicator that all is well in the hive, that the queen is starting to ramp up her egg laying rate and the numbers of hungry larvae are increasing.

There’s no need to open the hive to check for brood. Indeed, hive inspections (here at least) are probably at least 6 weeks away.

However, don’t ignore the colonies. The increase in brood rearing is a time when stores levels can quickly get critically low. There’s not a huge range of nectar sources about at the moment and the combination of a warm spell, increasing amounts of brood and a subsequent deterioration in the weather can rapidly result in colonies starving.

Hefting or a sneak peak

If you’ve been regularly hefting the hive to check its weight you should have a reasonable ‘feel’ for what it should be, and whether it’s significantly lighter. More accurately, but also more trouble, you can use luggage scales to record the week-by-week reduction over the winter.

It’s possible to determine whether there are sufficient – or at least some – stores by looking through a perspex crownboard at the tops of the frames.

Emptied bag of fondant

Emptied bag of fondant

Many of my hives went into the winter with the remnants of the autumn-fed fondant still present on the top bars. With a perspex crownboard it’s a trivial task to check if these stores have been used and – if they have – to heft the hive to see if they need more.

Fondant topups

Several hives have already had a fondant topup of about a kilogram placed directly onto the top of the frames. Alternatively, the hives with the Gruyere-like Abelo crownboards 1 get a fondant block slapped directly over the hole above the most concentrated seams of bees.

Fondant absorbs moisture from the atmosphere so you need to protect the faces of the fondant block not accessed by the bees. There are all sorts of ways to do this. A strong plastic bag with a slot or flap cut in the bottom is more than adequate.

Better still is to dole out the fondant into plastic food containers you’ve diligently saved all year. These are reusable, come in a variety of sizes and – ideally – are transparent. You can then easily see when and if the bees need a further topup.

Time for another?

Time for another?

I usually slice up a block of fondant and fill these food containers in midwinter, wrap them in clingfilm and carry them around in the back of the car for my occasional apiary visits. If a hive needs more stores I remove the clingfilm and simply invert the container over the bees.

Do remove the clingfilm! Bees tend to chew it up and drag it down into the brood nest, often embedding it into brace comb. It can be a bit disruptive during cool weather early-season inspections to remove it … hence the suggestion to use a strong plastic bag earlier.

Continued vigilance

Most of my hives will have had at least a kilogram of fondant by the end of February this year. One or two are likely to have had significantly more. I’ll keep a note of these in my records as – all other things being equal – I’d prefer to have frugal bees that don’t need fussing with over the winter.

As the days get longer and the season continues to warm the queen will further increase her laying rate. Until there are both dependable foraging days and good levels of forage there remains the chance of starvation.

Colonies are much more likely to starve in early spring than in the middle of a hard winter. If the latter happens it’s either due to poor winter preparation or possibly disease. However, if they starve in early spring it is probably due to unseasonably warm weather, a lack of available forage, increasing levels of brood and a lack of vigilance by the beekeeper.

Don’t delay!

If a colony is worryingly light don’t wait for a warm sunny day to feed them. Adding a block of fondant as described above takes seconds.

Everynuc fondant topup

Everynuc fondant topup

If a colony needs stores add it as soon as possible.

If it’s cold the bees will be reasonably lethargic and you may not even need to smoke them. I’ve only fired up the smoker once … to topup a colony of psychotic monsters ‘on loan’ from a research collaborator who shall remain nameless.

I managed to add the fondant without using the smoker but they then chased me across the field to thank me 🙁


 

Hanging around

I’ve recently discussed the misnamed ‘phoretic’ phase in the life cycle of Varroa destructor. Here we’ll briefly explore some features of this important, but non-reproductive, phase. It’s important because, as I’ll show, it influences subsequent mite reproduction.

I won’t rehash the life cycle of Varroa in detail as I’ve covered it previouslyVarroa is an ectoparasite of honey bees. It reproduces in capped cells, feeding on the developing pupa. A mated female mite enters the cell a few hours before capping and she and her incestuously mated daughters are released when the bee emerges.

The longer pupal development takes, the more progeny mites are produced, so Varroa has evolved to preferentially infest drone brood.

A smorgasbord of viruses

As an ectoparasite of honey bees, Varroa is responsible for the transmission of a smorgasbord of pathogenic viruses to the developing pupa. Subsequent virus replication, particularly by the aptly-named deformed wing virus, can result in developmental deformities.

Worker bee with DWV symptoms

Worker bee with DWV symptoms

Emerging workers with deformities are rapidly ejected from the hive. Other infested workers, with high viral levels, have reduced longevity. This is probably what accounts for the majority of overwintering colony losses. It may also explain so-called ‘isolation starvation‘.

The ‘phoretic’ phase

Mites outside capped cells are termed ‘phoretic’ mites. Recent studies have indicated that these mites are feeding on the workers to which they are attached. The same studies have shaken the long-held assumption that Varroa feeds on haemolymph 1 by rather neatly demonstrating that it is the fat body tissue of the bee that is the plat du jour.

The duration of the ‘phoretic’ phase is dependent upon the state of the colony. Since it is defined as the phase in which mites are not associated with developing pupae, in a broodless colony all the mites are ‘phoretic’. Under these circumstances mites remain ‘phoretic’ until either brood is produced, or they fall (or are groomed) off and drop through the open mesh floor.

The duration of the ‘phoretic’ phase

In colonies with ample brood the ‘phoretic’ phase is, on average, 6 days in length. The range often quoted is 4 – 11 days. The absolute figure must depend upon a number of factors. These include the chance of a mite encountering a late-stage larva. This is presumably influenced by the amount of suitable-aged brood in the colony and – because there is a division of labour in the hive – the type of bee upon which the mite is riding around the colony on.

For the purpose of this post we’ll consider bees of three ages – newly emerged, nurse bees and foragers. Newly emerged bees (days 1-2 post emergence) clean cells and nurse bees (days 3-11) feed developing larvae. Older bees are involved in wax production (days 12-17) and foraging (>18 days until death).

Logic would dictate that mites would ‘choose’ 2 to associate with bees that bring them into contact with developing larvae of the right age to infest.

Do they?

Hanging around with nurses

Xie et al., (2016)3 assembled artificial colonies containing equal numbers of new bees, nurse bees and foragers, all suitably marked so their age was known. These colonies were provided with a queen, open brood and stores. At the start of the experiment the colonies had 1500 bees and low Varroa levels.

The scientists then introduced 200 ‘phoretic’ mites from another colony 4 and left the colonies for 48 hours. They then age-sorted the bees and harvested all the ‘phoretic’ mites by washing them off in alcohol.

'Phoretic' mites prefer nurse bees

‘Phoretic’ mites prefer nurse bees

On average, ~16% of the nurse bees had ‘phoretic’ mites attached. In contrast, only ~10% of the foragers and ~5% of the new bees had mites. These studies involved seven individual experiments, in two countries and two separate years, using a different source colony for the mites. The statistics are significant.

So mites prefer nurse bees.

Is this ‘simply’ 5 because the nurse bees are more likely to bring the mite into close proximity with a suitably-aged larvae?

Or does associating with, and presumably feeding on, nurse bees have other benefits for the mite?

Mite fecundity and fitness

Fecundity is the reproductive productiveness 6 of an organism.

We’ve obliquely tackled this subject recently. Using an in vitro artificial ‘feed packet’ system, Ramsey and colleagues demonstrated that mites fed on the fat body of bees laid more eggs i.e. they had higher fecundity.

Xie et al., also tested fecundity of ‘phoretic’ mites from newly emerged bees, nurse bees and foragers. They did this by manually harvesting mites after a 3 day ‘phoretic’ phase, adding them to a pre-pupa and then counting the number of progeny female mites 9 days later.

Mite fecundity and fitness

Mite fecundity and fitness

‘Phoretic’ mites from nurse bees exhibited higher fecundity (more female offspring), higher fitness (more mature female offspring) and lower infertility (female mites that did not generate offspring).

So evolution has elegantly resulted in ‘phoretic’ mites associating with the right type of bee to bring them close to developing larvae (upon which they reproduce) and made them better able to reproduce once they get there.

Why do Varroa mites prefer nurse bees?

This is the title of the Xie et al., paper.

Xie et al., sort of answer the question they posed in the title. What they don’t do is explain why ‘phoretic’ mites on nurse bees are more fecund. However, the recent Ramsey paper suggests that this may be because nurse bees have a larger fat body and higher levels of vitellogenin.

If they’re better fed perhaps they produce more viable offspring? 7.

Another known unknown (semiochemicals)

How do mites detect the differences between new, nurse and older bees?

Perhaps they ‘smell’ different?

Mites preferentially infest drone brood because it produces a range of methyl and ethyl esters of straight-chain fatty acids, in particular methyl palmitate.

Similarly, the preference for nurse bees might be explained by their production of another semiochemicals 8. If we could identify this semiochemical it might be possible to create a ‘sponge’ soaked in it that attracted all the mites in the colony.

A bit simplistic, but you get the idea.

In reality, it’s likely that nurse bees are identified by the relative strengths of a range of semiochemicals produced by bees of different ages.

In reality it’s also likely that dropping a ‘sponge’ soaked in eau de nurse bee into the colony could unbalance all sorts of other events in the hive … 🙁

I told you it wasn’t simple.


Rattus norvegicus

Rattus norvegicus

Hanging Around is the fifth track on Rattus norvegicus, the 1977 debut album of one of the finest rock/punk bands of all time, The Stranglers. The album also includes the incomparable Peaches and (Get a) Grip (On yourself), both of which were released as singles.

No more heroes from the same year, but a different album, is also a classic by the same band.

You had to be there … I was 😉

 

 

Winter chores

After two weeks of mites, their diets and pedantry we’ll take a break this week for some practical beekeeping.

Or at least as close as you can get to practical beekeeping when it’s been as cold as -8°C.

Midwinter is a time to prepare for the season ahead, to stock up on new equipment during the winter sales, build more frames, plan the strategy for swarm control and think about stock improvement.

And – if you’re anything like as disorganised as me – it’s also the time to tidy up after the season just finished.

Which is what we’ll deal with today.

Tidy the shed

The original research apiary and bee shed is now under an access road for a new school. Fortunately, we managed to rescue the shed which has now been re-assembled in the new apiary.

In the longer term these sheds could together accommodate at least a dozen full colonies. However, in the shorter term it has allowed me to rationalise the storage, giving much more space to work with the colonies in the larger shed.

Supers and brood in the storage shed have all been tidied (see below) and are in labelled stacks ready to use. The other side of the store contains stacks of floors, split boards, clearers and roofs.

It’ll get messier as the season progresses, but it’s a good start.

I also spent a couple of weekends making some minor improvements to the bee shed following the experience last season.

The lighting has been increased and repositioned so it is ‘over the shoulder’ when doing inspections. On a dull winter day it is dazzlingly bright 1 but I fear it will still not be enough. I’m looking at creating some reflectors to direct the light better.

I’ve also used a few tubes of exterior sealant to block up all the holes and cracks around the edge of the shed roof. Last season was a bad one for wasps and we were plagued with the little stripy blighters.

Tidy the frames

Two of the most valuable resources a beekeeper has are drawn super frames and capped stores in brood frames.

Look after them!

I often end up uniting colonies late in the season, but then overwinter the bees in a single brood box. This means I can end up with spare frames of sealed stores. These should be protected from wax moth and mice (or anything else) as they are really useful the following year for boosting colonies that are light on stores or making up nucs.

Drawn supers can be used time and time again, year after year. They also need to be protected but – if your extraction is as chaotic as mine – they also usually need to be tidied up so they are ready for the following season.

I load my extractor to balance it properly, rather than just super by super. Inevitably this means the extracted frames are all mixed up. Since frames are also often drawn out unevenly this leaves me with a 250 piece jigsaw with billions of possible permutations, but only a few correct solutions.

Little and large - untidy frames and a breadknife

Little and large – untidy frames and a breadknife

And that’s ignoring all the frames with brace comb that accumulate during a good flow.

So, in midwinter I tidy up all the cleared super frames, levelling off the worst of the waviness with a sharp breadknife, removing the brace comb, scraping down the top bar and arranging them – 9 to 11 at a time 2 – in supers stored neatly in covered stacks.

And, if you’ve got a lot, label them so you know what’s where.

An hour or two of work on a dingy midwinter day can help avoid those irritating moments when – in the middle of a strong flow – you grab a super to find it contains just five ill-fitting frames, one of which has a broken lug.

The wax removed during this tidying up is usually lovely and white. Save it for making soaps, cosmetics or top-quality candles.

Wax extraction

Brood comb has a finite life. After about three years of repeated brood rearing cycles it should be replaced. Old comb contains relatively little wax but what’s there can be recovered using a solar or steam wax extractor. This also allows the cleaned frames to be re-used.

Processing a few dozen brood frames with a solar wax extractor during a Scottish winter is an exercise in futility. For years I’ve used a DIY steam wax extractor which worked pretty well but was starting to fall apart. I therefore recently took advantage of the winter sales and purchased a Thorne’s Easi-steam 3.

The Easi-steam works well and with a little further processing generates a few kilograms of wax for making firelighters or trading in … and a large stack of frames for re-use.

Remember to keep a few old dark brood frames aside for using in bait hives

Keep an eye on your bees

In between all these winter chores don’t forget to check on your bees.

There’s not a lot to do, but these checks are important.

Make sure the entrances are clear, that the mouse guards 4 are in place and that the roofs are secure.

Storm Eric brought us 50-60 mph winds and a couple of my hives lost their roofs. These had survived a couple of previous storms, but the wind was from a different direction and lifted the roofs and the bricks stacked on top. I got to them the following day but we’ll have to wait until the season warms up to determine if there’s any harm done.

Fondant top up

Fondant top up

Finally, as the days lengthen and it gets marginally warmer colonies should have started rearing brood again. Make sure they have sufficient stores by regularly ‘hefting‘ the hive. If stores are low, top them up with a block or two of fondant. This should be placed directly over the cluster, either over a hole in the crownboard or on the top bars of the frames.


 

Pedantically not phoresy

The life cycle of the ectoparasitic mite Varroa destructor essentially consists of two stages. The first is within the capped cell, where reproduction takes place. The second occurs outside the capped cell when the recently-mated female progeny mites matures while riding around the colony attached to a nurse bee.

Almost without exception this second stage is termed the phoretic phase.

It isn’t.

Phoresy

Phoretic is an adjective of the word phoresy. Phoresy is derived from the French phorésie which, in turn, has its etymological origins in the Ancient Greek word φορησις.

And φορησις means being carried.

Which partly explains why the correct definition of the word phoresy is:

An association between two organisms in which one is carried on the body of the other, without being a parasite [OED]

Phoresy has been in use for about a century, with the word phoretic first being recorded in the Annals of the Entomological Society of America (25:79) in 1932:

It is possible, as suggested by Banks (1915), that such young mites are phoretic, being carried about from place to place on the host’s surfaces.

And, no, they weren’t discussing Varroa.

“Without being a parasite”

These are the critical words in the dictionary definition of phoresy which makes the use of the word phoretic incorrect when referring to mites on nurse bees.

Because mites on nurse bees are feeding – or at least a significant proportion 1 of them are.

They are therefore being parasitic and so shouldn’t be described as phoretic.

Om, nom, nom 2

Last week I discussed the recent Samual Ramsey paper presenting studies supporting the feasting of Varroa on the fat body of bees.

In the study they harvested bees from a heavily mite-infested hive and recorded the location on the bee to which the mite was attached.

The majority were attached to the left underside of the abdomen. More specifically, the mite was wedged underneath the third abdominal tergite 3.

What were they doing there? Hiding?

Yes … but let’s have a closer look.

Ramsey and colleagues removed some of the mites and used a scanning electron microscope to examine the attachment point on the bee. Underneath the tergite there is a soft membrane. The imprint of the body of the mite was clearly visible on the membrane.

Varroa feeding location on adult bee

Scanning EM of Varroa feeding location on adult bee

The footpads of the mite were left attached to the membrane (left image, white arrows), straddling an obvious wound where the mouthparts had pierced the membrane (black arrow). Between them, the inverted W shape is presumably the imprint of the lower carapace of the mite.

The close-up image on the right even shows grooves at the wound site consistent with the mouthparts of the mite.

These mites were feeding.

Extraoral digestion

Varroa belongs to the order (a level of classification) Mesostigmata. Most mesostigmatids feed using a process termed extraoral digestion.

Extraoral digestion has also been termed ‘solid-to-liquid’ feeding. It involves the injection of potent hydrolytic enzymes which digest solid tissue, converting it to a semi-solid that can be easily ingested. It can reduce the time needed to feed and it increases the nutrient density of the consumed food.

If Varroa fed on haemolymph it wouldn’t need to use extraoral digestion. Instead it would need all sorts of adaptations to a high volume, low nutrient diet. Varroa doesn’t have these. It has a simple tube-like gut parts of which lack enzymatic activity … implying that digestion occurs elsewhere.

A picture is worth a thousand words

Do the images of feeding mites support the use of extraoral digestion?

EM cross-section of Varroa feeding

EM cross-section of Varroa feeding

The image above 4 shows the cross-section of a Varroa (V), wedged under the tergite (Te), feeding through a hole (arrow in the enlargement on the right) in the membrane (M). The fat body (FB) is immediately underneath the membrane. The scale bar is incorrectly labelled 5.

A close-up of the wound site shows further evidence for extraoral digestion.

Feeding wound at higher magnification

Feeding wound at higher magnification

Beneath the wound site (C, arrow) are remnants of fat body cells (white arrow) and bacteria (black arrow; of two types, shown in D). A closer look still at the remnants of the fat body (E and F) shows cell nuclear debris (blue arrows) and lipid droplets (red arrows).

These images are entirely consistent with extraoral digestion of fat body tissue by feeding Varroa. The presence of bacteria near the wound suggests that bacterial infection may result from Varroa feeding, possibly further contributing to disease in bees.

So, pedantically it’s not phoresy

So-called phoretic mites, unless they’re on the thorax or head of the bee, are not really phoretic. They are being carried about, but they are also likely feeding. By definition that excludes them from being phoretic.

Instead they are ectoparasites of adult bees.

What are the chances that beekeepers will stop using the term phoretic?

Slim to none I’d predict 6.

And, of course, it doesn’t really matter what the correct term for them is.

What’s more important is that beekeepers remember that it’s at this stage that mites are susceptible to all miticides.

The June gap

But it’s also worth thinking about the potential impact of brood breaks.

During brood breaks all the mites in the colony must be ‘phoretic’.

Generally, the majority of the mites in a hive are in capped cells. Depending upon the stage of the season, the egg-laying rate of the queen and other factors, up to 90% of the mites are associated with developing pupae.

But as the laying rate dwindles more and more mites are released from cells and become ‘phoretic’, unable to find a suitable late-stage larva to infest.

And which bees do the mites associate with?

Nurse bees primarily, for reasons I’ll discuss in the future. But – spoiler alert – one of the reasons is likely to be that they have a larger fat body.

So, a mid-season brood break (e.g. the ‘June gap’) is likely to result in lots more nurse bees becoming both the carriers and the dinner of the mite population.

Some or many of the nurse bee cohort may perish, perhaps from damage to the fat body or from the viruses acquired from the mite. However, bees exhibit phenotypic plasticity, meaning that older bees can revert to being nurse bees when the queen starts laying again.

Late season brood breaks

In late summer mite levels are usually at their highest in the hive. A brood break occurring now will release a very large number of mites to parasitise the adult bee population.

Presumably these mites select the bees best able to support them 7.

And which bees are these? The nurse bees of course. But it’s also worth remembering that there are key physiological similarities between nurse bees and winter bees. Both have low levels of juvenile hormone and high levels of vitellogenin (stored in the fat body).

So I’d bet that the ‘phoretic’ mites during a late season brood break would also preferentially associate with any early-produced winter bees.

Furthermore, once the queen starts laying again – perhaps in early/mid-autumn – the winter bees being produced would be subjected to the double-whammy of high levels of mite infestation and potential damage from ‘phoretic’ mites.

Practical considerations

More work is required to model or actually measure the impact of late season brood breaks, high levels of ‘phoretic’ mites, nurse bee numbers and winter bee development.

Compare two colonies of a similar size with a similar mite load, treated at the same time in early autumn with an appropriate miticide. If one of them experienced a late summer brood break (pre-treatment) and consequent high levels of ‘phoretic’ mites, does this reduce the chances of the colony surviving overwinter?

Who knows? Lots and lots of variables …

Fundamentally, it remains important to treat colonies early enough to protect the winter bee population. You’ve heard this from me before and you’ll hear it again.

However, it’s something to think about and I can see ways in which it might influence the strategy and timing of mite control used. I’ll return to this sometime in the future.