Frequently asked questions

The 2020/21 winter has been very busy with online talks to beekeeping associations. I’m averaging about five a month, with only the fortnight over Christmas and New Year being a bit quieter. 

When chatting to the organisers of these talks it’s clear that they are getting increasingly successful 1. Audience numbers are encouragingly high as people become more familiar with online presentations.

Beekeepers know they can lounge around in their pyjamas drinking wine, chat with their friends before and after the talk 2, and listen to a beekeeping presentation … a sort of lockdown multitasking.

Some of you that spend hours each day on Zoom will know exactly what I’m talking about 😉

I still lament the absence of homemade cakes, but I suspect the online format is here to stay. At least for some associations, or at least some of the winter programme each year. 

Talking to myself

There’s little point in doing science unless you tell others about it and, as as a scientist, I have presented at invited seminars and conferences for my entire career. 

Some readers will be familiar with public speaking in one form or another. They’ll be familiar with the frisson of excitement that precedes stepping up to the podium in a large auditorium. 

Assuming there’s a large audience filling the large auditorium of course 😉

Those with little experience of speaking might wish the audience was a bit smaller, or a lot smaller … or not there at all.

But the reality is that the audience is a really important part of a presentation. At least, they are once the speaker has sufficient confidence to calm down, to stop worrying they’ll say something stupid, and to ‘read’ the audience. 

An attentive beekeeping audience

By observing the audience the speaker can determine whether they’re still interested and attentive. Not just in the topic (after all, they’re sitting there rather than disappearing to the coffee shop), but in particular parts of the presentation. 

Are you going too fast?

Have you lost their attention?

Was that fancy animated slide you spent 20 minutes on a dismal failure?

Did that last witty aside work … or did it crash and burn? 3

Almost none of which can be determined when delivering a Zoom-type online presentation 🙁

You can ‘see’ the audience.

Or parts of it.

Postage stamp-sized headshots, with poor lighting, distracting backgrounds 4 and enough pixelation to make nuanced judgements about boredom or even species sometimes tricky.

Is that a Labradoodle in the audience … or just another lockdown haircut?

Has the internet frozen … or has everyone simply fallen asleep?

It’s not ideal, but it’s the best we’ve got for now.

Which makes the question and answer sessions even more important than usual.

Mixed abilities

My talks usually include a 5 minute intermission. Talking for an hour uninterrupted is actually quite tiring 5 and it’s good to make a cup of tea and gather my thoughts for ’round two’.

It also allows the audience to raise questions about subjects mentioned in the first half that left them confused.

Fortunately these ‘half time’ questions tend to be reassuringly limited in number 6.

Have a break, have a Kit Kat

However, at the end of the talk there is usually a much more extensive Q&A session. This often covers both the topic of the talk and other beekeeping issues. 

A typical audience contains beekeepers with a wide range of beekeeping experience. Enthusiastic beginners 7 jostle for screen space with ‘been there, done that, bought the T-shirt’ types who have forgotten more than I’ll ever know.

Inevitably this means the talk might miss critical explanations for beginners and omit some of the nuanced details appreciated by the more experienced. As the poet John Lydgate said:

You can please some of the people all of the time, you can please all of the people some of the time, but you can’t please all of the people all of the time 8.

Think about this simple statement:

Varroa feed on the haemolymph of developing pupae.”

The beginner might not know what haemolymph is … or, possibly, even what Varroa is.

The intermediate beekeeper might be left wondering whether the mite also feeds on nurse bees when ‘crowdsurfing’ around the colony during the phoretic stage of the life cycle.

And the experienced beekeeper is questioning whether I know anything about the subject at all as I’ve not mentioned fat bodies and their apparently critical role in mite nourishment.

So I encourage questions … to help please a few more of the people 😉

You’re on mute!

In my experience these are best submitted via the ‘chat’ function. The host – an officer of the BKA or a technically-savvy member press ganged into hosting the talk – can then read them out to me.

Or I can … if I can find my glasses.

One or two beekeeping associations have a Zoom ‘add in’ that allows the audience to ‘upvote’ written questions, so that the most popular appear at the top of the list 9. This works really well and helps ‘please more of the people more of the time’.

The alternative, of asking the audience member to unmute their mic and ask the question is somewhat less satisfactory. It’s not unusual to watch someone wordlessly ‘mouthing’ the question while the host (or I) try and explain how to turn the microphone on.

Finally, it’s worth emphasising that the Q&A session is – as far as I’m concerned – one of the most helpful and enjoyable parts of the evening.

Enjoyable, because I’m directly answering a question that was presumably asked because someone wanted or needed to know the answer 10

Helpful, because over time these will drive the evolution of the talk so that it better explains things for more of the audience.

Anyway – that was a longer introduction than I intended – what sort of questions have been asked frequently this winter (and the talks they usually appeared in).

What do you define as a strong colony? (Preparing for winter)

Strong colonies overwinter better than weak colonies. They contain more bees. This means that the natural attrition rate of bees during the winter shouldn’t reduce the colony size so much that it struggles to thermoregulate the cluster

Midwinter cluster

A strong colony in midwinter

I also think large winter clusters retain better ‘contact’ with their stores, so reducing the chances of overwinter isolation starvation.

Strong colonies are also likely to be healthy colonies. Since the major cause of overwintering colony losses is Varroa and the viruses it transmits, a strong healthy colony should overwinter better than a weak unhealthy colony. 

Colony age structure from August to December.

However, you cannot necessarily judge the strength of a colony in June/July as an indicator of colony strength in the late autumn and winter.

This is because the entire population of bees has turned over during that period. 

A hive bulging with bees in summer might look severely depleted by November if the mite levels have not been controlled in the intervening period.

The phrase ‘a strong colony’ is also relative … and influenced by the strain of bees. Native black bees rarely need more than a single brood box. Compare them to a prolific carniolan strain and they’re likely to look ‘weak’, but if they’re filling the single brood box then they’re doing just fine.

When should I do X? (Rational Varroa control and others)

When usually means ‘what date?’

X can be anything … adding Apivar strips, uniting colonies, adding supers, dribbling oxalic acid.

This is one of the least satisfactory questions to answer but the most important beekeeping lesson to learn.

A calendar is essentially irrelevant in beekeeping.

Due to geographic/climatic differences and variation in the weather from year to year, there’s almost nothing that can be planned using a calendar.

Only three things matter, the:

  1. state of the colony
  2. local environment – an early spring, a strong nectar flow, late season forage etc.
  3. development cycle of queens, workers and drones

By judging the first of these, with knowledge of the second and a good appreciation of the third, you can usually work out whether treatments are needed, colonies united or supers added etc.

This isn’t easy, but it’s well worth investing time and effort in.

Honey bee development

Honey bee development

The last of these three things is particularly important during swarm control and when trying to judge whether (or when) a colony will be broodless or not. The development cycle of bees is effectively invariant 11, so understanding this allows you to make all sorts of judgements about when to do things. 

For example, knowing the numbers of days a developing worker is an egg, larva and pupa allows you to determine whether the colony is building up (more eggs being laid than pupae emerging) or winding down for autumn (or due to lack of forage or a failing queen).

Likewise, understanding queen cell development means you know the day she will emerge, from which you can predict (with a little bit of weather-awareness) when she will mate and start laying.

How frequently should you monitor Varroa? (Rational Varroa control)

This question regularly occurs after discussion of problematically high Varroa loads, particularly when considering whether midseason mite treatment is needed. 

Do you need to formally count the mite dropped between every visit to the apiary?

Absolutely not.

If you are the sort that does then be aware it’s taking valuable time away from your trainspotting 😉 12

The phoretic mite drop is no more than a guide to the Varroa load in the hive. 

Think about the things that could influence it:

  • A colony trapped in the hive by bad weather has probably got more time to groom, so resulting in an increased mite drop.
  • An expanding colony has excess late stage larvae so reducing the time mites spend living phoretically.
  • A shrinking colony will have fewer young bees, so forcing mites to parasitise older workers. Some of these will lost ‘in the field’ and more may be lost through grooming.
  • Strong colonies could have a much lower percentage infestation, but a higher mite drop than an infested weak colony. You need to act on the latter but perhaps not the former.
  • And a multitude of other things that really deserve a more complete post …

So don’t bother counting Varroa every week … or even every month.

Does what it says on the tin.

I think checking a couple of times a season – towards the end of spring and in mid/late summer – should be sufficient. You can do this by inserting a Varroa tray for a week, by uncapping drone brood and looking for mites, or by doing an alcohol wash on a cupful of workers (but these methods aren’t comparable with each other as they measure different things with different efficiencies). 

But you must also look for the damaging effects of Varroa and viruses at every inspection.

If there are significant numbers of bees with deformed wings – characteristic of high levels of deformed wing virus (DWV) – then intervention will probably be needed. 

DWV symptoms

DWV symptoms

And if there are increasing numbers of afflicted bees since your last regular inspection it’s almost certain that intervention will be needed sooner rather than later.

I should add that I also count mite drop during treatment. This helps me understand the overall mite load in the colony. By reference to the late summer count I can be sure that the treatment worked. 

What do you mean by a quarantine apiary? (Bait hives for profit and pleasure)

This question has popped up a few times when I discuss moving an occupied bait hive and checking the health of the colony. 

A swarm that moves into a bait hive brings lots of things with it …

Up to 40% by weight is honey which is very welcome as they will use it to draw new comb. If there’s good forage available as well it’s unlikely the swarm will need additional feeding.

However, the swarm also brings with it ~35% of the mites that were present in the colony that swarmed. These are less welcome.

I always treat swarms with oxalic acid to give them the best possible start in their new home.

Varroa treatment of a new swarm in a bait hive…

More worrisome is the potential presence of either American or European foul broods. Both can be spread with swarms. The last things you want is to introduce these brood diseases into your main apiary.

For this reason it is important to isolate swarms of unknown provenance. The logical way to do this is to re-site the occupied bait hive to a quarantine apiary some distance away from other bees. Leave it there for 1-2 brood cycles and observe the health and quality of the bees.

What is ‘some distance?’

Ideally further than bees routinely forage, drift or rob. Realistically this is unlikely to be achievable in many parts of the country. However, even a few hundred yards away is better than sharing the same hive stand. 

If you keep bees in areas where foul broods are prevalent then I would argue that this type of precautionary measure is essential … or that the risk of collecting swarms is too great.

And how do you know if foul broods are prevalent in your area?

Register with the National Bee Unit’s Beebase. If there is an outbreak near your apiary a bee inspector will contact you.

Remember also that the presence of foul broods in an area may mean that the movement of colonies is prohibited.

‘Asking for a friend’ type questions

These are great.

These are the sort of questions that all beekeepers are likely to need to ask at sometime in their beekeeping ‘career’.

Typically they take the form of two parts:

  1. a description of a gross beekeeping error
  2. an attempt to make it clear that the error was by someone (anyone) other than the person asking the question 😉

Here are a couple of more or less typical ones 13.

  • My friend (who isn’t here tonight) forgot to remove the queen excluder and three full supers from their colony in August. Should I, oops, she remove them now?
  • Here’s an an entirely hypothetical scenario … what would you recommend treating a colony with in March if the autumn and midwinter mite treatments were overlooked?
  • Should my friend remove the Apiguard trays he a) added in November, or b) placed in his colonies before taking them to the heather?
  • I’d been advised by an expert beekeeper to squish every queen cell a few days after discovering my colony had swarmed in June. It’s now late September … how much longer should I wait for the colony to be queenright?

These are very good questions because they illustrate the sorts of mistakes that many beginners, and some more experienced beekeepers, make. 

There’s absolutely nothing wrong with making mistakes. The problem comes if you don’t learn from them.

I’ve made some cataclysmically stupid beekeeping errors. 

I still do … though fewer now than a decade ago, largely because I’ve managed to learn from some of them.

Partly I learned from thinking things through and partly from asking someone else … “A friend has asked me why his colony died. Was it the piezoelectric vibrations from the mite ‘zapper’ bought from eBay or was the hive he bought not suitable?


 

In the bleak midwinter

Winter has finally arrived.

Green thoughts in a white shade

We’ve had temperatures fluctuating around 0°C for the last two to three weeks now, with some very hard frosts and more than enough snow to make the track impassable.

Like the bees, I’ve spent the time hunkered down focusing on keeping warm and conserving my stores.

Unlike my bees, I’ve benefited from triple glazing and a wood burning stove 😉

And the main thing I’m worried about running out of is milk for my cappuccino 1.

The 20th was particularly cold with temperatures well below -5°C and stunningly clear. There was something strange about the conditions, as the loch froze. The surface, for 30 metres or more from the shore, had a thin film of ice covering it.

Ice, ice baby

As the tide dropped the shore was left with a sparkling crust of 1mm thick glass-like ice confetti.

The salinity of seawater is typically ~3.5% … this amount of salt reduces the freezing point to about -2°C, a temperature we’ve regularly experienced in the last fortnight. This suggests the ‘strange’ conditions were probably the absence of any swell coupled with the really calm conditions.

Whatever the cause, it was beautiful.

Early season forage … you must be joking 😉

Under conditions like these the bees are effectively invisible. They’re very tightly clustered . With daytime temperatures rarely reaching 3°C none venture out of the hive. With the exception of cleansing flights and the removal of corpses – and it’s too cold for either of these – there’s little reason for them to leave the hive anyway.

The gorse is in flower … somewhere under there

The only thing flowering is gorse and it would be a foolhardy bee that attempted to collect pollen at the moment.

I’ve previously written about the genetically-determined flowering time of gorse. In an attempt to improve forage at certain times of the year I’ve been collecting seed from suitable plants and germinating it indoors. As soon as the weather improves I’ll plant these seedlings out 2 as the amount of gorse around the apiary is quite limited.

Gorse (and some broom) seedlings

Gorse seed is painful to collect and germinates poorly. I pour boiling water over the seed and then let it soak for 24 hours, which improves germination at least ten-fold.

Hive checks

Every fortnight or so I check the hive weights by hefting. Only two colonies have had any extra fondant yet and that was through ‘an abundance of caution’. I suspect they actually didn’t really need it.

The next eight weeks (here 3 ) is when brood rearing should be starting to really ramp up. It’s during February and March that starvation is an issue.

Here on the west coast, my colonies are rearing brood. This tray has been in for about a week. I’m including it as I’ve been asked several times about how to determine if a colony is rearing brood without opening the hive.

Biscuit coloured (or a bit darker) cappings indicating brood rearing in this colony

The red arrows indicate the biscuit coloured cappings that have fallen from the seams in which they are rearing brood. The inset shows a magnification of the indicated part of the image. The photo was taken with a camera phone and the cappings are perhaps a bit darker than usual (though I also know there are a few older brood frames in this hive 🙁 ).

And if the conditions are right, even with a well-insulated poly hive, you can identify which wall the cluster is up against by the evaporation of the overnight damp from the outer surface of the hive.

The location of the cluster is clearly visible on this Abelo poly hive

This is the front of the same hive from which the Varroa tray was photographed – the cappings on the tray and the cluster location correspond perfectly.

By the way … don’t bother looking for Varroa on the tray. This hive is in a Varroa-free region 🙂

As I’ve said before, it’s not unusual for colonies in poly hives to cluster tightly against the wall in winter. Those in cedar are more often away from the wall in my experience (and the same thing applies to brood rearing other than at the height of the season).

Hey good lookin’

The Abelo hive above is a nice looking box. The paint finish is bonded well to the polystyrene and provides good protection.

If you leave unpainted polystyrene out in the elements it starts to look pretty tired, pretty quickly.

I don’t have any pictures as none of my poly hives are unpainted.

At least, none are any more 😉

I’d acquired some new Maisemores nucs with bees and had a number of unused and unpainted Everynucs. Most manufacturers recommend you paint poly hives with masonry paint of some kind, or they sell (often quite pricey) paint that’s suitable.

Here's three I prepared earlier ...

Everynuc poly nucs

I’ve painted a lot of nucs with masonry paint, using a paint spray gun. It goes on fast and is reasonably hardwearing … but not great.

Swienty brood box ...

Swienty brood box …

In contrast, my Swienty brood boxes look as good now as when they were first painted 5 years ago. These received two coats of ‘Buckingham green’ Hammerite Garage Door paint.

This paint is designed for galvanised metal garage doors (the clue is in the name 😉 ). It contains a bunch of unpleasant sounding solvents but, when dry, appears to be entirely safe. I’d recommend not reading the 13 pages of safety data sheets or you might never dare open the tin because of the imminent risk of explosion.

Melting polystyrene

These solvents have the effect of slightly ‘melting’ the surface of the poly hive. This creates a really strong bond between the paint and the hive surface. The melting isn’t enough that you can notice the surface texture change … it’s just an invisible chemical reaction going on as you brush the stuff on.

Maisemore’s poly nuc after the first coat

However, this reaction might account for the rather patchy coverage of a single coat. If you paint it on thickly enough to try and produce a nice even finish it tends to run and sag a bit.

So give it two coats … and then it looks excellent.

Oxbridge Blues – a few painted poly nucs ready for the season ahead

Several months ago I bought a ‘remaindered’ tin of Hammerite paint in Oxford blue. I had wanted a contrasting colour (to my other boxes) for these nucs to help orientate returning freshly mated queens.

I paint the entire box, avoiding any of the ‘touching’ faces which are left unpainted. Some paint usually seeps into joins between the roof, body and/or floor, but you can easily prise them apart with a judiciously applied hive tool.

I’m rather pleased with how smart they now look.

I’m somewhat less pleased with the quality control on some of the Everynucs 4. Several had the mesh floor stuck down incorrectly, with parts unattached. In places the gaps were big enough for a bee to enter.

Open mesh floor and big gap at the side in an Everynuc

I simply pulled them off and restuck them down with a glue gun. This is an easy fix but really should not be necessary on a nuc box that costs almost £60 🙁

A+E

With the current Covid pandemic we have a responsibility to minimise the demands we are placing on our heroically overstretched healthcare workers.

For this reason I’ve been avoiding doing any DIY for beekeeping for many months now 😉

However, the season is looming ever-closer and I want to try some new things.

My toolbox contains approximately equal amounts of disconcertingly sharp implements and elastoplast. I’m well prepared 😉

I’m also currently living very remotely. In the event of a bad injury I’m unlikely to ever trouble the staff in A+E … unless the accident conveniently coincides with the ferry timetable 🙁

I therefore decided to risk life and limb by building the things I need to try queen rearing using a Morris board.

I’ll describe full details of the method later in the year.

For me, this method should offer advantages due to the type of bees, the size of my colonies, the number of queens I want to rear and the period over which I want to rear them.

You can buy these boards (for about £30 each) … or you can build better ones for about a fiver from offcuts from the wood bin, a bit of queen excluder and a piece of aluminium. They are a bit fiddly to build, with four opening doors and a ‘queenproof’ slide, but the cost savings and satisfaction you gain more than outweigh the blood loss involved.

Here’s one I started earlier … a Morris board under construction

The very fact I’m still able to write this post shows that I managed to retain all my fingers. Whether or not the Morris board works 5 I consider that fact alone a success 🙂

Doing the splits

The Morris board works by allowing access to 5 frame upper brood box for defined periods. I therefore also needed a brood box divided in half.

I’ve been doing a lot of wax extracting recently and a couple of cedar boxes have cracked under the stress of repeated steam cycles. I split one down to its component boards, burning the bits that were unusable, but recycling one side into the central division of another old cedar box.

Split brood box – detailed view of my very poor workmanship

I’ll be queen rearing in two apiaries simultaneously, so will need two of these upper boxes. However, I only managed to salvage one sufficiently large board from the steam-damaged box.  Fortunately I have some cedar nucs built precisely (so clearly not by me 😉 6 ) to National hive dimensions, so I can use two of these side-by-side with the same design Morris board.

Late afternoon sun, 24th January

But queen rearing remains both a distant memory and a very long way off in the future. Until then it’s a case of enjoying the short winter days and drinking cappuccino in front of the fire.

Good times


Notes

Hammerite Garage Door paint is usually £15-20 a tin (750 ml). It’s worth shopping around as there’s quite a bit of variation. I found it remaindered and paid under a tenner 🙂

I reckon there’s enough in one tin to do two coats on 9-10 nucs as long as you take care not to over apply the first one. You could probably thin it a bit (though I’m not sure what with 7) but I’d take care you don’t create something that just melts the poly box.

Even at £20 it still works out at only about £2 a nuc. Considering these can cost £40-60 it seems like a reasonable investment of money to keep them looking smart for years.

And a good investment of time (it took me ~15-20 minutes per coat) … after all, what else are you going to do in the bleak midwinter?

Going the distance

I’m going to continue with a topic related to the waggle dance this week.

This is partly so I can write about the science of how bees measure distance to a food source.

But it’s also to encourage those who didn’t read the waggle dance post to visit it. Weirdly it was only read by about 50% of the usual Friday/weekend readership and I suspect (from a couple of emails I received) that the weekly post to subscribers ended up in spam folders 1.

If you remember, the duration of the waggle phase of the dance – the straight-line abdomen-wiggling sashay across the ‘dance floor’ – indicates the distance from the nest to the desirable food source 2. The vigour of the wiggle indicates the quality of the source.

How do bees measure distance?

Karl von Frisch, the first to decode the waggle dance, favoured the so-called ‘energy hypothesis’. In this, the distance to a food source was determined by the amount of energy used on the outbound flight.

Does that seem logical?

Foragers forage randomly, but usually return directly

If correct, foragers would only be able to determine the energy used after their second trip to a food source. This presumes their first trip was longer as they searched the environment for something worth dancing about 3.

This would be an easy thing to test, though I’m not sure it was ever investigated 4.

As it happens, far better brains determined that the energy hypothesis was probably incorrect. Many of these studies explored how gravity influences the distances reported by dancing foragers.

Going up!

Bees use more energy when flying up. For example, when flying from ground level to the top of a tall building, when compared to level flight. Similarly, they use more energy flying if they have small weights attached to them 5.

A series of experiments, nicely reviewed by Harald Esch and John Burns 6, failed to provide good support for the energy hypothesis. There were lots of these studies, involving steep mountains, tall buildings or balloons, between the 1950’s and mid-80’s.

Interesting science, and no doubt it was a lot of fun doing the experiments.

For example, bees flying to a sugar feeder situated on top of a tall building dance to ‘report’ the same distance as bees from the same hive flying to a feeder at ground level adjacent to the same building.

Similarly, foragers loaded with weights do not overestimate the distance to a food source, as would be expected if the energy expended to reach it was being measured 7.

Interesting and entertaining science certainly, but none of it providing compelling support for the energy hypothesis

It’s notable that there is a rather telling sentence from the Esch & Burns review that states “While reading the original papers, one gains the impression that evidence supporting the energy hypothesis was favored over arguments against it”.

Ouch!

Splash landing

Although Von Frisch was a supporter of the energy hypothesis 8 he also published a study that provided evidence for our current understanding of how bees measure distance.

Bees generally don’t like flying long distances over water. Von Frisch provided two equidistant nectar sources, one of which was situated on the other side of a lake.

Bees flying over calm water underestimate distances

On very calm days the bees that flew across the lake under-reported the distance to the feeder. This underestimate was by 20-25% when compared to bees flying to an equidistant feeder overland.

Von Frisch commented “the bee’s estimation of distance is not determined through optical examination of the surface beneath her”.

He assumed that the mirror-like water surface provided no optical input as it contained no visual ‘clues’. After all, one calm patch of water looks much like any other. Von Frisch used this as an argument for the energy hypothesis.

He also noted that the bees generally flew very low over the water surface, often so low that they drowned 🙁

Perhaps these bees were flying dangerously low to try and find optical clues.

Such as their height above the surface?

Or perhaps the distance travelled?

Going with the flow

Having debunked the energy hypothesis, Esch & Burns proposed instead the optic flow hypothesis. This states that “foragers use the retinal image flow of ground motion to gauge feeder distance”.

Imagine optic flow as tripping a little odometer in the bee brain that records distance as her eyes observe the environment flashing past during flight. The clever thing about that is that the environment is variable. It’s not like counting off regularly spaced telegraph poles from a train window.

When flying, environmental objects that are nearby will move across her vision much faster than distant objects. Bees don’t have stereo vision, but instead use this speed of image motion to infer range.

Optic flow – the arrow size indicates the speed with which the object apparently moves, and hence its range

Esch & Burns returned again to tall buildings to provide supporting evidence for their optic flow hypothesis. They trained bees to fly between two tall buildings with 228 metres separating the hive and the feeder 9.

Returning foragers reported that the food source was only 125 metres away.

However, the bees didn’t make a direct flight. Instead they flew at altitude for 30-50 metres, descended to fly much lower, then ascended again to approach the feeder again at altitude.

Esch & Burns experiment to support the optic flow hypothesis

The interpretation here was that the high altitude flight provided insufficient optic flow to measure distance. The bees descend to get the visual input needed to judge distance, but it’s only for part of the flight … hence leading to under-reporting the distance separating the hive and feeder.

Tunnel vision

Jurgen Tautz 10 and colleagues trained bees to forage in a short, narrow tunnel 11. This elegant experiment provided compelling support for the optic flow hypothesis.

The tunnel was ~6 m long and with a cross sectional area of ~200 cm2 – big enough for a bee to fly along, but sufficiently narrow so that the bee would be closer to the ‘walls’ than in normal free flight. The walls and floor of the tunnel had a random visual texture. Only the end of the tunnel facing the hive was open.

The tunnel experiment.

These studies were conducted when the terms round and waggle were used to distinguish the dance induced by food sources <50 m and >50 m respectively from the hive 12. Rather than emphasise the shape of the dance I’ll just describe it as a >50 m or <50 m waggle dance.

‘Tunneling’ bees misreport distances

In the first tunnel experiment (1) the feeder was 35 m from the hive. 85% of dances indicated the feeder was <50 m away. However, when the feeder was moved to the opposite end of the tunnel (2) – still only 41 m from the hive – 90% of the dances indicated the feeder was >50 m away.

To test how the random pattern influenced the perceived distance the scientists used a third tunnel (3) lined with lengthwise stripes. In this instance – despite the feeder position being unchanged from experiment 2 – 90% of the dances indicated the feeder was <50 m away.

The stripes were predicted to ‘work’ in the same way as the smooth lake surface, providing no visual clues.

In the fourth experiment (4) the feeder was 6 m along a randomly patterned tunnel, which was placed just 6 m from the hive. Over 87% of dances indicated that the feeder was >50 m away.

Interpreting the waggle run

In open flight 13 there is usually an excellent correlation between the duration of the waggle run and the distance to a feeder (see the graph below 14 ). By extrapolation, the bees in experiments 2 and 4 ‘thought’ they had flown 230 m and 184 m respectively. In reality they had flown only 41 m and 12 m in these experiments.

Determining distances from waggle dance observation

How could the bees get it so wrong?

Increased optic flow

Tunnel-traversing bees fly just a few centimeters away from the visible ‘environment’.

As a consequence, at the same flight speed, they experience greater optic flow.

If, instead of driving around in your lumbering old van, you pack your hive tool in a Caterham 7 for the trip to the apiary you’d be well aware of what I mean.

Caterham 7 … check out that optic flow … then make another trip to collect the smoker

30 mph in a Toyota Hilux feels very much slower than 30 mph in a Caterham 7. This is largely because visual reference points, like the broken white lines between lanes in the road, appear in and disappear from your field of view much faster … because you’re much closer to them.

Because the tunnel dimensions were known it was possible to calculate the calibration of the bee’s odometer. Classically this would be defined in terms of metres of distance flown generating a particular waggle run length or duration.

These tunnel studies demonstrate that distance flown is not what calibrates the odometer. Instead it’s quantified indirectly in terms of the image motion experienced by the eye. Since environments vary the way to express this is the amount of angular image motion that generates a given duration of waggle.

And, using some mathematical trickery we don’t need to bother with 15, it turns out that this angular motion is only dependent upon distance flown, not the speed of flight.

This is important. Headwinds or tailwinds could change the speed of flight, but not the distance flown 16.

It’s all relative

It’s worth emphasising that the dance followers in experiments 2 (above) should still find the feeder.

The waggle dance would ‘instruct’ them to fly 230 m at the bearing indicated and they’d experience the same visual clues en route.

This means that they should still enter the narrow tunnel and experience increased optic flow because of the encroaching walls. But they’d be experiencing the same optic flow the initial dancing bee had experienced, so would not attempt to fly further down the tunnel.

This means that the optic flow experienced is context dependent. It is related to the environment the bees are foraging in.

This makes sense as the dancing bees and dance followers all occupy the same environment.

How do we know this? 17

Changing the environment

If we change the environment the dance followers search at the wrong distance.

I qualified the statement above when I said that the dance followers should still enter the tunnel and find the feeder.

Actually, most recruits will miss the tunnel entrance – remember it’s smaller that a sheet of A5 paper. At 35 m distance a bee would have to get the bearing correct to about 0.16° to enter the tunnel 18.

So the bees that do not enter the tunnel experience a different environment.

Where do they search for the feeder?

They search at the distance indicated by the waggle duration … so bees that missed the tunnel entrance in experiment 2 (above) would have searched for the feeder 230 m from the hive. Similarly, the dance followers in experiment 4 would have searched 184 m away 19

Context dependent dance calibration

And, finally, the calibration of the odometer depends upon the environment.

Odometer calibration depends upon the environment

If the environment experienced by the dancing bee en route to the feeder in experiments 2 and 4 is different, then it generates a different relationship between waggle run duration and distance.

For example, if one feeder was across a closely mown lawn and the other was across dense shrubby woodland, they would each generate a unique optic flow, so changing the image motion experienced, and hence the waggle run generated.

In the diagram above, you shouldn’t use dance calibration for bees trained to direction A to determine the distance bees going in direction B would forage.

Phew!

Optic flow, waggle dancing and implications for practical beekeeping

None 😉

At least, none that I can think of.

A Caterham 7 isn’t an ideal car for a beekeeper but would be a lot of fun to help you understand optic flow 😉

Most of us keep our bees in mixed environments. Your apiary isn’t situated with a cliff edge on one side and an unbroken prairie on the other. Since the environment is mixed, the waggle dance calibration is not going to be wildly different, whichever way the bees fly off in. You can therefore use an approximate figure of 1 second per kilometre to estimate the the distance at which your bees are foraging, irrespective of the direction they go.


Notes

Most of the referenced studies are at least two decades old. Honey bees have remained a fertile research tool for neurobiologists. Our understanding of honey bee vision continues to improve. However, I cannot discuss any of these more recent studies with reference to optic flow. Anyway, just because they’re old doesn’t make the experiments any less elegant or interesting 🙂

 

The waggle dance

Ask a non-beekeeper what they know about bees and you’ll probably get answers that involve honey or stings.

Press them a little bit more about what they know about other than honey and stings and some will mention the ‘waggle dance’. 

Karl von Frisch

That the waggle dance is such a well-known feature of honey bee biology is probably explained by two (related) things; it involves a relatively complex form of communication in a non-human animal, and because Karl von Frisch – the scientist who decoded the waggle dance – received the Nobel Prize 1 for his studies in 1973.

Von Frisch did not discover the waggle dance. Nicholas Unhoch described the dance at least a century before Von Frisch decoded the movement, and Ernst Spitzner – 35 years earlier still – observed dancing bees and suggested they were communicating odours of food resources available in the environment.

Inevitably, Aristotle also made a contribution. He described flower constancy 2 and suggested that foragers could communicate this to other bees.

Language and communication are important. The development of language in early humans almost certainly contributed to the evolution of our culture, society and technology. Communication in non-human animals, from the chirping of grasshoppers to the singing of whales, is of interest to scientists and non-scientists alike.

It is therefore unsurprising that the ‘dance language’ of honey bees is also of great interest. Although not a ‘language’ in the true sense of the word, Von Frisch described the symbolic language of bees as “the most astounding example of non-primate communication that we know” over 50 years ago. This still applies.

The waggle dance

The waggle dance usually takes place in the dark on the vertical face of a comb in the brood nest, usually close to the nest entrance. The dance is performed by a successful forager i.e. one that has located a good source of pollen, nectar or water, and provides information on the presence, the quality, identity, direction and distance of the source, so enabling nest-mates to find and exploit it.

The dance consists of two phases:

  1. The figure of eight-shaped ‘return phase’ in which the bee circles back, alternately clockwise and anticlockwise, to the start of …
  2. The ‘waggle phase’, which is a short linear run in which the dancer vigorously waggles her abdomen from side to side.

The direction of the food source is indicated by the angle of the waggle phase from gravity i.e. a vertical line down the face of the comb. This angle (α in the figure below) indicates the bearing from the direction of the sun that needs to be followed to reach the food source. 

For example, if the dancer performs a waggle phase vertically down the face of the comb, the food source must be opposite the current position of the sun.

The waggle dance

The distance information is conveyed by the duration of the waggle phase. The longer this run is, the more distant the source. A run of 1 second duration indicates the food source is about 1 kilometre away.

The quality of the food source is indicated by the vigour of the waggling during the waggle phase and the speed with which the return phase is conducted. 

Surely it can’t be that simple?

Yes, it can.

What I’ve described above allows you to interpret the waggle dance sufficiently well to know where your bees are foraging.

Next time you lift a frame from a hive and see a dancing bee, circling around in a little cleared ‘dance floor’ surrounded by a group of attentive workers, try and decode the dance.

Remember that the dance is performed with relation to gravity in the darkened hive. You’re looking to identify the angle from a vertical line up the face of the brood comb to determine the direction from the sun.

Time a few waggle phases (one elephant, two elephants etc.) and you’ll know how far away the food source is.

Really, it’s that simple?

Of course not 😉

The waggle dance was decoded more than half a century ago and remains an active subject for researchers interested in animal communication.

What you’ll miss in your observations is an indication of the type of nectar or pollen resource that the dancing bee is communicating. The dancing worker carries the odour of the food source and may also regurgitate nectar, presumably helping those ‘watching’ (remember, it’s dark … nothing to see here!) determine the type of resource to look for when they leave the hive.

You will also be unable to detect the pulsed thoracic vibrations that the dancing bee produces. These are also indicators of the quality of the food source; better (e.g. higher sucrose content) resources elicit increased pulse duration, velocity amplitude and duty cycle, though the number of pulses is related to the duration of the waggle phase, and so is another potential indicator of distance.

Inevitably, there are also pheromones involved.

There always are 😉

The dancing bee produces two alkanes, tricosane and pentacosane, and two alkenes, Z-(9)-tricosene and Z-(9)-pentacosene. These appear to stimulate foraging activity 3.

But it’s cloudy … or rain stops play … or nighttime

What happens to dancing bees if foraging is interrupted, for example by poor weather or night? 

The dancing bee continues to change the angle of the waggle phase as the sun moves across the sky. This means that a dancing bee will correctly signal the direction to the food source, even if they have not left the hive for several hours.

During their initial orientation flights they learn the sun’s azimuth as a function of the time of day, and use this to compensate for the sun’s time-dependent movement.

Some bees even dance during the night, in which case the watching workers must presumably make their own compensations for the time that has elapsed since the dance 4.

And what happens if the sun is obscured … by clouds, or buildings or dense woodland? How can those directions be followed?

Under these circumstances the foraging bee detects the position of the sun by the pattern of polarised light in the sky. 

Scout bees

The waggle dance is also performed by scout bees on the surface of a bivouacked swarm. In this instance it is used to communicate the quality, direction and distance of a new potential nest site. 

Swarm of bees

Swarm of bees

The intended audience in this instance are other scout bees, rather than the general forager population 5. These scouts use a quorum decision making process to determine the ‘best’ nest site in the area to which the bivouacked swarm eventually relocates.

The shape of the bivouac often lacks a true vertical surface. However, since it’s in the open the dancing bees can orientate the waggle run directly with relation to the sun’s direction, rather than to gravity.

Under experimental conditions the dancing bee can communicate the presence and quality of a food source on a horizontal comb, but – with no reference to gravity – all directional information is lost 6.

The round dance

The duration of the waggle phase is related to the distance from the nest to the food source. Therefore the recognisable waggle dance tends to get difficult to interpret for sources very close to the nest.

It used to be thought that there was a distinct directionless dance (the ’round dance’) for these nearby i.e. 10-40 metres, food sources. However, more recent study 7 suggests that dancers were able to convey both distance and direction information irrespective of the separation of nest and food source. This indicates that bees have just one type of dance for forager recruitment, the waggle dance.

Do all bees communicate using a waggle dance?

There are a very large number of bee species. In the UK alone there are 270 species, 250 of which are solitary.

There’s a clue.

Solitary bees are like me at a disco … they have no one to dance with 🙁

I’ll cut to the chase to help you erase that vision.

The only bees that use the waggle dance are honey bees. These all belong to the genus Apis.

They include our honey bee, the western honey bee (Apis mellifera), together with a further seven species:

  1. Black dwarf honey bee (Apis andreniformis)
  2. Red dwarf honey bee (Apis florea)
  3. Giant honey bee (Apis dorsata)
  4. Himalayan giant honey bee (Apis laboriosa
  5. Eastern honey bee (Apis cerana)
  6. Koschevnikov’s honey bee (Apis koschevnikovi)
  7. Philippine honey bee (Apis nigrocincta)

Dancing and evolution

Dwarf honey bees nest in the open on a branch and dance on the horizontal surface of the nest. The waggle run is orientated ‘towards’ the food source. Apis dorsata is also an open-nesting bee, but forms large vertically-hanging combs. It dances relative to gravity, and indicates the direction by the angle of the waggle run in the same way that A. mellifera does.

The cavity nesting bees, A. cerana, A. mellifera, A. koschevnikovi, and A. nigrocinta produce the most developed form of the dance.

The dances of A. mellifera and A. cerana are sufficiently similar that they can follow and decode the dance of the other.

The complexity of the nest site and the waggle dance reflects the evolution of these bee species. The earliest to evolve (i.e. the most primitive), A. andreniformis and florea, have the simplest nests and the most basic waggle dance. In contrast, the cavity nesting species evolved most recently, form the most complex brood nests and have the most derived waggle dance.

When and why did the waggle dance evolve?

Assuming that the waggle dance did not independently evolve (there’s no evidence it did, and ample evidence due to its similarity between species that it evolved only once) it must have first appeared at least 20 million years ago, when extant honey bee species diverged during the early Miocene.

The ‘why’ it evolved is a bit more difficult to address.

Behavioural changes often arise in response to the environment in which a species evolves.

Bipedalism in non-human primates (like the australopithecines) is hypothesised to have evolved in part due to a reduction in forest cover and the increase in savannah. Apes had to walk further between clumps of trees and bipedalism offered greater travel efficiency.

Perhaps the waggle dance evolved to exploit a particular type or distribution of food reserves?

In this regard it is interesting that the ‘benefit’ of waggle dance communication varies through the season.

If you turn a hive on its side the combs are horizontal 8. Under these conditions the dancing bees can communicate the presence and quality of a food source. However, they cannot communicate its location (either direction or distance).

No directional or distance information is now available

In landmark studies Sherman and Visscher 9 showed that, at certain periods during the season, the absence of this positional information did not affect the weight gain by the hive i.e. the foraging efficiency of the colony.

They concluded that during these periods forage must be sufficiently abundant that simply stimulating foraging was sufficient. Remember those alkanes and alkenes produced by dancing bees that do exactly that?

Tropical habitats

This observation, and some elegant experimental and modelling studies, suggest that dancing is beneficial when food resources are: 

  • sparsely distributed – therefore difficult (and energetically unfavourable) to find by individual scouting
  • clustered or short-lived resources – when it’s gone, it’s gone
  • distributed with high species richness – if there’s a huge range of flowers, which are the most energetically rewarding (sugar-rich) to collect nectar from?

One of the experimental studies that contributed to these conclusions (though there’s still controversy in this area) was the demonstration that waggle dancing was beneficial in a tropical habitat, but not in two temperate habitats. This makes sense, as food resources have different spatiotemporal distribution in these habitats. Tropical habitats are characterised by clustered and short-lived resources.

Therefore the suggestion is that the waggle dance of Apis species evolved, presumable early in the speciation of the genus, in a tropical region where food resources were patchily distributed, available for only limited period and present alongside a wide variety of other (less good) choices.

For example, like individual trees flowering in a forest …

Finally, it’s worth noting that there is evidence that bees that dance are able to successfully exploit food resources further away than would otherwise be expected from their body size.

This also makes sense.

It’s much less risky flying off over the horizon if you know there’s something to collect once you get there 10.


Notes

If you arrived here from my Twitter feed (@The_Apiarist) you’ll have seen the tweet started with the words “Dance like nobody’s watching”, words that are often attributed to Mark Twain. 

The full quote is something like “Dance like nobody’s watching; love like you’ve never been hurt. Sing like nobody’s listening; live like it’s heaven on earth”.

Pretty sound advice.

But it’s not by Mark Twain. It’s actually from a country music song by Susanna Clark and Richard Leigh. This was first released on the Don Williams album Traces in 1987. So only about 90 years out 😉 

Midwinter chores

I was going to title this post ‘Midwinter madness’ until I realised that there’s nothing I could write about related to beekeeping that could compare with current political events. So, it’s Midwinter chores instead …

We’ve had a week or more of low temperatures with intermittent light snow, freezing rain and bright sunshine. During the latter I’ve escaped to walk in the local hills.

North Fife hills

The North Fife hills – when they’re not filled with the cacophony of shooting parties out after pheasant or partridge – are looking fantastic, with unrestricted views to the Angus Glens, Schiehallion and Ben Lawers.

Of these, Schiehallion has a very distinctive shape (it’s just visible in the centre of the horizon above) 1. Its isolation allowed Nevil Maskelyne to use it in 1774 to calculate the mass of the earth in the appropriately named Schiehallion experiment 2.

This experiment used a combination of physics and mathematics, both of which are well beyond me, but are subjects I’ll return to at the end of the post.

Winter checks

In between these gentle walks I’ve infrequently checked all my colonies.

Many of my hives are fitted with clear perspex crownboards. This allows me to have a quick peek at the position and size of the winter cluster. Here are two examples:

Winter cluster – hive #36

and …

Winter cluster – hive #29

These hives are adjacent to each other in the same apiary. Both are in identical 10-frame Swienty poly brood boxes.

What is notable in the pictures above?

The first is that the crownboard with the mesh-covered central hole has been almost completely filled with propolis. I see this time and time again and am convinced that bees do not appreciate any ventilation over the cluster. I think the oft-seen advice to prop the crownboard up on matchsticks is total nonsense, at least for hives with open mesh floors.

Secondly, there is effectively no condensation on the underside of either crownboard. In the absence of ventilation – though both have my homemade open mesh floors – this is because they are both very well-insulated.

Insulation

Both crownboards are topped with a 5 cm thick block of Kingspan insulation. This is an integral part of the crownboard in #36, but just sits on top of #29. This insulation is present all year round, summer and winter.

Here is a picture of the same hives taken in October.

Hive #36 and #29 – note the roofs

Hive #29 has one of my homemade Correx roofs. These cost me about £1.50 each and about 10 minutes to make. They provide negligible insulation as they’re only about 4 mm thick. However, as far as these hives are concerned this is irrelevant as it’s the underlying block of Kingspan that’s doing the insulation.

Perspex crownboard with integrated insulation

The £29 Abelo poly roof on #36, although undoubtedly a whole lot smarter, might add a bit more insulation, but it also made me a whole lot poorer 🙁

Cluster size

The cluster size in hive #36 appears significantly larger than that in hive #29. The area covered by bees under the crownboard is perhaps twice the size.

I don’t read a lot into this.

My notes suggest that hive #36 was a bit stronger towards the end of the summer season. Although it looks as though It’s on brood and a half, the super is actually nadired and was filled with partially capped frames that weren’t ripe enough to extract. I expect they are all now empty. However, the interrupted nature of my 2020 beekeeping meant there’s never been a good opportunity to recover the super.

It’s worth remembering that the bees visible under the crownboard now are not the same bees that were visible in late August, when I last inspected the colony.

These are the long-lived winter bees. Many of them will still be there in early March.

However strong the summer colony was, this is an entirely different population of bees.

Although I’m sure there’s a relationship between summer and winter colony strength, I bet it isn’t linear and I’m sure there are a number of things that can influence it.

For example, consider two identical summer colonies. One is treated with Apivar and the other with Apiguard. In my experience (I used Apiguard for 5 years before moving back to Scotland) the thymol-containing Apiguard inhibits many queens from laying for an extended period. If this occurs when the colony is rearing the winter bees then 3, unless the queen (or colony) compensates 4 the final colony size will be smaller when compared with the Apivar-treated colony 5.

Other things, like the age of the queen or the levels of pathogens, are known (or might be expected) to exert a significant effect on late season brood rearing, further emphasising that there isn’t a simple relationship between summer and winter colony size.

Cluster shape

It’s also worth noting that the orientation and organisation of the cluster will influence its appearance. Consider this picture:

Appearances can be deceptive

The area (or volume if I could have drawn it in 3D) occupied by the cluster of bees in red is identical, but viewed from above, the diameter of the cluster in the top box would be half that of the cluster in the lower box 6.

I’ve noticed before that hives with ample insulation over the crownboard often appear to contain unusually large winter clusters. I’ve always assumed that this is because the bees prefer to orientate themselves into the warmest, most energy-efficient shape to get through the winter.

This shape might need to change to allow access to stores as the winter progresses.

Remember that bees have evolved to occupy often oddly-shaped hollow trees. These might have thick and thin walled regions, or odd draughts, necessitating the reorganisation of the winter cluster to achieve the optimum energy efficiency.

Gaffer tape

The other thing to note from the photographs above is the parlous state of the second crownboard. Both the central mesh (now sealed up) and some of the wooden frame are held together with gaffer tape. This is a near-ubiquitous aspect of my beekeeping, and an essential inclusion in the bee bag.

With the exception of the Correx roofs I use the 3M duct tape sold cheaply in the ‘Middle of Lidl’. It’s great stuff, easy to tear with gloved hands, and pretty strong and sticky.

However, it’s not particularly waterproof. If you want gaffer tape to hold your roofs together for years then the Lidl stuff doesn’t ‘cut the mustard’. Instead use Unibond Waterproof Power Tape, which I’ve written about when discussing building Correx roofs. Mine have withstood the rigours of the Scottish climate for at least 6 years 🙂

Corpses

In discussing the winter bees (above) I wrote ‘many of them will still be there in early March‘.

Many, but not all.

Throughout the winter bees die. If the weather is too cold for flying these corpses simply accumulate on the floor of the hive.

With a strong colony and a prolonged period of cold or wet weather the number of corpses can be so numerous that there’s a danger the hive entrance will be blocked.

If that happens the undertaker bees will not be able to remove them when the weather picks up.

In fact, if that happens, no bees will be able to exit the hive.

Under normal conditions bees do not defecate in the hive. They store it all up during periods of adverse weather and then go on a cleansing flight when the weather improves.

But they cannot do this if the entrance is blocked. This can lead to rapid transmission of pathogens such as Nosema in the colony, with soiling of the frames and inside of the hive.

The L-shaped entrance tunnel of my preferred kewl floors can get blocked with corpses during very prolonged cold or wet periods 7, and I’ve also seen it with reduced width entrances and mouseguards.

Hive entrance cleaning gizmo (patent pending)

To avoid any problems I simply clear any corpses from the entrance using a bent piece of wire every fortnight or so. In my experience there’s no need to do it any more frequently than that.

Stores

Despite the intense cold, the Fife colonies now appear to be rearing brood. I’ve not opened the boxes, and have no intention of doing so just to confirm brood rearing. Instead I’ve infrequently monitored the Varroa trays left underneath the stands in the bee shed 8. These now have faint stripes of biscuit-coloured capping crumbs, clear evidence that there is brood emerging.

And if there’s brood emerging they must have been fed (as developing larvae) on the stored honey from the hive.

Which means that the levels of stores available in the hive to get the colony through the remainder of the winter will be reducing.

I’ve used this ‘no expense spared’ graph before to show how the rate at which stores are consumed increases once brood rearing starts.

Colony weight in early spring

Don’t read too much into the labelling on the horizontal axis. The point I’m trying to emphasise is that stores are used much faster once the colony starts rearing brood, not that the rate changes suddenly in mid/late January.

And, if there’s a lot of brood rearing happening over a prolonged period, there’s a possibility that the colony will run out of stores and starve.

This means that it is critical to monitor the weight of the hive in the early months of the year 9.

Weighty matters

The goal is to determine whether the colony has sufficient stores to survive until forage becomes available.

Experienced beekeepers will do this by hefting the hive. This involves gently lifting the back 10 of the hive a centimetre or so and judging it’s weight.

This will then be compared with either (or both) the weight of a similar e.g. poly, cedar, single or double brood, empty hive or the weight of the same hive a week or two earlier.

As you might guess, this is a pretty inexact science 🙁

It really helps if all your hives are standardised … same material (cedar, poly), same number of brood boxes and the same type of roof.

However, the photo of the three hives (above) is pretty typical of my apiaries … different material, different roof and a different number of boxes.

D’oh!

Nevertheless, all I usually do is heft the hives.

As an alternative approach you can use a set of digital luggage scales. These can be used to weigh each side of the hive, again simply lifting it off the stand a centimetre or so until a stable reading is obtained. Add the two readings together and record them in your notebook.

Weighing a hive ...

Weighing a hive …

This method has the advantage that you get an actual number to compare week to week, not some vague recollection of the ‘feeling’ of the colony and what you think it should weigh.

Popeye

But there’s a problem with using the digital luggage scales.

To obtain a reading stable enough to be recorded you need to lift the hive and hold it very steady. At least, that’s what is needed with the scales I purchased.

With luggage this is trivial. You just stand above the bag and lift it with a straight arm and … peep! … you have the weight.

But a hive on a hive stand means that the digital scales are probably already at thigh or hip height. Lifting 20-30 kg a short distance and holding it steady enough with a bent arm is very difficult.

At least it is if you don’t have forearms like Popeye or eat 2000 calories of protein shakes for breakfast before spending the morning doing benchpresses 🙁

Now you’re torquing

Which brings me back to maths and physics.

A comment on a post last season brought the eponymously named Fisher’s Nectar Detector to my attention. This is a digital torque wrench adapted to read hive weights. They retail for about $130 in the US, but I don’t think they’re sold in the UK 11.

The torque wrench is attached to a short L-shaped steel bracket that is inserted between the brood box and the floor of the hive. The weight is determined by gently applying torque, separating the box by a small distance and then lowering it again.

Although I don’t like the idea of separating the floor and the brood box, I’m intrigued by the advantages this method might offer. I also see no reason why you couldn’t lift the back of the hive from the hive stand, much in the same way as you manually heft a hive.

But the digital wrenches available here (for ~£25-50) record torque (e.g. Newton-metres), not weight. Converting one to the other isn’t difficult if you have a good understanding of basic physics.

I don’t … 🙁

But I think the Professor of Mechanics in the School of Physics might 😉

I’ll keep you posted.


 

A New Year, a new start

The short winter days and long dark nights provide ample opportunity to think about the season just gone, and the season ahead.

You can fret about what went wrong and invent a cunning plan to avoid repetition in the future.

Or, if things went right, you can marvel at your prescience and draft the first couple of chapters of your book “Zen and the Art of Beekeeping”.

But you should also prepare for the normal events you expect in the season ahead.

In many ways this year 1 will be the same as last year. Spring build-up, swarming and the spring honey crop, a dearth of nectar in June, summer honey, miticides and feeding … then winter.

Same as it ever was as David Byrne said.

That, or a pretty close approximation, will be true whether you live in Penzance (50.1°N) or Thurso (58.5°N).

Geographical elasticity

Of course, the timing of these events will differ depending upon the climate and the weather.

For convenience let’s assume the beekeeping season is the period when the average daytime temperature is above 10°C 2. That being the case, the beekeeping season in Penzance is about 6 months long.

In contrast, in Thurso it’s only about 4 months long.

More or less the same things happen except they’re squeezed into one third less time.

Once you have lived in an area for a few years you become attuned to this cycle of the seasons. Sure, the weather in individual years – a cold spring, an Indian summer – creates variation, but you begin to expect when particular things are likely to happen.

There’s an important lesson here. Beekeeping is an overtly local activity. It’s influenced by the climate, by the weather in an individual year, and by the regional environment. You need to appreciate these three things to understand what’s likely to happen when.

OSR ... can you believe it?!

Late April 2016, Fife … OSR and snow

Events are delayed by a cold spring, but if there’s oil seed rape in your locality the bees might be able to exploit the bounteous nectar and pollen in mid-April.

Mid-April 2014, Warwickshire

Foraging might extend into October in an Indian summer and those who live near moorland probably have heather yielding until mid/late September.

Move on

You cannot make decisions based on the calendar.

In this internet-connected age I think this is one of the most difficult things for beginners to appreciate. How many times do you see questions about the timing of key events in the beekeeping season – adding supers, splitting colonies, broodlessness – with no reference to where the person asking, or answering, the question lives?

It often takes a move to appreciate this geographical elasticity of the seasons at different latitudes.

When I moved from the Midlands to Scotland 3 in 2015 I became acutely aware of these differences in the beekeeping season.

When queen rearing in the Midlands my records show that I would sometimes start grafting in the second week in April. In some years I was still queen rearing in late August, with queens being successfully mated in September.

Locally bred queen ...

Locally bred queen …

In the last 5 years in Scotland the earliest I’ve seen a swarm was the 30th of April and the latest I’ve had one arrive in a bait hive was mid-July. Here, queen rearing is largely restricted to mid-May to late-June 4.

All of this is particularly relevant as most of my beekeeping is moving from the east coast to the west coast of Scotland this year.

I’m winding down my beekeeping in Fife and starting afresh on the west coast.

The latitude is broadly the same, but the local environment is very different.

And so are the bees … which means there are some major changes being planned.

What are local bees?

I’m convinced about the benefits of local bees. The science – which I’ve discussed in several previous posts – shows that locally-reared bees are physiologically adapted to their environment and both overwinter and survive better.

But what is local?

Does it mean within a defined geographical area?

If so, what is the limit?

Five miles?

Fifty miles?

What is local? Click to enlarge and read full legend.

I think that’s an overly simplistic approach.

The Angus glens are reasonably ‘local’ to me. Close enough to go for an afternoon walk, or a summer picnic. They’re less than 40 miles north as the bee flies 5.

However, they’re a fundamentally different environment from my Fife apiaries. The latter are in intensively farmed, low lying, arable land. In Fife there’s ample oil seed rape in Spring, field beans in summer and (though not as much as I’d like) lime trees, clover and lots of hedgerows.

The Angus glens

But the Angus glens are open moorland. There’s precious little forage early in the season, but ample heather in August and September. It’s also appreciably colder in the hills due to the altitude 6.

I don’t think you could keep bees on the Angus hills all year round. I’m not suggesting you could. What I’m trying to emphasise is that the environment can be dramatically different only a relatively short distance away.

My bees

I don’t name my queens 7 but I’m still very fond of my bees. I enjoy working with them and try and help them – by managing diseases, by providing space or additional food – when needed.

I’ve also spent at least a decade trying to improve them.

Every year I replace queens heading colonies with undesirable traits like running on the comb or aggression or chalkbrood. I use my best stocks to rear queen from and, over the years, they’ve gradually improved.

They’re not perfect, but they are more than adequate.

When I moved from the Midlands to Scotland I brought my bees with me.

Forgot the scythe

Delivering bees from the Midlands to Fife

I ‘imported’ about a dozen colonies, driving them up overnight in an overloaded Transit van. The van was so full of hive stands, empty (and full) beehives and nucs that I had a full hive strapped down in the passenger seat. Fortunately the trip went without a hitch (or an emergency stop 🙂 ).

Passenger hive

Passenger hive

They certainly were not ‘local’ but I’d invested time in them and didn’t want to have to start again from scratch. In addition, some hives were for work and it was important we could start research with minimum delay.

But I cannot take any of my bees to the west coast 🙁

Treatment Varroa free

Parts of the remote north and west coast of Scotland remain free of Varroa. This includes some of the islands, isolated valleys in mountainous areas and some of the most westerly parts of the mainland.

It also includes the area (Ardnamurchan) where I live.

Just imagine the benefits of not having to struggle with Varroa and viruses every season 🙂

Although I don’t feel as though I struggle with managing Varroa, I am aware that it’s a very significant consideration during the season. I know when and how to treat to maintain very, very low mite levels, but doing so takes time and effort.

It would certainly be preferable to not have to manage Varroa; not by simply ignoring the problem, but by not having any of the little b’stards there in the first place 😉

Which explains why my bees cannot come with me 8. Once Varroa is in an area I do not think it can be eradicated without also eradicating the bees.

A green thought in a green shade … Varroa-free bees on the west coast of Scotland

I’ve already got Varroa-free bees on the west coast, sourced from Colonsay.

Is Colonsay ‘local’?

Probably. I’d certainly argue that it’s more ‘local’ to Ardnamurchan than the Angus glens are to Fife, despite the distance (~40 miles) being almost identical. Both are at sea level, with a similar mild, windy and sometimes wet, climate.

Sometimes, in the case of Ardnamurchan, very wet 🙁

My cunning plans

Although the season ahead might be “same as it ever was”, the beekeeping certainly won’t be.

My priorities are to wind down my Fife beekeeping activities (with the exception of a few research colonies we will need until mid/late 2022) and to expand my beekeeping on the west coast.

Conveniently, because it’s something I enjoy and also because it’s not featured very much on these pages recently, these plans involve lots of queen rearing.

Queen rearing using the Ben Harden system

In Fife I’m intending to split my colonies to produce nucs for sale. I’ll probably do this by sacrificing the summer honey crop. It’s easier to rear queens in late May/June and the nucs that are produced can be sold in 2021, or overwintered for sale the following season.

If I leave the queen rearing until later in the summer I would be risking either poor weather for queen mating, or have insufficient time to ensure the nucs were strong enough to overwinter.

It’s easier (and preferable) to hold a nuc back by removing brood and bees than it is to mollycoddle a weak nuc through the winter.

And on the west coast I’ll also be queen rearing with the intention of expanding my colonies from two to about eight. In this case the goal will be to start as early as possible with the aim of overwintering full colonies, not nucs. However, I’ve no experience of the timing of spring build up or swarming on the west coast, so I’ve got a lot to learn.

Something old, something new

I favour queen rearing in queenright colonies. This isn’t the place to spend ages discussing why. It suits the scale of my beekeeping, the colonies are easy to manage and it is not too resource intensive.

I’ve written quite a bit about the Ben Harden system. I have used this for several years with considerable success and expect to do so again.

I’ve also used a Cloake board very successfully. This differs from the Ben Harden system in temporarily rendering the hive queenless using a bee-proof slide and upper entrance.

Cloake board ...

Cloake board …

Using a Cloake board the queen cells are started under the emergency response, but finished in a queenright hive. It’s a simple and elegant approach. In addition, the queen rearing colony can be split into half a dozen nucs for queen mating, meaning the entire thing can be managed starting with a single double brood colony.

One notable feature of the Cloake board is that the queen cells are raised in a full-sized upper brood box. During the preparation of the hive this upper box becomes packed with bees 9. This means there are lots of bees present for queen rearing.

Concentrating the bees ...

Concentrating the bees …

It’s definitely a case of “the more the merrier” … and, considering the size of my colonies, I’m pretty certain I can achieve even greater concentrations of bees using a Morris board.

A Morris board is very similar to a Cloake board except the upper face has two independent halves. It’s used with a divided brood box (or two 5 frame nucleus boxes) and can generate sequential rounds of queen cells. I understand the principle, but it’ll be a new method I’ve not used before.

Since the bees are concentrated into half the volume it should be possible to get very high densities of bees using a Morris board.

And since I like building things for beekeeping 10, that’s what I’m currently making …

Which explains why I’ve got bits of aluminium arriving in the post, chopped up queen excluders on my workbench and Elastoplast on three fingers of my left hand 🙁

Happy New Year!


Notes

I’m rationalising my beekeeping equipment prior to moving. I have far too much! Items surplus to requirements – currently mainly flat-pack National broods and supers – will be listed on my ‘For Sale‘ page.

 

Top of the Posts

The last post of the year is one that almost no-one will read because they’re too busy unwrapping presents, overeating and enjoying seeing friends and family.

Or perhaps not 🙁

A socially distanced Christmas is an oxymoron, but is also unfortunately what many responsible people will be ‘enjoying’ this year.

I’m writing this as the government imposes ever-tighter restrictions in England, and the Scottish government imposes further preventative measures. Our long-suffering NHS is beginning to struggle …

Entirely predictable, completely necessary, but nevertheless disheartening.

At times like these it’s reassuring to have something else to focus on, a reminder of good times passed, and the promise of better times in the future.

The winter solstice

Long before Christmas became an orgy of overindulgence, before snowmen, robins, reindeer and religion, there were pagan festivals associated with the increase in day length.

The Romans celebrated dies solis invicti nati (“day of the birth of the unconquered sun”) just after the winter solstice, on the 25th of December 1. The winter solstice itself – the date with the shortest amount of daylight – varies a bit from year to year. This year, in my location, it was on the 21st of December when the day was just six hours and 47 minutes long 2.

Before the Romans, there’s evidence that the winter solstice was significant to much older civilizations. Maeshowe, a 5000 year old Neolithic chambered cairn on Orkney, has an entrance corridor directly aligned with the setting sun of the winter solstice.

With the benefit of atomic clocks and a proper understanding of the solar system we now know that the winter solstice can fall anytime between the 20th and 23rd of December. The back wall of Maeshowe is illuminated by the setting sun for a few days either side of the winter solstice. Do not let this detract from the wonder of Maeshowe or the, similar but even older, Newgrange in Ireland.

And, for beekeepers, the winter solstice is also of significance as many choose to treat their colonies with oxalic acid in the holiday period after the winter solstice, and before they return to work in early January 3.

An opportunity for tasseographers?

But as I’ve discussed before … that may be too late. My bees in Fife, broodless in late October, are now rearing brood again. There’s ample evidence 4 for that on the Varroa trays left on the floor underneath the hive stands.

Scores on the doors

So, having already reviewed the 2020 beekeeping year last week, what was notable on The Apiarist this year?

The combined effect of furloughing 5, isolated living and copious amounts of caffeine (on which, more later) – coupled with my natural tendency to prattle on a bit – meant that the average length of posts increased by 40% to ~2500 words. 

Eight years of The Apiarist … and a 12,000-fold increase in visits

This extra effort didn’t go unnoticed, with a greater than 50% increase in both visitors and page reads.

Regular readers should realise I’m mixing correlation and causation here.

The increases in both readers and reading might really be because everyone is locked down and bored witless 😉

Comments

On average, most visitors only read a couple of pages and, of those, only 0.3% leave a comment. However, I’m very grateful to those that do. It allows me to clarify points that were garbled and to elaborate on topics dealt with in too little detail.

Or to answer a completely unrelated question 😉

As an aside, the server cunningly filters out spam comments from real ones. I periodically check it’s not being overzealous but cannot 6 look at all of them.

If you submitted a comment and it was missed it was either because it was:

  • too short
  • abusive 7 or full of irrational ranting 8 
  • advertising fake RayBans 9

The posts from 2020 that generated the most discussion were:

I almost always respond to comments, often simply by redirecting the reader to a previous post (or promising to cover the topic in more detail sometime in the future). Consequently, old posts still get read quite frequently.

Speaking of which … what were the most popular posts of 2020 and the most read posts of the year?

The most frequently read posts of 2020

I’m going to ignore the Google-promoted mid-June post I mentioned last week. That post, A June Gap, was notable for being read thousands of times on the day it appeared (and on the couple of days afterwards). Since then it’s been accessed just a few hundred times and has effectively disappeared without trace from current reading stats.

It’s what a statistician would call an ‘outlier’.

Other than that, these were the most read posts that were written in 2020:

  • Swarm prevention (17/4/20) – an overview of why colonies swarm and how beekeepers can delay (and sometimes even prevent) swarming, before implementing swarm control. Also notable as it received far fewer comments than the majority of posts written this season.
  • Queen cells … quantity and quality (22/5/20) – how many queen cells should you leave during swarm control? I also discussed the ‘features’ of a good queen cell.
  • Oxalic acid (Api Bioxal) preparation (13/11/20) – an update of a post from several years ago about the preparation of Api Bioxal solution for trickle treating colonies in the winter. This post also discussed the differences in the historic oxalic acid concentration used in the UK, and those in the published instructions with Api Bioxal.
  • Principles of swarm control (24/4/20) – an overview of how swarm control works, or should work if you do things correctly. As the title indicates, this post discusses the principles of the process and how it applies in several common methods of swarm control.
  • The nucleus option (1/5/20) – how to make up nucleus colonies.

So, with the exception of the rehash of some recipes, an emphasis on the principles and mechanics of swarm control. This is something that many beekeepers struggle with, but can be reliably achieved by understanding what triggers the process coupled with an appreciation of the makeup of a colony and the development cycle of queens and workers.

The most frequently read posts of all time

In which ‘all time’ actually means since late 2013 when the first posts appeared online.

  • Queen cells … don’t panic (15/6/18) – what to do when you discover queen cells during a regular inspection. This was little read when it first appeared, but became very popular this summer. I presume the 100’s still reading it every week this October/November are in Australia and New Zealand 11.

Queen cells … don’t panic

  • When to treat? (5/2/16) – in terms of presentation this post is showing its age. I’ll probably update it next year. However, the content remains as valid now as when it was written, emphasising the importance of protecting the winter bee population to successfully overwinter a colony. I think this is the most important lesson that new beekeepers need to learn.
  • Honey pricing (4/10/19) – what they don’t tell you during your “Begin beekeeping” course, and often won’t tell you afterwards. Do not undervalue your honey. Every super or bucket produced is worth hundreds of pounds 12.
  • The nucleus method (22/3/19) – my favoured swarm control method. Totally foolproof if conducted properly. It was the only method I used this year and was 100% successful.
  • Vertical splits and making increase (19/7/15) – how to do an artificial swarm using less equipment and less space. Another post that is, presentationally at least, showing its age and likely to be updated next year (if I remember 😉 ).

So, with the exception of the post on honey pricing, more articles on swarming and mite control.

You’d almost think that these topics were a particular problem for beekeepers 😉

Honey and coffee

I’m particularly pleased to see that the honey pricing post is popular. This is an important topic and beekeepers, like the general public, too often assume that supermarket prices are representative, or what they are competing with.

We should be aiming to produce a top quality product. It is made from the nectars available in ~8 square miles of land surrounding your hives. Aside from the fact it’s absolutely delicious, it’s also unique – a snapshot of a time and a place 13 – and should be priced accordingly. 

Don’t compare it with £1 a pound supermarket rubbish, containing a “Product of EU and non-EU countries”. That could mean anywhere or anything (and increasingly actually means adulterated with rice or corn syrup).

A much better comparison would be with the price premium of a top quality wine or malt whisky.

I’ll be returning to honey pricing and provenance again in 2021.

Of over 40,000 ‘clicks’ on ~2,000 links embedded in the posts, 1% were to Buy me a coffee. I set this up in June after the old server fell over due to overwork, and I was forced to upgrade.

Flat white …

I am particularly grateful to the ~100 supporters who have ‘bought me a coffee’ to fuel late night writing marathons. It is you are largely responsible for the 40% increase in the length of posts this year 14.

Thank you 🙂

Readers, readers everywhere …

Perhaps unsurprisingly, because of a shared language, the top 6 countries (of 193 in total) in the visitors list were the UK (53%), USA (24%), Ireland (4%), Canada (3%), Australia (3%) and New Zealand (1%). These figures make sense, but aren’t particularly trustworthy as you can be wherever you want with a properly configured VPN. 

Finding your way to here

New posts are automagically promoted on my (otherwise totally neglected) Facebook page and via Twitter. Of the two, Facebook generates about four times more traffic than Twitter.

I don’t use either for two-way communication. I’m old skool and prefer email 15, so don’t bother trying to reach me using either.

Don’t try using Pinterest either (does this even have a messaging function? I told you I was old skool 😉 ), which also generates quite a bit of traffic.

Subscribers receive an email whenever a new post appears, and if you submit a comment you can opt in to receive an email update when I (or someone else) adds further comments to a post. I restrict comments to the two years after a post appears. Therefore, if you sign up for comment emails they’ll stop when commenting on a particular post is closed.

Like page reads and site visitors, subscriber numbers have also increased significantly (~50%) this year … Welcome!

Remaining traffic arrives at this site from search engines like Google, Bing, DuckDuckGo and Yahoo. Increasingly these encrypt the search terms so I only see about 10% of them and they don’t seem to be as amusing as they used to be.

Finding your way from here

When you visit a website the server records where you came from, both geographically and in terms of the last webpage visited.

When you follow a link in one of the posts the server also records which link you followed to leave the page 16.

Other than links elsewhere on this site, the most popular destination was the equipment suppliers E.H. Thorne’s.

The regular links I make there are an example of pragmatism, not promotion.

There are many other good quality equipment suppliers. However, there aren’t any others 10 minutes down the road from me 😉  A combination of convenience and my dislike of P&P charges means the relatively few things I purchase these days come from Thorne’s.

2021, a fresh start

Of the links to Thorne’s, the most often followed was to this honey creamer … if you want one, mine is for sale 😉

One careful owner etc.

I’m in the process of planning for the season ahead. This includes reviewing things that are  “surplus to requirements” and having a bit of a clear out.

There are going to be some very major changes to my beekeeping in 2021 (and 2022) which will involve an emphasis on making bees, rather than making honey.

But that’s for a future post. 

Social distancing, online beekeeping talks and hand washing are going to remain the norm for 2021. Less than 1% of the UK population have received their first dose of the vaccine in the first fortnight after the vaccines became available. At that rate (and it will speed up) it will be 11 years until the population is all vaccinated 17

Enjoy your holiday/break from furlough/family-free time/oxalic acid dribbling (delete as appropriate).

I hope you’ll visit again in the New Year …

Happy Christmas 🙂


 

2020 in retrospect

Almost exactly a year ago I wrote my retrospective review of the 2019 season.

At the time I was thinking “What a nightmare! If I never again have a year like that it’ll be too soon.”.

This was due to a major fire in my research institute which terminated a 30 year research programme and drowned me in a tsunami of administration.

The little beekeeping I did in 2019 kept me sane. Insurance issues and a new research facility took every waking hour. There was no ‘active’ queen rearing and my swarm control involved littering half of Fife with bait hives.

I piled on the supers, crossed my fingers and hoped for the best.

And got away with it 🙂

But by February 2020, the anniversary of the fire, it was looking as though those problems were just the hors d’oeuvres.

Coronavirus (Google Trends search terms, 12 months to mid-December 2020)

‘Coronavirus’ was a word transitioning from white-coated virology nerds with expansive foreheads to everyday, and then every minute, usage.

Covid and stockpiling

The word ‘Covid’ was first used in 1686. For its first 333 years it referred to an Anglo-Indian unit of linear measurement 1. On the 11th of February it appeared as a hashtag on Twitter and today it features a dozen times on the BBC homepage.

By early March it was clear that major societal changes were going to be needed to control virus transmission. A couple of days after spring talks to Oban beekeepers, Edinburgh and District BKA and the SNHBS the country went into lockdown …

The wild west

… by which time I was jealously guarding my panic-bought toilet rolls 2 on the remote west coast of Scotland.

The national beekeeping associations negotiated travel arrangements for animal husbandry purposes and the rest, as they say, is history.

I’ve already written about the practicalities of the small amount of long distance beekeeping I did in 2020. I won’t rehash the gory details here, but will make a few more general comments.

Highs and lows

It was a pretty good beekeeping start to the year. The spring was significantly drier than the 30 year average. This meant that the bees could get out and exploit the oil seed rape (OSR).

Spring 2020 rainfall anomaly

Consequently the honey yield per colony was the best I’ve had in the five years I’ve been back in Scotland. I think it would have been even better had I been present to add the supers in a more regulated manner … and to remove them before they crystallised.

In contrast, the summer was characterised by a series of lows … low pressure systems, bringing more rain than usual.

This probably reduced the time available for foraging, but perhaps was compensated by better nectar flows. My two main production apiaries performed very differently.

One generated almost no honey per hive, the other again generated record yields of outstandingly flavoured summer honey.

Summer honey

Guess which apiary contained more production hives?

Typical 🙁

Putting the control into swarm control

Swarm control usually involves careful observation of colony development coupled with a timely intervention to split the colony and prevent swarming.

The timely intervention is often at different times for different colonies, even in the same apiary.

There was none of that this year.

With only about four inspections all season I implemented swarm control  in the majority of colonies well before queen cells developed.

The method should be termed something like split and hope 😉

In practical terms it involved preemptive application of the nucleus method of swarm control.

The only decision I made for each colony was whether to apply swarm control or not.

I then made up the queenright nucs all on the same day. The nucs were made significantly weaker than usual to delay the time when I’d have to expand them up to a full colony.

Overall the approach worked very well, at least in terms of swarm control, as none of my colonies swarmed 🙂

The colonies that weren’t split were given lots of room and a combination of inspired judgement a long June gap and some iffy midsummer weather meant they stayed together.

Hieroglyphics

I need to go back through my notes to determine how individual colonies performed in terms of honey production. Other than the absence of any summer honey from one apiary, were there differences in terms of the amount nectar collected between colonies that were split or not?

Unfortunately, the (frankly) manic beekeeping that resulted from compressing everything into a few inspections over the season meant my notes are, in places, rather sparse 3.

Too weak to split

+3 supers Q+ good

WMCLQ WTF?

Grrr 4

Deciphering my hieroglyphics will necessitate a large glass of shiraz and a long winter night – two other things, along with the loo roll, I have an abundance of at the moment.

Varroa management

The other reason I need to review my notes is to look at the relationship (if any) between the in-season colony management 5 and end-of-season mite levels.

I do have some reasonably good counts of the mite drop during late summer and midwinter treatments 6. These are particularly reliable for the colonies in the bee shed because the floors I use have a tightly fitting Varroa tray, meaning that anything that drops, stays dropped 7.

Cedar floor and plywood tray …

In addition, I’m confident that the colonies received their ‘midwinter’ treatment – in mid/late November – when totally broodless.

There were significant differences between the mite drops of colonies in the bee shed. Some dropped 250-500 8 while others dropped less than 75. Those figures are totals over 8-9 weeks with Apivar plus the fortnight or so after oxalic acid treatment.

All other things being equal I’ll use the colonies with lower mite levels for queen rearing next season. For whatever reason, those colonies appear better able to manage their Varroa levels. Perhaps this is due to increased grooming or better defence (e.g. turning away potentially mite-laden drifting workers 9). If their temperament is good and they overwinter well they will be a good choice to rear queens from.

Inevitably all things will not be equal, but at least I’ll have tried.

And I’m hoping to be doing a reasonable amount of queen rearing in 2021 … though after a devastating fire and a global pandemic I wouldn’t be surprised if the Earth was obliterated by an asteroid just as I start grafting 🙁

Going Varroa free

I’ve spent almost all year on the west coast, and will be spending increasing amounts of time here in the coming years. The area is remote, very sparsely populated and Varroa free.

It also has spectacular sunrises …

Red sky in the morning …

… and scenery …

View from Ben Laga to Mull

Actually, until I imported 10 a couple of colonies, it appeared to be completely honey bee free. I’ve sourced Varroa-free colonies from an island off the west coast of Scotland.

I’ve often written about the importance of being ‘in tune’ with the local beekeeping environment. It’s already clear that the east and west coasts of Scotland 11, despite being separated by only ~120 miles, have distinct climates, nectar and pollen availability.

What? No oil seed rape?

On the west coast there’s no OSR. In fact, there’s almost no arable farming at all. I’ll be interested to see what the bees access for spring and mid-season nectars. With mixed woodland, and more being planted, and lots of native flowers they should have a good selection.

Early season primroses

There are some huge lime trees just down the road. These need rain to generate good levels of nectar, and rain is something else we have in abundance 😉

The main source of nectar is the heather. This is something 12 I have almost no experience of. In the Midlands I was always too busy to transport hives to Derbyshire for the heather. Fife, despite being in Scotland, has very little heather moorland and most beekeepers have to take their hives to the Angus Glens. I never bothered.

Now there’s acres of the stuff just up the hill at the back of the house. Not particularly good quality heather moorland, but lots of it.

I’ll return to this when I discuss planning for the season ahead, sometime in the New Year.

The Apiarist – online and offline

This is the 51st post of the year.

Regular as clockwork

With a bit of luck I’ll also scribble something for the 25th, so completing a ‘full house’ for 2020. It’s too soon to look at any year-end statistics, but it’s clear that lots of people had lots more time for lots more reading this year.

I wonder why?

Everything came to a grinding halt in mid-June when a post featured on one of the Google news sites. In one afternoon the server was inundated with people eager to read about the June gap.

Thousands and thousands of them 🙁

Since most of them didn’t look elsewhere on the site I suspect the topic was a bit too niche for the majority of the internet illiterati.

After a couple of hiccups and a faltering stagger the server collapsed under the onslaught. I spent an afternoon moving it to a host with four times the capacity (at four times the cost) and it’s hung on gamely ever since.

Not only have beekeepers been doing lots more reading, they’ve also doing lots more listening and watching.

Online beekeeping talks

Many beekeeping associations – both local and national – have developed online winter talk programmes.

I’ve attended lively SBA Q&A sessions, BIBBA webinars by Adam Tofilski on preserving native bees, and I spent yesterday evening learning all about distinguishing Apis mellifera mellifera from ligustica or carnica or Buckfast or mongrels, care of the SNHBS.

And I’ve delivered more talks to bigger audiences this winter than in all of the last few years combined.

These talks – not mine specifically, but all of those available – fill the void between September and April. Although perhaps not the easiest way to establish new friendships 13 they are an excellent way to keep in contact with people from all over the country. In that regards they’re much better than ‘in person’ evening talks, and much more akin to the annual beekeeping conventions.

Though, unlike the conventions, my wallet doesn’t return emaciated from an hour or two going round the trade stalls.

Online talks are also good for keeping in contact with people on the other side of the county, let alone the country. It’s not unusual for my talk to be sandwiched by friendly banter between beekeepers separated by both distance and Covid.

Will this continue? I expect so. I don’t expect in person talks will start until 2022 at the earliest. However, I think – just as remote working will increase – online talks will be a regular feature of the winter beekeeping calendar. The benefits outweigh the slightly impersonal format, and many people appreciate the convenience of not having to travel 14.

Science aside

The enforced downtime, with labs closed and staff furloughed, has enabled me to finally write up a backlog of papers on honey bee virus research. A few of these have featured on this site already, in discussions of whether DWV replicates in Varroa, or in bumble bees, and in the inexorable rise of chronic bee paralysis virus as an emerging pathogen of honey bees.

I’ve yet to find time to write about our green bees because I want to include a really elegant experiment we have yet to complete. These bees are infected with a virus that expresses a green fluorescent protein from a jellyfish. When visualised under UV illumination the individual cells and tissues in which the virus replicates are easily detected. More about this next year.

Green bees

Several more papers are in the pipeline or in preparation, on rescuing hives with catastrophically high mite loads, on competition between different variants of DWV and on the landscape-scale control of Varroa.

Lessons learned

Considering the paucity of beekeeping this year I’ve still managed to learn a few new tricks and improve a few old ones.

I’ve learned how little intervention is required to manage colonies adequately (defined by good health and no swarms, though undoubtedly at the cost of maximising the honey yield).

‘Adequately’ because I also learned how unrewarding it was keeping bees without beekeeping.

For the first time I used air freshener to unite lots of colonies during a particularly busy long weekend when I requeened the majority of my hives. It’s a new trick to me, though widely used by others. Having used it, I’m now confident it works. I’ll use it again if I’m similarly rushed for time, but expect to usually rely on uniting over newspaper.

I’ve gained more confidence in accurately guesstimating how weak I can make up nucs, without them succumbing to robbing, wasps or starvation. Undoubtedly I was aided with reasonable weather and good nectar and pollen availability, but it will be a skill I’ll be able to use again in future years.

I also learned  – or at least reinforced my appreciation of (as I’ve done this previously) – how to hold back the nucs, so preventing them swarm, by removing lots of brood 15. The brood was used to boost honey production colonies which were requeening themselves. With some good judgement, and a big slice of luck, this all went very well.

The importance of regularly checking bait hives was also emphasised when I found this …

Just when you thought it was safe to go back in the bee shed …

This season was unusual as I didn’t attract a single swarm to a bait hive, probably the first time that’s happened for a decade. Partly this was because I set so few out, but presumably it also reflected my dalliance with waspkeeping.

Finally, I’ve learned there are quicker ways to prepare spreadable ‘soft set’ honey that the interminable Dyce method. I’ve recently acquired a new honey creamer and the first fifty jars have been distributed to friends and family for Christmas. I expect very positive feedback 16 due to the extensive product testing and quality control applied during its preparation 😉


 

Queens and amitraz residues in wax

A question following a recent evening talk to a beekeeping association prompted me to look back at the literature on amitraz and wax residues.

The question was about reuse of honey supers that were present on a colony during miticide treatment.

With the exception of MAQS, there are no approved miticides that should be used if there are honey supers on the hives. The primary reason for this is that there is a risk that the miticide will taint the honey. Since the latter is for human consumption this is very undesirable.

However, it’s not unusual at the end of the season to have a half empty super, or a super containing just uncapped stores. Typically this would be ‘nadired’ i.e. placed below the brood box, with the expectation that the bees will move the stores up into the brood chamber 1.

Two colonies overwintering with nadired supers

And sometimes this super remains in place during the annual early autumn Varroa slaughter. 

The question was something like “Can I reuse the honey super next season?”

My answer

As anyone who has heard me speak will know, my answer was probably rambling, repetitive and slightly incoherent 🙁

However, the gist of it was “Yes, but I don’t”.

With Zoom talks and written questions from the audience you often don’t get all the details. The answer must be sufficiently generic to cover most eventualities 2 including, for example, the range of possible miticides that were used for treatment.

Assuming the nadired super is emptied by the bees during the winter, what are the chances that the wax comb will be contaminated with miticides?

This depends upon the miticide used.

I explained that the organic acids (formic or oxalic) are not wax soluble and so the super can be reused without a problem. 

In contrast, Apistan (a pyrethroid) is known to be wax soluble, so it should probably not be used again to avoid any risk of tainting honey subsequently extracted from it 3.

But (I probably digressed) you really shouldn’t be using Apistan as resistance in the mite population is already widespread.

But what about Apivar (the active ingredient of which is amitraz)?

Since Apivar isn’t wax soluble it would probably be OK to reuse the super … but I qualified this by saying that I don’t reuse them “just to be on the safe side”.

What they don’t tell you about Apivar

This wasn’t really an application of the precautionary principle.

Instead, it reflected a dim memory of some posts I’d read earlier in the year on the Bee-L discussion forum. This is a low volume/high quality forum frequented by scientifically-inclined beekeepers.

It turns out that, although amitraz (the active ingredient in Apivar) is not wax soluble, it’s broken down (hydrolysed) to a formamide and a formamidine

Read that again … I didn’t write the same word twice 😉

The formamide has no residual activity against mites. In contrast, the formamidine retains miticidal activity and is wax soluble

Is this a problem?

Well, possibly. One of the things discussed by Richard Cryberg on Bee-L was that there appears to be no toxicology data on these two products. It’s probably been done, just not published.

Perhaps we can assume that they’re not hideously toxic to humans (or bees)? If it was, amitraz (which is the active ingredient in all sorts of mite and tick treatments, not solely for bees) would carry sterner warnings.

Or should 🙁

The residual miticide activity is potentially more of a problem. A well understood route to developing miticide resistance involves long-term exposure to sub-lethal doses. There are several reports of amitraz resistance in the scientific literature, and bee farmers are increasingly providing anecdotal accounts of resistance becoming a problem.

This, and the possibility of tainting honey, are reason enough in my opinion to not reuse drawn supers that have been on the hive (e.g. nadired) during Apivar treatment.

But it turns out that there are additional potential issues with amitraz residues in comb.

Miticide residues in wax

Commercial wax foundation – like the stuff you buy from Thorne’s or Maisemores or Kemble Bee Supplies – is often contaminated with miticide residues. A large US survey of drawn comb from hives and foundation demonstrated that:

Almost all comb and foundation wax samples (98%) were contaminated with … fluvalinate 4 and coumaphos 5, and lower amounts of amitraz degradates and chlorothalonil 6, with an average of 6 pesticide detections per sample and a high of 39.

I’m not aware of an equivalent published analysis of UK foundation. I’m know one has been done and I’d be astounded if it produced dramatically different results. There’s a global trade in beeswax, some of which will be turned into foundation. The only exception might be certified organic foundations.

Freshly drawn comb

A freshly drawn foundationless frame

I always purchase premium quality foundation but am under no misapprehension that it doesn’t also contain a cocktail of contaminants, including miticides and their ‘degredates’. 

I’d be delighted to be proved wrong but, since I think that’s unlikely, it’s one reason I use an increasing number of foundationless frames … which also saves quite a bit of cash 🙂

Drones and queens and miticides in wax

Numerous studies have looked at the influence of miticide residues on worker, drone and queen development. These include:

  • Sublethal doses of miticides can delay larval development and adult emergence, and reduce longevity 7
  • Tau-fluvalinate- or coumaphos-exposed queens are smaller and have shorter lifespans 8
  • Queens reared in wax-coated cups contaminated with tau-fluvalinate, coumaphos or amitraz attracted smaller worker retinues and had lower egg-laying rates 9.
  • Drones exposed to tau-fluvalinate, coumaphos or amitraz during development had reduced sperm viability 10.

All of which is a bit depressing 🙁

These studies used what are termed ‘field-realistic’ concentrations of the contaminating miticide. They didn’t use wax saturated in miticide, but instead contaminated it with parts per million (ppm), or parts per billion (ppb).

These are the highest concentrations reported in surveys of comb tested in commercial beekeeping operations in the US, so hopefully represent a ‘worst case scenario’.

It’s also worth noting that some commercial beekeepers in the US use significantly more – both in amount and frequency – miticides than are used by amateurs. If you read American Bee Journal or the Beesource forums it’s not unusual to find accounts of spring, mid-season, late-summer and mid-winter treatments, often of the same colonies.

Queen mating

To add to the literature above, a new paper was published in November 2020 which suggested that amitraz residues in wax increased the mating frequency of queens.

The paper is by Walsh et al., (2020) Elevated Mating Frequency in Honey Bee (Hymenoptera: Apidae) Queens Exposed to the Miticide Amitraz During Development. Annals of the Entomological Society of America doi: 10.1093/aesa/saaa041

This piqued my interest. Queen mating frequency is an important determinant of colony fitness.

If a queen mates with more drones there’s inevitably increased genetic diversity in the colony and, in landmark studies by Thomas Seeley, an increase in colony fitness 11

Colony fitness includes all sorts of important characteristics – disease resistance, foraging ability, overwintering success etc.

So, perhaps this is a benefit of amitraz residues in your wax foundation … the reduced egg-laying rate being compensated by increased patrilines 12 and a fitter colony?

The study

Walsh and colleagues grafted queens into JzBz queen cups containing wax laced with one or more miticides. They reared the queens in ‘cell builders’ that had not been miticide treated, shifted mature queen cells to mating nucs and then – after successful mating – quantified two things:

  • the viability of spermatozoa in the queen’s spermatheca
  • the mating frequency of the queen

Irrespective of the miticides incorporated into the wax lining the queen cup, sperm viability was very high (98.8 – 99.5% viable), and no different from queens not exposed to miticides during development. 

Queen cells after emergence in mating nucs

This suggests that miticide contamination of queen cells is unlikely to have a deleterious effect on sperm viability in mated queens.

However, rather oddly, this contradicts a not dissimilar study 5 years ago from some of the same authors where the presence of tau-fluvalinate and coumaphos did reduce sperm viability 13, as did an earlier study looking at the effect of amitraz 14.

This contradiction is pretty-much ignored in the paper … clearly something that “needs further investigation”.

It might be due to experimental differences (for example, they used different methods to determine sperm viability). Alternatively, since the queens were open-mated, it might reflect differences in the miticide-exposure of the donor drones.

Mating frequency

The authors used microsatellite analysis to determine the mating frequency of the queens reared during the study. They compared queens reared in the presence of amitraz or tasty cocktails of tau-fluvalinate & coumaphos, or clorothalonil & chlorpyrifos 15, with those reared in the absence of chemicals contaminating the waxed queen cup.

They measured the observed mating frequency and then calculated the effective mating frequency (me). Conveniently they describe the difference between these parameters:

The observed mating frequency refers to the total number of drone fathers represented in a queen’s worker progeny. The effective mating frequency uses the proportion of each subfamily within a colony and compensates for calculating potentially skewed estimates of paternity (i.e., unequal subfamily proportions in sampled pupae) and intracolony genetic relatedness.

‘Convenient’ because it saves me having to explain it 😉

The observed mating frequencies of the control queens (untreated wax), or those reared in the presence of amitraz or tau-fluvalinate & coumaphos cocktails were not statistically different. However, queens reared in clorothalonil & chlorpyrifos-laced wax had a lower observed mating frequency.

Strikingly though, when calculated, the effective mating frequency of amitraz- or tau-fluvalinate & coumaphos-exposed developing queens was significantly higher (~12.9-13.4) than either the untreated controls or clorothalonil & chlorpyrifos (~8.2-8.8) 16.

And … ?

The amitraz result is new.

The influence of tau-fluvalinate & coumaphos on effective mating frequencies has been reported previously (by some of the same authors 17) which, since this was a new study in a different region, is at least encouraging because it supports the earlier work.

Taken together, these results suggest that miticide residues (of at least two chemically different types) increase the number of drones that a queen mates with.

The discussion of the paper speculates about why this difference is observed. 

The number of drones a queen mates with is influenced by several things. These include the number and duration of the mating flights. Perhaps the amitraz-exposed queen can’t count properly, or loses her ability to judge time … or just flies more slowly?

All of these would result in exposure to more drones.

Before returning to the hive, a queen must be able to determine whether she has mated with sufficient drones. It is suggested that stretch receptors in the oviducts are involved with this, forming a negative feedback stimulus once the oviducts are full. Perhaps amitraz impairs stretch receptor function or signalling?

Clearly there’s a lot left to learn.

Hyperpolyandry

The effective mating frequencies determined in the presence of amitraz (and tau-fluvalinate & coumaphos) were higher than the controls. However, they still appear rather low when compared with previous reports of hyperpolyandrous 18 colonies with up to 77 distinct patrilines (I’ve written about this previously, including descriptions of how it was determined).

Don’t mix the two observations up. In the studies of hyperpolyandry they analysed queens to determine their patriline.

A queen from a very rare patriline is still a queen, so can be screened.

In contrast, if you only screen a handful of workers (from the thousands present in the colony), you are very unlikely to find extremely rare patrilines. Those you do find will be the ones that are most common. 

A logical extension of the studies reported by Walsh et al., would be to determine whether hyperpolyandry also increased in amitraz-exposed colonies. If the effective mating number is increased you should observe a larger number of patrilines.

Alternatively, perhaps Withrow and Tarpy (who published the hyperpolyandry paper 19) should look again at whether the colonies they screened had a long history of amitraz exposure.

And what about that nadired super?

It’s probably fortunate I’d not fully read the literature before answering the question after my talk. 

If I had, I’d have tried to paraphrase the ~2000 words I’ve just written … so making my answer interminably long.

Of course, it’s unlikely that an amitraz (Apivar) contaminated super will ever be visited by a queen (but these things do happen 🙁 ).

Or be a location for developing queen cells. 

So, in this regard, I think it’s irrelevant whether the super is reused.

In contrast, the wax solubility and residual miticide activity of one of the hydrolysis products of amitraz is more of a concern. I don’t want this near honey I’m going to extract, and I’d rather not have it in the hive at all.

All of which explains the “Yes, but I don’t” answer to the original question about whether the super can be reused.

Fondant feeding on a colony with a nadired super

The super in the picture above will be removed early next season, before the queen starts laying in it. The super will be empty and I’ll melt the wax out in my steam wax extractor. 

In a good nectar flow the bees will draw a full super of comb very quickly. Yes, they’ll use some nectar that would otherwise be used make honey, but that’s a small penalty.

And what will I do with the extracted wax? 

I’ll probably trade it in for new foundation 20.

And since this is what many beekeepers do it explains why I’m certain that most commercial foundation is contaminated with miticides 🙁

But don’t forget …

Mite management is important. Miticides are chemicals and, like other medicines, have both beneficial and detrimental effects. The beneficial effects far outweigh the detrimental ones. If you do not treat, the likelihood is that mites and viruses will kill the colony … if not immediately, then eventually.


 

The winter cluster

We had our first snow of the year last night and the temperature hasn’t climbed above 3°C all day. The hills look lovely and, unsurprisingly, I’ve not seen a single bee venturing out of the hives.

Winter wonderland

If you crouch down close to the hive entrance and listen very carefully you’ll be able to hear …

… absolutely nothing.

Oh no! Are they still alive? Maybe the cold has killed them already?

If you rap your knuckles against the sidewall of the brood chamber you’ll hear a brief agitated buzz that will quickly die back down to silence.

Don’t do that 😯

Don’t disturb them unless you absolutely have to. They’re very busy in there, huddling together, clustering to maintain a very carefully regulated temperature.

Bees and degrees

Any bee that did venture forth at 3°C would get chilled very rapidly. Although the wing muscles generate a lot of heat (see below), this uses a large amount of energy.

If the body temperature of an individual bee dips below ~5.5°C they become semi-comatose. They lose the ability to move, or warm themselves up again. Below -2°C the tissues and haemolymph starts to freeze.

However, as long as they’re not exposed to prolonged chilling (more than 1 hour) they can recover if the environmental temperature increases 1.

An individual bee has a large surface area to volume ratio, so rapidly loses heat. Their hairy little bodies help, but it’s no match for prolonged exposure to a cold environment.

But the bees in your hives are not individuals. Now, perhaps more than any other time in the season, they function as a colony. Survival, even for a few minutes at these temperatures, is dependent upon the insulation and thermoregulation provided by the cluster.

All for one, one for all

The temperature in the clustered colony is always above the coma-inducing 5.5°C threshold, even for the bees that form the outer surface layer, which is termed the mantle.

And the temperature in the core of the cluster is much warmer still, and if they’re rearing brood (as they soon will be 2) is maintained very accurately.

The mantle

The temperature inside the hive entrance, some distance from the cluster, is the same as the external ambient temperature. On a cold winter night that might be -5°C (in Fife), or -35°C (in Manitoba).

Studies have shown that clustered colonies can survive -80°C for 12 hours, so just a few degrees below freezing is almost balmy.

The winter cluster

Due to thermal radiation from the clustered colony, the temperature of the airspace around the colony increases as you get nearer the cluster. Draught free hives – and beekeepers that refrain from rapping on the brood box sidewall – will reduce movement of this air, so reducing thermal losses from convection.

The clustered colony is not a uniform ‘ball’ of bees. It has two distinct layers. The outer layer is termed the mantle and is very tightly packed with bees facing inwards. These bees are packed in so tightly that their hairy bodies trap air between them, effectively forming an insulating quilt.

To reduce heat loss further these mantle bees have a countercurrent heat exchanger (between the abdomen and the thorax) that reduces heat loss from the haemolymph circulating through their projecting abdomens.

The mantle temperature is maintained no lower than about 8°C, safely above coma-inducing lower temperatures.

Penguins and flight muscles

I’ve seen it suggested that the mantle bees circulate back into the centre of the cluster to warm up again, but have been unable to find published evidence supporting this. It’s an attractive idea, and it’s exactly what penguins do on the Antarctic ice sheet … but that doesn’t mean it’s what bees do.

Penguins, not bees

Although bees can cope with temperatures of 8°C, they cannot survive this temperature for extended periods. If bees are chilled to below 10°C for 48 hours they usually die. This would support periodically recirculating into the centre of the cluster to warm up.

Bees do have the ability to warm themselves by isometric flexing of their flight muscles. Essentially they flex the opposing muscles that raise and lower the wings, without actually moving the wings at all.

This generates a substantial amount of heat. On a cool day, bees warm their flight muscles by this isometric flexing before leaving on foraging flights. They have to do this as the flight muscles must reach 27°C to generate the wing frequency to actually achieve flight. Since bees will happily forage above ~10°C this demonstrates that the isometric wing flexing can raise the thoracic flight muscle temperature by at least 15-17°C.

But, briefly back to the penguin-like behaviour of bees, neuronal activity is reduced at lower temperatures. In fact, at temperatures below 18°C bees don’t have sufficient neuronal activity to activate the flight muscles for heat generation. This again suggests there is a periodic recycling of bees from the mantle to the centre of the cluster.

How can bees fly on cool days if it’s below this 18°C threshold? The day might be cooler, but the bee isn’t. The colony temperatures are high enough to allow sufficient neuronal activity for the foragers to pre-warm their flight muscles to forage on cool days.

Anyway, enough of a digression about flight muscles, onward and inward.

The core

Inside the mantle is the core. This is less densely occupied by bees, meaning that they have space to move around for essential activities such as brood rearing or feeding.

The temperature of the core varies according to whether the colony is rearing brood or not. If the colony is broodless the core temperature is maintained around 18°C.

The tightly packed mantle bees reduce airflow to the core. As a consequence of this the CO2 levels rise and the O2 levels fall, to about 5% and 15% respectively (from 0.04% CO2 and 21% O2 in air). A consequence of this is that the metabolic rate of bees in the core is decreased, so reducing food consumption and minimising the heat losses from respiration.

Brood rearing

My clustered winter colonies are probably just thinking about starting to rear brood 3.

Bees cannot rear brood at 18°C. Brood rearing is very temperature sensitive and occurs optimally at 34.5-35.5°C.

Outside that narrow temperature band things start to go a bit haywire.

Pupae reared at 32°C emerge looking normal (albeit a day or so later than the expected 21 days for a worker bee), but show aberrant behaviour. For example, they perform the waggle dance less enthusiastically and less accurately 4. In comparison to bees reared at 35°C, the ‘cool’ bees performed only 20% of the circuits and the ‘waggle run’ component was a less accurate predictor of distance to the food source.

Neurological examination of bees reared at 35°C showed they had increased neuronal connections to the mushroom bodies in the brain, when compared with those reared as little as 1°C warmer or cooler. This, and the behavioural consequences, shows how critical the brood nest temperature is.

The cluster position

The cartoon above shows the cluster located centrally in the hive. This isn’t unusual, though the cluster does tend to move about within the volume available as they utilise the stores.

You can readily determine the location of the cluster. Either insert a Varroa tray underneath an open mesh floor for a few days …

All is well ...

Tell tale signs of a brood-rearing cluster …

… or by using a perspex crownboard. I have these on many of my colonies and it’s a convenient way of determining the size and location of the cluster with minimal disturbance to the colony.

Perspex crownboard

Perspex crownboard …

Though you don’t need to check on them like this at all.

The photograph above was from late November (6 years ago). The brood box is cedar and therefore provides relatively poor insulation.

While checking the post-treatment Varroa drop in my colonies this winter it was obvious that cluster position varied significantly between cedar and poly hive types.

In poly hives (all my poly hives are either Abelo or Swienty) it wasn’t unusual to find the cluster tight up against one of the exterior side walls. In contrast, colonies hived in cedar brood boxes tended to be much more central.

This must be due to the better insulation of polystyrene compared with cedar.

Insulation

Although I don’t think I’ve noticed this previously in the winter, it’s not uncommon in summer to find a colony in a poly hive rearing brood on the outer side of the frames adjacent to the hive wall. This is relatively rare in cedar boxes, other than perhaps at the peak of the summer.

If you’re interested in hive insulation, colony clustering and humidity I can recommend trying to read this paper by Derek Mitchell.

I don’t provide additional insulation to my colonies in the winter. It’s worth noting that all my hives have open mesh floors. In addition, the crownboard is topped by a 5 cm thick block of insulation throughout the year, either integrated into the crownboard or just stacked on top.

Perspex crownboard with integrated insulation

If you use perspex crownboards you must have insulation immediately above them. If you don’t you get significant amounts of condensation forming on the underside which then drips down onto the cluster.

The winter cluster and miticide treatment

The only time you’re likely to see the winter cluster is when treating with an oxalic acid-containing miticide. And only then when trickle treating.

With the choice between vaporising or trickle treating, I tend to be influenced by the ambient temperature.

If the cluster is very tightly clustered (because it’s cold) I tend to trickle treat.

If it is more loosely clustered I’m more likely to vaporise.

The threshold temperature is probably about 8°C, but I’m not precious about this. The logic – what little is applied – is that the oxalic acid crystals permeate the open cluster better than they would a closed cluster.

I’ve got zero evidence that this actually happens 😉

However, it’s worth reiterating the point I made earlier about airflow through the mantle. Since this is restricted in a tightly clustered colony – evidenced by the reduced O2 and elevated CO2 levels – then it seems reasonable to think that OA crystals are less likely to penetrate it either.

Of course, there’s an assumption that the trickled treatment can penetrate the cluster, and doesn’t just coat the mantle bees with a sticky OA solution.

Which neatly brings us back to penguins … if these mantle bees do recirculate through the cluster core they’ll take some of the OA with them, even if it didn’t get there directly.

Finally, it’s worth noting that cluster formation starts at about 14°C. As the temperature drops the cluster packs together more tightly. Between 14°C and -10°C the volume of the cluster reduces by five-fold.

By my calculations 5, at 2°C and 8°C the cluster is three and four times it’s minimal volume respectively, so perhaps both OA vapour and trickled solution could permeate perfectly well.