Category Archives: Miscellaneous

Is queen clipping cruel?

Synopsis : Is clipping the queen a cruel and barbaric practice? Does it cause pain to the queen? Surely it’s a good way to stop swarming? This is an emotive and sometimes misunderstood topic. What do scientific studies tell us about clipped queens and swarming?

Introduction

After the contention-free zone of the last couple of weeks I thought I’d write something about queen clipping.

This is a topic that some beekeepers feel very strongly about, claiming that it is cruel and barbaric, that it causes pain to the queen and – by damaging her – induces supersedure.

Advocates of queen clipping sometimes recommend it as a practice because it stops swarming and is a useful way to mark the queen 1.

I thought it would be worth exploring some of these claims, almost all of which I think are wrong in one way or another.

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

Here’s one I didn’t lose earlier – swarm with a clipped queen from the bee shed

I clip and mark my queens.

You can do what you want.

This post is not a recommendation that you should clip your queens. Instead, it’s an exploration of the claimed pros and cons of the practice, informed with a smattering of science to help balance the more emotional responses I sometimes hear.

By all means do what you want, but if you oppose the practice do so from an informed position.

Having considered things, I believe that the benefits to my bees outweigh the disadvantages.

And I deliberately used the word ‘bees’ rather than ‘me’ in the line above … for reasons that should become clear shortly.

What is queen clipping?

Bees have four wings. The forewings 2 are larger and provide the most propulsive power.

Each wing consists of a thin membrane supported by a system of veins. The veins – at least the larger veins – have a nerve and a trachea running along them. Remaining ‘space’ in the vein is filled with haemolymph as the veins are connected to the haemocele.

Queen ‘clipping’ involves using a sharp pair of scissors to remove a third to a half of just one of the forewings.

Done properly – by which I mean cutting enough from one wing only whilst not amputating anything else (!) – significantly impairs the ability of the queen to fly.

She will still attempt to fly but she will have little directional stability and is unable to fly any distance.

Easy to see

Easy to see – clipped and marked queen

It shouldn’t need stating 3 but it’s only sensible to clip the wing of a mated, laying queen.

Although you can mark virgin queens soon after emergence – before orientation and mating flights 4 – clipping her wing will curtail all mating activity 5.

How to clip the queen

If I know I want to mark and clip a queen I find my Turn and Mark cage, Posca pen and scissors. The cage is kept close to hand, the pen and scissors are left in a semi-shaded corner of the apiary.

Tools of the trade – Turn and Mark cage, Posca pen and sharp scissors

Then all you need to do is:

  • Find the queen, pick her up and place her in the cage. Leave the caged queen with the pen/scissors while the frame is returned to the hive 6.
  • Holding the cage in my left hand and scissors in my right I gently depress the plunger and wait until she reverses, lifting one forewing through the bars of the cage. At that point I depress the plunger a fraction more to hold her firmly in place.
  • Cut across the forewing to reduce its length by 1/3 to 1/2. Be scrupulously careful not to touch the abdomen with the scissors, or to sever a leg by accident 7.
  • Mark the queen with a single spot of paint on her thorax then leave the queen in the cage for a few minutes while the paint dries.
  • Return the queen to the hive. The simplest way to do this is to remove the plunger and lay the barrel of the cage on the top bars of the frame over a frame of brood. The workers will welcome her and, in due course, she’ll wander out and down into a seam of bees.

Returning a marked and clipped queen to a nuc

Don’t real beekeepers just hold the queen with their fingers?

Probably.

Maybe I’m not a real beekeeper 😉

I prefer to cage the queen before clipping and marking her.

I wear nitrile or Marigold gloves (or one of each) to keep my fingers propolis free. If the gloves are sticky with propolis I don’t want this coating the queen. I also prefer to keep my scents and odour off the queen 8.

The other reason I prefer to cage the queen is to reduce the potential for damaging her with the scissors.

You’d have to be even more cackhanded than me 9 to pierce the abdomen of a caged queen with the scissors. In addition, her ability to raise a hind leg up and through the bars of the cage is restricted. In contrast, when held in the fingers, both these can be more problematic.

Mr Blobby goes beekeeping

Finally, briefly caging the queen allows me to use both my hands for other things – like completing the colony inspection without any risk of crushing the queen.

Yes, I could unglove before clipping and marking the queen, but it’s almost impossible to get nitriles back on if your hands are damp.

Does queen clipping stop swarming?

No.

Is that it? Nothing more to say about swarming?

OK, OK 😉

If the queen is not clipped the colony will typically swarm on the first suitable day after the new queen cell(s) in the hive are sealed. The swarm bivouacs nearby, the scout bees find and select a suitable new nest site and the bivouacked swarm departs – often never to be seen again – to set up home.

I’ll return to the subsequent fate of the swarm at the end of this post.

A colony with a clipped queen usually swarms – by which I mean the queen and up to 75% of the workers leave the hive – several days after the new queen cell(s) is capped.

Ted Hooper 10 claims a colony headed by a clipped queen “swarm(s) when the first virgin queen is ready to emerge” 11. This is not quite the same as when the first virgin emerges.

Since queen development takes 16 days from the egg being laid this theoretically means you could conduct inspections on, at least, a fortnightly rota. Unfortunately, it’s not quite that simple as bees could choose an older larva to rear as a new queen.

Hooper has a page or so of discussion on why a 10 day inspection interval achieves a good balance between never losing a swarm and minimising the disturbance to the colony. 12.

What happens when a colony with a clipped queen swarms?

A clipped queen cannot fly, so when she leaves the hive with a swarm she crashes rather unmajesterially 13 to the ground.

In my experience there are two potential outcomes:

  • the bees eventually abandon her and return to the hive. Usually the queen will perish. They are still likely to swarm when the virgin queen(s) emerge. All together now … “queen clipping does not stop swarming”.
  • the queen climbs the leg of the hive stand and often ends up underneath the hive floor. The bees join her. In this case you can easily retrieve the swarm together with the clipped queen. Temporarily set aside the brood box and supers and knock the clustered bees from underneath the floor into a nuc box.

I spy with my little eye … a clipped queen that swarmed AND was abandoned by the bees. It’s a tough life.

Sometimes both the queen and the swarm re-enter the hive (or I return them to the hive). In my experience these queens often don’t survive, presumably being slaughtered by a virgin queen.

So that addresses the swarming issue 14. What about the more contentious aspect of queen clipping causing pain?

Do queens feel pain?

I discussed whether bees feel pain a couple of years ago. The studies on self-medication with morphine following amputation are relevant here. Those studies were on worker bees, but I’ve no reason to think queens would be any different 15. I’m not aware of more recent literature on pain perception by honey bees though it’s well outside my area of expertise, so I may have missed something.

Therefore, based upon my current understanding of the scientific literature, I do not think that worker bees feel pain and I’m reasonably confident that queens are also unlikely to feel pain.

It’s worth noting here that it’s easy to be anthropomorphic here, particularly since we (hopefully) all care about our bees. Saying that your bees are happy, or grumpy or in pain, because it’s a nice day, or raining or you’ve just cut her wing off, are classic examples of ascribing human characteristics to something that is non-human.

We might think like that 16 but it’s a dangerous trap to fall into.

Is clipping queens cruel and barbaric?

According to my trusty OED, cruel means “Of conditions, circumstances: Causing or characterized by great suffering; extremely painful or distressing.”

Therefore, if clipping a queen’s wing causes pain and distress then it should be considered a cruel practice.

I’ve discussed pain perception previously (see above). If bees, including queens, do not feel pain then clipping her wing cannot be considered as cruelty.

Someone who is barbaric is uncultured, uncivilised or unpolished … which surely couldn’t apply to any beekeepers? In the context of queen clipping it presumably means a practise known to cause pain and distress.

Having already dealt with pain that brings me to ‘distress’.

How might you determine whether a queen with a clipped wing is distressed?

Perhaps you could observe her after returning her to the colony? Does she run about wildly or does she settle back immediately and start laying again?

Returning a marked and clipped queen – no apparent distress, just calmly disappearing into a seam of bees

But, let’s take that question a stage further, how would you determine that it was the clipped wing that was the cause of the distress? 17

That pretty much rules out direct observation. Queens are naturally photophobic 18 so you’d need to use red light and an observation hive. I’m not aware that this has been done.

Instead, scientists have observed the performance of colonies headed by clipped and unclipped queens. I’d argue that this is a convenient and suitable surrogate marker for distress. You (or at least I) would expect that a queen that was in distress would perform less well – perhaps laying fewer eggs, heading a smaller colony that collected less honey etc.

Are clipped queens distressed? Is their performance impaired?

Which finally brings us to some science. I’ve found very little in the scientific literature about queen clipping, but there is one study dating back over 50 years from Dr I.W. Forster of the Wallaceville Animal Research Centre, Wellington, New Zealand 19. I can’t find a photo of Dr. Forster, but there’s an interesting archive of photos from the WARC provided online from the Upper Hutt City Library.

Wallaceville Animal Research Centre staff photo 1972. Presumably Dr. Forster is somewhere in the group.

The paper has a commendably short 37 word results and discussion section 😉  20

The study involved comparing performance of colonies headed by clipped or unclipped queens over three seasons (1968-1970), a total of 124 colony years. They 21 scored colony size (brood area), honey per hive (weight) and the the number of supersedures.

I’ll quote the single sentence in the results/discussion on honey production in its entirety:

There was no significant variation in honey production between hives headed by clipped and unclipped queens.

Forster 22 didn’t specifically comment on colony size/strength in the discussion. Had it differed significantly some convoluted explaining would have been needed to justify the similarity in honey production.

Comparative colony strength of colonies headed by clipped or unclipped queens.

And it doesn’t.

Each column represents the average number of frames of brood in 6-29 colonies headed by clipped or unclipped queens. Statistically there’s no also difference in this aspect of performance (entirely unsurprisingly).

Colonies headed by clipped queens are not impaired in strength or honey production, so I think it’s reasonable to assume that the queen is probably not distressed.

Do clipped queens get superseded (more) frequently?

I suspect most beekeepers underestimate supersedure rates in their colonies.

I clipped and marked a queen last weekend. In early August last year my notes recorded her as ’BMCLQ’ i.e. a blue marked clipped laying queen 23. In mid/late April this year she was unmarked and unclipped … and stayed that way until it was warm enough to rummage through the hive properly.

She’s now a YMCLQ 24 and was clearly the result of a late season supersedure.

Every spring I find two or three unmarked queens in colonies. Sometimes it’s because I’d failed to find and mark them the previous season. More usually it’s because they have been superseded.

The Forster study recorded supersedure of clipped and unclipped queens. It varied from 10-25% across the two seasons tested (’68 and ’69) and was fractionally lower in the clipped queens (20% vs. 22.5%) though the difference was not significant.

So, to answer the question that heads this section … yes, clipped queens do get superseded 25. However, done properly they do not show increased levels of supersedure 26.

Let’s discuss swarming again

In closing let’s again consider the fate of swarms headed by clipped or unclipped queens.

If a colony with the clipped queen swarms the queen will either perish on the ground, or attempt to return to the hive. If the swarm abandons her they will return to the hive … but may swarm again when the first virgin emerges.

If she gets back to the hive she may be killed anyway by a virgin queen.

You might lose the queen, but you will have gained a few days.

If a colony with an unclipped queen swarms … they’re gone.

Yes, you might manage to intercept them when they’re bivouacked. Yes, they might end up in your bait hive. But, failing those two relatively unlikely events, you’ve lost both the queen and 50-75% of the colony.

What is the likely fate of these lost swarms?

They will probably perish … either by not surviving the winter in the first place, or from Varroa-transmitted viruses the following season.

Studies by Tom Seeley suggest that only 23% of natural swarms survive their first winter. Furthermore, the survival rates of previously managed colonies that are subsequently unmanaged – for example, the Gotland ‘Bond’ experiment – is less than 5%.

Let’s be generous … a lost swarm might have a 1 in 4 chance of surviving the winter, but its chances of surviving to swarm again are very slim.

Anecdotal accounts of ’a swarm occupying a hollow tree for years’ are common. I’m sure some are valid, but tens of thousands of swarms are probably lost every season.

Where does that number come from?

There are 50,000 beekeepers in the UK managing 250,000 colonies. On average I estimate I lose swarms from 5-10% of my colonies a season, and my swarm control is rigorous and reasonably effective 27. If there were over 25,000 swarms ‘lost’ a year in the UK I would not be surprised.

Free living colonies are not that common, strongly suggesting most perish.

Where do these ‘lost’ swarms go?

There are four obvious possibilities. They:

  1. voluntarily occupying a bait hive and become managed colonies
  2. occupy a hollow tree or similar ‘natural’ void
  3. set up a new colony in an ‘unnatural’ void like the roof space of a children’s nursery or the church tower
  4. fail to find a new nest site and perish
Natural comb

A colony settled here and subsequently perished

Of these, the first means that it’s likely the colony will be managed for pests and disease, so their longer term survival chances should be reasonably good.

In contrast, the survival prospects for unmanaged colonies are bleak. They will almost certainly die of starvation or disease.

What about the lost swarm that occupies the loft space in the nursery or the church tower? Whether they survive or not is a moot point (and the same arguments used for ‘bees in trees’ apply here as well). What is more important is that they potentially cause problems for the nursery or the church … all of which can be avoided, or certainly reduced, if the queen is clipped.

And if you conduct a timely inspection regime.

Why I clip my queens

Although it is convenient to reduce the frequency of colony inspections, that is not the main reason I clip my queens.

I clip my queens to help keep my worker population together, either to increase honey production or to provide good strong colonies for making nucs (or queen rearing).

This has the additional benefit of not imposing my swarms and bees on anyone else. Whilst I love my bees, others may not.

An additional, and not insignificant, benefit is that the prospects for survival of a ‘lost’ swarm are very low.

By reducing the loss of swarms I’m “saving the bees”.

More correctly of course, I’m preventing the loss of an entire colony. I think clipping queens is therefore an example of responsible beekeeping.

I also think queen clipping is acceptable as I’ve seen no evidence – from my own beekeeping or in the literature – that it is detrimental to the queen or the colony.

Thou shalt not kill

Finally, there are some that argue you should never harm or kill a bee. I have two questions in response to that view;

  • What do you do with a queen heading up a truly psychotic colony? Do you kill her and replace her or do you put up with the aggravation and make the area around the hive a ‘no go zone’ for anyone not wearing a beesuit?
  • How many beekeepers can honestly say that no bees are harmed when returning frames during an inspection, or putting heavy supers back on a hive? 28

I would have no hesitation in killing and replacing a queen heading an aggressive colony.

Again, I think that’s responsible beekeeping.

Similarly, although I’m as careful and gentle as I can be when conducting inspections or returning supers, to think that no bees are ever injured or killed is fantasy beekeeping.


Note

This is an emotive topic and I’ve written far more than I’d intended – that’s due to a couple of days of rain and the ‘expectant father’ wait for my new queens to start laying. I could have written half as much again.

The time spent writing meant I’ve not done an exhaustive literature search. I know that Brother Adam wrote in 1969 that he’d clipped queens for over 50 years without noticing any disadvantages. I realised during the week that my American Bee Journal subscription has lapsed so I’ve not managed to go through back issues, though I have searched almost 30 years of correspondence on Bee-L. If an ABJ turns up more relevant information I’ll revisit the subject.

Timing is everything

Synopsis : The invariant timings of brood development dictate many beekeeping events including colony inspections, queen rearing and Varroa management. It makes sense to understand and exploit these timings, rather than ignore or fight against them.

Introduction

There are some inherent contradictions involving timing in beekeeping that can confuse beginners. Actually, they can confuse anyone – beginner or old lag 1 – who doesn’t appreciate the considerable flexibility of some of the timings and the near-total inflexibility of others.

I think that many of the inherent difficulties in beekeeping e.g. judging when to do what to the colony, comparing seasonal differences or deciding whether intervention is needed or ill advised, are due to a lack of appreciation of the relative importance of some of these timings.

I gave an overview of some of the ‘flexible timings’ a couple of weeks ago when discussing the year to year climatic variation that compounds differences caused by latitude.

The onset of brood rearing in midwinter, the crossover date 2, the start of swarming and the timings of the major and minor nectar flows can all vary from year to year.

To appreciate these you need to be observant, but predicting their impact can be tricky. Some are multi-factorial e.g. colony strength and development in a warm, dry spring can be different to a warm, wet spring.

I’ve probably written enough about some of these flexible events already so will instead focus on some of the ‘inflexible timings’ that dictate the activity of the colony and, by extension and through necessity, the activity of the beekeeper.

In many ways these are easier to understand.

By definition, they are invariable 3.

Less to remember … but remembering them is important 😉

The environment

Those ‘flexible timings’ I refer to above mainly reflect the year-to-year climatic variation – warm springs, Indian summers, hard winters.

In contrast, inside the hive the environment is remarkably stable.

It can vary from 4°C to 40°C outside – even on a single day – but the temperature in the brood nest is controlled within a narrow 33-36°C range.

Hives in the snow

Freezing outside, 34.5°C in the broodnest

In fact, in the very centre of the brood nest – the region where pupal development takes place – it is as near as makes no difference 34.5°C.

The workers thermoregulate the hive, heating the comb where needed 4 or evaporating water to cool the hive.

With hive monitoring equipment and suitably placed thermometers you can tell when a colony shifts into brood rearing mode in the spring – the varying temperature of the clustered bees increases and stabilises to a near-invariant 34 and a bit degrees Centigrade.

Brood rearing starts ...

Brood rearing starts – indicated by stabilisation of brood temperature (arnia.co.uk)

The image above is from Arnia who make hive monitoring equipment. The key phrase in the sentence above is ‘suitably placed thermometers’. You tend to have only one or two and they can’t be everywhere, so it’s easy to miss the onset of brood rearing.

Temperature, behaviour and neuroanatomy

Stable temperatures are important for brood development. Worker bees reared at 32°C are less good at waggle dance communication. They only complete about 20% of the circuits (less enthusiastic) and exhibit more variability in the duration of the waggle phase (the distance component) when compared to bees reared at higher temperatures within the ‘normal’ range 5.

In further studies, bees reared at abnormally low or high temperatures (though varying by only 1-2 °C from normal hive temperatures) exhibited differences in neuroanatomical development 6. Of the regions of the brain studied, the numbers of microglomeruli within the mushroom bodies of the brain, areas involved in memory and learning, differed significantly when the pupation temperature was as little as 1°C over or under 34.5°C.

Despite these behavioural and developmental differences, the emergence rate and the duration 7 of development are somewhat less influenced by brood nest temperature.

Influence of temperature on pupal brood development – duration (left axis) and emergence rate (right axis)

In the graph above the duration of pupal development is 10-11 days between 34.5°C and 37°C, and eclosion (emergence) rates exceed 90% from 31-36°C.

Correct development of honey bee workers therefore requires a stable brood nest temperature.

As a consequence of this stability the duration of the development cycle is highly reproducible and – more to the point – predictable.

Before discussing the development cycle it’s worth noting that queens and drones are reared under similarly stable conditions. I’ve discussed the influence of temperature on queen development before but am unaware of similar studies on drones.

The development of workers

The graph above shows the influence of temperature on the duration of pupal development. This is not the same as sealed brood development. 8. The 10-11 days shown above needs to be extended by 2 days (48 hours) when considering the more beekeeper-friendly concept of sealed or capped brood.

Under normal conditions worker development takes 21 days. Three days as an egg, five as an open larva and 13 capped 9.

During those 21 days bees go through a series of six molts between five developmental stages termed instars. The first molt is the egg hatching, molts 2-4 occur during the first few days of larval feeding. Molt 5 is the change from the pre-pupal capped larva to the pupa and the final molt occurs at emergence.

Once the brood is capped there’s nothing much the beekeeper needs to worry about (or can do). In contrast, the early days of worker development involve at least one notable event 10.

Young larvae and queen rearing

The worker larva is fed progressively, which essentially means almost all the time. Nurse bees visit the larva thousands of times, initially feeding a mix of secretions from the hypopharyngeal and mandibular glands. The diet is then switched to one lacking the mandibular gland component and is finally supplemented with pollen and honey.

This dietary switch takes place around day three of larval development and effectively seals the fate of the developing bee as a worker.

Before day three of larval development, larvae destined to be workers or queens receive the same diet. After day 3 a series of genetic switches are ‘pushed’ that prevent the larva developing into a queen.

This means that larvae of less than three days old are needed to produce new queens. A terminally queenless colony will sometimes attempt to rear a new queen from an older larva (if nothing else is available) but these are usually substandard – so called scrub queens – or fail.

The adult worker

After emergence the worker fulfils a number of roles for the colony; nurse bee, comb builder, guard, scout, forager etc. The precise timings of these are flexible. Not all bees of the same age have the same role, and they can even be reversed. However, as far as practical beekeeping is concerned 11, the only other timings that really matter are the longevity of workers; in the summer this is about 6 weeks and in the winter, 6 months.

The timings to remember – workers

The full development cycle takes 21 days. Larvae more than 3 days old 12 are unsuitable for queen rearing (and, as I shall discuss in a future post, better queens are produced from younger larvae). The adult worker spends the first half of her 6 week life within the hive, and the last 3 weeks as a forager. Winter bees live for many months.

The development of queens

The development cycle of the queen bee is shorter than that of the worker because their diet is much richer. Of course it’s not quite that straightforward (it wouldn’t be, would it?). Because of the diet there are a number of genetic pathways turned on or off in the developing queen that ensure she is ‘fit for purpose’ on emergence. The developing queen goes through the same number of molts and instars, but they are compressed in time.

Sealed queen cell ...

Sealed queen cell

The queen cell is sealed on the ninth day of development, the fifth day after hatching from the egg, and the queen emerges on the 16th day.

The adult queen

Relative to workers and drones the queen appears almost immortal. A queen may live for at least three years and, if well looked after, longer than that. Most of this aftercare is provided by the hive, but the beekeeper can influence things as well. High quality ‘breeder queens’ are often kept in nucs and discouraged from laying excessive amounts of brood. This prolongs their effective lifespan.

As far as timings are concerned – and assuming we’re not dealing with a $500 breeder queen – the only three things that are important relate to the mating of the queen.

After emergence the queen needs to reach sexual maturity before she can go on her mating flights, this takes 5-6 days. Once mated there is a further delay of 2-3 days before the queen starts laying. The final number to remember is that adult queens older than 26-33 days are too old to mate.

The timings to remember – queens

The full development cycle takes 16 days. The cell is capped on the 9th day after the egg was laid 13. Upon emergence, queens take 5-6 days before they are mature enough to mate. A mated queen starts laying 2-3 days after returning from her last mating flight. If they’re not mated within about 4 weeks of emergence then they’ve blown it.

Therefore, the minimum duration to go from newly laid egg to mated, laying queen is at least 23 days. Alternatively, assuming a 2-3 day old larva is available, this time period is reduced to about 18 days.

From emergence, it’s theoretically possible 14 to have a mated, laying queen within 8 days.

However, in my experience, queen mating usually takes longer than these minima … and always longer than I want. Other than confirming emergence I always leave a new queen a minimum of a fortnight before checking if she’s laying, and longer if the weather has been unsuitable for mating.

The development of drones

Like teenage boys getting up late and then doing nothing other than lounge around eating and thinking about sex 15, the drone takes the longest to emerge. The full development cycle from the laying of an unfertilised egg to emergence takes 24 days.

As before, the number of molts and instars are the same as undergone by queens and workers.

The adult drone

Like the queen, the drone needs to become sexually mature before going on a mating flight. This takes 10-12 days after emergence. The drone has a finite lifespan and usually lives no more than about a month during the summer.

Drones that successfully mate with a queen prematurely die. Those that don’t mate either die trying or are ejected from the hive by the workers at the end of the season.

It’s not unusual to hear beekeepers talk about finding drones overwintering. I’m not aware whether these are exceptionally long-lived drones laid by the queen the preceding summer/autumn, or laid by a failing queen during the winter, or even by laying workers in a queenless colony overwinter 16.

The timings to remember – drones

The full development cycle takes 24 days. It takes about five weeks between the appearance of the first eggs in drone cells and the presence of sexually mature drones in the hive.

Swarming cannot happen until there are drones in the area, so it’s worth keeping an eye of drone brood production.

Hive inspections and queen rearing

So, there you have it, just a few numbers to remember … and, more importantly, to understand their significance for beekeeping.

Unusually I’ve prepared an oversized figure to illustrate these timings 17 with colour-coding worker, queen and drone events in green, blue and red respectively.

Worker, drone and queen development and key post-emergence timings

Note that some timings have dual significance. Worker larvae no more than three days old (day 6 – in green) can be reared as queens with suitable feeding.

Hive inspections … and caveats

It should now be obvious why regular weekly hive inspections are recommended in the time leading up to and during the peak swarming period.

If there are no charged queen cells – those containing eggs or developing larvae – during an inspection then any that do develop in the seven days before the next inspection will still not be sealed (and therefore the colony will not have swarmed).

This assumes that the colony swarms on or after the day that the queen cell is sealed.

Sometimes – rarely – the swarm goes early, apparently leaving only uncapped swarm cells. When I’ve had this happen a thorough examination of the brood frames has sometimes turned up a sealed cell, tucked away against a sidebar, that I’d missed in the previous inspection … the colony had not swarmed early, I’d 18 not been observant enough.

With a well-populated colony it’s sometimes necessary to shake all the bees off each frame to be certain there are no queen cells lurking under the ruffled curtain of workers.

Not all queen cells are this obvious

Colonies containing clipped queens tend to delay swarming (but they certainly still swarm) and you can usually get away with a 10 day interval between inspections. Furthermore, since the clipped queen cannot fly, even if the colony does swarm they usually return and end up clustered underneath the OMF after she has crawled back up the leg of the hive stand.

Outside the main swarming period inspections can be much less frequent. I usually inspect only once or twice between mid-July and the end of the season.

Queen rearing

One of my (few) poorly tempered hives unexpectedly contained several 3+ day old queen cells last Sunday. I made up a nuc with the old queen, destroyed all the queen cells and closed up the hive.

They will produce more queen cells 19, but they cannot swarm as there’s no queen.

At my inspection this Sunday I will destroy all the new queen cells.

The genetics of this colony are (at best) ‘undesirable’ 🙁 

Since there’s been no laying queen in the hive for 7 days there cannot now be any larvae young enough to be reared as a new queen 20. Therefore, having destroyed all the queen cells, I’ll add a frame of eggs and larvae from a (well-behaved and so genetically desirable) neighbouring colony 21.

If they want a new queen 22 they will rear one from this donated frame.

The 23 egg in the graphic above is the earliest you can expect a laying queen. In reality – as explained above – it usually takes longer. A minimum of 30 days from egg to egg-producing queen is perhaps more dependable.

Therefore, in around 24 to 30 days – and most likely the latter – this colony will have a new queen which will hopefully improve their behaviour.

The timing of Varroa treatment(s)

But think about what’s happening to the rest of the brood in that colony.

The last eggs laid in the colony was on the Sunday the 1st of May. By the 21st of May all the worker brood will have completed development and emerged. By the 24th of May all the drones will have emerged.

The colony should therefore be broodless in the last week of May.

Even if the new queen is laying by then (some chance!) she won’t have produced any sealed brood.

If needed I could use this 7 day window of opportunity to treat the colony with oxalic acid and reduce the Varroa levels in the hive.

It’s unlikely I’ll need to as the mite numbers have been low this season. However, it’s very reassuring that I have the option should I need it 24.

Adding a Varroa board to check mite drop

But … hang on a moment.

Why did I write that the colony only should be broodless?

What about the eggs and larvae on the frame I added from the donor colony? 25

These will be up to one week younger than any brood in the queenless colony.

Potentially those young eggs and larvae will close that ’window of opportunity’.

Perhaps the easiest way around this is to excise one good sealed queen cell from the donated frame and leave it in queenless colony, and then remove the donated frame and use it elsewhere.

If the colony produces several good quality queen cells it’s likely that I’ll chop them all out and make up some nucs – queen rearing without all the graft.

Literally 😉

Conclusions

I’ve written far more than I intended but I think this reflects the importance of the – effectively invariant – timings of brood development.

These dictate so many of our beekeeping activities that it makes sense to learn to work with them, rather than forever struggling against them.

With good observation and regular colony inspections – weekly during the the main part of the season – there should be little or no chance of losing a swarm.

Furthermore, should a colony show signs of swarm preparation, timely intervention coupled with an appreciation of the timings of brood development, mean you have the opportunity to conduct both stock improvement and mite management.

Nice one 😉


 

Brood in all stages

Synopsis : The presence of brood in all stages (of development) is an important indicator of the state of your colony. Is it queenright? Is it expanding or contracting? Quantifying the various developmental stages – eggs, larvae and pupae – is not necessary, but being able to determine changes in their proportions is very useful.

Introduction

There’s something very reassuring about the words ’brood in all stages’ to a beekeeper, or at least to this beekeeper.

It means, literally, that there is brood in all stages of development i.e. eggs, larvae and pupae.

Record keeping

Update the notes …

As far as I’m concerned, it’s such an important feature of the hive that it gets its own column in my hive records, though the column heading is conveniently abbreviated to BIAS.

And BIAS is what I’ll mostly use for the remainder of this post, again for convenience.

Why is it so important?

Why, when you conduct an inspection of the colony, is the presence of BIAS so important?

And why should you be reassured if it is present?

Broadly I think there are two reasons:

  • it tells you the likely queenright status of the hive. Is there a laying queen present?
  • (with a little more work) you can determine the egg laying rate of the queen and whether it’s changing. This is important as it provides information of the likely adult worker strength of the colony in a few weeks’ time. Are there going to be enough bees to exploit the expected nectar flow? Will there be sufficient young bees for queen rearing?

Of course, detailed scrutiny of the eggs, larvae or pupae in the hive can provide a wealth of information about the health of the colony. I will mention one specific example later, but it’s not the main focus of this post.

The development cycle of the honey bee

The post last week emphasised the variation – from year to year – in the climate 1. In contrast, despite the temperature fluctuating outside the hive, the environment inside the hive is remarkably stable. Partly as a consequence of this the development of the brood is very predictable.

Honey bee development

Honey bee development

Worker bees take 21 days to develop, by which I mean that an egg laid on day 1 will – assuming development is successful – result in an adult worker emerging 2 on day 21. There can be a few hours variation, largely influenced by temperature, but as far as we need to be concerned here worker bee development takes 21 days.

Days 1 to 3 are spent as an egg. The egg then hatches to release a larva which is fed for a little over five days before capping. The developing bee then pupates for about 13 days before emergence.

For simplicity it helps to think of the development cycle as 3 days as an egg, 5 days as a larva and 13 days as a pupa. EEELLLLLPPPPPPPPPPPPP 3 or 3:5:13 … I’ll return to these numbers later.

In fact it’s a little more complicated than that. The larva actually pupates after the cell is capped, so it exists in two states; an open larval stage during which is is fed by nurse bees and a capped larval stage which is more correctly termed the pre-pupal stage. The larva then metamorphoses into a pupa within the capped cell.

None of this really matters as far as your interpretation of the ’brood in all stages’ you see in the colony during a regular inspection. However, it’s reassuring to know that there’s lots of complicated things with weird names and confusing terminology going on in there … which I’ve simplistically distilled to 3:5:13.

But, if you do want to know more you could have a read of this article by Rusty Burlew which also appeared in the American Bee Journal 160:509-511 (2020).

Queenright or not?

So, if there are eggs present there must be a queen present, right?

Wrong 🙁

But it is more than likely 🙂

In fact, if there are eggs, larvae and sealed brood present i.e. BIAS, then you can be pretty confident there is a queen present.

Or, more correctly, that there was a queen present within the last 3 days.

If an egg takes three days to hatch then it is possible that the queen laid the eggs and has subsequently disappeared.

For example, the colony may have swarmed in the intervening period.

Alternatively, during that ’quick-but-entirely-unnecessary-peek’ you took inside the hive two days ago you inadvertently crushed the queen between the bars of a Hoffman frame.

Oops … eggs but no queen 🙁

Slim Jim Jane and pre-swarming egg laying activity

When a colony swarms the mated, laying queen leaves with the swarm. To ensure that she can fly sufficiently well she is slimmed down in the days before swarming and her egg laying rate slows significantly.

Despite searching – both the literature and my own memory banks 4 – I’ve failed to find any detailed information on how long before swarming her laying rate slows. It appears as though she generally does not stop laying before swarming, but it’s down to just a trickle (if that’s the right word) in comparison to when she’s ‘firing on all cylinders’.

Queen cells and laying workers

The other telltale sign that a swarmed colony leaves is the presence of one or (usually) more queen cells. Typically some of these are capped, with the colony swarming on the first suitable day after the first cell is capped.

Queen cells – good and bad

So, back to your colony that may or may not be queenright … the presence of only a small number of eggs compared to capped brood levels and one or more queen cells suggests that they have swarmed within the last 3 days.

In contrast, If there are ‘normal looking’ eggs present, even if few in number, and you didn’t have a ’quick-but-entirely-unnecessary-and-actually-a-bit-clumsy-peek’ two days ago, it’s likely that your colony is queenright.

I prefixed eggs (above) with ‘normal looking’ because there is one further situation when the colony has no queen but there are eggs present. That’s when the colony has developed laying workers.

Under certain conditions unmated worker bees can lay unfertilised eggs.

However, in contrast to the queen, workers have short, dumpy abdomens and cannot judge whether the cell already contains an egg. As a consequence they lay multiple eggs in cells and many of these eggs are in unusual positions – rather than being central at the bottom of the cell they are on the sidewalls, or the sloping edges of the base of the cell.

Drone laying workers ...

Multiple eggs per cell = laying workers (usually)

These eggs are usually laid in worker cells. Being unfertilised they can only develop into drones, and since they are in cells that are too small for drones they end up protruding like little bullets from the comb.

Laying workers ...

Laying workers …

They are also scattered randomly around the frame, rather than being in the concentric ring pattern used when the queen lays up a frame.

BIAS and the queenright status of the colony

So, let’s summarise that lot before (finally) getting back to 3:5:13.

If:

  • there is BIAS and no queen cells present and you’ve not disturbed the colony in the last few days … then the colony is most likely queenright. Yes, there’s an outside chance she recently dropped dead, but it’s much more likely that you just can’t find her. Don’t worry, the presence of BIAS and the other supporting signs tell you all you need to know … there’s a queen present and she’s laying. All is good with the world. Be reassured 🙂
  • there is BIAS and capped queen cells … then it’s likely they swarmed very recently 🙁
  • eggs are present, possibly together with some small, unsealed queen cells and you had a ’quick-but-entirely-unnecessary-and-frankly-a-bit-stupid-in-retrospect-peek’ two days ago … then all bets are off. The colony may or may not be queenright. Only inspect when you need to and be very careful returning frames to the hive 5. If you didn’t open the hive in the last few days (and accidentally obliterate the queen) the presence of BIAS and unsealed queen cells usually means that the colony is queenright but is preparing to swarm. Swarm control is urgently needed.
  • multiple eggs are present in strange places in cells, coupled with scattered bullet-shaped capped cells (and oversized larvae in worker cells) … then there are laying workers present. Your colony is not queenright. Technically I suppose there is brood in all stages, but the brood looks odd. But there’s somethings else as well … laying workers develop in the absence of pheromones produced by open brood (larvae). Therefore to develop laying workers a colony transitions through a period when there is not brood in all stages. In my experience laying workers usually develop after a colony experiences a protracted period when it is totally broodless i.e. no eggs, larvae or pupae.

Let’s move on.

3:5:13

If the queen is laying at a steady rate i.e. the same number of eggs per day, then the ratio of eggs to larvae to sealed brood will be about 3:5:13.

This means for every egg present you should expect to find just less than two larvae and slightly more than four capped worker cells.

I’m not suggesting you count them, but you should be able to judge the approximate proportions of the three brood types during your inspections.

This is more complicated than it sounds (and it already sounds quite complicated). The queen lays eggs in an expanding 3D rugby-ball shaped space – the ellipsoid broodnest – moving from frame to frame. Consequently, individual frames will contain different proportions of eggs, larvae and capped pupae, but the overall proportions should work out to be about 3:5:13.

And this is where things start to get a little more interesting 6.

A picture is worth a thousand words

I’ve drawn some simple Excel charts to illustrate some of the points I want to make. For each of the charts I’ve assumed the queen lays at 1000 eggs per day for the first 5 days and then she either stops altogether (perhaps one of those ’quick-but-entirely-unnecessary-and-frankly-idiotic-peek’ queen-meets-Hoffman-frame scenarios), or either speeds up or slows down her laying rate by 200 eggs per day.

The numbers don’t matter, just focus on the proportions of different classes of brood.

Speeding up

If there are more eggs and larvae expected – when compared to the levels of capped brood – then the laying rate of the queen is increasing. For example, here is what happens when she increases her laying rate from 1000 to 2000 eggs/day over 5 days.

Queen increasing her laying rate

The line graph is perhaps less clear than a simple plot of the percentages of the three types of brood. Note the relative reduction in capped brood (pupae) around day 15.

Changes in percentages of brood as queen increases her laying rate

If this occurs it means that the colony has the resources – pollen and nectar – to expand and that you’ll have more young adult workers in another fortnight or so, and an increased foraging force in 4-5 weeks. These things are important if you are thinking about the ability to exploit a summer nectar flow, or perhaps to rear queens in the colony.

Slowing down

Conversely, if eggs and larvae are much less than about 40% of the total brood 7, then the queen is reducing her laying rate. Perhaps there is a dearth of nectar or pollen? Does the colony have sufficient stores? Do you need to feed – little and often – some thin syrup to stimulate brood rearing?

Queen slowing her laying rate (e.g. prior to swarming)

Or is the colony slimming down the queen in preparation for swarming? Do they have sufficient space? Is the colony backfilling brood cells with nectar?

Changes in percentage of brood as the queen slows her laying rate (e.g. prior to swarming)

Note how 12 days after the Q slows her laying rate (assuming she stops entirely 8 ) then the only things left in the colony is sealed brood.

Queen-meets-Hoffman-frame scenario

This is essentially the same as slowing down, except it all happens more abruptly.

Disappearance of brood after the queen abruptly disappears

If you inadvertently kill the queen the colony very quickly runs out of eggs and larvae. Using the emergency response you would expect the colony to raise queen cells promptly.

Estimating brood area during inspections

I’m not suggesting you count eggs, larvae or sealed brood. Inspections are best when they are relatively non-intrusive. It disturbs the colony, it can agitate the bees and it changes the pheromone concentrations and distribution which control so much of what happens in the hive.

But it is worth learning how to determine whether there is more or less sealed brood than open brood and eggs.

Scientists have developed a number of ways to accurately quantify colony strength and population dynamics.

The classic approach, developed between the 1960’s and 1980’s is termed the Liebefeld Method and was nicely reviewed by Ben Dainat and colleagues in a recent paper in Apidologie 9. More recent strategies include the use of digital photography and image analysis, either using ImageJ or semi-automated python scripts such as CombCount.

But none of those approaches are really practical during a normal colony inspection.

I guesstimate the relative proportions of eggs + larvae and sealed brood, and also try and work out the approximate total levels of BIAS present in the colony.

If about 60% of the brood is sealed and there are 3 full frames and about 6 half frames of brood in all stages I would be happy that the colony was queenright, that the laying rate of the queen was probably stable and I’d record the total levels of BIAS as 6 (full frames in total).

Eyeballing sealed brood levels

When you get a frame like the one below it’s easy to work out how much brood it contains.

That'll do nicely

That’ll do nicely …

It’s as near as makes no difference one full frame (assuming the other side looks similar).

But most frames contain a more or less oval brood pattern, some of which may have already emerged.

Brood frame

In these instances it helps to guesstimate what halves, quarters, eighths look like. Or use the diagrams of brood patches on Dave Cushman’s site to work out the approximate total levels.

It’s also worth remembering that the presence of adult bees on the frames will confound things.

Lots of capped brood … somewhere under all those bees

To properly judges the levels of brood you need to shake the bees off the frames. This adds even more disruption to the inspection and I only ever really do it in two specific situations:

  • when looking for signs of brood disease, such as foulbrood
  • when I have to find every single queen cell in the colony

During normal inspections I work with what I can see … and if I need to see more (eggs, larvae or sealed brood) I gently run the back of my hand over the attached workers, or blow gently on them. Both these methods encourages them to move aside, without the ignominy of being dumped in a writhing heap at the bottom of the brood box.

In conclusion

As described – other than the Liebefeld Method – estimating the amount of brood in all stages (BIAS) is a rather inexact process. However, despite this, it’s a useful exercise that helps you judge the state of the colony, and gives you some insight into what is likely to happen over the next few weeks.

And, let’s face it, anything that gives us a better idea of what to expect is useful 😉


Note

Eagle eyed readers will realise there’s a slight glitch in the numbers graphed above. I realised this as silly o’clock 10 this morning and haven’t had time to go back and butcher the spreadsheet and redraw all the graphs. My error does not fundamentally change the patterns observed, but just alters the percentages slightly. I’ll update them once I’ve had a nap 😉

Latitude and longitude

Synopsis : Bees don’t use a diary. Colony development is influenced by local environmental conditions. These are largely determined by latitude and longitude but also vary from year to year. Understanding these influences, and learning how to read the year to year differences, should help you judge colony development. You’ll be better prepared for swarm prevention and control, and might be able to to identify minor problems before they become major problems.

Introduction

Writing a weekly post on beekeeping inevitably generates comments and questions. Over the last 5 years I’ve received about 2500 responses to posts and at least double that in email correspondence. That works out at ~30 comments or questions a week 1.

Every one of them – other than the hate mail and adverts 2 – has received a reply, either online or by email.

Some are easy to deal with.

It takes just seconds to thank someone for a ”Great post, now I understand” comment, or to answer the ”Where do I send the cheque? question.

Others are more difficult … and the most difficult of all are those which ask me to diagnose something about their hive.

I almost always prefix my response by pointing out that this sort of online diagnosis is – at best – an inexact art 3.

Patchy brood pattern

Patchy brood & QC’s …

Think about it … is your definition of any of the following the same as mine?

  • a strong colony 4
  • an aggressive colony
  • a dodgy-looking brood pattern 5
  • a ‘large’ queen cell

Probably not.

Engaging in to and fro correspondence to define all these things isn’t really practical in a week containing a measly seven 24 hour days.

Geography

However, having stated those caveats, there’s still the tricky issue of geography.

Many correspondents don’t mention where the hive is – north, south, east, west (or in a couple of instances that they are in the southern hemisphere 6).

Location has a fundamental impact on your bees. The temperature, rainfall, forage availability etc. all interact and influence colony development. They therefore determine the timing of what happens when in the colony.

And so this week I decided to write a little bit about the timings of, and variation in, environmental events that influence what’s going on inside the hive.

I’ll focus here on latitude and temperature as it probably has the greatest influence. My comments and examples will all be UK based as it’s where a fraction over 50% of the readers are, but the points are relevant in all temperate areas.

Latitude

Temperate climates – essentially 40°-60° north or south of the equator – experience greater temperature ranges through the year and have distinct seasons (at least when compared with tropical areas). Whilst latitude alone plays a significant role in the temperature range – smaller nearer the equator – the prevailing wind, altitude, sea currents and continentality 7 also have an important influence.

For starters let’s consider the duration of the year during which foraging might be possible. I’ll ignore whether there’s any forage actually available, but just look at the temperature over the season at the northern and southern ends of mainland Great Britain.

I arbitrarily chose Thurso (58.596°N 3.521°W) and Penzance (50.119°N 5.537°W) for these comparisons. Both are lovely coastal towns and both are home to native black bees, Apis mellifera mellifera 8.

The lowest temperature I have observed my native black bees flying on the west coast of Scotland was about 8°C 9. So, let’s assume that the ‘potential foraging’ season is defined by an average maximum daily temperature above 8°C.

How do Penzance and Thurso compare?

Thurso – average Max/Min temperatures (°C)

In Thurso there are eight months (November just squeezed in by 0.1°C) where the average maximum daily temperature exceeds 8°C.

Penzance – average Max/Min temperatures (°C)

In contrast, every month of the year in Penzance has an average maximum daily temperature exceeding 8°C.

Thurso and Penzance are just 950 km apart as the bee flies.

Forage availability

I don’t have information on the forage available to bees in Penzance or Thurso, but I’m sure that gorse is present in both locations. The great thing about gorse is that it flowers all year, or – more accurately – individual, genetically distinct, plants can be found every month of the year in flower.

Based upon the temperature it’s possible that Penzance bees could forage on gorse in midwinter and so be bringing fresh pollen into the hive for brood rearing.

The gorse is in flower … somewhere under there

However, further north, gorse might be flowering but conditions may well not be conducive for foraging.

Inevitably, warmer temperatures will extend the range of forage types available, so increasing the time during the year in which brood rearing can occur 10.

In reality, at temperatures below 12-14°C bees start to cluster 11 and bees chilled to 10°C cannot fly. It’s unlikely much foraging could be achieved at the 8°C used in the examples above 12.

The point is that different latitudes differ greatly in their temperature, and hence the forage that grows, the time it yields nectar and pollen, and the ability of the bees to access it.

Brood rearing

The availability of forage has a fundamental impact on the ability of the colony to rear large amounts of new brood.

It’s not until foraging starts in earnest that brood rearing can really ramp up.

Similarly, low temperatures in autumn, reduce the availability of nectars and ability of bees to forage, so curtailing brood rearing 13.

And the ability to effectively treat mites in the winter is largely determined by the presence or absence of sealed brood. If there is sealed brood in the colony there will also be mites gorging themselves on the capped pupae. These mites are untouched by the ‘usual’ winter miticide, oxalic acid.

Therefore, effective midwinter mite management should be much easier in Thurso than Penzance.

I’ve not kept bees in either of those locations, but I know my bees in Fife (56°N) are reliably broodless at some point between late October and mid-December. Varroa management is therefore relatively straightforward, and Varroa levels are under control throughout the season.

In contrast, when I kept bees in Warwickshire (52°N) there were some winters when brood was always present, and Varroa control was consequently more difficult. Ineffective control in the winter results in higher levels of mites earlier in the season.

Brood rearing models

To emphasise the differences here are two images generated from Randy Oliver’s online Varroa Model, just showing the amounts of brood in all stages and adult bees 14. The overall colony sizes and amount of brood reared are about the same, but the ‘hard winter’ colony (no foraging for five months) is broodless for a much greater period.

The brood and bee population in hives that experience ‘default’ and ‘hard’ winters

Without knowing something about the latitude and/or the likelihood of there being capped brood present in the hive, it’s impossible to give really meaningful answers to questions about winter mite treatment.

This also has a bearing on when you conduct your first inspections of the season.

It is also relevant when comparing what other beekeepers are discussing on social media – e.g. those ’8 frames of brood’ I mentioned last week. If it’s early April and they’re in Penzance (or Perigord) then it might be understandable, but if you’re in Thurso don’t feel pressurised into checking your own colonies as it may well be too early to determine anything meaningful.

Year on year variation

But it’s now approaching late April and most beekeepers will be starting to think/worry about swarm control.

When should you start swarm prevention and, once that fails, when must you apply swarm control?

Or, if you’d prefer to take a more upbeat view of things, when might you expect your bait hives to be successful and when should you start queen rearing?

Again, like almost everything to do with beekeeping, dates are pretty meaningless as your colonies are not basing their expansion and swarm preparations on the calendar.

They are responding to the environmental conditions in your particular locality and in that particular year.

Which brings me to year on year variation.

Not every year is the same.

Some seasons are warmer than others – the spring might be ‘early’ or there might be an ‘Indian summer’. In these instances foraging and brood rearing are likely to start earlier or finish later.

One way to view these differences is to look at the Met Office climate anomaly maps. These show how different the climate – temperature, rainfall, sunshine etc. – can be from year to year when compared to a 30 year average.

Met Office anomaly charts – spring temperatures 2020 and 2021 (compared to 30 year averages)

Here are the anomaly maps for the last two springs. For almost all of the country 2020 was unusually warm. Penzance was 1.5°C warmer than the 30 year average. In contrast, over much of the country, 2021 was cooler than the 1990-2010 average.

So when considering how the colony is developing it’s important to consider the local conditions.

Those Met Office charts are retrospective … for example, you cannot see how this spring compares with previous years (at least, not yet 15.).

Rainfall

And, while we’re on the subject of anomalies … here are the rainfall charts for the summers of 2012 and 2021.

Met Office anomaly charts – summer rainfall 2012 and 2021 (compared to 30 year averages)

I suspect that both were rather poor years for honey. 2012 was – with the exception of Thurso! – exceedingly wet. My records for that year don’t include honey yield 16.

Last year was generally dry, and very dry in the north and west 17. Since a good nectar flow often needs moisture in the soil it may have been poor for many beekeepers.

It was my first full season on the west coast and the heather honey yield was disappointing (but it’s not a great heather area and I’ve nothing to compare it with … perhaps I’ll be disappointed every year?). However, I managed a record summer honey crop in Fife from a reduced number of hives. Quite a bit of this was from lime which I always think of as needing rain to get a good flow from, so perhaps the little rain we did have was at the right time.

Local weather and longitude

If you really want to know what the weather has been doing in your area you probably need something more fine-grained and detailed than a Met Office chart. There are very large numbers of ‘personal weather stations’, many of which share the data they generate with websites such as windy.com or wunderground.com.

Find one by searching these sites and you’ll be able to access recent and historical weather data to help you determine whether colony build up is slow because it’s been colder and wetter than usual. Or – if the conditions have been ideal (or at least normal) but the colony is struggling – whether the queen is failing, if there’s too much competition for forage in the neighbourhood, or if there might be disease issues.

Of course, judgements like these mean you need to have good records year on year, so you know what to expect.

My main apiary on the west coast has it’s own weather station.

Weather station and a typical west coast sky

To emphasise the local influence of prevailing winds and warm sea currents it’s interesting to note that my west and east coast apiaries – which are at almost the same latitude 18 – experience significantly different amounts of rainfall.

We had >270 mm of rain in November 2021 on the west coast, compared to ~55 mm on the east. In July 2021 the figures were 43 mm and 7 mm respectively.

All of which I think makes a good argument for rearing local bees that are better adapted to the local conditions 19. That’s something I’ve discussed previously and will expand upon further another time.

Phenology

Rainfall charts and meteorological tables are all a bit dull.

An additional way a beekeeper can observe the progression of the season, and judge whether the colony is likely to be developing as expected, or a bit ahead or a bit behind, is to keep a record of other environmental events.

This is phenology, meaning ‘the timing of periodic biological phenomena in relation to climatic conditions’.

  • Are frogs spawning earlier than normal?
  • When did the first snowdrops/crocus/willow flower?
  • Are the arrival dates of migrant birds earlier or later than normal?

I’m poor at identifying plants 20 so tend to focus on the animals. The locals – frogs, slow worms, toads, bats, butterflies, dragonflies – are all influenced by local conditions. Many don’t make an appearance until well into the beekeeping season.

Frogspawn

Or perhaps I just don’t notice them?

In contrast, the avian spring migrants appear in March and April. These provide a good indication of whether the spring is ‘early’ or ‘late’.

For example, cuckoo arrived here in 2020 (a warm spring) on the 18th of April. In 2021, a cold spring, they didn’t make an appearance until the 24th.

This year, despite January to March being warmer than average, they have yet to arrive. The majority of GPS-tagged birds are still en route, having been held up by a cold start to April 21, though some have just 22 arrived in southern Scotland.

Wheatear are also several days later this year than the last couple of seasons, again suggesting that the recent cold snap has held things back.

You can read more about arrival dates of spring migrants on the BTO website.

Beekeeping is not just bees

Much of the above might not appear to be much to do with beekeeping.

But, at least indirectly, it is.

Your bees live and work in a small patch of the environment no more than 6 miles in diameter. That’s a very small area (less than 30 square miles). The local climate they experience will determine when they can forage, and what they can forage on. In turn, this influences the timing of the onset of brood rearing in the spring (or late winter), the speed with which the colony builds up, the time at which winter bees start to be reared and the duration of the winter when it’s either too cold to forage or there’s nothing to forage on (or both).

As a beekeeper you need to understand these events when you inspect (and judge the development of) your colonies. Over time, with either a good memory or reasonable hive records, you can make meaningful comparisons with previous seasons.

If your colony had ’8 frames of brood’ in mid-April 2020 (a warm year) and your records showed they swarmed on the 27th, then you are forewarned if things look similar this season.

Conversely, if spring 2020 and this year are broadly similar (and supported by your comprehensive phenological records 23 ) but your bees have just two frames of brood then something is amiss.

Of course, the very best way to determine the state of the colony is to inspect it carefully. Understanding the environmental conditions helps you know what to expect when you inspect.


 

Early season inspections

Synopsis : The first inspection of the season needs to be late enough that the colony is expanding well, early enough that it isn’t making swarm preparations and timed to coincide with reasonable weather. Tricky. When you do open the hive you have to deal with whatever you find and leave the colony in a suitable state for the upcoming season.

Introduction

It is often tricky to decide when to do the first inspection of the season.

Too early and the bees will appear disappointingly understrength. If the weather is borderline you risk chilling the brood or the bees may get very defensive.

Or typically, both 🙁 .

Too late and the colonies may have backfilled the comb with early nectar and already started to make swarm preparations.

Early season – pollen pattie and brace comb

Twitter has been busy with beekeepers proudly announcing “8 frames of brood” or “Supers on this weekend”, without reference to local conditions or sometimes even their location.

Remember, some of these regular ‘tweeters’ are in France 😉 .

It must be particularly confusing for beekeepers starting their first spring with bees. They are desperate to start ‘real beekeeping’ again, which means opening colonies and looking for queens and brood, just like they were doing at the end of last season 1. However, they get dispirited if the colony is defensive or appears weak (less than 8 frames of brood!), and they kick themselves for not starting sooner if there are queen cells already present.

So what’s the best thing to do?

You have to use your experience and your judgement … or failing those, use some common sense.

I have reasonable amounts of experience and (sometimes) have good judgement, but I mainly rely upon a combination of common sense and local observation 2.

Together with a soupçon of opportunism.

Sometimes my timing is spot on, and sometimes I’m early or a bit late.

In these circumstances you have to deal with whatever you find in the colony and make the best of it.

A false start

Despite the incessant storms and getting trapped in a December blizzard (!) it has been a mild winter. We’ve had an unusually low number of frosts – none in January, one in February and two in March.

I was beginning to think that the season proper was going to start unusually early.

That was reinforced by the weather in the the last fortnight of March, which was fantastic.

Late afternoon sun on Beinn Resipol, Ardnamurchan, March 2022

Fantastic for March that is 3. Warm days, bees busy with the early season flowering gorse (it flowers all season), even a little nectar being collected.

About half my colonies had received an extra kilo or two of fondant in February or early March, and all received at least one pollen substitute pattie to help get them off to a good start. By late March the colonies were looking good 4.

I’m still a long distance beekeeper, with my colonies about equally split between the east and west coasts of Scotland. I therefore book hotels weeks or months in advance for some of my beekeeping. Predicting the weather that far ahead is impossible, so it involves some guesstimates and, inevitably, some beekeeping in unsuitable weather.

Early season is usually particularly difficult, but by late March this year I was feeling quietly confident 5.

And then April started with several hard frosts and the temperature dropped to single digits (°C) for days at a time.

Still, I was committed to make the trip to Fife … and I’m pleased I went.

And they’re off!

I have a couple of apiaries in Fife. I usually visit both on each of successive days on a trip. That allows me to store all the equipment in one apiary, without having to transport it back and forth across Scotland. This works well and means I can cope with most eventualities.

It was 9°C with a chilly easterly when I got to the first apiary. On removing the lid on the first hive it was very clear that I was (fashionably, of course 😉 ) late to the party … the bees were already building brace comb in the headspace between the top bars of the frame and the underside of the inverted crownboard.

That’s what you’ve been getting up to …

I had no spare equipment with me 6, but it was obvious that the colony needed a queen excluder and a super … as well as quite a bit of tidying up.

Which was going to be the story of the trip.

With infrequent apiary visits – either enforced by distance (in my case) or imposed by bad weather (not unusual in spring) – you have to deal with whatever situations you find when you have the opportunity to open hives.

It was clear from the state of this colony, which was on a single brood box, that the bees had expanded well during the warm weather and were going to rapidly run out of space.

Other colonies in the same apiary were on double brood boxes and were heavy with remaining winter stores – and, no doubt, some early season nectar – and reassuringly packed with bees.

It looked like a very promising start to the season.

More of the same

I travelled on to my main apiary to review the situation there. This is the apiary with my bee shed and all of my stored equipment. It is closer to the coast and the wind blows in directly from the North Sea.

It was colder and even less welcoming.

However, the bees were all in a very good state and clearly needed more space and a little post-winter TLC to get them ready for the season.

However, the temperature precluded any meaningful colony inspections. I could check for laying queens, get an approximation of colony strength (frames of brood) and give them space for further expansion. Anything more than this and there would be a risk of chilling the bees. Because of the low temperature I took relatively few photos.

Interestingly, colonies outside the bee shed were significantly better advanced than those inside. This is the first time I’ve seen this, and I’ve previously commented that the bees in the shed are often a week or two ahead of those outside.

However, in looking back through my notes I think it’s a reflection of the quality and early winter state of the colonies that currently reside in the shed. These are the ones mainly used for research and which regularly have brood ‘stolen’ for experiments (even late into the autumn). Consequently they were probably weaker going into the winter. At least one of the colonies had been united late in 2021 to ensure they would make it through the winter … and they had 🙂 .

What follows is a discussion of a few of the problems (and some potential solutions) that you can encounter at this time of the season.

‘Dead outs’ and ‘basket cases’

I’m not going to dwell on these as there’s not a lot to say and often little that can be salvaged.

Some colonies die overwinter.

I’ve discussed the numbers (and their questionable reliability) before. Most annual surveys show that about 10-35% of colonies die overwinter. The precise percentage depends upon the size and rigour of the survey 7, the severity of the winter 8 and the honesty of the beekeepers who respond 9.

Let’s just accept that quite a few colonies are lost overwinter.

I strongly suspect the majority of these losses are due to poor Varroa management. I’ve previously discussed the reasons uncontrolled mite levels are deleterious, and the – relatively straightforward – solutions that can be applied to prevent these losses 10.

It’s always worth conducting a post-mortem on ‘dead outs’ to try and work out what went amiss.

Queen failure

Some queens fail overwinter. This is probably unrelated to poor Varroa control and is ’just another thing that can go wrong’.

They either die, stop laying fertilised eggs or stop laying altogether.

They may or not be present when you check the colony in spring.

Whatever the failure, the overall result is much the same, although the appearance of the colony might differ (in terms of numbers of bees and the proportion of drones present). The colony will be significantly understrength, with little or no worker brood … and may have lots of drones.

I consider colonies with failed queens are a lost cause in March or (at least here in Scotland) much of April.

The bees that remain are likely very old. There’s no use providing them with a frame of eggs in the hope they’ll rear a new queen as it’s unlikely that there are sufficient drones about. If there aren’t flying drones I certainly wouldn’t bother.

You could provide them with a new queen if you can find one, but is it worth it?

The colony will be ‘well behind the curve’ in terms of strength for a month or two. You may have to boost them with additional brood. Unless you have ample spare brood in other colonies (as well as a spare queen and a willingness to commit these resources) I really wouldn’t bother.

Fortunately, at least so far (and I won’t be certain until later this month), all my colonies have survived and are flourishing … so let’s move on to a couple of solvable problems instead.

Brace yourself

When I add a fondant ‘top up’ to a colony I remove the crownboard and place the container of fondant directly over the cluster. This ensures that the bees can immediately access the fondant, rather than negotiating their way through a hole in the crownboard to the cold chilly space under the roof. To provide space for the fondant container I either use an eke or one of my deep-rimmed perspex crownboards.

A consequence of this is that, as the colony expands, they may build brace comb in the headspace over the top bars.

What a mess … some tidying required before the super can be added

Sometimes they fill the space entirely, though you might be lucky and find they’ve only built inside the fondant container.

Brace comb hidden inside the empty fondant container

Irrespective of the extent of comb building I usually take this to indicate that the colony needs additional space and that they should be supered.

Pronto.

Removing and reusing brace comb

I smoke the bees down – as gently as practical – and cut off the brace comb using a sharp hive tool. In the photos above the comb was filled with early season nectar.

When cutting off the comb I try and prevent too much of the nectar from oozing out and down between the frames. A sharp hive tool held almost parallel to the top bars is often the best solution. Working fast but carefully, I dumped the nectar-filled brace comb into the empty fondant container and then quickly checked the colony. The latter consisted of little more than gently splitting the brood nest and checking the approximate number of frames of brood in all stages.

I added a queen excluder, a super and a crownboard with a small hole in it, above which I placed the salvaged brace comb, surrounded by an empty super.

Crownboard and nectar-filled brace comb – stored overwinter and (hopefully) used in the spring

Finally, I added a second crownboard with some additional honey-filled brace comb they’d built last September. I wrote about this in Winding down last year. The intention is that the bees will take down the nectar/honey above the lower crownboard and either use it for brood rearing (if it’s too cold to forage) or store it properly.

If all this works as hoped the empty comb can be melted down and turned into beeswax wraps.

Waste not, want not 😉 .

The accidental ‘brood and a half’

My colony #7 has a stellar queen who produces prolific, gentle bees and who lays gorgeous slabs of brood with barely a cell missed. I used her as a source of larvae for queen rearing last season and will do so again this year.

“Gorgeous slabs of brood”

The colony entered the winter with a ‘nadired super’. I’ve discussed these somewhere before 11. Essentially this means a stores-filled super underneath the (single in this case) brood box.

Often the bees will empty the super before the winter and it can be safely removed.

Or, as in this instance, completely forgotten 🙁 .

When the bees had emptied it or not is a moot point … by last weekend they’d part filled it again.

With brood.

The queen had moved down into the super and laid up half the frames, at least two of which were drone comb 12.

I consider ‘brood and half’ an abomination. I prefer the flexibility offered by just one size of brood frame and also prefer using a single brood box if possible.

Despite perhaps swearing quietly when I realised the super was half-filled with brood (the drone brood was almost all capped) it’s only really a minor inconvenience.

Furthermore, this is a good queen and is likely to produce drones with good genes. How could I get rid of the ‘brood and a half’ setup as soon as possible and save all those lovely drones with the hope that they could spread their genes far and wide?

Upper entrances

The obvious answer was to add a queen excluder and a super, but to move the nadired super containing brood above the queen excluder.

If there had been no drone brood in this ‘super’ that would have been sufficient. However, drones cannot get through a queen excluder and distressingly 13 die trying.

Rearrangement to provide an upper entrance – before (left) and after (right)

I therefore added an upper entrance to the colony, immediately above the queen excluder. The easiest way to do this is to use a very shallow eke. I build them just 18 mm deep from softwood, with a suitably placed slot only half that depth.

The brood is directly above the brood box and so will be kept warm. The drones can emerge in due course, and fly from the upper entrance. Some will return there but – ‘boys will be boys’ – many will distribute themselves around the apiary waiting for better weather and potential queen mating.

Standard and upper entrance

If there is a strong nectar flow the bees can fill the new empty super and they will backfill the no-longer-nadired super once the brood emerges.

And finally … what did I fail to mention in this colony rearrangement ?

That’s right, the thing I failed to mention because I failed to check 🙁 ?

Where was the queen ?

It is important that the queen is in the brood box, rather than the no-longer-nadired super, when you reassemble the hive. If she isn’t, you’ll return to find two supers full of brood and an empty brood box.

A very quick check confirmed that the queen was in the brood box so I left them to get on with things.

Stores

I didn’t do a full inspection on any of the colonies I checked.

It was far too cold to spend much time rummaging around in the boxes. However, I did confirm that all were queenright and had brood in all stages.

I also ‘eyeballed’ the approximate strength of the colonies in terms of frames of brood. Typically this just involves separating the frames and looking down the seams of bees, perhaps partly removing the outer frames only to confirm things. Even just doing this I still saw a few queens which was doubly reassuring 🙂 .

The weakest colonies – those in the shed – had 3-4 frames of brood. The strongest were booming … perhaps even the 8 cadres de couvée 14 you read about on Twitter 😉 .

All of the colonies had ample stores, and several had too much.

The capped frames of stores were occupying valuable space in the brood box that the colony will need to expand into over the next 2-3 weeks. I therefore used my judgement to replace one or two frames 15 of capped stores with drawn comb or new frames. I save the frames of stores carefully and will use them to make up nucs next month.

Here are some I saved for later

I’ve heard mixed reports of winter survival and spring build up this year. I’m aware that some beekeepers in the south of England are reporting higher than usual colony losses. Others were reporting very strong expansion in the early spring and even a few early swarms.

It will be interesting to see how the season develops. As always it will be ’the same, but different’ which is one of the things that makes beekeeping so challenging and enjoyable.


 

It makes you go blind

Synopsis: There is a sexual arms race between the queen and the drones she mates with. The queen needs to mate with multiple drones to maximise colony fitness. Conversely, it’s in the interest of individual drones to reduce the number of additional partners who mate with the queen. Recent studies have demonstrated that drones reduce repeat mating flights by impairing the eyesight of the queen. Potential implications of this for practical beekeeping are discussed.

Introduction

Honey bee queens are described as polyandrous 1 because they copulate with multiple drones during one or more mating flights taken shortly after emergence.

These multiple matings are a risky business 2.

It takes longer to mate with multiple drones than it does to mate with one, but this time is minimised by reducing the number of mating flights. Rather than leaving the hive, mating once, returning and then repeating the process, the queen flies some distance to a drone congregation area and copulates with multiple drone before returning to the hive.

Shallow depth of field

One of many …

I’ve discussed the location and locating drone congregation areas previously and the distances the queens and drones respectively fly to reach these (which are different to avoid inbreeding).

Between the queen returning from the mating flight and the onset of egg laying there is a delay of a few days. During this period the queen is storing the sperm from the drones in her spermatheca. These are the sperm storage organs within which sperm stays active for years … a necessity as, after the onset of laying, the queen will not go on any more mating flights.

Perhaps surprisingly, only about 3-5% of the sperm transferred from each drone is stored by the queen.

I hope that makes you wonder why she bothers mating with so many drones … it should.

Polyandry and hyperpolyandry

Just before I explain why she only stores 3-5% of the sperm from each of several drones, rather than storing it all from one twentieth the number (and thereby reducing the risks of longer mating flights) of drones, I need to explain the poly bit of polyandry.

How many drones does the queen mate with?

The usual figures quoted are in the high teens, with a range extending from single digits into the low forties. These numbers are determined using a variety of different techniques, at least some of which are likely to underestimate the actual number of drones.

Marked queen surrounded by a retinue of workers.

Here’s one I made earlier …

Think of it like this, if you have a large population of something – like beekeepers – how many would you have to ‘sample’ to find one called ’David’.

Not many, it’s a common name.

But what about ’Atlas’ or ’Zebedee’?

You’d have to sample a lot more apiarists to find any with these rarer names, though I bet they’re out there somewhere. You might even have to use a different way to screen the population.

And it’s the same when determining the numbers of drones that the queen mates with.

Search and ye shall find – detecting rare patrilines

When you use a method that specifically looks for rare patrilines – essentially genetically distinct offspring fathered by different drones – you can find them. This suggests that the queen probably mates with more than the 15-19 drones usually quoted, and that hyperpolyandry is perhaps a better term to describe the mating behaviour of queen honey bees.

There’s evidence that these very rare patrilines (so-called ‘Royal patrilines’) are preferentially selected when rearing queens under the emergency response.

Colony fitness

So now we’ve defined what the poly in polyandry means … but we still don’t know why the queen risks all those aerial shenanigans to mate with so many different drones.

By mating with multiple drones she ensures that the workers in the colony are genetically diverse. This genetic diversity increases the rather-difficult-to-grasp concept of colony ‘fitness’. In this instance fitness is used to mean a combination of adaptability, resistance to stress or pathogens, increased foraging activity, better overwinter survival etc.

I’ve discussed this concept before and suggest you revisit that post for all the gory details.

The bottom line is that colonies that are headed by queens that are mated with very many drones (50+) produce more brood, have better disease resistance and have many other desirable traits (that benefit both the colony and the beekeeper).

The final piece of this introductory jigsaw I need to mention is that drone sperm is used randomly. It’s not a case of ‘first in, last out’. The 3-5% of sperm stored from each drone is mixed thoroughly in the spermatheca.

This makes sense in light of the comments above about colony fitness. If the sperm were used in batches from each drone you’d have cohorts of young bees being produced that had reduced genetic diversity, thereby potentially compromising colony fitness.

It takes two to tango

But let’s think about the poor drones for a moment.

Drones have two fates (excluding getting eaten by a bee eater); they either die while mating with a queen, or they get turfed out of the hive and starve to death towards the end of the season.

If the drone fails to mate with a queen he’s genetic dead end.

If he does mate with a queen there’s a good probability that the genes he carries will be passed on to the following generation.

There is therefore a lot of competition for the queen in the drone congregation areas (DCA).

The drones, once sexually mature, fly every (suitable) day to several DCAs, one after the other. In addition, they fly relatively short distances from the hive to maximise their time within the DCAs.

Heat map of the landscape used by drones – bright spots are DCA’s

This competition is intense, and it doesn’t stop once the drone has mated (and died).

If a queen mates with a relatively small number of drones – let’s say 10 for the sake of argument – the chance of the sperm from any one of those drones being used to fertilise an egg is much greater than if the queen had mated with 50 drones.

The fewer drones the queen mates with the better the chances that the genes from any one of her successful suitors will be passed on to the following generation.

Paradoxically, it therefore benefits the drone 3, if the queen mates with fewer other drones.

And, remarkably, drones have evolved a way to reduce the number of additional drones that a queen mates with.

A sexual arms race

Before I describe the mechanism, it’s worth emphasising here that best interests of the colony are served by the queen mating with many drones, but those of the drones are best achieved by limiting the polyandrous activity of the queen.

These two processes are therefore in direct competition.

There are some additional subtleties.

If the drone simply prevented the queen from mating again 4 it would be detrimental if that drone was the first with which the queen mated. The resulting colony would have little genetic resilience and would be unlikely to survive.

Any one drone must therefore allow the queen to mate with sufficient other drones to ensure colony fitness.

In addition, the more mating flights that a queen goes on, the greater the chances she will be predated by a passing bird, or get lost on the return flight.

From the drones point of view it would probably be beneficial for the queen to go on only one mating flight, but that she mates with sufficient (but no more than that) drones on that flight.

And finally, before I get to the mechanism by which all this is achieved – a compromise solution, like all the best solutions – I’ll remind you that studies have shown that queens go on about 5 mating flights spread over 3, usually successive, days.

Love is blind

At least, too much love is … 😉

Liberti and colleagues have recently published a snappily titled paper on how drones reduce the number of mating flights taken by a queen. The paper is Open Access so you can get all of the nitty-gritty details I don’t have time, energy or intelligence to include in the summary below.

The paper is:

Seminal fluid compromises visual perception in honeybee queens reducing their survival during additional mating flights by Joanito Liberti et al., (2019) eLife 2019;8:e45009

As with all science, the results published in this paper were a continuation of earlier studies of queen honey bees. In particular, these included studies by some of the same authors who had showed that seminal fluid contained proteins that had the ability to interact with neurons.

In addition, in Drosophila melanogaster (the fruit fly, and genetically best studied insect) there was evidence to suggest that seminal fluid promotes fast oviposition and reduces the willingness of females to seek additional copulations.

Drosophila mating in captivity

Now, Drosophila mating behaviour is very different to that of honey bees, but there was clearly a precedent here in which some of the components of seminal fluid – the ‘carrier’ that keeps sperm alive and motile and protects against pathogens – influenced subsequent mating in insects.

Or the lack of mating.

The study by Liberti et al., involves an elegant combination of hardcore molecular gene expression analysis coupled with electroretinography 5 and field work. I’ll skip briefly through the first two of these and provide a bit more detail on the last.

Analysis of gene expression

Virgin queen bees were instrumentally inseminated with seminal fluid (i.e. no sperm) or a control saline solution. Subsequent analysis of the brains of the bees – using a method called RNA-Seq which allows the qualitative and quantitative changes in gene expression to be accurately determined – demonstrated reproducible changes in the gene expression of dozens of genes.

Venn diagram of differential gene expression in instrumentally inseminated queen bees

Detailed analysis of which genes had changed in expression showed that several so-called signalling and metabolic cascades were modified in response to seminal fluid, and many of these mapped to the phototransduction pathways i.e. those involved in sight.

Several of the genes that were detected encoded proteins that were implicated in the conversion of light into the electrical signals in photosensitive electrical cells.

Inevitably, that one sentence has probably confused half the readers that have persevered to this point in the post …

Essentially what this means is that there are components within drone seminal fluid that change the ability of the queen to perceive light, or to see.

So, do they?

Visual perception of queens

The gene expression studies in this paper are complicated (for a molecular biologist). The electroretinography is an order of magnitude more complicated for this molecular biologist to understand … but here goes.

Electroretinography involves measuring the electrical signals generated by particular neurones that are connected to the compound eyes and ocelli 6. This allows the consequences of the changes in gene expression to be determined in terms of the vision of the queen bee.

These studies showed that queens instrumentally inseminated with seminal fluid had lower responses to low frequency flickering light, and that that this response (or lack of response) increased on the second day after insemination.

There were additional changes in the response of the ocelli in queens inseminated with seminal fluid.

Taken together, these results show that queens exposed to seminal fluid experience reduced visual performance.

They are not blinded, but their vision is impaired.

Does this visual impairment have any influence on their mating behaviour?

Mating flight behaviour

Finally, we come to something that’s a bit easier to comprehend, not least because I’ve previously discussed the technology used – the RFID tagging of individual bees to monitor their flight frequency and duration.

RFID-tagged queens (34 in total) were instrumentally inseminated (either mock, or seminal fluid or semen) and subsequently monitored when going on mating flights. Those receiving either seminal fluid or semen were more likely to get lost on these flights, and repeatedly triggered the hive entrance sensors, suggesting they were disorientated by sunlight after leaving the hive.

Of the 21 queens that returned, 81% went on mating flights of more than 7 minutes which was considered a conservative threshold for a completed mating flight i.e. flight to a DCA, mating(s) and return to the hive, and about 50% laid worker brood.

Notably, of the 17 queens that went on ‘successful’ (by duration, not necessarily by outcome) mating flights, those receiving the control saline solution left 1-2 days later than those that had received seminal fluid or semen.

Seminal fluid and semen induce alterations of mating flight behaviour in honeybee queens

These results show that exposure to seminal fluid induces significant changes in queen mating flight behaviour, presumably as a consequence of the alteration to the vision of the queen.

Therefore, the implication from these results is that proteins in the seminal fluid of drones impairs the visual perception of queens, thereby reducing the likelihood that the queen will embark on additional mating flights.

Queens that had already mated (or been instrumentally inseminated in this study) were more likely to get lost on subsequent mating flights, and embarked on these flights earlier.

But what about swarming?

The hive – or a natural nest site – is a low-luminance environment. Queens do not need fully functional eyesight once they have returned from their mating flights. In the hive communication is non-visual, mediated by pheromones, contact, vibrations and sound.

However, although a queen only goes on a few mating flights, she will also leave the colony if it swarms.

Swarm of bees

Swarm of bees

What are the implications for the this study on the eyesight of queens during swarming?

This isn’t really discussed in the paper, but I think there are two likely scenarios:

  • the changes in visual perception by the queen are transient and return to ‘normal’ after a few days, weeks or months
  • swarming is a fundamentally different activity in which thousand of bees leave the hive and for which accurate vision is not needed by the queen.

There’s a world of difference between embarking alone on a mating flight of several kilometres and having to return to the exactly the same location, and leaving on a one-way trip with a swirling mass of attendees with dozens of scout bees leading the way.

Further studies will be needed to determine whether the changes in vision are transient or permanent, as well as to identify the ‘active ingredient’ in seminal fluid that is responsible for the degradation of the mated queen’s vision.

I also think further studies will be required to determine the relationship between dose and timing of the response.

How long does it take for the reduction in visual perception? If the first and second mating flight are taken on successive days is the “return rate” greater than if they are taken a few days apart?

How many drone matings are needed to reduce the visual acuity of the queen? I would predict that this would be a number consistent with the lower estimates of polyandrous matings needed to generate fitness in the resulting colony.

And implications for practical beekeeping?

Perhaps none directly, though I’m interested in the answers to the questions I posed in the paragraphs above.

In an area with low drone densities and those with shall we say ‘variable’ weather – such as my apiaries on the west coast of Scotland (or for that matter, any beekeepers living in remote northerly areas with just a few hives) – is colony fitness compromised by reduced matings?

An isolated apiary

Conversely, is mating success lower because more queens fail to return from subsequent mating flights that they have to take to try and mate with enough drones?

Can mating success and colony fitness be increased by boosting drone numbers?
And is this achievable at a scale meaningful to a small-scale beekeeper?

If a measurable increase in mating success took a 1000-fold increase in drone numbers it’s probably not achievable.

However, if all it took was an extra frame of drone comb in every hive in the apiary, then that’s quick win.


 

Battlefield bees

Synopsis: For millennia bees were used as weapons of war. They are now being developed as ‘weapons of peace’ to help clear the millions of anti-personnel mines left after active conflict ends. Their legendary scent detection abilities combined with high-tech ‘bee detection’ methods show promise and may help reduce the thousands of civilian casualties that occur decades after the war ends.

Introduction

The weekly posts on this website are about bees and beekeeping.

In the same way that I deliberately shun sponsorship and avoid advertising 1 I also try and avoid politics, law and other divisive subjects. These cause enough problems without adding my opinions into the mix … and worse, having to moderate the opinions of others in the subsequent comments.

So, although I might write about the detrimental effects of thiamethoxam on bees, I would focus on the science of neurotoxins rather than politics of lifting the ban of the use of this neonicotinoid in the UK .

It is harmful to bees, but the aphid-transmitted yellows viruses may otherwise decimate our sugar beet crop, and might not the alternative pesticides be more harmful to bees?

Do we even need that much sugar beet?

And what about the livelihoods involved?

You can see how quickly it gets very messy.

But, at the same time, I strive to make posts relevant and even topical. When viewed retrospectively – even if just by me – the posts represent a snapshot of my jumbled thoughts of what’s current at the time.

There are ageing posts on oxalic acid treatment that don’t reference ApiBioxal (the good old days as I like to call them), and others that make passing mention of maximising the oil seed rape (OSR) crop, or processing OSR honey 2.

All of which means I cannot really avoid mentioning the recent Russian invasion of Ukraine 3.

Six-legged soldiers and one-legged civilians

Two years ago I wrote a post about the use of bees in warfare. For many hundreds of years they were an effective tactical weapon to be dropped on or fired at the enemy.

Not individually – that would be just silly – but a hive at a time.

I’ve been present when someone has dropped a full brood box. The whirling cloud of angry bees was reminiscent in shape, though nothing else, to the mushroom-shaped cloud over Hiroshima. Lots of people got stung in the training apiary during that session.

Unfortunately, the ingenuity of man knows no bounds when it comes to killing and maiming others.

The thermobaric weapons employed today are very different from the torsion-powered ballista siege engines used by the Ancient Greeks over two millennia ago 4.

Soldiers now wear carbon and kevlar rather than Corinthian helmets and short-sleeved tunics.

Although you can buy a camouflaged bee suit, it’s not designed for the battlefield, and is likely to be about as much use as the hoodies, jeans and T-shirts that the innocent civilians inevitably caught up – or deliberately targeted – in today’s wars are wearing.

The legacy of war

And long after the battle has ended – years or even decades later – those surviving civilians continue to be maimed and killed by unexploded ordinance and, particularly, by anti-personnel mines.

Minefield sign, Cyprus

So, rather than dwell on the horrors of the present – which is about as far removed from beekeeping as it’s possible to get – I’m going to discuss some more hopeful stories of how bees might help reduce the deaths and injuries caused by anti-personnel mines.

Those readers expecting the (un)usual humour may be disappointed this week … this is not a topic that lends itself well to jokes.

The solutions that scientists are developing to detect anti-personnel mines use a clever combination of the truly awesome scent detection capabilities of honey bees coupled with some very clever technology.

The problem

In 2021 there were 61 countries which were ‘contaminated’ with anti-personnel mines. These mines are typically produced for a few dollars, are perhaps 30 cm in diameter and are buried just sub-surface … and often forgotten.

One definition of the word minefield is ‘a situation or subject presenting unseen hazards’. The plural hazards, and use of ‘field’, indicate that lots of anti-personnel mines are usually buried across an area, thereby rendering it too dangerous to enter.

Farming, trade and communication is inhibited as people have to avoid the minefield(s) … and, if they don’t then the consequences can be devastating.

The International Campaign to Ban Landmines recorded over 7,000 casualties in 2020, 2,500 of whom were killed.

80% of these casualties were civilians and – where the age was known – over 50% of the casualties were children.

Aside from banning the use of anti-personnel mines in the first place, a priority must therefore be to find and removes mines from these areas.

Typically this involves using metal detectors or sniffer dogs for detection, followed by manual clearance. Inevitably, there are considerable risks involved in both the detection and – to a lesser extent – the clearance. These risks make the process time-consuming and expensive.

Which is where honey bees come in …

”I love the smell of Napalm in the morning”

So said Lieutenant Colonel Kilgore (Robert Duvall) in the film Apocalypse Now.

Landmines don’t contain Napalm, but about 90% if them contain TNT (trinitrotoluene).

And not only does TNT have an odour, but landmines continue to emit this odour for years after they have been buried. On a calm day there are vapour plumes of TNT above each of the buried mines 5.

The vapour concentration of TNT is measured in parts per trillion (pptr) and is usually in the range 0.01 – 100 pptr.

Just as the usual way to express areas is by comparison to Wales 6, the ‘volume comparison’ is typically made to an Olympic swimming pool.

1 part per trillion is about the same as half a teaspoon added to an Olympic swimming pool. Not very concentrated …

… but well within the detection capabilities of honey bees. For comparison, this is similar to that of sniffer dogs 7.

To cut a long story short, scientists 8 trained bees to feed on syrup laced with trace quantities of TNT. They then tested the ability of these bees to detect targets emitting field-realistic amounts of TNT.

The results were very encouraging. 97-99% of targets were detected with 1-2.5% of false-positives.

More importantly, the false-negatives (targets that were missed) were less than 1%. It’s much more important to not miss any than to ‘find’ some that aren’t there.

Lidar

The authors neatly sum up the benefits and principles of the study:

Bees do not cause mines to explode, do not require a handler, and can be trained more rapidly than dogs. This technique makes use of the natural foraging behavior of bees, which frequently cover ranges up to several km around a hive. The bees identify the sample location by their increased dwell time while flying in its vicinity.

And it’s that last sentence that should give you pause for thought.

How do you detect the “increased dwell time” – a fancy term meaning spending more time flying in one small area than the remainder of the study area – if you’re trying to find mines in an area about the size of a couple of football pitches 9.

Remember, as if you’d forgotten, you cannot enter the minefield because of those unseen hazards that are lurking just under the surface waiting to blow your legs off.

Bees are pretty small. I can see them against the clear blue sky at 20-30 metres range, but I can’t see them against mixed foliage at anything like that distance.

One potential solution is light detection and ranging (lidar) technology. Essentially this involves shining a scanning laser across an area and detecting the light scattered when it ‘hits’ objects – such as flying bees 10. For additional discrimination, changes in the polarisation of the scattered light has been used to distinguish between bees and what the scientists termed ‘clutter’, which I take to mean foliage.

And it works.

Lidar detection of bees; a) bee heatmap, b) chemical detection (5 is a false positive), and c) visual mapping of bees.

Not only in theory but also in practice … lidar has been used to detect bees detecting mines in an active ‘minefield’. Mines were buried in known locations, trained bees were released and their ‘dwell times’ were recorded using lidar (with the detector about 80 metres away).

Football fields and minefields

But there’s a problem.

Lidar involves a laser scanning horizontally 30-60 cm above the ground. Anything lower than this and the foliage prevents accurate (or any) detection of the bees.

And, even though a minefield might be the size of a football field, it doesn’t look like a football field … either when mined in the first place and definitely not after a few years.

Minefield in the Golan Heights

Unfortunately, there’s also an additional problem.

Tragically the sign above was probably erected after someone inadvertently stepped on a mine. Until that fateful day it might have just been ‘that scrubby bit of field bordering the river’.

Detecting the location of mines in a minefield is one problem.

Detecting whether a field is a minefield is a different – albeit related – problem.

And it turns out that bees might be able to help us discriminate between minefields and football fields, or any other sort of equally harmless fields.

I’ll discuss this before returning to the detection of individual mines in a minefield.

REST (and be thankful)

REST is an acronym for Remote Explosive Accent Tracing 11 .

Since those buried anti-personnel and landmines give off a vapour plume of TNT there are methods of sampling the air and testing it for the presence of trace amounts of explosives.

The ‘sampling’ is highly technical and outside the scope of this post 12.

The ‘testing’ involves sniffer dogs and lots of doggy treat-type rewards. Consequently it is a time-consuming and therefore costly procedure.

However, honey bees are covered in tiny hairs. Through electrostatic interactions, these pick up molecules while they are out foraging. Graham Turnbull 13 and colleagues have shown that flying bees can pick up molecules of TNT (from buried mines) which can subsequently be detected.

The bees are therefore used for wide area sampling, but how is the TNT detected? Graham is a physicist whose speciality is organic semiconductor sensing films … essentially thin films that change fluorescence when certain chemicals are deposited on their surface.

The hive entrances were modified so that the bees passed through a tube. This was made of a special material to pick up – and since lots of bees were making the trips, to also concentrate – the molecules that adhered to their hairs whilst out foraging.

Quenched photoluminescence (red bars) compared to negative control areas (black line)

To cut another long story short, the concentrated molecules were then transferred to the semiconductor sensing film and the photoluminescence quantified. A reduction in the photoluminescence (quenching) was indicative of TNT detection 14.

So honey bees can be used to discriminate between minefields and, er, other fields.

Detecting mines not minefields

I should add that the bees used in the study above were not trained 15 in any way. They simply placed feeders on the opposite side of the uncontaminated test or mined field to encourage them to sample in a reasonably defined area. The bees were not searching for mines, or the TNT vapour plumes, they were just flying back and forth ‘doing their stuff’ and foraging.

Bees are fast learners and can – as described briefly above – readily be trained to associated particular scents (such as TNT) with rewards (i.e. syrup). When you release these trained bees into an area with TNT vapour plumes they home in on these looking for the rewards … and hence exhibit those previously mentioned ’increased dwell times’ near buried mines.

But there’s still the problem of how the bees can be detected.

Huge advances have been made in unmanned aerial vehicles (UAV’s or drones), GPS and video technology in the 15+ years since the original use of lidar to detect bees detecting landmines.

The combination of these technologies now provides a way to detect individual bees, and consequently anti-personnel mines, within an area.

Using drones to monitor bees

A drone flying 10 m above the minefield 16 was used to record high resolution video from which the locations of individual bees could be (computationally) determined.

By detecting bees on individual frames (from video taken at 45 fps), rather than tracking each bee, it was (again computationally) relatively straightforward 17 to generate spatial density maps showing where the bees preferentially concentrated.

Video stills (left) and bee location heat maps (right). The blue circles show mine locations. Bee numbers on scale.

The accurate spatial location was ensured by using a modification (RTK) to GPS which involved an additional ground base station. This increased the standard GPS resolution to provide a horizontal accuracy of 5 cm. The bright coloured foci of ‘increased dwell times’ were less than 0.5 x 0.5 m.

Conclusions and problems

These studies are encouraging. They suggest that a biohybrid system 18, combining advanced physics and area-wide sampling of bees, with the exquisite scent detection of trained foragers coupled with highly accurate video monitoring, might help reduce the number of victims of landmines that occur long after the original conflict ended.

However, there are a few problems that remain to be resolved.

Bees learn fast, but they also forget fast. The authors developed some reinforcement training exercises to ‘remind’ them that they were searching for things scented with TNT.

Bees are not ideal chemical biosensors. They are potentially easily distracted by a strong nearby nectar flow, they don’t forage 19 in poor weather and their availability might be seasonal, depending upon the latitude.

Drones have limited flight times and long vegetation still impedes accurate video detection. Either the bees fly at lower altitudes or the foliage is disturbed by rotor downwash and so increases background noise.

Nevertheless, the expected costs and time involved in both the wide-area sampling and mine detection are lower, and the mine detection per se is much safer.

The mines still have to be destroyed, but knowing precisely where they are – and where they are not – is much more than half the battle … in solving the lethal legacy of a possibly long-forgotten battle.


 

Winter weight

Synopsis: With colonies now rearing brood there is a risk of them starving. Here are a couple of ways of checking the winter hive weight to determine if you need to add fondant. These checks should be conducted every 2-3 weeks until the bees are foraging in the warmer spring weather. 

Introduction

Last week I described how to determine what was happening inside the hive in winter.

By carefully inspecting the debris that falls through the open mesh floor (OMF) you can tell:

  • the size and position of the cluster,
  • whether they are rearing brood (or, more precisely, whether there is brood being uncapped … I don’t think you can tell if there is open brood simply by inspecting the debris),
  • if frames of stores distant from the cluster are being used.

In addition, I explained the importance of checking that the hive entrance was clear of corpses. These accumulate during long periods of cold or inclement weather. If the hive entrance is small enough to prevent mice from getting in – and it should be – then there’s a chance these corpses will build up sufficiently to stop bees getting out.

Entering the ‘danger zone’ – rearing brood, too cold to forage – don’t let them starve

These two checks take no more than a few minutes and should be conducted at least monthly. There’s no harm in doing them more frequently because – performed correctly – the colony isn’t disturbed at all.

Last week I described these as ”The bees don’t even know they’re being checked” checks.

The final important winter check is to determine the weight of the colony.

Avoirdupois 1

If the bees are rearing brood they will be using their winter stores. Of course, they will have been using these stores throughout the late autumn and winter, but critically, the rate at which they use their stores will increase once brood rearing starts.

I’ve illustrated this before schematically, but have attempted to improve the diagram a little this year.

Once they have reared some brood, they’ll have more bees to help them rear some more brood, meaning that the rate at which the stores are used will increase.

Schematic diagram of winter hive weights

The solid black line is the weight of the colony. In the late autumn the colony almost certainly goes through a broodless period 2. During this broodless period the colony is simply using stores to maintain the adult bees in the cluster. I’ve drawn this as a straight line (i.e. a constant rate of stores usage), but I bet it varies with the ambient temperature as more or less stores are required for essential metabolic processes.

But at some point the queen starts laying again and the colony have some larvae to feed.

I’ve indicated the start of brood rearing by a dashed vertical line. Typically I usually guesstimate this occurs around the winter solstice 3, but for our purposes the precise timing is irrelevant.

Twenty one days later these bees emerge, by which time the queen has already laid some more eggs.

Things start to pick up.

What started as a small palm-sized patch of brood now covers almost the side of a frame, in a month it will be double that.

Or more.

And all of those hungry mouths mean more stores are needed, so the rate at which the stores are consumed will increase, meaning that the colony weight will decrease … and it will continue to get lighter faster 4.

Silent spring

A few crocus and snowdrops are out, but the weather is too poor for foraging.

The weather gradually improves and more spring flowers become available.

There’s gorse available, of course. There always is.

Late December gorse ...

Late December gorse …

The bees can now forage a little more. On unseasonably warm days the bees take cleansing flights and might collect a little pollen and nectar.

I’ve imaginatively and artistically illustrated this in the graph with some little yellow flowers 🙂

But, all the time, more brood is being reared.

If the nectar coming in is insufficient to feed the brood – and early in the season it will be – then the bees will continue to make inroads into their precious stores.

And the colony will get lighter.

And lighter.

Until it drops below some critical threshold and enters the ‘danger zone’ – the absolute weight doesn’t matter 5 – at which point the colony must go into self-preservation mode.

Brood will be abandoned, cannibalised and/or ejected from the hive. The queen will stop laying. The colony will be forced back into a ‘maintenance’ state.

A protracted cold period, or a fortnight of rain, and there’s a very real danger the colony will starve to death.

At the very best the early spring expansion of the colony will be severely retarded and it is unlikely to recover until mid-season.

All of which is easily avoided by carefully monitoring the amount of stores the colony has.

A brood frame full of stores

However, remember you’re supposed to be conducting ”The bees don’t even know they’re being checked” checks, not pulling open the brood box and rummaging through to count frames of sealed stores.

But since the number of bees in the colony is steady (or likely decreasing slowly) and there’s effectively no nectar being collected, the weight of the hive is a good surrogate measure to determine the level of stores available.

Winter weight

There are all sorts of ingenious solutions to determine the weight of a full hive.

Probably the most complicated and expensive is to purchase (or build) a set of electronic hive scales that automagically communicate with an app on your smartphone to give you a real-time readout of the hive weight in kilograms. You can record the weight of a few thousand foragers leaving the hive in the morning 6, and see them return by nightfall together with the 1500 g of nectar they’ve collected.

Arnia hive data

Arnia hive data

At the other end of the spectrum – in terms of both cost and information – is hefting the hive. Using nothing more than than a gentle lift and good judgement you can readily tell whether the hive contains sufficient stores for the bees to continue to rear brood. You won’t be able to tell the exact weight of the hive, but you will be able to determine whether it weighs enough.

I’ve used both methods.

However, I routinely only do the latter.

I’ll leave a discussion of automated hive monitoring to another day 7 and will instead briefly discuss two methods that are quick, cheap and easy (choose any three).

One method – hefting the hive – costs nothing, but requires a bit of experience and judgement. The second method involves – inaccurately, but reproducibly – weighing the hive. This costs about £10 to implement and provides a good way to build up your confidence that your hive hefting is probably good enough to ensure colony survival.

And good enough is probably all you need …

Hefting the hive

This is easier to show than describe:

The general idea is that you judge how much effort is required to lift one edge of the hive – typically the back – a couple of centimetres off the hive stand. As you can see from the video, other than slackening off the strap that secures the hive to the stand 8 there’s nothing else involved.

Comparisons help here.

It helps to have the ‘muscle memory’ of how much the hive weighed last time you checked, or – even better – how heavy it should feel like at this stage of the winter.

Both come with experience, and improve with lots of experience.

If you have several hives in the apiary, all with the same hardware, then hefting one after the other makes this comparison relatively easy. If – like in my apiaries – you have a range of different roofs, it can help to remove the roof to get a better ‘feel’ for the hive weight.

The hive should feel heavy.

If the hive feels light it probably is light.

Too light.

Weighing the hive

This second method is a little bit more involved.

I’ve previously recommended using a set of luggage scales to weigh the hive. You attach them to one edge of the hive floor, pull up gently, let the weight stabilise and then record the value on the digital display.

Don’t try this using luggage scales with an analogue display, or ones that don’t emit a helpful ‘beep’ and freeze the display when the weight stabilises.

Just don’t 🙁

Suitable luggage scale cost about a tenner. Mine are very friendly but cannot spell.

Friendly scales ...

Friendly scales …

However, those of you who have tried this method will be aware of the world of grief that is encapsulated in the words ”let the weight stabilise”, particularly if you do not have a lot of upper body/arm strength.

Here’s the problem … you are trying to hold half the weight of a full hive stationary. Probably 9 your arms will be bent at the elbow.

The hive will probably weigh 30+ kg.

Even half that is a lot to hold steady while you wait for the tinny electronic ‘beep’ to tell you to relax and lower the hive gently back onto the hive stand.

I struggle to do this (more now than I used to) and I’m tall and relatively strong.

Before I explain an easier way to achieve the same thing I ought to say a couple of words about determining the total hive weight.

Physics … Ewwww!

If everything – frames, bees, stores – in the hive are evenly distributed, then opposite sides of the hive (weighed as described above) will be a fraction less than half the total weight 10.

Weighing hives

Since the ‘stuff’ in the hive is probably not evenly distributed the weight you record will either be less than or more than half the weight of the hive, depending on whether you have picked the heavy (C in the figure above) or light (D) side of the hive.

However, the sum of the two sides (C + D) will – with the exception of the fraction lost due to vectors as described in the last footnote – still equal the total weight of the hive and contents.

So, if you want to know the total weight either measure the weight of opposing sides and add them together.

Or, measure one side, double it, assume everything is about even and enjoy being a beekeeping free spirit.

You radical 😉

Let the weight stabilise

The solution to the arm-wrenching, patience-draining, interminably-wobbling, weight stabilising problem is to use a lever.

You need two pieces of stout wood, a strong nut and bolt and a few suitably sized washers. One piece of wood forms a vertical support. The second piece of wood is a lever. It is attached near the top of the support using the bolts/washers/nut.

Hive scales

The digital luggage scales are tied to one end of the lever.

You need a way of attaching the hive to the scales. I use a 6 mm roofing bolt.

Now you see it …

All my hive floors are drilled with a 6-7 mm hole through the middle of each side of the floor 11. This is in the side runner of my kewl floors, underneath the OMF and the Varroa tray.

The roofing bolt is pushed fully into this hole and holds everything very securely.

Now you don’t … when pushed fully home the hive is securely attached to the scales

Using this ‘Heath Robinson’ contraption is simplicity itself.

Place the support vertical and adjacent to the hive, attach the scales to the hive floor, gently press down on the other end of the lever and lift the hive no more than 1-2 cm from the hive stand.

Wait a few seconds for the ‘beep’ from the scales, lower the hive gently onto the stand and record double the weight in your hive records.

Or for those of you who are not free spirits but wear a belt and braces with your beesuit, weigh the opposite side of the hive as well, add the weights together and write up your notes 😉

How reproducible is this?

Actually, pretty good 🙂

I did a bunch of measurements on a range of dummy hives of known weights 12.

By measuring both sides and adding the recorded weights together I determined that the underestimate of the true hive weight was about 8%. With care, the variation in weight of repeated independent measurements of one side of the hive was in the range 0.3 – 1.7%.

That’s more than close enough for me.

You do need to take care to standardise the method you use:

  • make sure the upright support is vertical
  • ensure that the pull exerted by the scales is as vertical as possible.
  • lift the hive by the same distance off the stand. The smaller the distance the more accurately you will determine the total weight 13.
  • push down on the lever gently and smoothly. Don’t jerk the hive. It takes relatively little effort to hold the hive stable for the weight to be recorded 14

All of which is pretty easy to achieve.

Remember – and this is the last time I’ll write this – these inspections are ”The bees don’t even know they’re being checked” checks 15. All of the above can be achieved in 1 minute with no disturbance to the colony if you are reasonably careful.

Then what??

Remember, the weight of the hive is not important, it’s whether they have enough stores to rear brood. However, regularly recording the weight as I describe here will allow you to judge how fast the colony is getting through the stores.

Ideally weigh the hive and heft the hive.

You will then more quickly learn to make a judgement based upon hefting along.

Will the colony be underweight – based upon the hive hardware, the weight of the bees, frames and stores – in a week or two when you next visit?

Bees can use their stores fast when they’re unable to forage and rearing brood. Studies by Tom Seeley have demonstrated colony weight reduction in ‘maintenance’ mode was perhaps 1 kg per week, but that this level increased significantly once brood rearing started in earnest.

If you consider that the colony is already too light, or will be too light before your next visit, you must add some stores.

And, at this time of the year you should use fondant, not syrup, to feed bees.

Feeding fondant

I’ve written extensively about feeding fondant to bees, both in midwinter and at the end of the summer. I only use commercial baker’s fondant, not the overpriced stuff sold to gullible wealthy beekeepers.

The priority is to add the fondant as close as possible to the cluster. You want the bees to have immediate access to it. You don’t want them to have to crawl half way across the hive, up through a hole in the crownboard and into that cold empty void under the roof.

Which bees are better able to access the fondant?

Brrrr.

I add fondant in 1 – 5 kg blocks. The amount depends upon the size of the colony, the likely time of my next visit and the probability of their being nectar readily available before then.

I always err on the side of generosity 16.

You can easily remove unused fondant …

… or you can guiltily remove pathetic handfuls of starved bees.

Your choice 🙁

Pack the fondant into clear plastic food trays 17 rescued from the recycling bin. Once filled, wrap them with a couple of layers of clingfilm, or place them in a securely sealed plastic bags. The fondant will absorb moisture from the environment, particularly if it’s warm. I just keep a pile of them in the car for my winter visits to the apiary.

Spot the blocks of fondant and the scales

Remove all the clingfilm. Bees have a horrible habit of dragging it down into the brood nest, chewing it up and incorporating it into brace comb.

I place the fondant on top of the frame bars, directly over the cluster. My crownboards are reversible and have a deep upper (i.e lower when reversed!) rim which accommodates the tray of fondant.

Fondant block under an inverted perspex crownboard

I add the insulation block back over the crownboard and replace the roof, secure in the knowledge that the colony has sufficient food for the next 2-3 weeks.

If your crownboards aren’t reversible with a deep rim make some that are use an eke or an empty super.


 

Winter wait

Synopsis: In the winter bees are low maintenance, but they’re not no maintenance. You need to carry out a few regular winter checks to help them overwinter successfully. Here are the first two things to check … I’ll deal with the third and final check next week.

Introduction

The ‘beekeeping season’ runs from spring until autumn. Quite when it starts and stops depends upon your latitude and enthusiasm 1.

More of each have opposing effects in the spring.

More latitude and the season starts later, more enthusiasm and you might be tempted to start colony inspections (the first ‘proper’ beekeeping of the year) in early spring.

I’m certainly enthusiastic but I live in Scotland. I therefore rarely open a hive before mid/late April. In some seasons it might even be mid-May.

But that doesn’t mean that there’s nothing to do between the end of the preceding season and the start of the next.

The winter wait (for the start of the season) doesn’t meant that there’s nothing to do.

During the winter months of the year bees are really low maintenance, but they’re not no maintenance.

You need to check the hives at about monthly intervals. More frequent checks will do no harm – these are ”The bees don’t even know they’re being checked” checks – but probably aren’t necessary. These checks are important to ensure the bees overwinter successfully.

Spring is on the way … Fife snowdrops, mid-February 2022

Of course, you should also check after high winds or heavy rain (very timely as I’m writing this as Storm Eunice bears down on the south west) as an overturned hive or a badly flooded apiary aren’t conducive to colony survival.

So, what do these checks entail?

What are you actually looking for?

How can you tell much of anything from an inanimate cedar or poly box on a miserable, cold, wet February afternoon?

Essentially it comes down to three things … the state of the colony, access to the hive and weight.

What’s happening in the box?

Mid-February, it’s 5°C, there’s a squally northerly blowing intermittent sharp hail showers down from the hills. No self-respecting bee would venture out in conditions like these.

Most self-preserving beekeepers would probably prefer to be sat in front of the fire reading Gilles Fert’s Raising honeybee queens 2.

However, there’s work to be done.

What on earth can you judge about what’s happening inside the box on a day like this?

If you’re a relatively new beekeeper (and this applies to some of us who have been keeping bees for many years) you would probably like to know if there are any live bees in the box.

After all, you’ve not see a flying bee for months.

Perhaps they all froze to death in those heavy frosts over the previous week?

Don’t rap sharply on the outside of the box and listen for an answering angry buzz. Yes, it’s a way of detecting whether there’s ‘life in the old box yet’, but it’s an unnecessary disturbance for the bees.

How would you like it?

There are two relatively simply methods, one much more useful than the other.

The first is to use a clear perspex crownboard on the hive 3. It’s then a simple matter to lift the roof and observe the state of the colony.

Colony viewed through a perspex crownboard – mid-February 2022

Here’s one of my colonies from last weekend. I can tell from the size of the cluster that the colony is reasonably strong.

That’s a good start.

The bees are moving on the periphery of the cluster, so they’re alive 4.

In addition, though it’s not entirely clear from this photograph, there are at least 2-3 frames of capped stores at the opposite side of the hive to the cluster.

Condensation

One of the things missing from the picture above is any significant amount of condensation on the underside of the perspex crownboard. This is because the deep inner rim of the crownboard is usually filled with a 50 mm thick block of insulation.

Perspex crownboard with integrated insulation

This is essential unless the roof is very well insulated. Without insulation immediately above the perspex the high level of humidity within the hive will lead to large amounts of condensation on the underside of the perspex.

This condensation – or at least some of it – will then drip down onto the cluster, making it a pretty unpleasant environment for the bees.

So, by simply building a ‘window’ into the top of the hive you can determine the size of the colony, whether it’s alive and possibly judge something about the level of stores in the hive.

All of which, and more, you can achieve another (better) way … read on 😉

I quite like the perspex crownboards I use on some of my colonies. However, I consider them far from essential and can judge the state of the colony much better by ‘observing’ them from below rather than from above.

Open mesh floors

When I say ‘observing’ them from below, I don’t mean a glass bottomed hive and I don’t mean directly observing them from below 5.

If you use open mesh floors (hereafter OMFs) you can collect and inspect what falls through the floor and get a very good idea of the size, state, health and activity of the colony.

Wow 🙂

An OMF should have a white (or pale yellow) coloured plastic tray or sheet that can be slid underneath the floor to catch the debris that falls through.

Not black and definitely not Varroa-coloured 😉

White polystyrene Varroa trays really need painting as they discolour badly after a couple of seasons.

Abelo poly Varroa tray

Abelo poly Varroa tray – draughty and easily discolours. Yuck.

A well designed OMF – and there are many that are not 6 – should have a close-fitting tray so that those gusty February squalls don’t disturb the debris that falls through. The position and type of debris is important and if it has been blown about all over the place – or half-eaten by slugs or ants – then your task will be that much harder.

Or impossible.

Varroa tray – single brood box, busy colony, mid-February 2022

This is a tray from a reasonably strong colony in a single brood box. You can just about make out 10 fuzzy horizontal lines of debris. These lines are made up of stuff that’s fallen through the OMF.

You realise that ‘stuff’ is a highly technical beekeeping term that covers everything from antennae, legs, wax cappings, pollen and Varroa to a range of other unidentifiable crap 7.

Tasseography

Tasseography (or tasseomancy) appears to be an entirely made up word 8 for reading tea leaves.

Deciphering the debris on a Varroa tray is a more exact science than tasseography which – and at the risk of offending any fortune-teller-beekeeping readers – isn’t.

It’s not science and it’s not exact 9. The existence of well-reviewed books on the subject proves nothing other than the gullibility of purchasers I’m afraid 10.

So, let’s look again at the debris in the picture above.

The four rows in the centre/top are darker. These are directly below the cluster and are cappings produced (and dropped) as brood emerges. Brood capping are biscuit-coloured (think a sort of dark digestive, not a pale custard cream), presumably because of the incorporated pollen and associated pupal casings.

In addition, mixed in with these rows is some paler granular debris, and there is a lot more of this in the very obvious rows towards the bottom of the picture.

These are the wax cappings that are produced when the bees uncap stores. If you have a close look at these rows you can also see some white or off-white sugar crystals.

So, we can tell the approximate size of the brood nest, we know they’re rearing brood and that they are busy uncapping stores.

Hive health

The one thing you won’t see on that tray are any Varroa 11. That particular tray was left in situ from 17/1/22 to 13/2/22. I can therefore be reasonably confident that the colony is healthy, with low Varroa levels.

I can see a tall, handsome stranger in your future … and a lot of Varroa

This second tray is from another colony in a single brood box. They are also rearing brood but have yet to venture much beyond the cluster when uncapping stores.

However, looking closely at this tray I can see a disappointingly high Varroa drop … somewhere in the region of 30-50. Again, this tray has been under the colony for a month, so I’ll need to monitor Varroa levels carefully as they build up during the spring.

As an aside, both these colonies have an identical record of miticide treatments 12 and both are in the same apiary. My records show that the colony with the higher Varroa natural drop (i.e. not due to recent treatment, the tray was cleaned in mid-January and they were last treated in November) in winter have consistently had higher mite levels.

All other things being equal – e.g. temper, behaviour, frugality 13 – I would choose to rear queens from a colony with the low mite levels.

The colony that first Varroa tray was from are not ‘mite resistant’.

They will have Varroa.

My post-treatment mite counts showed a modest mite drop and I’m confident that the treatment will have been no more than 95% effective. However, low mites are better than loadsa mites 14 and it will be interesting to see if colonies headed by daughter queens behave similarly.

Entrances

The late summer/early autumn colony reduces in size as the year progresses and as bees die off. At some point in early spring that daily births outnumber daily deaths (Murray McGregor calls this ‘crossover day’) and the colony starts to expand again.

So what happens to all those corpses?

The bees fall down through the cluster to the hive floor. On good flying days the undertaker bees will carry these away and discard them outside the hive.

However, during protracted cold or wet periods when the bees cannot fly the corpses can end up covering the floor and eventually blocking the hive entrance.

Multi-purpose Swiss Army penknife for beekeepers (sort of)

So the second check you need to perform is to ensure that the hive entrance is clear. This might mean removing the mouseguard and gently raking out the accumulated corpses.

In the kewl floors I favour the L-shaped entrance requires a correspondingly L-shaped piece of wire (a repurposed stainless steel spoke from a bicycle wheel) to check it’s clear. The same tool works perfectly well on almost all other hive entrances as well.

Be aware that you might inadvertently disturb workers near the hive entrance … these can fly out and aggressively ‘ask’ you to move away 15.

Tunnel entrances

The only entrances this multipurpose-and-soon-to-be-patented tool 16 is unsuitable for are those on the hives in my bee shed.

Entrance duct and hive floor ...

Entrance duct and hive floor … brood box removed for clarity

These have a 6” tunnel entrance. Even with a torch it’s difficult to see whether the inner hive entrance is blocked or not.

However, since you’ve already removed the Varroa tray it’s easy to look up through the OMF and check it’s clear.

There are two ways to do this:

  1. Prostrate yourself and look though the OMF while at the same time getting a gentle dusting of the stuff raining down from the cluster, or
  2. Use the phone on your camera to take a quick photo (you’ll need to use the flash).

Nothing to see here … other than some clown photobombing the hive checkup

If you do find the floor covered in corpses and the entrances blocked – whether the hives are in a shed or outside) it’s very important to clear them before leaving the apiary.

Blocked Kewl floor

Blocked Kewl floor …

Simply separate the brood box from the floor, no need to remove the crownboard, set it gently aside. Clear the floor and the entrance and replace the brood box.

Fortunately, the floors of my hives were all reassuringly clear of corpses.

In the photo from underneath the floor you can see the bottom bars of the frames and, between them 17 the serried rows of bees on the underside of the cluster. There are a lot of bees in the box.

Winter weight

So, without disturbing the colony you now know:

  • the colony is alive
  • they are rearing brood
  • stores are being consumed
  • something of the strength of the colony (in terms of number of seams of bees present)
  • whether they have low or high Varroa levels
  • if they are free to fly when the weather becomes suitable

Not a bad result for 5 minutes work.

But there’s one more thing to check.

Do they have sufficient stores to survive until your next visit to the apiary?

Actually, not just survive, but do they have sufficient stores to continue to rear brood so that the colony expands to be strong enough to exploit the early season forage when it’s available.

And I’ll deal with that question next week as I’m already fast approaching 2500 words 18 and there’s quite a bit more to cover on hive weights and winter feeding.


 

Queen mating flights

Synopsis: How far does a queen fly to mate? Studies using RFID-tagged queens are providing insights into the frequency, duration and temperature dependence of queen mating flights … all of which have practical implications for beekeeping.

Introduction

Although it tends to be a rather poor topic of conversation at dinner parties 1, I’m getting increasingly interested in the mating biology of honey bees. This is an essential part of the life cycle of our bees, and one that has been – and continues to be – well studied.

Marked queen surrounded by a retinue of workers.

Here’s one I made earlier …

When I lived in the Midlands there were a seemingly endless supply of bees in the area. Beebase reported that there were about 200 other apiaries within 10 km of my main apiary. Assuming an average of 5 hives per apiary 2, and ignoring any wild or feral colonies, that’s 1000 hives producing drones with which the queen could mate 3.

Of course, it’s not quite that simple, but bear with me.

In Fife, on the east coast of Scotland, my apiaries are in areas with about 35-40 other apiaries within 10 km, so – using similarly dodgy maths – perhaps 200 hives.

Nevertheless, bees are in apparently plentiful supply.

What do I mean by ‘plentiful’?

As a beekeeper, the two main ways – other than Beebase or by physically searching for them – I can judge the numbers of bees in the environment are, the:

  • success of my bait hives in attracting swarms 4, and
  • the ease with which my queens get mated

If I catch lots of swarms and a high percentage of my queens mate successfully then there must be a lot of bees about.

Apiary density

I was intending to start this post with a discussion of the evenness or otherwise of the distribution of apiaries within the Beebase-defined 10 km radius.

However, it turns out 5 that my maths are not good enough to plot a truly even distribution of hives/apiaries 6. Anyway, common sense dictates that apiaries are not evenly distributed … so let’s instead just consider the number of hives per square kilometre within that Beebase 10 km boundary.

Neighbouring apiaries, hive density and queen mating distances (see text for details)

In the diagram above the enclosing black circle indicates the area within which Beebase reports ‘neighbouring’ (i.e. within 10 km) apiaries. Inside that I’ve shown just four of the 314 one km2 blocks (in blue). On average, in the Midlands each of these would contain ~3.2 managed hives 7. In Fife, there would be – on average again – about 5 times fewer hives per blue square.

Several studies suggest that drones fly relatively short distances from the hive to the drone congregation areas (DCA) where they loiter with intent’ (of finding a virgin queen to mate with). I’ve discussed the use of harmonic radar tracking studies to identify these locations.

So, how many of these hives are actually within the range of a queen on a mating flight?

Where do you go to my lovely?

I posed the question How many of these hives … ? as we don’t know where the actual DCAs are.

The radar mapping study identified several within a few hundred metres of three drone producing colonies, so it seems reasonable to simply assume the DCAs are near the hives, and we know the average density of these.

Harmonic radar tracking of tagged queens visiting DCAs was not successful. It’s a short range technique, and the queen is known to sometimes fly long distances to visit DCAs.

I’ve discussed some of the studies used to determine these long-distance virgin queen flights, but summarise them again here:

  • In studies almost 90 years ago, Klatt observed successful mating on an isolated peninsula when the queen and drones were 6.3 miles (10.1 km) apart
  • In the mid-50’s Peer 8 demonstrated matings could occur when the queen and drones were 10.1 miles (>16 km) apart
  • Jensen 9 demonstrated mating when the queen and drones were 9.3 miles (15 km) apart

Of course, in all these studies it was not determined whether the queen and drones flew similar distances to the DCA. Since we know that drones probably fly relatively short distances it’s likely that the queen does the majority of the leg wing-work.

Ignore the outliers

The Peer studies showed that, although mating could occur when drones and queens were very widely separated, there was an inverse relationship between mating success and distance.

Just because 5% 10 of queens can mate following combined flight distances of 15 km does not mean that’s the distance they usually travel.

Actually, if only 5% of queens get mated at that distance then we can be pretty sure they usually fly much shorter distances.

Fortunately, Jensen did a more thorough analysis of this and showed that 90% of all matings occurred within 4.6 miles (7.4 km) and 50% within 1.5 miles (2.4 km).

And those are the 50% and 90% circles plotted on the diagram above, encompassing an area of 18 km2 and 174 km2 respectively.

Or, to express that area in potential drone donor colonies, 58 or 548 respectively in the Midlands, with a hive density of 3.2/km2 11.

So, in areas with reasonable densities of bees, knowing the majority of queens fly no more than 7.4 km, there are potentially hundreds of colonies producing drones that the queen could mate with.

All of which is a rambling introduction to looking at queen mating distances using a different approach.

Rather than work out how far she flies, what happens if we measure how long she takes?

If we know how fast the queen can fly we can again calculate distances and the number of potential drone producing colonies within range.

Time and weather dependence

But there are additional advantages of looking at queen mating flight duration.

If we can do it accurately we can also determine the:

  1. time of day when most mating flights take place,
  2. influence of the weather on the duration and frequency of queen mating flights,
  3. number of orientation and mating flights the queen takes.

And frankly, as a practical beekeeper, I’m much more interested in the first two of these than I am in the absolute distance she flies for her dalliances.

In an area well-populated with hives, understanding when the queen is likely to be away on a mating flight will help me avoid interrupting her return, and determining when she is likely to start laying.

But, as a scientist, I’m also really interested in the third point as there is some interesting recent work to suggest that drones try and restrict queens taking multiple mating flights 12.

Heidinger et al., studied the mating behaviour of queens using radio frequency identification (RFID) tags 13. Although the study produced no dramatically new results, it was a neat application of technology and allows me to discuss when mating flights occur and the influence of the weather in a little more detail.

The paper is Open Access if you’d like to read it. I’m not going to go through every subtle wrinkle and nuanced argument in the study, but will instead just focus on the important ’take home message(s)’.

RFID tagged queens

This is something I don’t need to discuss in anything other than cursory detail as I wrote about it three weeks ago in ’Chips with everything’.

Or perhaps I do? The post was only read by about 25% of the visitors who read the following week’s ’What they don’t tell you’ … it’s almost as though the hardcore science is less interesting than anecdotes about starting beekeeping. Surely not?

Essentially you stick a unique tag onto a bee and record when it enters or exits a hive using a sensitive reader at the hive entrance.

RFID tagged bees and RFID readers on a feeder

You don’t need to stand by the hive and watch anything.

All the ‘observations’ are made automagically and recorded digitally for subsequent analysis. You can therefore monitor hundreds of workers or dozens of queens simultaneously, thereby increasing the statistical robustness of the results obtained.

The Heidinger et al., study monitored the mating flights of 64 queens.

Of these, 11 were ‘missing in action’ 14 and never returned to the mating nuc.

Fifty three (83% … a figure very close to that quoted above from completely different studies) mated successfully and started laying eggs. However, two of these managed to get out and mate successfully without ever being detected by the RFID reader, meaning that flight times, frequencies and durations are from 51 queens 15.

The study was conducted in two apiaries about 4 km apart in Middle-Thuringia, Germany, in June/July.

Logistics and data wrangling

Conducting these types of field studies is not straightforward. Queens have to be produced in batches and then introduced to mating nucs.

A week of bad weather means the queens will have aged before they have a chance to fly.

What do you do about queens that return from a mating flight but that cluster underneath the mating nuc, only entering (and triggering the reader) after an hour or two?

To accommodate these vagaries the authors:

  • grouped queens according to age,
  • considered flights less than 3 minutes long as orientation flights
  • ignored mating flights of longer than one hour

And whatever filtered through from that pre-screening was then subjected to rigorous statistical analysis.

Time and duration of mating flights

Queens went on mating flights for 1 to 5 days, with an average of 2.2 +/- 0.98 day 16. In easier-to-comprehend terms this means that about 70% of all the queens went on mating flights on 1 to 3 days.

Since it’s often quoted that queens leave the hive ‘once to mate’ this might be a surprise to some.

Perhaps even more surprising is that queens went on a total of 1 to 16 mating flights, with an average of 5.04 +/- 3.11.

One particularly enthusiastic queen went on 7 mating flights in one day. The very definition of ’hot to trot’.

The timing of queen mating flights

Over 80% of these mating flights took place between 1pm and 4pm. From a practical beekeeping standpoint, by avoiding this period for hive inspections you will significantly reduce the chances of being in the way when a queen returns to a mating nuc.

The duration of mating flights

The average length of a mating flight was a bit less than 18 (17.69 +/- 13.19) minutes. Of approximately 255 mating flights (i.e. flights of 3-60 minutes duration) monitored, about 180 (70%) were of 20 minutes or less.

All of these results are in pretty good agreement with a wealth of literature collected using different methods over the last few decades.

Can we use some of these figures to calculate queen mating flight distance?

Duration x speed = distance

I can find nothing in the literature on the speed at which a queen flies. However, I do know that the escapee virgin queens I try and catch usually fly just too fast 🙁

Let’s assume for the sake of argument that the queen flies at about the same speed as a worker bee. This is usually reported as 25 km/hr unladen and about 17 km/hr when laden with pollen or nectar.

Therefore, a queen mating flight of 20 minutes at 25 km/hr involves flying a total distance of no more than 8.3 km. A 10 minute mating flight at 17 km/hr equates to 2.8 km.

These distances include three components, an inward and outward leg separated by the flight time within the DCA. Your guess is as good as mine as to how long the latter takes 17.

However, not knowing something is the perfect opportunity for some informed speculation (or, as here 18, wild guesswork).

Wildly uninformed guesswork

The queen mates with several drones while in the DCA. Although each mating takes a very short time (seconds) there is competition between the drones while they chase the queen, so she must stay within the DCA for a reasonable period.

Time for another assumption … this time let’s assume that the queen spends one third of the duration of her mating flight within the DCA or 4 minutes, whichever is the shorter 19.

If that were the case, a 10 minute mating flight at 17 km/hr, with a third of the flight time being spent in the DCA, would mean the mating site was just 940 metres from the hive. Conversely, if the queen spent no more than 4 minutes in the DCA during a 20 minute mating flight at 25 km/hr, then the mating site must be 3.33 km from the hive.

Either my guessestimate for the time spent in the DCA is too high (quite possible), or the predicted flight speed of the queen is too low (unlikely to be wildly wrong, she’s not going to rush there at 75 km/hr) … or the typical distances queens travel to a DCA are significantly less than those measured using isolated queen and drone-producing colonies in the studies cited earlier by Jensen, Peer or Klatt (see above).

Relationship of time spent in DCA and potential maximum mating flight distance

The table above shows why I think queens likely spend less than 4 minutes in the DCA. Distances in red are within 2.4 km that Jensen showed 50% of matings occur in, those in yellow are within the 7.4 km that 90% of matings occured in 20.

The influence of the apiary

Let’s stop all this wild guesswork and return to the calming certainties of statistically compelling data 😉

The Heidinger study involved two apiaries separated by a few kilometres. All the data discussed above uses recordings pooled from both apiaries. However, queens in one apiary went on more mating flights than in the other. The difference isn’t huge (5 vs. 4 flights in the first three flight days), but is statistically significant.

Mating flight number (a) in different apiaries, and (b) at different temperatures

The queens are described as ‘sister queens’ and I assume this means they are all reared from larvae from the same mother queen, though this isn’t made explicit. If that is the case, it suggests the geography of the area influences queen mating flight frequency.

I say geography, rather than drone availability, as they also added an additional 47 (!) drone producing colonies near one apiary and observed no influence on queen mating flight characteristics.

Although the number of mating flights the queens went on differed, the duration of the flights did not.

The data start to get a bit more complicated when they considered the age of the queens and the duration of the first, second, third etc. flight … so I’ll skip all that and finally just consider the influence of temperature on mating flights.

Some like it hot

It is regularly stated that virgin queens need calm, sunny afternoons with a temperature exceeding 20°C before embarking on mating flights.

This is somewhat disconcerting for a beekeeper living on the cool/wet/windy – but exceeding beautiful – extremities of the UK.

July rain squalls across Mull, Skye and the Sound of Sleat

In fact, mating flights – by which I mean flights of 3-60 minutes (as no record of successful mating on individual flights was made) – occurred in the Heidinger study between a range of 14°C and 25°C.

In cooler weather, queens tended to take more mating flights (shown in the right hand panel on the graph above). The line is a ‘best fit’ and it’s clear there is quite a bit of variation. However, at 15°C the queens would take about 7 flights, compared to only about 4 flights at 24°C 21.

Unsurprisingly therefore, individual mating flights were of greater duration during warmer weather. Again the ‘best fit’ line is shown together with the variation in the primary data.

Relationship between temperature and individual mating flight duration

I found these last two graphs quite reassuring … there were lots of flights below 20°C.

Geek alert

I’m starting to get a bit obsessed with the weather here on the west coast and installed a weather station last summer. I only have complete records from July, but know we had a total of only 27 days on which the temperature exceeded 20°C from July and September.

August 2021 temperatures in Ardnamurchan

2021 was an outstanding summer here on the west coast.

Next year I’ll have data for the full queen rearing season so hope to understand this aspect of the mating biology of my queens a little better.

Conclusions

I’ve covered a lot of ground in this post … from the how far can she fly to mate? studies of the 1930’s to what appear to be short duration, and therefore relatively local, mating flights of RFID-tagged bees.

Understanding when a queen is likely to go on a mating flight should help you with timing your colony inspections. It should certainly help curb your impatience as you wait for your queens to get mated.

Finally, knowing that she can fly on much cooler days than the widely-cited 20°C gives those of us living in more northerly latitudes some reassurance that our queen rearing efforts are not entirely futile.


Notes

Some figures I meant to quote earlier; if the queen only flies between 940 m and 3.33 km to the DCA (see Duration x speed= distance above), and assuming colony densities of either 0.6/km2 or 3.2/km2 (see Apiary density about 3000 words ago 🙁 ) the number of hives ‘within mating flight range’ are between 1.7 and 111.

Quite a range, so ample opportunity for good numbers of genetically diverse drones, though remember that apiaries are not evenly distributed and DCA’s are variable distances from drone producing colonies.

Treat all of my numbers (and particularly my calculations) with considerable caution.