15 min read

Irregular inspections and swarm prevention

Regular hive inspections during the oil seed rape flow, what happens when you don't and useful swarm prevention tactics that help queen rearing.
Oil seed rape on the Fife coast, May 2024
Oil seed rape on the Fife coast, May 2024

Book III of Geoffrey Chaucer's epic Medieval poem, Troilus and Crisedye, contains the line:

And after winter folweth grene May

Even with only a cursory understanding of Middle English, it's pretty obvious that Chaucer is commenting on May being the first month of the year when everything is verdant.

Winter is over, the trees are in full leaf.

However, despite my colour blindness, the colour I mostly associate with May is yellow ... the flowering gorse, the broom and - of course - the oil seed rape (OSR).

Oil seed rape flowers
Oil seed rape flowers

Troilus and Crisedye was written in the mid-1380's, a couple of centuries after rapeseed, or oil seed rape (Brassica napus), started to be grown as a crop in Europe. US readers will know it as canola.

Rapeseed is one of the oldest farmed crops, with evidence of its cultivation dating back at least 6,000 years, and possibly as many as 10,000, to the dawn of agriculture. Although the acreage grown has reduced over the last decade or so (though it's up again following the Russian invasion of Ukraine, usually a major exporter) it remains a dominant presence in terms of spring forage for bees in many areas of the country.

Those dazzling yellow fields produce huge volumes of sugar-rich nectar, the amount dependent upon the particular strain and the genetics of the plant. A typical open pollinated OSR strain such as Cash, Fashion or Quartz will produce about 0.5 ยตl of nectar per flower in 24 hours, with each plant bearing ~900 flowers (Carruthers et al., 2017) {{1}}.

You need to read the post in a web browser to access the {{footnotes}}.

The bees love it.

A combination of a few dozen acres of OSR and good weather ensures that the supers fill rapidly and, if you're not careful - or miss an inspection due to illness - they'll fill the brood box with ripening nectar, run out of space and swarm.


Education, entertainment or schadenfreude?

I've described some of my beekeeping seasons as "a series of catastrophes interrupted by winter" which, although thankfully not the norm, has certainly provided a wealth of experience from which I should have learned.

It's also provided a number of anecdotes which I've used to illustrate particular aspects of our hobby in the hope that, even if I've not learned, you might.

I read all the comments from subscribers, sponsors and those that support The Apiarist via the coffee 'tip jar'. It's clear that many readers enjoy these tales of mishap and mayhem, hopefully from an educational point of view, or from simple entertainment ... or perhaps it's schadenfreude?

Stuff goes wrong ... not always, but frequently enough to remind me that I'm working with the bees, and that I don't control them.

I might think I am in control, but it doesn't take much to show I'm not ... or, at least, not completely.

Shirtsleeves and sou'westers

Here in Scotland, the transition from April to May often sees a significant change in the weather. Heavy rain, frost and snow is not unusual in April, but May is usually more benign.

My apiary trips take me through Glencoe or past Creag Meagaidh and its surrounding Munros, the high tops of which are often snow-capped until at least mid-May.

The Post Face, Coire Ardair, Creag Meagaidh ยฉ Jim Barton (cc-by-sa/2.0)
The Post Face, Coire Ardair, Creag Meagaidh, June 2015 ยฉ Jim Barton (cc-by-sa/2.0)

This year the weather has been a bit warmer and more settled, and these hills now have little more than wedges of snow packed into the high gullies.

But my beekeeping is done at lower altitudes, and this month I've experienced the full gamut from torrential rain, low temperatures and relentless haar to a sweaty and energy-sapping 25ยฐC.

Where's my neoprene beesuit?

For reasons too dull to recount (involving road closures, ferry timetables and hotel bookings) I had to inspect about ten colonies in the late afternoon on the first Sunday of May.

Not in itself a problem. It was a bit later in the day than I'd like to start beekeeping, but 'needs must' as they say. The day was cool and overcast in the morning, pleasantly warm at lunchtime before cooling off by ~5 pm.

At which point the rain started.

The first few tentative spots greeted me as I pulled on my beesuit and lit the smoker. Once I was 'suited and booted' it was definitely spitting. By the time the first hive roof was off it was raining, albeit gently.

But it appeared to be getting heavier.

Rainfall graph, 5th May 2024, Fife

It was.

In ~75 minutes almost 7 mm of rain fell.

I was soaked to the skin. A polycotton beesuit offers no protection from the rain. I had water sloshing around in my wellies. Upturned hive roofs (on which I'd stood the supers) had to be emptied of water before returning them to the hive.

It was too wet to use the camera or the voice recorder. Heck, it was too wet to really use a hive tool. It was, in equal measure, completely mad and strangely invigorating.


Throughout the inspections the bees were exceptionally well-tempered. No stings, no aggression, no more than a resigned 'Really? In this? OK, get on with it'.

Whilst I might generously interpret this as the just reward for years of repeated selection for well-mannered bees, I think it was more likely a simple act of self-preservation on their part.

I'm not suggesting you do your inspections in the rain.

However, if it's raining, and you must inspect the colonies, then you can inspect them in the rain.

I had no choice. The OSR was just ramping up, the weather was set fair, and I was concerned that the bees would run out of space before I returned a week later.

Almost every colony I looked at needed an additional super and/or space in the brood box.

In the same verse as Chaucer's 'And after winter folweth grene May' is the line:

That after sharpe shoures been victories

This was more than a sharp shower, but I'll still count it as a win {{2}}.

Regular inspections

The importance of regular inspections is probably never greater than during the OSR nectar flow (and shortly afterwards {{3}}). Colonies that have built up strongly after the winter rapidly outgrow the space they have available.

Inspections should be every seven days.

This not quite the same as once a week.

The latter could be interpreted as last Monday, this Tuesday and next Thursday. Every seven days means last Monday, this Monday and next Monday.

Yes, yes. Clipped queens. I'll discuss those shortly. If the queen is clipped, you can inspect at 9-10 day intervals. You should not lose the colony through swarming, but you might well lose the queen.

The timing is, like so many things to do with beekeeping, determined by the development cycle of the queen. Colonies tend to swarm on, or shortly after, a developing queen cell is sealed {{4}}. This occurs about eight and a half days after the egg was laid. Therefore, if the colony had no queen cells at the last inspection, they are unlikely to swarm within the seven days before the next inspection.

Unlikely does not mean 'will not' ... under some conditions colonies can swarm before any queen cells are sealed.

If beekeeping was completely logical and predictable it would be much less interesting ... I'm not even sure that this behaviour makes much sense to the colony.

I schedule apiary visits throughout May and early June every 7 days and stick rigidly to this schedule.

Unless I can't.

And this month I had Covid and was lying in bed feeling very sorry for myself when I should have been out checking my bees.

So, when I did finally get to the apiary, after more than a week of good weather in the middle of a strong OSR nectar flow, I was more than a little apprehensive about what I would find.

Super early for swarm prevention

The hives were all fine.

Heavy supers, a little backfilling of the brood boxes, but only one that looked like it was thinking of swarming (on which I started a vertical split, to be described in a future post).

Partly to delay the need for swarm control, and partly due to laziness {{5}}, I tend to add supers before they are needed. Typically, I'll add a couple of supers initially, and add a third and even a fourth early/mid-flow {{6}}. Supers are added directly to the top of the stack ... scientific studies have shown it makes no difference to how much honey is stored.

So the hives, all generously supered, didn't miss me. And, more importantly, I didn't miss the queens.

Nucs and clipped queens

The same cannot be said of the overwintered nucs ๐Ÿ˜ž.

Brood frame filled with OSR nectar
No room for brood

With no space - other than the brood frames - to store incoming nectar, and a rapidly expanding foraging force, things had rapidly got out of control.

One nuc had swarmed, and the queen was long gone. No eggs and a couple of sealed queen cells were all the evidence I needed.

You win some and you lose some

Although the queen had gone, the bees had not. The box was packed with workers. This is because I had clipped one wing of the queen, so preventing her from flying (or, at least, flying well).

The colony swarms and the queen leaves, but she crashes to the ground and is often then lost.

Swarmed clipped queen and a small cluster of bees
Swarmed clipped queen and a small cluster of bees

On the day of the swarm, it's not unusual to find the queen and a small cluster of bees on the ground near the hive. However, over time (perhaps later the same day if it gets chilly), the bees return to the hive and abandon the queen.

Check the floor

Another nuc was a bit more interesting. Again, it was packed with bees (and stores). However, on removing the frames to check for queen cells, I noticed a lot of bees when looking down through the open mesh floor of the nuc.

Hive inspections are what they say they are ... inspections of the hive, not just of the frames in the hive.

Not all clipped queens perish. This one had managed to crawl back up the leg of the hive stand, but had failed to find the hive entrance {{7}}.

Clump of bees under the floor of a nuceus hive
Somewhere in there is a clipped queen

Having removed any queen cells and two full frames of stores (replacing them with one of foundation and drawn comb) I gently shook the clump of bees back into the box, found the queen, checked she was OK {{8}}, and then returned her to the box as well.

Picture of queen found under the floor of a nucleus hive
There she is!

Yes, they might well try again, but they've got much more space, the nectar flow is lessening, the weather is predicted to be less good, and I plan to be back there well before they could produce any sealed queen cells.

It's one of those calculated risks I discussed a couple of weeks ago.

Sometimes these 'reassembled' colonies quickly do away with the queen and go on to produce a replacement. Others just go back to being a properly functioning colony.

Cell raisers and swarm prevention

In addition to the early supering, the likely other reason that swarm control was not (yet) needed is that I had 'harvested' a frame or two of bees and brood from many of the hives to make up a double-decker queenless cell raiser for queen rearing.

I prepare a large double nuc, consisting of two stacked boxes, each with 6 brood frames. The Maisemore's poly nucs are ideal for this as the bee space between the boxes is correct. Stacked Langstroth nucs are not, at least not if you are using National frames in them.

I populate this box by harvesting brood frames and the adhering bees from at least six colonies. This is an example where experience and judgement becomes important {{9}}. If the brood box has 8-9 frames of brood I'll probably just remove one, 9-11 frames of brood and I'll be happy to take a couple.

Preparing a double decker cell raiser (Q = queen cell, X = destroyed queen cell)
Preparing a double decker cell raiser (Q = queen cell, X = destroyed queen cell)

I choose frames filled with sealed and emerging brood, and it is critical that a queen is not transferred to the nuc box! It's also important that the frames chosen have no queen cells on them {{10}}.

I replace the removed frames with foundation, foundationless or frames of drawn comb, depending upon what I have available and the perceived strength of the 'donor' colony.

It's an inexact science (at least it is when I'm involved ๐Ÿ˜‰), but this depletion of the workforce - perhaps coupled with giving them some more comb to draw - holds them back a bit and helps delay the need for swarm control.

Mix and match

It does not matter what order the frames are in when added to the cell raiser. Since you're mixing workers from 6+ colonies, they don't fight. Instead, they soon settle down to rear the queen that they are missing.

I make up the cell raiser in one apiary and then move it to a distant apiary to ensure I don't 'lose' bees that return to their original hives.

Over the following week much of the brood emerges leaving a box packed with young bees ... an ideal environment for rearing new queens.

Entrance to a nucleus hive with pollen-laden bees returning
Spot the pollen baskets on the forager returning to a queenless cell raiser

If you check the hive entrance of a known-to-be-queenless cell raiser, you may well see foragers returning laden with pollen ... perhaps not as many as to a queenright nuc, but more than enough to make you (or me) question the statement some beekeepers make about "pollen going in (the hive) indicates there's a queen present".

(Approximately) One week later

With no queen and no queen cells, it will be at least two weeks before the double-decker cell raiser could produce a new virgin queen.

Even after choosing frames packed with sealed brood, the cell raiser always manages to find a few eggs or larvae that are young enough to rear as new queens {{11}}. It is therefore important that these cells are found and removed before using the box to rear your selected queens.

After 7 days, any eggs laid immediately before a frame was transferred would have hatched and subsequently developed into four day old larvae. These are too old to rear as queens. Therefore, if you remove all queen cells 7 days after assembling the cell raiser (the two central panels in the diagram above), it will be terminally queenless and in the perfect state to receive your selected eggs or larvae.

I separate the two brood boxes and leave the upper box to the side while dealing with the bottom box. The bees must be shaken off every frame (into the box), and anything looking like an open charged or sealed queen cell must be destroyed.

Sealed queen cell
Make sure you remove all the queen cells from the cell raiser, not just the obvious ones

Once the bottom box has been checked, add back the upper brood chamber and go through that box thoroughly as well.

Remember that many of the bees will be very young and may not have ventured outside the hive yet ... make sure you shake them off the frames back into the box to avoid losing bees.

Lots and lots of young bees
Lots and lots of young bees

Inspect the nuc, not just the frames

When I'd assembled my double-decker nuc I'd included a couple of super frames packed with brood.

These had been in the donor hives to encourage the bees to draw drone comb underneath the super frame. Since this is some of the first drone brood of the season, it acts as a mite-magnet. I had therefore sliced it off (I don't want drones or mites in my cell raiser) and discarded it before adding the super frames to the cell raiser.

By chance, one of these super frames had been pushed up against the side wall of the nuc. Since all the worker brood had emerged, I decided to omit this frame and use the space created in the rearranged box to accommodate my cell bar frame (see below).

View between frames of a nucleus hive
What's hiding down there?

When reassembling the nuc I felt resistance when adding a brood frame in the space that had previously been occupied by the super frame against the side wall of the hive.

This side wall was covered with a 2 cm thick carpet of bees, but there was also clearly something more solid 'in the way'.

Queen cells found attached to the side wall of a nuc.

A gentle puff of smoke and a bit of probing about with a hive tool uncovered two sealed queen cells.

Remember, it's a hive inspection, not a frame inspection! It's deja-vu all over again.

These cells must have been drawn from the bottom edge of the super frame, becoming fused to the side wall during their construction. Had I not discovered (and removed) them, assuming they were intact, the cell raiser would have singularly failed to raise any cells.

And relax ...

Checking the cell raiser for queen cells is, of necessity, a very disruptive process.

Cell raiser ready for use

The space created by removal of a (now empty) brood frame is arranged in the middle of the upper box. Finally, the cell bar frame carrying the Jenter queen cups which will - in due course - contain the eggs/larvae selected for queen rearing is gently lowered down into the mass of bees.

I usually leave the cell bar frame in situ to acclimatise for 24 hours before adding grafted larvae. This acclimatisation process is not really needed (there are studies showing equal rates of larval acceptance irrespective of whether the cell bar frame is acclimatised or not), but it certainly does no harm. To speed the process along I often spray the cell bar frame with 1:1 w/v syrup to encourage the bees to clamber all over it.

More importantly, this 24 hour acclimatisation period allows the colony to settle down after the disruption I caused rummaging through it for hidden queen cells.

Leave the cell raiser 24 hours before adding the grafted larvae

I want the eggs/larvae I add to immediately receive the undivided attention of the nurse bees ... and that is much more likely to occur in a calm colony.

It also allows me to relax before doing the grafting or retrieving eggs/larvae from the donor colony (if I've been trying to exploit the maternal effect) ... both topics I'll cover in a future post.

Go check your hives ... not just the frames!

Informative? Useful? Entertaining? ... choose any three.
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Thank you


Schadenfreude - meaning 'harm-joy' - is of German origin. While looking up the etymology of schadenfreude I discovered that there's a little-known English equivalent, epicaricacy. This derived from a Greek word first attributed to Aristotle who, although not a beekeeper, was an acute observer of bees and beekeeping.

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Carruthers, J.M., Cook, S.M., Wright, G.A., Osborne, J.L., Clark, S.J., Swain, J.L., and Haughton, A.J. (2017) Oilseed rape (Brassica napus) as a resource for farmland insect pollinators: quantifying floral traits in conventional varieties and breeding systems. GCB Bioenergy 9: 1370โ€“1379 https://onlinelibrary.wiley.com/doi/abs/10.1111/gcbb.12438.

{{1}}: Genic male sterile OSR hybrids produce 1.5-2 times the amount of nectar, but no pollen. For the uninitiated, 1 ยตl is 0.001 ml. OSR can produce half a teaspoon of nectar a day per plant.

{{2}}: My rudimentary understanding of Middle English suggests that sharpe shoures actually means 'attacks' rather than specifically referencing rain.

{{3}}: When bees no longer engaged with nectar collection often decide to swarm after all.

{{4}}: Weather permitting. They won't swarm in sharpe shoures.

{{5}}: Like hubris and impatience, a virtue for computer programmers, and beekeepers?

{{6}}: Remember, this is Scotland; don't go expecting double brood boxes with teetering towers of supers needing a step-ladder to add/remove the roof.

{{7}}: Of course, I don't know she flew at all ... she might have just sauntered out of the entrance, flapped busily to show willing, then ambled off underneath the box. The nuc was in the middle of a stand, with hives on either side, so she would have had to negotiate other hive entrances if she had clambered back up from the ground.

{{8}}: 1 head, thorax and abdomen, 2 antennae, 3.5 wings, 5 eyes, 6 legs etc.

{{9}}: Meaning, of course, that I don't always get it right.

{{10}}: I usually put the frame with the queen aside while selecting frames to 'harvest'. However, I don't shake the bees off the selected frames as there's another chance to destroy any queen cells. If there were queen cells on these frames, it's likely the donor colony would need swarm control ... just removing a frame or two will not stop them!

{{11}}: After all, if they didn't, they would be doomed.

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