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Mini-nucs: tips and tricks

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Synopsis : More discussion of modifying and maintaining mini-nucs for queen mating; judging queen quality, repeat queen mating, season’s end and overwintering mini-nucs.

Introduction

A couple of weeks ago I described some of the basics of using mini-nucs for queen mating. I’ll try and avoid overlaps with that post in the following discussion of ‘tips and tricks’, effectively a rag-bag collection of stuff I failed to cover last time, interspersed with some typical problems that might be encountered.

Inevitably some of the discussion will be about specific modifications to the particular mini-nucs I use (Kieler or Warnholz polystyrene mating nucs). I settled on these because I needed a dozen one season, I had zero experience in using any so had nothing to compare and I couldn’t afford Apidea’s.

Kieler mini-nucs: four topbar frames and an integral feeder

Overall I’ve been reasonably satisfied with the choice my younger, poorer 1 and (even more) ill-informed self made. Over a decade later I’m using the same mini-nucs and I’ve not been tempted to try anything else 2.

Nevertheless, despite a Kieler-centric flavour to some of the comments below, most still apply directly (or with a little finagling) to other makes of mini-nuc.

Finally, I’ll repeat the point I made last time … mini-nucs are ’high maintenance’. They are not ’fit and forget’ beekeeping. Unless placed in the shade they may well abscond on a lovely day 3. Late in the season, without care and attention, they can get robbed out by wasps in hours. If there’s no nectar flow they will need feeding.

But, looked after carefully, they can be an efficient way to get queens mated .

Painting and decorating

Any poly hive needs painting to protect it from UV degradation. Most of my mini-nucs were first painted with el cheapo masonry paint. This has a matt finish and has been reasonably hard wearing.

More recently, I’ve started painting – or overpainting – them with Hammerite garage door paint. This is an oil or solvent based gloss paint. It causes the surface of the polystyrene to melt (very slightly) and therefore bonds extremely well. The Swienty brood boxes I painted several years ago look as good now as they did then. The Hammerite paint comes in a range of colours, including a rather nice green or blue.

Hammerite Oxford blue, since you asked

Successful queen mating needs reasonable weather (and patience). However, it also needs the returning mated queen to successfully find the mini-nuc she set out from. It therefore makes sense to either place the mini-nucs in separate and distinctive locations, or (perhaps that should be and/or) to paint them in distinctive colours.

Red ‘Wilko’ masonry paint and ‘bin end’ yellow gloss

I tend to place mine in pairs and so often have a plain and coloured one on the same stand, facing in opposite directions to further help the queen discriminate between entrances.

Entrances and exits

Kieler-type mini-nucs have a rotatable entrance with three or four options – blanked off, ventilation, a queen excluder or fully open. I shouldn’t need to mention that, if there’s a virgin queen in the hive (that you want mated), the entrance must be fully open.

But I will 😉

Entrance discs for mini-nucs

You can purchase replacement entrance disks like those in the photo above from a range of suppliers (or eBay, which is significantly less expensive). Using these may help queens return to the correct mini-nuc after orientation or mating flights.

Oops, almost forgot … bees have a tendency to nibble away at the polystyrene around the entrance of these Kieler nucs (or at the ‘under entrance’ which I’ve never used) while confined. It’s therefore worth painting the entrance tunnel as well as the outside.

Crownboards

Apidea’s and several other mini-nucs I’ve looked at are sold with clear semi-rigid plastic crownboards. Some have integral flaps for adding the queen cell or feeding the mini-nuc without letting clouds of bees escape (admittedly small clouds, as they’re only primed with a few hundred millilitres of bees).

Kieler’s are sold without a crownboard. Don’t let that put you off. A thick piece of clear plastic works just fine as a crownboard and you can easily engineer (i.e. cut) a small flap to add the queen cell between the topbar frames. I use a small piece of tape to hold in down.

Plastic crownboard. Note flaps for adding the queen cell and (above the feeder) adding syrup

You can put an additional small flap above the feeder that allows you to add syrup without any bees escaping. This only needs to be a few millimetres square and doesn’t need taping down. Even if you don’t think you’ll be feeding syrup – which you do using a small funnel – this modification takes seconds and won’t be in the way (but you’ll be glad it is there if you need it).

Hold the crownboard in place with drawing pins. That way there’s less chance it will blow away should you open the box on a windy day. It also means the crownboard stays stuck to the brood body, rather than being removed with the tightly-fitting roof.

Feeder mods

The Kieler integral feeder has some good and bad points.

It’s a good size, so reducing the chance of the mini-nuc starving if left for an extended period. However, this inevitably cuts into the space available for bees and brood, meaning that retention of the feeder can lead to rapid overcrowding.

You win some, you lose some!

The feeder is easy to remove and only fits in one orientation. Irritatingly it is too deep to fit into the ‘second storey’ extension (see below). It also has no cover or queen excluder and the queen can sometimes end up in the feeder, particularly if the bees build comb there.

Feeder with queen excluder

I therefore usually fit a small rectangle of plastic queen excluder, balanced on map pins stuck into the inner walls of the feeder. This stops the queen entering the feeder, but doesn’t necessarily stop the bees building comb there.

Be thankful for small victories … 😉

If you need more brood space you can easily replace the integral feeder with a homemade frame feeder designed to feed fondant. I build these shorter than the integral feeder so that they can be used interchangeably in the ‘second storey’ extension.

Kieler frame feeders

These work well, cost pennies to make and can be quickly exchanged when needed. When I’ve overwintered queens in these mini-nucs I’ve always used these fondant frame feeders in the upper storey, with frames filling the entire lower level. This reduces disturbance when you need to feed them.

Frames

The Kieler is a mini-topbar hive. Each topbar has a longitudinal slot cut into its underside designed to take a strip of foundation. They also have a ‘pinched’ central area, so that a queen cell can be easily inserted between two adjacent bars.

The bars themselves are just 15 x 8 mm softwood. Purchased separately they cost 36 p each (Yikes! … and those don’t even appear to have the central pinched indent).

If you need more (and you will … to replace losses and for the the upper storey should you buy one) just make your own with some wood from the store, a metal ruler, a Stanley knife and some antiseptic cream and Elastoplast.

And, while you’re at it, don’t go fiddling about with little strips of foundation held in place with melted wax. I did this for years. They work perfectly well, but they are fragile. The foundation in unused topbar frames will get bent or broken, and then you’ll have to start all over again.

Instead, eat as many Fruit Splits, Rocket lollies or Twister’s as you can stomach 4 and keep the sticks. Split these lengthwise and glue them into the longitudinal slot in the Kieler topbar using normal wood glue and 5 never re-wax them again.

Kieler mini-nuc topbar frames – no need for foundation or waxing

And, no, you don’t need to cover them in melted wax or anything else. All the bees need is a guide to help them draw the comb in the right place.

I’m sure there’s stuff I’ve forgotten about, but that lot will do for the moment. Let’s move on to four specific practical aspects of using mini-nucs.

Judging queen quality

You can’t … or at least I can’t.

I don’t think you can meaningfully determine the quality of the queen in a mini-nuc. The time between when she starts laying and when she runs out of comb is sometimes too short to even check whether she’s producing worker brood.

I usually leave her in the box until there’s some capped worker brood present and then – ideally – move her to a 2-5 frame nucleus colony. At the same time I clip and mark her. As long as she’s laying one egg per cell (and she sometimes starts laying more than this, but should slow down after a day or so) and the brood develops into worker brood then things should be OK.

However, it’s not until she’s laid a full frame or three of brood that you can judge the laying pattern (remembering that the laying pattern may also depend upon the bees in the box with her).

Brood frame with a good laying pattern

Furthermore, to properly judge her you need to observe the behaviour of the bees that develop from the eggs she lays.

Are they well tempered? Are they steady on the comb? Do they have the other traits you are keen to promote? Frugality? Good pollinators? Preferential collection of avocado nectar (Afik et al., 2010).

OK, perhaps not the last of those, but you’d be surprised about the traits some beekeepers favour.

Queen introduction

I remove the mated queen from the mini-nuc, place her in a JzBz cage without attendants and introduce her in the usual way to a queenless full-frame nucleus colony; I leave the sealed cage hanging between frames overnight and – assuming there are no signs of aggression to the caged queen – I remove the plastic cap and leave the workers to eat their way in through the fondant-plugged entrance/exit tube.

If there are signs of aggression, leave it another 24 hours.

Checking for aggression

A well designed introduction cage has some protection for the queen so she can avoid aggressive workers that can otherwise damage her feet. I’ve had considerable success with the JzBz cages (and happen to have inherited a bucket full and so don’t use anything else 😉 ).

I’ve inadvertently left a queen trapped in one of these cages for 6 days with no ill effects. Don’t rush things.

Rear some spares

What do you think happens with commercially reared queens, many or most of which are mated from mini-nucs?

Exactly … nothing, other than being popped into a shipping cage and having a £40 price tag attached.

In contrast, you have the opportunity to check your queens more thoroughly.

Rear a few more than you need, check out their performance, keep the best and donate the unwanted to one of the many, many beekeepers clamouring for queens – particularly late in the season. Even the also-rans are likely to be OK 6. Not necessarily great, but more than good enough to get the colony through to the next season 7.

Queen rearing diary; automagically populates days and events

And finally, make sure you keep good records. The first couple of times you do this you’ll think you will be able to remember the key points the following year; the dates of emergence, the time it took to have mated queens, the origin of the queen cell used to prime the mini-nuc etc.

But you probably won’t. The notes will be very useful for planning your queen rearing the following season.

Keeping things going

Populating mini-nucs early in the season is often a thankless and unpleasant task. The weather is cool, the bees are tetchy and – as described a fortnight ago – you may have had to shake through the colony twice to get the young workers.

That’s not the sort of task I like to repeat if I can possibly avoid it.

If you’re rearing queens all through the summer you can simply remove one mated queen and, shortly afterwards (within a few hours), add a new mature queen cell. This is the ideal situation and, with good organisation, good weather and good mating success, you can get three or four queens out of a single mini-nuc in one season.

Mainly good organisation.

You need to ensure you have a succession of mature queen cells ready at the about right time, remembering that queen mating often takes longer than expected (or wanted).

Scrub ‘caretaker’ queens

If that’s not possible, or if you want (or have) to interrupt queen cell production (e.g. your queenright cell starter swarms or a round of grafting fails) you can remove the mated queen from the mini-nuc and allow the bees to rear a ‘scrub’ queen.

A well populated mini-nuc will readily do this. The resulting queen is usually a bit on the small side, but she will keep the worker population ticking over and ready to accept a new mature queen cell in due course. In addition, the enforced brood break while they rear the scrub queen helps prevent the mini-nuc from getting too overcrowded.

These ‘caretaker’ queens are reared under the emergency response and – assuming there are suitable eggs in the little colony – emerge about 15 days after you remove the mated queen (remember, the bees preferentially choose 3 day old eggs to rear queens under the emergency response). A fortnight or so later the queen should be mated and laying. This approach therefore means you can take 4-6 weeks off if needed.

The end of the queen rearing season

What do you do with the contents of the mini-nuc after you’ve taken the last of the mated queens out? The little hive may well be bursting with bees, with all 4-6 combs containing brood.

Many beekeepers shake the bees out in front of a strong hive. The majority of the workers will be accepted, but the brood is wasted.

To avoid this I’ve used ‘zip’ ties to secure two Kieler topbar frames into a standard brood frame. At the very least these can be placed into a full sized hive for the brood to emerge. Usually, by the time of year I get round to this the bees have stopped drawing comb. Once the brood has emerged I move the frame to the side of the brood box and remove it.

Dave Cushman has details of some clever frame modifications that allow Kieler-type (he calls them Kirchhain mating hives) frames to be drawn at the beginning of the season and used to accommodate brood-filled frames at the end.

Unsurprisingly, when I’ve done this it’s been a lot more ’Heath Robinson’. The Kieler topbar frames are a little too long to fit end-to-end in a National frame. I therefore built some with a scrap 8 mm thick spacer (shown in black below) tacked under one side of the frame. I then use zip ties to hold everything more or less in place.

Using mini-nuc brood frames

Despite being a total bodge this has generally worked well. I’m pleased not to waste the brood.

Now I know the air freshener trick (described in this 2020 post) I’d probably just add the frames as shown in the diagram above together with the adhering bees, and give them and the recipient colony a quick blast of ’Sea breeze’ before uniting them.

Overwintering mini-nucs

Alternatively, with a little care you can overwinter queens in mini-nucs. This saves you the faff of emptying them at the end of the season, and means they are ready for queen cells the following year (after removing the queen of course) 8.

I’ve overwintered queens successfully quite a few times but certainly don’t consider myself an expert at it. There’s quite a high attrition rate. Remember how small these colonies are, how limited the space is for stores and the relatively small population of bees present to stop the colony freezing in the winter.

I think every mini-nuc I’ve overwintered successfully has been a double-decker, with the standard Kieler brood box underneath an additional extension brood body. These almost double the volume of the mini-nuc.

The mini-nuc needs to be strong in mid/late autumn, almost certainly boosted by combining the contents of two separate mini-nucs. You can unite them over paper in the same way you’d treat a full sized hive.

Unfortunately, the upper and lower brood boxes have different depths, so comb drawn in the bottom box needs to be trimmed to fit in the upper box. A messy and irritating task.

I replace the lower integral feeder with additional brood frames and place one or two fondant frame feeders in the upper chamber – usually one at either end to ensure the mini-cluster is near to one of them.

Place the box somewhere sheltered, leave the entrance open to allow the bees to fly for cleansing flights and cross your fingers …

Gimme shelter

I’ve not overwintered mini-nucs since returning to Scotland, though I know several beekeepers here who do this successfully. In the Midlands we often had quite harsh winter weather – certainly much colder than we usually get here on the north-west coast of Scotland.

Two double decker mini-nucs overwintered successfully in an unheated greenhouse

A decade ago, well before my bee shed experiments, I was successfully overwintering mini-nucs in an unheated greenhouse with entrance tunnels from the hive to the outside. These worked surprisingly well and got queens through some really hard weather (note the snow in the picture above – late March 2013).

Tunnel entrances to overwintered mini-nucs

If the winter was particularly severe I would cover the mini-nucs with a thick layer of bubble wrap to try and retain as much warmth as possible. The levels of stores needs to be checked regularly, particularly once brood rearing starts in earnest. These little colonies can starve surprisingly quickly 🙁 . It takes seconds and causes minimal disruption to swap out those fondant frame feeders.

With a little luck and the normal amount of good judgement it was sometimes possible to remove the overwintered queen to make up a nuc in mid/late April, replacing her with a queen cell from the first round of grafting.

Of course, it rarely worked quite as smoothly as that … 😉 9

Finally

The one thing I would not recommend you try is allow the mini-nuc to build up to a full-sized nuc without supplementing it with additional brood and bees. A mini-nuc is too small and it will take too long rearing a few hundred bees at a time to make even a five frame nuc. I’ve tried and it’s a waste of effort.

References

Afik, O. et al. (2010) ‘Selection and breeding of honey bees for higher or lower collection of avocado nectar’, Journal of Economic Entomology, 103(2), pp. 228–233. Available at: https://doi.org/10.1603/ec09235.

Winter weight

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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.

 

DIY queen cell incubator

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NOTE: This post is now redundant as I have designed, built and tested version 2 of my portable queen cell incubator. I’m leaving this post here for those who wanted to read some of the background information.

You can please some of the people all of the time, you can please all of the people some of the time, but you can’t please all of the people all of the time … so said John Lydgate (1370-1450).

And he wasn’t wrong.

This is something I’m particularly aware of writing a weekly post on beekeeping. Much like my talks to beekeeping associations, the ‘audience’ (in this case the readership) ranges from the outright beginner to those with way more experience than me.

An article, like the one last week, on transporting your first nuc home and transferring it to a new hive, is unlikely to be of much interest to an experienced beekeeper.

Conversely, a post on something esoteric – like Royal patrilines and hyperpolyandry – is probably going to be given a wide berth by someone who has recently started beekeeping 1.

There’s no way I can write something relevant, interesting and topical for the entire breadth of experience of the readers 2. 

Going by the popularity of certain posts it’s clear that many readers are relatively inexperienced beekeepers.

The post entitled Queen cells … don’t panic! contains little someone who has kept bees for five years doesn’t or shouldn’t already know 3. Nevertheless, it is one of the most popular pages over the last couple of years. It has already been read more times this year than all previous years 4.

I suspect the majority of these thousands of viewings are from new(ish) beekeepers.

If you’re in this group then I suggest you look away now 😉 5

I’m going to discuss a pretty focused and specialised topic of relevance to perhaps a fraction of 10% of all beekeepers

The 10%

When I started beekeeping I was certain I would never be interested in queen rearing.

In fact I was so certain that, when repeatedly re-reading Ted Hooper’s book Bees and Honey, I’d skip the chapter on queen rearing all together. 

By ‘queen rearing’ I mean larval selection, grafting, cell raisers, cell finishers, mini-nucs, drone flooding etc. 

Queen cells from grafted larvae … what a palaver!

What a palaver!

All I wanted was a few jars of honey.

Oh yes, and slightly better tempered bees.

And perhaps a nuc to overwinter ‘just in case’.

What about a queen or two ‘spare’ for those swarms I miss?

A year or two later I had the opportunity – through the generosity of the late Terry Clare – to learn the basics of queen rearing and grafting. 

A week later I had a go on my own.

Amazingly (though not if you consider the tuition) it worked 🙂 . I successfully reared queens from larvae I’d selected, transferred, produced as capped cells and eventually got mated.

It was probably the single most significant event in my experience as a beekeeper. I got my nuc to overwinter and I’ve gradually improved my bees through selecting from the best and requeening the worst. I know how to produce ‘spare’ queens, though need them less frequently as my swarm control has also improved 😉  6

I don’t know what proportion of beekeepers ‘actively’ rear their own queens. I suspect it’s 10% or less.

But even that select group aren’t the target audience for this post.

The target audience are queen rearers who need to incubate queens or queen cells for protracted periods (hours to days) without constant access to mains electricity.

Let me explain

The peripatetic beekeeper

I live on the remote west coast of Scotland 7 but keep the majority of my bees in Fife. 

My apiaries in Fife are 30-40 minutes apart, and I drive past one on my way to my main apiary (in St Andrews). If I need a ‘spare’ queen in an out apiary (and have one in St Andrews) it adds over an hour to what is already a four hour beekeeping commute.

That’s an hour of my life I’ll never get back and something I’d really like to avoid 8.

On the west coast beekeepers and bees are very thin on the ground. I’ve just started queen rearing here and (again) have a 45 minute commute between apiaries 9. I’m working with another beekeeper and larvae are sourced from one and the cells are raised in another.

You can move frames of larvae about if you keep them warm and humid – a damp tea towel works well – at least if the times/distances are not too great.

But there’s an added complication … this area is Varroa free and I don’t want to be moving potentially mite-infested frames into the area. Nor do I want to deplete any of the donor colonies of brood frames.

All I want to move are a few larvae … but they’re a lot more fragile and sensitive.

So … two slightly unusual situations.

It seemed to me that my life would be a lot easier if I had some sort of portable queen and queen cell incubator.

My trusty honey warming cabinet

More than most events in beekeeping, the timing of the various stages of queen rearing is very clearly defined. You graft day old larvae and use the cells 10 days later. This timing currently defines the dates of my trips … except that sometimes there are diary clashes.

If my apiary with the cell raising colony was a mile away I could just go later in the day. 

But it’s not … 🙁

Before I started this (temporary) life as a travelling beekeeper I’d sometimes needed to incubate queen cells that were near to emergence. Once the cell is capped you can put it in an incubator, either until you use it as a capped cell, or until the virgin queen emerges. You then requeen a colony using the recently emerged virgin queen.

This was clearly another option to make the diary clashes less of an issue – raise the cells and then incubate them (outside the hive) until emergence, and then use the queens.

I’d already used my trusty honey warming cabinet to incubate queen cells. When I built this I used an Ecostat chicken egg incubator element rather than a 100 W incandescent bulb. The Ecostat heaters are thermostatically controlled and do a pretty good job of maintaining a stable temperature, anywhere between the high 20’s (°C) and about 55°C.

A day in the life of my honey warming cabinet (click for explanation of fluctuations)

There were two minor issues … the incubator needed a 240 V mains supply and was about the size of my car 10.

Honey warming cabinet. The Apiarist

Honey warming cabinet …

However, it’s perfect if you need to incubate 800 queen cells at once 😉

What I needed was a smaller, more portable, ‘battery’ – or at least 12V – powered version … 11

Beekeepers have short arms and deep pockets

One obvious solutions was to use a commercially available hen egg incubator. Brinsea are one of the market leaders and I know several beekeepers who use them as queen cell incubators. 

Although they are usually mains powered, they actually have an integral transformer and run at 12V, so could be powered from a car cigarette lighter socket. Temperature and humidity are controlled. They start at about £80 and would need modifying to accommodate queen cells, or Nicot cages containing queens.

The beekeeping-specific commercial solution is the Carricell.

Carricell queen cell incubator

These are manufactured in New Zealand in three sizes – for 40, 70 or 144 queen cells. Swienty (and presumably others) sell the 70 cell variant 12 over here for €636 13.

Excluding VAT 🙁

Beekeepers are notoriously commendably parsimonious. Since I have an alter ego named Dr. Bodgit, it seemed logical to try and build my own.

For a little less that €636 …

And ideally less than £80 😉

But first I needed to know more about the influence of temperature on queen cell development.

Temperature and development

The usual temperature quoted for the broodnest is about 35°C. Numerous studies have shown that, although the temperature is never constant, it is always in the range 33-36°C 14. 

It is reasonably well known that temperature can influence the development time of honey bees. At lower temperatures, development takes a little bit longer.

More significantly, Jürgen Tautz and colleagues showed almost two decades ago that honey bee workers reared (as pupae) at low temperatures have behavioural deficiencies 15.

For example, workers reared at 32°C showed reduced waggle dance activity when compared to bees reared at 36°C. Not only were they less likely to dance to advertise a particular nectar source, but they would dance less enthusiastically, performing fewer dance circuits.

In tests of learning and memory – for example associating smells with syrup rewards – bees reared as pupae at 32°C were also impaired when compared to bees reared at 36°C.

Tautz also demonstrated that bees reared at the lower temperature were more likely to go ‘missing in action’. They disappeared at a faster rate from the hive than the bees reared at the higher temperature. This strongly suggests their compromised memory or learning also had a negative influence on their survival. For example, in predator evasion, flight duration or the ability to find the hive.

OK … so temperature is really rather important for worker development.

Perhaps very accurate thermostatic control will be needed?

But what about queens?

There are good reasons to think that queen development might not be quite as sensitive to lower temperatures.

Queen cells are relatively rarely found in the centre of the broodnest. Those that are are often considered to be ‘supersedure cells‘, though location alone is probably not definitive.

Where are queen cells more usually found?

At the periphery of the broodnest, decorating the lower edges of the frame and even protruding down into the space below the bottom of the comb.

Queen cells

Queen cells …

Logic suggests that these might well experience lower temperatures simply by being at or near the edge of the mass of bees in the cluster. 

Perhaps queen development is less temperature sensitive?

Fortunately, I don’t need to rely on (my usually deeply flawed) logic or informed guesses … the experiment has been done 16.

Chuda-Mickiewicz and Samborski incubated queen cells at 32°C and 34.5°C. Those incubated at the lower temperature took ~27 hours longer to emerge than those at 34.5°C (which emerged at 16 days and 1 hour after egg laying).

However, of the variables measured, this was the only significant difference observed between the two groups. Body weights at emergence were similar, as were the spermathecal volume and ovariole number.

In both temperature groups ~90% of (instrumentally) inseminated queens started laying eggs.

So perhaps development temperature is not so critical (for queens after all).

The cheque queen is in the post

Finally, I expected my bodged incubator would also be used to transport mated queens. There’s good evidence that these are very robust 17. After all, you can get them sent in the post 18. 

Again, the experiment has been done 🙂

Survival of adult drones, queens and workers at 25°C, 38°C and 42°C

Jeff Pettis and colleagues investigated the influence of temperature on queen fertility 19 and concluded that incubation within the range 15-38°C are safe with a tolerance threshold of 11.5% loss of sperm viability 20. 

In addition, Pettis looked at the influence of high or low temperatures on adult viability (see graph above). Queens and workers survived for at least 6 hours at 25°C or 42°C. In contrast drones, particularly at high temperatures, ‘dropped like flies’ 21.

Stand back … inventor at work

Version 1 of the incubator was built and has been used successfully.

Queen cell incubator – exterior view (nothing to see here)

It consists of a polystyrene box housing a USB-powered vivarium heating mat. This claims to offer three heating levels – 20-25°C, 25-30°C and 30-35°C – though these are not when confined in a well-insulated box where it can reach higher temperatures. I’m not sure I believe the amperage/wattage information provided and don’t have the equipment to check it.

I run it from a 2.1A car USB socket, or a similar one that plugs into the mains.

The battery pack in the picture above runs the Raspberry Pi computer that is monitoring the temperature 22. It’s important to have accurate temperature monitoring and to do some trial runs to understand how quickly the box warms/cools. In due course all this wiring can either be omitted or built in … but it wouldn’t be a proper invention unless it looked cobbled together 😉

Not a lot to see here either …

Inside the box is a lot of closed cell foam – some crudely butchered to accommodate Nicot queen cages – sitting on top of a large ‘freezer block’. This acts as a hot water bottle. There’s also a plastic tray holding some soggy kitchen towel to raise the humidity.

Define ‘success’

The box has been used for the following:

  • transfer grafted larvae from an out apiary to a cell raising colony an hour away. Success defined by getting the grafted larvae accepted by the cell raiser.
  • transport queen cells up to 7 hours by car 23. Success defined by requeening colonies with the cells.
  • transport and maintain virgin queens for 7-10 days. These emerged in the incubator and then accompanied me back and forth before being used. All are now in hives and out for mating.

While powered – either in the house or the car – the box is easy to maintain at an acceptable temperature for extended periods, though it takes some time to reach the operating temperature.

An afternoon collecting and distributing queen cells to an out apiary

Even when opening the lid as queen cells are added/removed the temperature fluctuates by no more than 2-3°C. The graph above was generated from temperature readings taking queen cells from one apiary to another.

I’ll describe maintaining queens for extended periods in an incubator (with no attendant bees) in a future post.

The future

This really is a bodged solution.

At the moment the temperature has to be changed manually to keep it within the 32-35°C range. This might only be every few hours, depending upon how frequently the box is opened.

The combination of the insulation and the ‘hot water bottle’ freezer block means it can be left unattended overnight.

However, it really needs to have automatic temperature control. This should be trivial to add but will require more time than I have at the moment and for the box to be empty. It’s accompanying me on an exotic holiday to Glenrothes for the next three days 24 and will be in use for much of July as I start to make up nucs for overwintering.

So … as promised, an inelegant but working solution for a fraction of the 10% of beekeepers who rear queens. 

At a fraction of the price of a commercial one 🙂

STOP PRESS – update 7th September ’21

I now have a working solution with proper thermostatic temperature control. It’s currently going through a final series of tests. I strongly suggest you don’t follow the botch-up design described above, but wait for another post on this subject sometime this winter. It’s possibly to build a queen cell incubator with fully automatic temperature control of ±0.5°C that will work at home or in a vehicle for about £60.

STOP PRESS – update 26th November ’21

Full details of version 2 have now been published and this page is left here for historical reasons only …