The danger zone

… your bees are entering it about now.

I had hoped to start this post with a pretty picture of a row of colourful hives topped with a foot or more of snow. It would have been an easy picture to take … we’ve certainly got the snow.

And this was before we had a load more snow in the afternoon …

It would have been an easy picture to take … had I been able to get to the apiary 🙁

I’m writing this in central Fife. We’ve had the heaviest snowfall I’ve seen here in 6 years (well over a foot) and the roads are just about impassable. Why risk a shunt for a pretty picture?

Little snow, big snow. Big snow, little snow.

So here’s one taken earlier in the winter.

So what’s all this about the danger zone?

The danger zone

Bees that are rearing brood in the winter use stores at twice the rate when compared with bees that are not rearing brood.

How do we know this?

Clayton Farrar (1904 – 1970) was Professor of Entomology at the University of Wisconsin, Madison. He retired from his role as chief of the USDA Laboratories in Beekeeping in 1963. He’s well known (at least within certain beekeeping circles) for promoting two-queen honey production hives.

However, he also conducted lots of other studies on honey bees. Some of these were on the importance of pollen for brood rearing. Studies back in the 1930’s showed that when pollen was unavailable, brood rearing ceased.

Farrar compared the winter weight loss by colonies that were starved of pollen and those which had ample pollen. Those starved of pollen used their stores up only 50% as fast as those busy rearing brood.

Why do they use more stores?

I’ve recently discussed the winter cluster. In that post I made the point that the temperature of the winter cluster is carefully regulated.

In the absence of brood rearing, the core temperature of the cluster is about 18°C.

However, at that temperature honey bee development cannot happen 1.

When brood rearing the colony must raise the temperature of the core of the cluster to ~35°C.

The bees in the cluster achieve this elevation of temperature by isometric flexing of their flight muscles.

And they need energy to do this work … energy in the form of sugar stores.

Biphasic stores use

What this means is that as a colony transitions from a broodless (which may or may not occur, depending upon your latitude, climate, temperature 2 ) winter period to rearing brood, they start consuming the stores faster.

You can see this clearly in the right hand side of this graph from a paper from Tom Seeley, presented in his excellent book The Lives of Bees. This shows the winter weight change through two and a bit seasons. I’ve marked the approximate position of the winter solstice with a black arrow and mid-February (i.e. about now) with a red arrow.

Colony weight (top) and weekly weight change (lower).

Just focus on the 1928/83 winter as this most clearly shows an inflexion point in the rate of stores usage (we know it’s stores being used as it’s midwinter, so there’s no forage available).

The colony transitions from a maintenance rate to a brood rearing rate and the slope of the weight loss line steepens.

You can also see the same thing happening in the 80/81 and 81/82 winters, though it’s less obvious.

My colonies started rearing brood soon after the winter solstice. Yours might have not had a brood break at all.

However, in both cases the colony is likely to be rearing more brood now than it was 5-6 weeks ago.

Therefore it will be using more stores now … and so there’s an increased chance of the colony running out of stores.

It’s also appreciably colder over much of the UK now than it was a few weeks ago. We’ve had temperatures as low as -12°C this week, meaning the bees need to maintain a 49°C temperature differential to protect the developing brood in the hive.

This means that – all other things being equal – the colony will be using even more stores now than they were a month ago to maintain the same critical core temperature of the cluster for brood rearing.

Duunnn dunnn… duuuunnnn duun… duuunnnnnnnn dun dun dun …

That’s a rather poor attempt at spelling out the opening few bars of the Jaws theme 😉

The danger zone is in the late winter or early spring.

The colony must rear more brood to become strong enough to reproduce (swarm) in late April to early June.

And, from a beekeeping perspective, they must rear more brood to become a strong enough colony to properly exploit oil seed rape and other early nectars for the spring honey crop.

But there’s no forage available and/or it’s too cold to venture out for early nectar.

Snowdrops and gorse are flowering … somewhere over there

So the danger is that they starve to death 🙁

I’ve recently discussed determining whether your colony is rearing brood (and it will almost certainly have started by now, even if it’s taking a brief temporary break when the temperature plummeted) and also given an overview of ‘hefting’ hives and monitoring colony weight.

Fondant topups

If the colony feels light, or your records suggest it is dangerously light, you urgently need add a readily available (to the bees, if not to you) and easy to access source of sugar.

Syrup is not suitable at this time of the year. Even with lots of insulation, the space above the crownboard is a pretty chilly environment. A bucket of syrup placed there is likely to be simply ignored … at least until the ambient temperature has increased.

By which time it might be too late.

If the colony feels light they need stores now, not when it warms up (though they’ll also need stores then … if they survive that long).

Fondant is the stuff to use.

I’ve written extensively about it previously and I buy it by the pallet load. It stores perfectly for months or years, so I always have it available. I use it for almost all my bee feeding.

Fondant mountain ...

Fondant mountain …

You can also make it relatively easily 3.

Fondant is ~80% sugar. It’s also malleable but semi-solid … a bit like plasticine.

But it tastes appreciably better 😉

I’ve found the best way to provide fondant is in transparent (or at least translucent) shallow food containers.

Waste not, want not

In the photo above the clear(ish) ones are much better than the brown or green ones. Better still are the double-area ones you buy chicken breasts in 4. These are wide but shallow and can accommodate at least 2 kg of fondant.

Where to place the fondant

I stressed that the fondant must be easy to access by the bees.

There’s no point in adding it if they don’t have immediate access to it.

And if it’s -8°C outside the bees are not going to be wandering around looking for food … any that leave the cluster will soon get chilled, become torpid and perish.

You therefore need to put the fondant directly in contact with the bees.

Often the advice is to provide the fondant over the hole in the crownboard.

However, consider the this diagram.

Plan view of fondant above the feed hole in a crownboard

If your bees form a large cluster – like A above – they are in contact with the fondant that has been placed directly above the central feed hole in the crownboard.

And, if they stay there, all will be OK.

But what about the smaller cluster (B)?

These bees don’t have direct access. If the weather is cold enough and the space above the crownboard is badly insulated the fondant might as well have been left in the packet.

In the shed 🙁

I therefore add the fondant under the crownboard.

Fondant block ...

Fondant block …

I place the fondant block, inverted, covering part of the cluster. They can immediately access it and they will soon use it if they need it.

Time for another?

Time for another?

The photo above shows why clear or translucent containers are preferable – you can easily tell how much of the fondant remains.

In the photos above the cluster is located approximately centrally within the brood box. However, think back to the colony I discussed a fortnight ago. In that, the cluster was tight up against the polystyrene side wall of the hive, some distance from a central hole in the crownboard (if mine had a central hole 😉 ).


These plastic food containers are about 5 cm deep. Filled to the brim they can hold about 1.2 kg of fondant. That might well not be enough … hence my preference for the larger containers.

Or just use two of them …

Fondant absorbs moisture from the environment, softening the surface. With the fondant directly in contact with the top bars of the frames and the bees, this softened fondant is readily used.

I made the mistake once of wrapping the fondant in clingfilm and providing a hole for the bees to access it. Over time they drag the shredded clingfilm down into the hive, incorporating it into brace comb.

It makes a right mess. Avoid clingfilm.

If you are concerned about sloppy fondant dribbling down onto the cluster (something I’ve noticed a couple of times with either very weak colonies or in very damp environments) you can cover the face of the block with a sheet of plastic. Cut a 2 cm square hole in this and place it over the centre of the cluster.

And how do you accommodate this 5 cm block of fondant under the crownboard?

You can use a 5 cm deep eke, with your normal crownboard on top.

Alternatively, you can build crownboards that have a single bee space on one side and an integral ‘eke’, in the form of a 5 cm deep rim, on the other.

Perspex crownboard with integrated insulation

I built a few of these many years ago, with perspex and an inbuilt block of ‘Kingspan’ insulation. They work really well.

When you need the headspace – for example for a block of fondant – you simply invert the crownboard and place the insulation on top, under the roof.

What, no fondant?

If you haven’t got any fondant, don’t despair.

But also don’t delay while you try and source some fondant.

Fondant is sugar after all, and everyone should be able to get sugar.

Despite having a mountain of fondant squirreled away, I still keep a few bags of granulated sugar ‘just in case’.

Emergency rations

Cut a 2 x 2 cm hole in the front of bag of sugar and add about a half teacup full of water. Let it soak in for a few minutes. Add less than you think is needed … you can always add a bit more.

You want to dampen the sugar, not dissolve it. The aim is to be able to invert the bag directly over the cluster 5.

So do that as soon as you can.

Bees need water to be able to ‘eat’ granulated sugar, so dampening it helps both keep it in the bag and saves them doing extra work collecting condensation from the hive walls.

And, just to avoid any ambiguity, only used white granulated sugar.

It takes bees to make bees … and honey

Colonies that are strong early in the season are better able to exploit the spring nectar, including that from oil seed rape.

Mid-April in the apiary ...

Spring in a Warwickshire apiary …

Some beekeepers feed their colonies thin syrup (1:1 w/v) in early spring to boost brood rearing in time to have booming colonies ready for the rape.

I’ve not done this, or ever felt I really needed to. However, I’m not commercial and do not rely on the honey harvest to feed the family, pay the kids’ school fees or fuel the Porsche.

And, other than feeding the family, I don’t know any commercial beekeepers who rely on honey sales for those other things either 6.

Usually the combination of young queens, low Varroa levels and ample autumn feeding produces colonies strong enough for my beekeeping in the spring.

Rapidly expanding colonies in March and early April require good amounts of brood to be reared during the dark winter days in January and February. After all, you cannot rear lots of bees without having lots of bees available to do the brood rearing.

This is an area where it is beneficial to have young queens heading the colony. These lay later into the autumn, resulting in more winter bees.

If these bees are healthy and well fed the colony should have a flying start to the following season, if you’ll excuse the pun.

But check them nevertheless as they enter ‘the danger zone’.

As you add your third or fourth super to a hive in early May, think back to that cold, wet day three months earlier when you gave them an extra block of fondant … and give yourself a pat on the back 😉


I finally managed to get out a couple of days after it stopped snowing.

Hives in the snow

The two hives on the right have a 4 mm thick Correx roof, directly on top of a 5 cm thick block of Kingspan. Going by the amount of snow still sitting on top of these hives they’re not losing too much heat through the roof 🙂

The Danger Zone was a song by Kenny Loggins that featured in the 1986 movie Top Gun. In retrospect, it’s a pretty cheesy movie. However, 35 years ago it was the first VHS videotape I purchased. It had a Dolby soundtrack and, played loud through the stereo speakers while sitting close to the TV (to get that ‘widescreen’ cinema feeling) it sounded pretty good 😉

I do not often listen to Kenny Loggins but when I do, so do my neighbors …


  1. The correct temperature really is critical for successful brood rearing – worker bees reared at 32°C, just 3°C below the normal temperature, show behavioural abnormalities and other defects.
  2. And possibly a host of other factors.
  3. I’ve not done this (for obvious reasons if you look at the photograph above) so cannot provide a recipe I’ve used. Here is one from a trustworthy beekeeping source.
  4. Or at least I buy chicken breasts in … for all I know you are vegetarian. Or you might ‘grow your own’ and keep chickens.
  5. Again, under the crownboard. You might need a double height eke or a super to provide the necessary headspace.
  6. Though I’m told there’s at least one individual in the beekeeping business who drives a Lamborghini …

    Not an Italian supercar

    … it’s not me.

42 thoughts on “The danger zone

  1. chris

    how to add more fondant without crushing the bees that were enjoying the remnants of the old containers…..i did a quick swap over but slapping a heavy clear box of fondant down …worried I clobbered a few bees in the process …..

    also I am doing thru the blowhole in the crownboard option …appreciate its not ideal based on your advice

    1. David Post author

      Hi Chris

      Several possible answers:

      1. The tough love version … If you keep livestock you’ll have deadstock and the benefits to the colony outweigh the small number that get inadvertently squidged during the process
      2. The take care doing it version … smoke the top of the colony gently, or push the bees aside with the back of your gloved hand
      3. The do your homework version … make up the fondant block leaving a beespace gap between the surface of the fondant and the rim of the plastic container. Place it down gently, shiggling it from side to side to move the bees aside

      Take you pick. I usually intend to do 3 but end up doing 2.


    2. Ian Robinson

      Chris- I find that I can move a new fondant container ovet the hole in the crownboard as I gently slide the part full one to one side so that there are two containers each over half of the hole, In this way the bees can access both pots and when they finish the part full one I slide it off. Only works if your pots are small enough to get two on the crown board but it might help. Ian R

    1. David Post author

      Hello Roger

      Don’t you just love these articles that quote the numbers of bees, rather than the numbers of hives/colonies?

      All very commendable and hugely environmentally friendly no doubt … but does it compensate for the 18 mpg and 320 g/km of CO2 produced by their c. £400,000 Phantom model?

      I think not 🙁

      I’m afraid I’d class their 250,000 bees as ‘greenwash‘ …


  2. Mike

    I always enjoy your posts and learn a lot. You’ve shown your transparent crown boards a couple of times now in photos. How do you ensure proper ventilation out the top to remove excess humidity?


    1. David Post author

      Hi Mike

      I don’t think they need any more ventilation than is provided by the open mesh floor. All the evidence I’ve seen suggests that bees dislike (as much as they like/dislike anything) vents or holes above the cluster. For example … this is what they do to the ventilation holes in an Abelo crownboard:

      Filled in ventilation

      With an open mesh floor I have no concerns over excess humidity, or humidity at all.


      1. Roger Gill

        Come on David, a full post about the use of matchsticks to ensure a good flow of freezing cold air around a huddled, shivering, clustered colony in the middle of winter (aka ventilation) is long overdue…

  3. Elaine Robinson

    Hi David, is there a good case now, given brood rearing will have started, to keep the varroa trays in til the weather starts to warm up? Help reduce heat loss & excessive use of stores, whilst still allowing airflow through the bottom (mouse guarded) entrance….
    Also wonder with sustained low temperatures and snow since early Jan here in the Pennines, whether Nosema is a risk given bees haven’t been out for cleansing flights since Xmas?
    Good news, the weather is forecast to rise end of next week to 10-11C. For 2 days!!

    1. David Post author

      Hello Elaine

      Frankly, I’m not sure how much of a difference it’s likely to make. Unless your Varroa trays are very tightly fitting I suspect there’s little difference between the temperature (but I’d be happy to be convinced otherwise). Other than when I’m actually interested in seeing what falls out through the OMF my trays stay out.

      Nosema can be a problem with bees that are confined, but there’s not much you can do about it. I’d be surprised if any of my bees have been on a cleansing flight in 2021 either. With >9°C predicted for next week (here, warmer elsewhere obviously) I’m going to carry an umbrella 🙂


  4. Joanne Kelly

    Hi there

    I have a question for you. As you know we’re novice beekeepers. I’m pretty sure our bees are breeding and have been worried for a while about the fondant being in the wrong place. It’s above the central crown board hole but our bees are against the wall. I’d like to move the fondant to directly above the bees on the frames but in this cold weather I’m worried about chilling them too much. What do you suggest?

    1. David Post author

      Hi Joanne

      Firstly … it should only take seconds to lift the crownboard and relocate the fondant if you really need to. Secondly … it’s going to warm up considerably within a few days (8-9C for you by Monday/Tuesday). I’d wait until then and do it in the warmest part of the day. If you need to … you might find they’ve already located the fondant.

      There’s a video on this site of me trickle treating a colony with OA in midwinter. The entire procedure, from opening the crownboard to replacing it, takes a bit less than 50 seconds. It was 3C when I made the video. The bees were fine. Moving or adding a block of fondant will take much less time than that.

      Don’t disturb them unnecessarily, but they’re remarkably resilient if you do need to do something.


      1. Susan

        Hmm. Even at 12 C my hives would be perfect for z Killer Bees movie. They turn into missile killers if we need to lift lud for OA or fondant replace in winter.
        Nice as pie in summer.

        1. David Post author

          Hi Susan

          You might have more success opening the hive when it’s a bit cooler and they’re feeling a bit more lethargic 😉

          Nevermind … it’s more important that they’re well tempered in the summer than when you rudely disturb them in the winter.


  5. Kevin Barron

    Very apt blog David
    I added fondant this morning to a nuc and a hive, just in case!
    Still learning here in my first year.
    Loved the Top gun piece, well I am of that vintage.
    Enjoy your blog as always.
    Keep well

    1. David Post author

      Thanks Kevin

      Top Gun is one of those guilty pleasures … rubbish, but enjoyable. There are so many others …


  6. Mark Haworth

    What’s the reason for placing the fondant in a container please? I use fondant every year, but never thought to place it in one? Don’t the bees have access to more surface area if the fondant is placed directly?

    1. David Post author

      Hello Mark

      Nominally yes … but it’s cold and they’re not going far from the cluster. They won’t approach it from the top. It’s easier to handle (store transport etc.) in a container and the sides and upper face would otherwise absorb moisture from the environment, making the whole thing a sloppy mess.

      Sometimes I simply slice a 5 cm thick lump off one end of a complete block of fondant, but I don’t unwrap it before using it.


    1. David Post author

      Just trying to save you some money … caster and icing sugar is about three times the price of granulated sugar 🙂

      1. Reto

        Ah, I am doing my shopping outside of the UK. Granulated sugar is more expensive here than white sugar. I guess I stick with that then. 🙂

  7. Kim Beresford

    Hi David,

    I was interest to see that although they’re developed completely independently you’re insulated crown boards look very similar to to ones that I make, with edges sealed with gaffa tape. I’ve modified mine to include a feed cavity which seems to work really well, but I’d be interested in your thoughts?

    I’ve put together a couple of short videos that show their function. If you can spare a few minutes to view them here are the links: –

    All the very best to you and many thanks for your excellent posts.
    Kim Beresford

    1. David Post author

      Hello Kim

      Very smart. I made some years ago for an early model Paynes poly nuc with a much cruder feed cavity (wow! … that post was almost 7 years ago). It worked well and I still use them, though they’re looking a bit tatty now … and downright shoddy in comparison to yours.

      Kingspan, Correx and gaffer tape are three essential items for beekeepers. There’s almost nothing that cannot be made, or at least partly made, from them.


  8. Lindsay Bryning

    Re granulated sugar – my understanding is that caster and icing sugars often have a powder added to improve the “flow” qualities – maybe calcium carbonate???? Trying to make up syrup with caster sugar in an emergency once, there was a very grey looking scum on the surface – never again! Love the blog, David.

    1. David Post author

      Hi Lindsay

      You’re absolutely right … I forgot about the ‘anti-caking agents’. Wikipedia reports that powdered sugar may contain 2-5% corn starch, potato starch or tricalcium phosphate. I’d assume that none of these are actively harmful to bees.

      Of course, those of us who vaporise Api-Bioxal also give them a blast of an un-needed anti-caking agent (powdered silica in that case I think) every time we treat.

      Delighted you enjoy the posts.


  9. Trish the Beekeeper

    love love love the tip about using granulated sugar IN THE BAG. I am going to try that out. I’ve been using a queen excluder with an empty super as the casing around a 10 lb sugar brick that results from pouring damp sugar into the “mold” formed by the empty super. It works but leaves something to be desired.

    1. David Post author

      Hi Trish

      There are some methods on the internet that describe it better than I have. I’ve seen some that dip the entire bag, or use golf tees to make a dozen holes and then dip the bag … I suspect it’s dependent on the material the bag is made from.

      Fondant really has a lot going for it 🙂


  10. Simone

    I’m in the processing of cleaning my first hive for my first bees…. Your posts are a life saver thank you. They do take some reading and thinking… not a bad thing for a total beginner!

  11. Mhairi

    Thank you for such useful and Timely information. My bees appreciate it hugely.

    Is there any difference between granulated sugar from sugar beet and that from sugar cane? Or is it all just ‘sucrose’ so no need to differentiate?

    1. David Post author

      Hi Mhairi

      No need to differentiate … as you say, they’re just ‘sucrose’.
      The one people get concerned about is HFCS … high fructose corn syrup.


  12. Susi

    I’ve been enjoying your articles for about a year now, I love the weekly managable and entertaining format. Great job, thank you. This time I am wondering about the empty space between the bees and the crownboard when putting the fondant underneath the crownboard. Air is difficult to keep warm so generally I would rather have the crownboard straight on top of the bees and the fondant on the holes (mine has 2 for the porter bee escapes). I may turn the crownboard 90 degrees if I know they are in a particular place (as per evidence on the varroa board), and – maybe as I’m down in mild Devon – they have so far always found the fondant. So I am wondering where the balance lies between having to heat the extra space and quicker access to the feed to having the eke above the crownboard to cover them closer.

    1. David Post author

      Hello Susi

      Rotating a crownboard with an off-centre hole certainly works. It leaves the fondant in the cold headspace … and presumably there’s heat from the colony escaping through the unused hole into that cavity. You can avoid this by filling the space above the crownboard with an insulating material. The temperature in that space will be influenced by how well insulated your roof is (it’s something I’ve been meaning to investigate). My hives all have a big block of Kingspan over the crownboard, irrespective which way ‘up’ the crownboard is. I suspect – but should check – that this headspace doesn’t result in a loss of heat …

      Your temperatures are very different from ours. Tomorrow is the first day with a predicted double-digit temperature since early January. Since well before Christmas we’ve only had one day when the temperature was in double digits (not counting the minus 12°C one night) and the average for the last 2 months is about 1.9°C …

      On the plus side … it’s a whole lot easier managing Varroa here 😉


  13. Elaine Robinson

    Hi David
    Following your post, I visited all my hives today, wonderful to see them all flying for the first time since Xmas (Yorkshire Pennines)! All present and correct. I’ve been weighing mine with a luggage scale for the first time this year and they mostly seem fine for stores. Just have one which is hovering just below 20lb, so wondering at what weight would you consider adding fondant? I’ve tended to add for ‘insurance’ previously but attempting to be more ‘scientific’.
    Only one of my 12 colonies had any varroa drop in the last 11 days, the one that did had a drop of 5 mites. Similar picture for the preceding 10 days. Would you advise an additional early Spring varroa treatment & if so, what would be your choice in March / April? I treated for 10 weeks with Apivar late summer & gave a one off Oxalic acid vap early Dec.
    Many thanks

    1. David Post author

      Hello Elaine

      What weight would you consider adding fondant? … is an impossible question to answer as it depends upon the material the hive is made from (cedar, poly) and the setup (14 x 12, single brood, brood and a half etc.). Even with my own hives I don’t have a cutoff weight below which I feed. Instead it’s whether it’s feeling a bit light considering the hive material and setup …

      The Varroa drop is unlikely to be hugely informative at this time of the season. If the colony are building up there will be a good amount of larvae of a suitable age to infest, so the mites are unlikely to spend prolonged phoretic periods, so may be less likely to come unstuck or get removed by grooming.

      I almost never treat in March/April (actually, I’m struggling to think if I’ve ever treated at that time of year). 95% of my treatments are just late summer and when broodless in the winter. The remainder are during midseason splits, if needed.

      I’d suggest forking out some of the first drone brood in the colony in April. These will be very popular with the mites. If there’s a heavy infestation level you should consider treating.


  14. Paula

    Thank you so much for a very interesting post. I found the top ventilation comments especially interesting. As a Oregon, USA beekeeper of 5 years, I’ve always worried about not giving them enough ventilation. My hives have an inner cover with the standard “oval” opening in the center; 2 inches by 4 inches, plus! A small opening to the outside (screened) in the inner cover wall. I do have screened bottom boards w/ varroa trays on all, however. I am rethinking the top ventilation now for winter, which will make it much easier to insulate the top, feeding, etc. as I worry they do not have enough ventilation.
    P.S. the poly for the inner covers plus the eke frames will be an addition to my apiary this year:)

    1. David Post author

      Hello Paula

      It’s always worth remembering that beekeeping is essentially a ‘local’ activity, acutely influenced by the local conditions. My understanding of the Oregon climate is that it’s not hugely different from Scotland, but it’s worth carefully monitoring any changes you make to ensure that it suits the bees.

      I’ve been managing my colonies with no top ventilation, solid “inner covers” (crownboards!) and a big block of insulation over the top, for all the time I’ve been living in Scotland and it seems to suit the bees well. I checked all my colonies yesterday and they looked excellent considering the conditions we’ve had for the last two months.


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