Winter Hive Population Reduction

[RichardK]

This is my first looming winter with bees. On average, by what percentage do colonies reduce in population over winter? 20%, 50%..... really ...I have no idea what to expect come spring!

 

[Boston Bees]

Huge variation, but here's a good chart - admittedly from much colder climate than ours, but the basic shape will be right.

As you can see, assuming a healthy colony, the population doesn't fall much from Nov to Feb (those long lived winter bees), but then declines rapidly in March as the winter bees die off.

So, it depends what you mean by "over winter" and "spring" .....

Of course, if your bees are sick with varroa-induced viruses, the population WILL fall sharply between Nov and Feb.

 

[pargyle]

In my experience it varies from colony to colony but generally a reduction of about 50% from the peak in mid summer to the same colony after winter and prior to the spring build up. Bear in mind you will already have 'lost' about 20% of the colony bulk after the drones are evicted in the autumn.

But it's not the size of the colony or the drop off that you need to worry about - it's the general health of the colony going into winter and the stores situation that is required to see them through. Even the smallest colony, as long as it is healthy, will explode in growth once spring and decent forage arrives.

I think well insulated hives seem to lose less bees overwinter - probably because they don't need to work as hard to keep warm.

Bill Bielby said in his booklet 'Home Honey Production' in 1972 "For most economical wintering, hives should be highly insulated and completely draughtproof." and "There is no such thing as too much insulation" .... it takes a while in beekeeping for good ideas to catch on.

https://library.uniteddiversity.coop/Beekeeping/Home_Honey_Production.pdf

 

[user 20297]

In my experience it varies from colony to colony but generally a reduction of about 50% from the peak in mid summer to the same colony after winter and prior to the spring build up. Bear in mind you will already have 'lost' about 20% of the colony bulk after the drones are evicted in the autumn.

But it's not the size of the colony or the drop off that you need to worry about - it's the general health of the colony going into winter and the stores situation that is required to see them through. Even the smallest colony, as long as it is healthy, will explode in growth once spring and decent forage arrives.

I think well insulated hives seem to lose less bees overwinter - probably because they don't need to work as hard to keep warm.

Bill Bielby said in his booklet 'Home Honey Production' in 1972 "For most economical wintering, hives should be highly insulated and completely draughtproof." and "There is no such thing as too much insulation" .... it takes a while in beekeeping for good ideas to catch on.

https://library.uniteddiversity.coop/Beekeeping/Home_Honey_Production.pdf

Thank-you for that link. I'm not far into reading it, but already found much wisdom akin to that which you described. Maybe the best yet, (and one I have already learned for myself) is; ".......don't take too much notice of old beekeepers."

 

[pargyle]

Thank-you for that link. I'm not far into reading it, but already found much wisdom akin to that which you described. Maybe the best yet, (and one I have already learned for myself) is; ".......don't take too much notice of old beekeepers."

It's an internet copy of a little book I found in a second hand bookshop ... Bill Bielby was a very thinking beekeeper - well ahead of his time in lots of ways - I had come to the conclusion that insulation was a key factor in keeping bees and had 'invented' clear crown polycarbonate boards - there's nothing much new in beekeeping and in some respects, after reading the book, it was very reassuring to find that a beekeeper with so much experience and knowledge was already ahead of me. There's a few things in there that are out of date and questionable but ...that line 'Don't take too much notice of old beekeepers' is a gem ...

The book pre-dates varroa and was written in the early years of poly hives and I wonder what Bill would have made of 'modern' beekeeping !

 

[RichardK]

Huge variation, but here's a good chart - admittedly from much colder climate than ours, but the basic shape will be right.

As you can see, assuming a healthy colony, the population doesn't fall much from Nov to Feb (those long lived winter bees), but then declines rapidly in March as the winter bees die off.

So, it depends what you mean by "over winter" and "spring" .....

Of course, if your bees are sick with varroa-induced viruses, the population WILL fall sharply between Nov and Feb.

View attachment 28326

Thanks for that - it's quite amazing to think a colony could shrink from around 54k at it's height down to c. 8k....and then ramp right back up agian all being well.

 

[RichardK]

In my experience it varies from colony to colony but generally a reduction of about 50% from the peak in mid summer to the same colony after winter and prior to the spring build up. Bear in mind you will already have 'lost' about 20% of the colony bulk after the drones are evicted in the autumn.

But it's not the size of the colony or the drop off that you need to worry about - it's the general health of the colony going into winter and the stores situation that is required to see them through. Even the smallest colony, as long as it is healthy, will explode in growth once spring and decent forage arrives.

I think well insulated hives seem to lose less bees overwinter - probably because they don't need to work as hard to keep warm.

Bill Bielby said in his booklet 'Home Honey Production' in 1972 "For most economical wintering, hives should be highly insulated and completely draughtproof." and "There is no such thing as too much insulation" .... it takes a while in beekeeping for good ideas to catch on.

https://library.uniteddiversity.coop/Beekeeping/Home_Honey_Production.pdf

Very interesting - I'll have to get hold of the book for some Autumnal reading.

Do you insulate your hives and if so, how?I used to live in Newbury so not too far from your neck of the woods.

 

[pargyle]

Thanks for that - it's quite amazing to think a colony could shrink from around 54k at it's height down to c. 8k....and then ramp right back up agian all being well.

Personally, that's a pretty extreme example ... 50,000 bees is a big colony - the average colony (not artificially boosted) is around 35k to 40k bees.

Depending on lots of factors they will reduce over winter but I think, post-winter, in a well managed and insulated hive with plenty of stores they should come through with about half the colony alive. They then can shrink rapidly as the forage comes on stream and the old winter bees are the foragers, they are old bees and wear out quite quickly - this usually happens before the queen really starts to lay and you then have a three week gap until the new brood emerges and colony number start to explode.

It's the time when some beekeepers get caught out - if the hive is not well stocked when they need easy access food, the foragers die off, workers and food are required to tend the brood and keep it warm at a time when the weather can be notoriously fickle.

Get it wrong and fail to recognise what is going on and a colony can die out in a matter of days.

They are a fascinating organism ... they need beekeepers who can think to look after them - it's not a hobby with hard and fast rules and time scheduled procedures.

 

[user 20297]

......................The book pre-dates varroa and was written in the early years of poly hives and I wonder what Bill would have made of 'modern' beekeeping !

He would have had fun with our "debate" about fondant. He quotes an article wholesale from Alfred Hebden in which the use of the more solid forms of sugar is not recommended. The argument put forward is that bees first have to dilute sugar using water whch they have to collect. Then after storing it, the same water has to be evaporated. Whereas when syrup is fed, the bees are excused from the process of collecting water.

 

[pargyle]

Very interesting - I'll have to get hold of the book for some Autumnal reading.

Do you insulate your hives and if so, how?I used to live in Newbury so not too far from your neck of the woods.

I have Paynes poly hives so they are already well insulated, I make my own clear polycarbonate crown boards that are sealed (no ventilation or holes) and on top of that I permanently have an empty super with at least 50mm of Kingspan or Celotex (and more often than not 100mm) on top of the crownboard inside the super. The hives have mesh floors which remain open but my hive stands have a skirt to prevent draughts.

The book comes up for sale regularly on ebay ... I paid 50p for mine in the bookshop but you should find a copy on ebay for a few pounds .. long out of print now so second hand only. Here you gp £2.81 inc postage !

https://www.ebay.co.uk/itm/384261314397?epid=90396631&hash=item5977c2575d:g:M3gAAOSwIUxg5F85

 

[elainemary]

It's an internet copy of a little book I found in a second hand bookshop ... Bill Bielby was a very thinking beekeeper - well ahead of his time in lots of ways - I had come to the conclusion that insulation was a key factor in keeping bees and had 'invented' clear crown polycarbonate boards - there's nothing much new in beekeeping and in some respects, after reading the book, it was very reassuring to find that a beekeeper with so much experience and knowledge was already ahead of me. There's a few things in there that are out of date and questionable but ...that line 'Don't take too much notice of old beekeepers' is a gem ...

The book pre-dates varroa and was written in the early years of poly hives and I wonder what Bill would have made of 'modern' beekeeping !

Love reading old beekeeping books. Some may say they are out of date but you always find gems of wisdom from old timers with 40years + experience.
A contact in a neighbouring association gave me these two, which I’m saving for winter reading, dating back to 1923 and 1943 respectively. Will post any nuggets when I’ve read!

 

[pargyle]

He would have had fun with our "debate" about fondant. He quotes an article wholesale from Alfred Hebden in which the use of the more solid forms of sugar is not recommended. The argument put forward is that bees first have to dilute sugar using water whch they have to colllect. Then after storing it, the same water has to be evaporated. Whereas when syrup is fed, the bees are excused from the process of collecting water.

Wouldn't he just ? As a Yorkshireman I suspect he would have been fairly robust and forthright on here ...

Sadly, I never met him but I've met couple of people who did. He died aged 91 in 2012 in New Zealand although he spent most of his life in Yorkshire and was a well respected and active beekeeper there for many years. At one point he was the County Bee Officer. To all accounts he was a helpful, friendly and understanding person who gave his knowledge freely and was not judgemental about other people's ideas... He, clearly, had his own and pinched a few from others .... beekeeping needs people like this and fortunately there are still some out there like him.

 

[RichardK]

The book comes up for sale regularly on ebay ... I paid 50p for mine in the bookshop but you should find a copy on ebay for a few pounds .. long out of print now so second hand only. Here you gp £2.81 inc postage !

https://www.ebay.co.uk/itm/384261314397?epid=90396631&hash=item5977c2575d:g:M3gAAOSwIUxg5F85

Done. Purchased. Thanks for the link!

 

[RichardK]

I have Paynes poly hives so they are already well insulated, I make my own clear polycarbonate crown boards that are sealed (no ventilation or holes) and on top of that I permanently have an empty super with at least 50mm of Kingspan or Celotex (and more often than not 100mm) on top of the crownboard inside the super. The hives have mesh floors which remain open but my hive stands have a skirt to prevent draughts.
https://www.ebay.co.uk/itm/384261314397?epid=90396631&hash=item5977c2575d:g:M3gAAOSwIUxg5F85

Do you keep the open mesh floors open to help prevent too much moisture build-up bearing in mind you have a well sealed roof? I've been wondering what to do with the mesh floors. On 10 frame hives I have an insertable plastic floor for winter to effectively block close off the mesh - there will be some air flow, but very small. On the wooden nucs though (homemade), although they have mesh floors, I haven't any plan as yet on how to block them off (possibly a wood insert....). I hadn't thought about some sort of skirt though to keep air flow, buy stop drafts. How do you do yours? Or a picture would be great if you have one?

 

[oliver90owner]

I would say zilch, or close to it is the target. There will always be a few casualties - snow flights, cleansing flights, late foraging, etc. But there should not be a great carpet of bees on the hive floor, come springtime.

10% would be quite good, I would suggest.

Varroa-free winter bees are the single most important thing, before they cluster for the winter. Too many in later autumn (when the winter bees are brooded) and many of those bees will be adversely affected and likely die during the winter. Also, the first brood cycles in late winter/early spring will soon introduce short-life bees and a burgeoning varroa load (depending on varroa load and number of eggs being laid).

Non-interference by the beekeeper is high on the list, too. I only trickled oxalic for one season before turning to effective autumn treatments to reduce the varroa load before winter bees were produced and then left the bees (fully stockpiled with stores) until late February (except for a couple of colonies that were encouraged to brood early - by feeding with thin syrup). There was usually plenty of early pollen available but no nectar.

Insulation and only bottom ventilation was another facet for minimum population loss. I changed to 14 x 12 broods with OMF and found that to be the best for winter survival, as the bees could cluster either to the bottom of the frames or contract further into the combs during adverse weather. Hives were protected from high winds wherever possible, mostly either in a sheltered apiary, my garden or in hedgerows.

After my first couple of seasons, when I lost quite a few colonies (due to following decidedly dodgy advice) my 100% bee losses (ie dead-outs) dwindled to around 2-4% for several seasons and with no carpets of dead bees for the survivors to clean out.

I am presuming you mean the percentage of bees lost in any particular colony and not including a calculation based on all colonies including dead-outs?

 

[pargyle]

Do you keep the open mesh floors open to help prevent too much moisture build-up bearing in mind you have a well sealed roof? I've been wondering what to do with the mesh floors. On 10 frame hives I have an insertable plastic floor for winter to effectively block close off the mesh - there will be some air flow, but very small. On the wooden nucs though (homemade), although they have mesh floors, I haven't any plan as yet on how to block them off (possibly a wood insert....). I hadn't thought about some sort of skirt though to keep air flow, buy stop drafts. How do you do yours? Or a picture would be great if you have one?

As long as you have top insulation (in timber hives particularly) there will only be condensation on the walls of the hive which will run down and drain out or more likely will be used by the bees as it saves them collecting water from outside. You don't need to close off the mesh floor as long as there are no holes in the crownboard at the top of the hive.

You will find my hive stands here:

https://www.flickr.com/photos/99514363@N06/albums/72157644503927472

 

[RichardK]

I am presuming you mean the percentage of bees lost in any particular colony and not including a calculation based on all colonies including dead-outs?

Exactly. As a new bee keeper facing his first winter I'm wondering what sort of population I should be facing in Spring (compared to say now) assuming they are a healthy colony?

 

[RichardK]

As long as you have top insulation (in timber hives particularly) there will only be condensation on the walls of the hive which will run down and drain out or more likely will be used by the bees as it saves them collecting water from outside. You don't need to close off the mesh floor as long as there are no holes in the crownboard at the top of the hive.

You will find my hive stands here:

https://www.flickr.com/photos/99514363@N06/albums/72157644503927472

Thanks for that. All my hives / nucs are timber, with mesh floors & insulated roofs. Last Feb the coldest mornings we had at c. 7am was -6C which was a shock (probably had a week of those). At that temperature is it still OK with an open mesh floor? February is generally our worst month.

I like your stands...very clean and tidy.

 

[pargyle]

Thanks for that. All my hives / nucs are timber, with mesh floors & insulated roofs. Last Feb the coldest mornings we had at c. 7am was -6C which was a shock (probably had a week of those). At that temperature is it still OK with an open mesh floor? February is generally our worst month.

I like your stands...very clean and tidy.

Yes ... even with temperatures as low as that, as long as there are not draughts around the bottom of the hive there won't be a problem .... depending on your stand - just tack some material of some sort around the base to deflect any draughts ...

 

[RichardK]

Yes ... even with temperatures as low as that, as long as there are not draughts around the bottom of the hive there won't be a problem .... depending on your stand - just tack some material of some sort around the base to deflect any draughts ...

Thanks for that. My base is simply breeze blocks 2 high supporting wooden joists on which the hives sit. I could as you suggest just tack something to the wood.