Tag Archives: mites

The flow must go on

Except it doesn’t 🙁

And once the summer nectar flow is over, the honey ripened and the supers safely removed it is time to prepare the colonies for the winter ahead.

It might seem that mid/late August is very early to be thinking about this when the first frosts are probably still 10-12 weeks away. There may even be the possibility of some Himalayan balsam or, further south than here in Fife, late season ivy.

However, the winter preparations are arguably the most important time in the beekeeping year. If you leave it too late there’s a good chance that colonies will struggle with disease, starvation or a toxic combination of the two.

Long-lived bees

The egg laying rate of the queen drops significantly in late summer. I used this graph recently when discussing drones, but look carefully at the upper line with open symbols (worker brood). This data is for Aberdeen, so if you’re beekeeping in Totnes, or Toulouse, it’ll be later in the calendar. But it will be a broadly similar shape.

Seasonal production of sealed brood in Aberdeen, Scotland.

Worker brood production is down by ~75% when early July and early September are compared.

Not only are the numbers of bees dropping, but their fate is very different as well.

The worker bees reared in early July probably expired while foraging in late August. Those being reared in early September might still be alive and well in February or March.

These are the ‘winter bees‘ that maintain the colony through the cold, dark months so ensuring it is able to develop strongly the following spring.

The purpose of winter preparations is threefold:

1. Encourage the colony to produce good numbers of winter bees
2. Make sure they have sufficient stores to get through the winter
3. Minimise Varroa levels to ensure winter bee longevity

I’ll deal with these in reverse order.

Varroa and viruses

The greatest threat to honey bees is the toxic stew of viruses transmitted by the Varroa mite. Chief amongst these is deformed wing virus (DWV) that results in developmental abnormalities in heavily infected brood.

DWV is well-tolerated by honey bees in the absence of Varroa. The virus is probably predominantly transmitted between bees during feeding, replicating in the gut but not spreading systemically.

However, Varroa transmits the virus when it feeds on haemolymph (or is it the fat body?), so bypassing any protective immune responses that occur in the gut. Consequently the virus can reach all sorts of other sensitive tissues resulting in the symptoms most beekeepers are all too familiar with.

Worker bee with DWV symptoms

However, some bees have very high levels of virus but no overt symptoms ¹.

But they’re not necessarily healthy …

Several studies have clearly demonstrated that colonies with high levels of Varroa and DWV are much more likely to succumb during the winter ².

This is because deformed wing virus reduces the longevity of winter bees. Knowing this, the increased winter losses make sense; colonies die because they ‘run out’ of bees to protect the queen and/or early developing brood.

I’ve suggested previously that isolation starvation may actually be the result of large numbers of winter bees dying because of high DWV levels. If the cluster hadn’t shrunk so much they’d still be in contact with the stores.

Even if they stagger on until the spring, colony build up will be slow and faltering and the hive is unlikely to be productive.

Protecting winter bees

The most read article on this site is When to treat? This provides all the gory details and is worth reading to get a better appreciation of the subject.

However, the two most important points have already been made in this post. Winter bees are being reared from late August/early September and their longevity depends upon protecting them from Varroa and DWV.

To minimise exposure to Varroa and DWV you must therefore ensure that mite levels are reduced significantly in late summer.

Since most miticides are incompatible with honey production this means treating very soon after the supers are removed ³.

Time of treatment and mite numbers

Once the supers are off there’s nothing to be gained by delaying treatment … other than more mite-exposed bees 🙁

In the graph above the period during which winter bees are being reared is the green arrow between days 240 and 300 (essentially September and October). Mite levels are indicated with solid lines, coloured according to the month of treatment. You kill more mites by treating in mid-October (cyan) but the developing winter bees are exposed to higher mite levels.

In absolute numbers more mites are present and killed because they’ve had longer to replicate … on your developing winter bee pupae 🙁

Full details and a complete explanation is provided in When to treat?

So, once the supers are off, treat as early as is practical. Don’t delay until late September or early October ⁴.

Treat with what?

As long as it’s effective and used properly I don’t think it matters too much.

Amitraz strip placed in the hive.

Apiguard if it’s warm enough. Apistan if there’s no resistance to pyrethroids in the local mite population (there probably will be 🙁 ). Amitraz or even multiple doses of vaporised oxalic acid-containing miticide such as Api-Bioxal ⁵.

This year I’ve exclusively used Amitraz (Apivar). It’s readily available, very straightforward to use and extremely effective. There’s little well-documented resistance and it does not leave residues in the comb.

The same comments could be made for Apiguard though the weather cannot be relied upon to remain warm enough for its use here in Scotland.

Another reason to not use Apiguard is that it is often poorly tolerated by the queen who promptly stops laying … just when you want her to lay lots of eggs to hatch and develop into winter bees ⁶.

Feed ’em up

The summer nectar has dried up. You’ve also removed the supers for extraction.

Colonies are likely to be packed with bees and to be low on stores.

Should the weather prevent foraging there’s a real chance colonies might starve ⁷ so it makes sense to feed them promptly.

The colony will need ~20 kg (or more) of stores to get through the winter. The amount needed will be influenced by the bees ⁸, the climate and how well insulated the hive is.

I only feed my bees fondant. Some consider this unusual ⁹, but it suits me, my beekeeping … and my bees.

Bought in bulk, fondant (this year) costs £10.55 for a 12.5 kg block. Assuming there are some stores already in the hive this means I need one to one and a half blocks per colony (i.e. about £16).

These three photographs show a few of the reasons why I only use fondant.

: 11:42:56 … Ready

: Take care with sharp knives … much easier with a slightly warm block of fondant

: 11:44:18 … GO!

It’s prepackaged and ready to use. Nothing to make up. Just remove the cardboard box.
Preparation is simplicity itself … just slice it in half with a long sharp knife. Or use a spade.
Open the block like a book and invert over a queen excluder. Use an empty super to provide headroom and then replace the crownboard and roof.
That’s it. You’re done. Have a holiday 😉
The timings shown above are real … and there were a couple of additional photos not used. From opening the cardboard box to adding back the roof took less than 90 seconds. And that includes me taking the photos and cutting the block in half 🙂
But equally important is what is not shown in the photographs.
- No standing over a stove making up gallons of syrup for days in advance.
- There is no specialist or additional equipment needed. For example, there are no bulky syrup feeders to store for 48 weeks of the year.
- No spilt syrup to attract wasps.
- Boxed, fondant keeps for ages. Some of the boxes I used this year were purchased in 2017.
- The empty boxes are ideal for customers to carry away the honey they have purchased from you 😉
The final thing not shown relates to how quickly it is taken down by the bees and is discussed below.

I’m surprised more beekeepers don’t purchase fondant in bulk through their associations and take advantage of the convenience it offers. By the pallet-load delivery is usually free.

Fancy fondant

Capped honey is about 82% sugar by weight. Fondant is pretty close to this at about 78%. Thick syrup (2:1 by weight) is 66% sugar.

Therefore to feed equivalent amounts of sugar for winter you need a greater weight of syrup. Which – assuming you’re not buying it pre-made – means you have to prepare and carry large volumes (and weights) of syrup.

Meaning containers to clean and store.

But consider what the bees have to do with the sugar you provide. They have to take it down into the brood box and store it in a form that does not ferment.

Fermenting stores can cause dysentry. This is ‘a bad thing’ if you are trapped by adverse weather in a hive with 10,000 close relatives … who also have dysentry. Ewww 😯

To reduce the water content the bees use space and energy. Space to store the syrup and energy to evaporate off the excess water.

Bees usually take syrup down very fast, rapidly filling the brood box.

In contrast, fondant is taken down more slowly. This means there is no risk that the queen will run out of space for egg laying. Whilst I’ve not done any side-by-side properly controlled studies – or even improperly controlled ones – the impression I have is that feeding fondant helps the colony rear brood into the autumn ¹⁰.

Whatever you might read elsewhere, bees do store fondant. The blocks I added this week will just be crinkly blue plastic husks by late September, and the hives will be correspondingly heavier.

You can purchase fancy fondant prepared for bees with pollen and other additives.

Don’t bother.

Regular ‘Bakers Fondant’ sold to ice Chelsea buns is the stuff to use. All the colonies I inspect at this time of the season have ample pollen stores.

I cannot comment on the statements made about the anti-caking agents in bakers fondant being “very bad for bees” … suffice to say I’ve used fondant for almost a decade with no apparent ill-effects ¹¹.

It’s worth noting that these statements are usually made by beekeeping suppliers justifying selling “beekeeping” fondant for £21 to £36 for 12.5 kg.

Project Fear?

Colophon

The title of this post is a mangling of the well-known phrase The show must go on. This probably originated with circuses in the 19th Century and was subsequently used in the hotel trade and in show business.

The show must go on is also the title of (different) songs by Leo Sayer (in 1973, his first hit record, not one in my collection), Pink Floyd (1979, from The Wall) and Queen (1991).

2017 in retrospect

The end of the year is a good time to look back at the highs and lows of the season. What worked … what didn’t work … what on earth happened to our weather in June?

Early June 2017 …

June is an important month here in Fife. Early season colony buildup should be pretty much complete, most colonies will have had some sort of swarm control measures in late May, virgin queens may well be present in many hives, the OSR is over and colonies need to consolidate for the main summer flows.

But instead it just rained.

Rainfall in Fife was 225% the 40 year average, access to apiaries was problematic due to flooding and queens could only get out to mate if they were wearing ‘water wings‘.

Big mistake

Many colonies needed to be, or should have been fed, during June. Mine had reasonable levels of stores as I’d not taken much early season honey. I therefore chose not to feed them. In retrospect I think this was a big mistake.

Although not monitored carefully, I suspect brood rearing slowed, so reducing the colony size to effectively exploit the July/August flows. It was my worst summer honey crop in years.

Lesson one … If this happens next season I’ll continuously feed thin syrup to keep the queen laying strongly.

Doing the splits

Notwithstanding the incessant rain, swarm control – and the inevitable associated queen mating – went pretty well. I generally use splits of one form or another and most queens got out to mate, albeit a little slower than I’d have liked. If swarm control is needed for colonies in the bee shed we can’t do vertical splits (because of the way entrances are organised) and instead just take a nucleus colony away and let them rear a new queen.

Only ‘pretty well’ though because I suspect I lost a cast from a vertical split that went calamitously wrong. I’d left the queenless half far too strong and inadvertently also left multiple developing queen cells.

D’oh!

This wasn’t going to end well 🙁

I did manage to capture and hive another cast from the same colony, but the first virgin queen and well over half the workers were long gone.

So, lesson two (which I’ve been taught many times before 😥 ) is to be decisive when there are multiple queen cells in a split. Either knock them back appropriately (which I’ll explain next year) or split the box up into multiple nucs. Don’t dither. Don’t prevaricate and don’t – as I think I did this year – simply forget to check.

All the gear, some idea

I blatantly poached how to build foundationless frames with bamboo skewers from the internet. I claim zero originality here. It isn’t my idea. However, I’m pleased to say it was a great success. Simple wooden starter strips were also a roaring success. It’s very satisfying when you realise you don’t need to spend £1 per frame on foundation.

Nearly completed …

I’ve used quite a few Abelo poly hives this season. They’re a strident colour – blue and yellow – but reasonably well made. Colonies checked this winter are doing well in them, with bees right up to the side walls on sub-zero days. This suggests to me that they are well insulated.

An Abelo/Swienty hybrid hive …

There are some aspects of these hives I have yet to be fully convinced by; upper entrances, the crownboard, high condensation levels and a small Varroa tray. I’ll review them more fully when I’ve been using them for at least a full year.

Old invasives …

The bête noire of most beekeepers, the Varroa mite, has featured heavily throughout the year. In print, though thankfully not in my colonies. I’ve tried to emphasise the need to treat appropriately, using the right miticide at the right time. Since most approved (and even some unapproved 😉 ) miticides are all pretty effective, the timing of treatment is probably the most important point.

2016 temperature data and OA treatment …

In three recent posts I presented the importance of midwinter treatment, how to prepare the oxalic acid-containing miticide and how to administer it. These should probably be read in conjunction with an earlier article on when to treat, which I’ll come back to in a minute. Finally, as far as Varroa is concerned, I discussed potential ways to optimise the timing of the winter treatment by watching the weather. I suspect that most beekeepers treat too late in the winter.

If you have yet to treat this winter … get a move on!

… and new ones

The new invasive that got some coverage was, inevitably, the Asian hornet. Having first arrived in 2016 I think we’ll be subjected to annual incursions until it gets established here. Constant vigilance is going to be needed to help postpone what might be inevitable. Just because it is inevitable doesn’t mean we shouldn’t try and delay it’s permanent arrival.

Devon beekeepers got some first-hand experience of how vigilant you need to be to both spot and photograph Asian hornets in September. Martin Hocking has written about his experience in the Devon Beekeeper (pp172 and also in November’s Bee Craft) which should be required reading for beekeepers, with a follow up article about his experience in December (see pp196). There’s an open meeting on the 20^th of January at Harberton Parish Hall, TQ9 7SD where the threat posed by the Asian hornet – and how to mitigate it – will be discussed.

Although rarely mentioned this year, Small Hive Beetle now appears to be established in the Calabria region of Southern Italy. Data updated in late September and November indicates that positive wild colonies and sentinel nucleus colonies are still being found, indicating that attempts to eradicate the beetle have failed. Infested colony numbers are perhaps a bit lower than previous years, but since there’s no readily-available data on the level of surveillance, it’s not clear whether this shows that control is having an effect, or if people are just not looking as hard.

www.theapiarist.org

Posts have been made every Friday of the year, with a few additional ones when something important happened (Asian hornets or I was ‘advertising’ a Convention I was speaking at … OK, my talk wasn’t important, but the Welsh Beekeepers Convention was 😉 ).

Regular as clockwork …

The Friday posts are intentional. It’s when most of us have time to read stuff. The regularity was not and, frankly, it’s a bit of a surprise I’ve achieved it. However, there it is. No promises it’ll continue like that. You can register to receive email notification of new posts in the right hand panel.

Visitor numbers to the site are markedly increased from last year. Page views per visit are down fractionally, but not significantly. It’s clear that more are finding the site as it becomes better indexed by the search engines, and as pages are referenced by other sites.

24 months on www.theapiarist.org …

My attempts at generating a presence on Facebook was an abject failure. I simply don’t have time to do anything other than automagically post updates from here on Facebook (as I do on Twitter, which I’m a bit more familiar and competent with … follow me on @The_Apiarist). Apologies if you tried to ‘Friend’ me (or whatever) on Facebook. I’ve cancelled all the email updates as I simply couldn’t keep up. Or, when I tried, I didn’t know how to! I belong to the pre-FB generation, or the one before that.

Beekeeping is international, with different problems – but many shared ones – globally. I’m grateful to the visitors from 161 different countries and the European Union 🙂 Less than 50% of the readers are from the UK, despite the UK-centric bias I inevitably exhibit (°C, colour, no mention of queen castles or slatted racks, precious little discussion of Langstroth hives etc.). Southern hemisphere beekeepers don’t even do things at the same time of the year, so many of the posts aren’t even topical for readers in Australia, New Zealand and South America. Whatever, I’m grateful people took the time to visit and read stuff.

And the winner is …

I don’t publish visitor numbers, but I do comment on the popularity of particular pages. For several years a post on my honey warming cabinet has been the most popular. It was originally posted ‘way back’ in 2014. Frankly, it was useful, but not particularly challenging or exciting.

But it’s all change this year. Aside from the homepage, the archive and blog pages, all of which people arrive at to to get the most recent posts, the honey warming cabinet post was a distant fourth in the 2017 rankings.

Above it were posts on vertical splits and making increase, feeding fondant and – particularly pleasingly and top this year – when to treat colonies with miticides against Varroa. I say particularly pleasingly as the When to treat? post is a serious article on an important subject, underpinned by scientific arguments. The timing of the late summer treatment is probably one of the most important events in influencing the health and overwintering success of the colony. This post was almost twice as popular as any other post this year which – because it originally appeared in early 2016 – suggests it is finally being widely cited and accessed by beekeepers.

When to treat? Finally getting read when it should be.

And what does the future offer?

Frankly, as I write this in mid-December with a streaming cold, a box of tissues and slathered in Vicks VapoRub (really, it’s not a pretty sight) I don’t know. I have two priorities at the moment; getting the new bee shed properly setup and (with my researcher hat and lab coat on) starting studies of Chronic Bee Paralysis Virus. Both will get coverage here.

Bee Shed 2 … the windows still need some work …

In terms of the website I’m acutely aware there’s no proper indexing or rational list of articles on particular subjects, perhaps other than Varroa. I hope to bring some order to the chaos, allowing me to not repeat myself, to develop some themes more fully and to not repeat myself 😉 . I also know I have a load of unwritten stuff on queen rearing.

Winter time is also DIY time … dabbling with wood, perspex, Correx and Elastoplasts. Something will surely result from this, in addition to the blood loss and bad language.

If there are things you’d particularly like to read drop me a note. I’m interested in the science underlying beekeeping and have little patience with some of the dogma and That’s the way we’ve always done it stories. I’ve already written about the importance of training and the responsibilities of beekeepers. I’ve got some more on these areas planned as I think they’re too often ignored by beekeepers in the UK.

With Best Wishes for 2018. May your colonies be docile, your supers unliftable, your queens well-mated and your swarms (again) in my bait hives 😉

Happy New Year

Weather to treat

Not Whether to treat? … to which the answer is yes. Instead, a poor pun on the choice of how I use temperature as an indication of when to treat colonies in midwinter …

Midwinter OA-based treatments

Oxalic acid-based treatments for midwinter Varroa control are most effective when colonies are broodless^†. This is because oxalic acid (OA) treatments only kill phoretic mites and are ineffective against mites in sealed cells. They are therefore ideal for use on swarms, packages and broodless colonies in midwinter.

Winter in the apiary

These OA treatments include Api-Bioxal, the VMD-approved treatment, and unmodified oxalic acid, it’s active ingredient. The importance of midwinter treatments, the preparation of the OA solution and how to trickle treat have recently been covered. I’ve previously discussed sublimation and will do so again in a longer article in the future.

The beekeepers winter dilemma

How can you tell whether your colonies are broodless in midwinter?

On a warm, sunny, Spring afternoon this takes just a couple of minutes … remove the roof, crack off the crownboard, gently lift out the dummy board and the adjacent frame, look carefully at the mass of bees covering the top bars, aim for about the middle and gently prise apart those two frames, lift out a frame from one side of the ‘gap’ and – Hey presto – brood.

Just writing that in early December makes me hanker for much warmer days …

Memories of midseason

Actually, you can do exactly the same in midwinter. There are videos on the internet showing an experienced and (in)famous Finnish beekeeper opening his colonies at -10ºC.

I’ve opened and briefly inspected colonies at low temperatures (though not sub-zero). The bees are usually pretty torpid, reluctant to fly – or simply too cold to – and you can be in and out in just a minute or so. Bees cope pretty well with this. It undoubtedly disturbs them a bit and it breaks the propolis seal on the crownboard, but – done carefully and quickly – it’s the only foolproof way to determine whether a colony is broodless in midwinter.

But what if they’ve got brood and it’s therefore not the optimal time to treat? Do you go back and repeat the entire process in 1-2 weeks? What if it’s snowing next time, or there’s a howling gale blowing?

An alternative approach is needed^∞.

The annual brood rearing cycle

As the colony moves from summer to autumn the egg laying rate of the queen drops. It goes on dropping, although not necessarily smoothly, as the days shorten further, the temperature drops and the sources of pollen and nectar disappear. If the queen stops laying altogether then the colony will become broodless about 21 days later.

At some point, perhaps early in the New Year, the queen starts laying again. Slowly at first, but at increasing levels as the season starts. Once foraging starts in earnest the egg laying rate increases markedly and peaks sometime in June.

The precise timing of all these changes cannot be predicted. It’s likely to be dependent on a range of factors – nectar and pollen availability, the strain of bee, day length (and whether it’s increasing or decreasing) and temperature.

Of these, temperature probably has the greatest influence.

Probably^ß.

Generalised annual brood and worker numbers …

Here’s a quick’n’dirty graph put together with BEEHAVE showing a generalised annual cycle of total brood (blue) and adult bee (red) numbers. Under the conditions in this model the colony is broodless for ~30 days at the end if the year.

Temperate(ure)

Part of the problem with being definitive about the annual brood cycle is the temperature variation with latitude. Temperate regions stretch – in Europe – from Northern Finland to Southern Spain. Bees are kept throughout this range, but obviously experience wildly different climates.

And then there’s the year to year variation.

So if you can’t predict when the colony is going to be broodless, perhaps you can observe the weather – and in particular the temperature – and make an educated guess.

Watch the weather

Over the last few years I’ve applied my midwinter treatment soon (<6 days) after the end of the first extended cold period of the season. This is generally earlier than most beekeepers, who often treat between Christmas and New Year, or early in January.

So, how do we reasonably accurately monitor the weather for a suitable time to treat?

Ho ho ho

Most of us live in centrally-heated splendour, protected from the day-to-variation of temperature by heated car seats, air conditioning, hot water bottles, Thinsulate and wood-burning stoves. Do you know what the temperature was today? Rather than trust the wildly-variable (in accuracy) national^‡ weather reports for the actual temperature near my apiaries, I instead use very much more local data from Weather Underground.

There are hundreds of ‘amateur’ weather stations across the country that upload data to wunderground.com. Most of these provide current and historic data, including temperature (max, min and average). Here’s one for Auchtermuchty in Fife (on wunderground.com) and directly from the weather station.

Once the weather cools I keep an eye on the average temperature over an extended period of a fortnight or so. If it remains low I wait a bit more … but I then treat as soon as practical after it warms up to 8-10°C or so.

The proof of the pudding

Here’s a graph of the temperature data for 2016^§. As indicated on the graph, I treated colonies on the 7^th of December.

2016 temperature data and OA treatment …

I didn’t open my colonies, but others opened on the same day nearby were all broodless. The 7^th was chosen as it was the first warm (relatively!) day after a 19 day window in which the average temperature had barely climbed above 5°C.

These treated colonies went into the New Year with vanishingly low Varroa levels.

And again …

This year appears to be repeating a very similar pattern. We’ve had frosts most nights since the 10^th of November. It started to warm up significantly in early December as storm Caroline bore down on Scotland and I treated most of my colonies on the 6^th…

… by the light of a head torch, in light rain and strengthening wing at 7pm after work.

No, I didn’t open any of the hives to check if they were broodless 😉

It was over 11°C in the apiary when I treated, the barometer was plummeting and the forecast was for near-zero temperatures within 24 hours and remaining that way for another 10 days.

Some of my hives have perspex crownboards. These allow me to check both the state of the colony and if the vapour from my Sublimox has permeated to every corner of the hive. All the colonies were very loosely clustered, with a few bees even wandering out briefly onto the landing board in the dark as I bumbled around preparing things.

The Varroa trays will now be checked in a week or so to work out the mite infestation levels. In the meantime, I can start planning for the coming season knowing I’ve done the best I can to reduce virus levels in the colonies, so giving them a good start to the year.

A Hi tech solution?

Colonies rearing brood maintain a higher, and stable, broodnest temperature (32-35°C) than colonies without brood. It is therefore possible to determine whether a colony has brood by monitoring the temperature directly, rather than trying to infer it from the ambient temperature.

Brood rearing starts …

Arnia make hive monitors that allow this sort of thing to be measured. It would be interesting to relate the brood temperature to the ambient temperature (described above) to determine how accurate or otherwise simply ‘watching the weather’ is. Of course … what you’d really want to do is monitor when brood rearing stops and treat soon after that.

Stop press

I treated colonies in our research apiary the following day – the 7th – with dribbled Api-Bioxal. The temperature had dropped almost 7°C since the previous evening and colonies were again beginning to cluster tightly. Under these conditions I’m never confident that the OA vapour penetrates fully, so prefer to trickle treat.

I briefly checked one strong colony in a poly hive for brood.

It was broodless, as I’d hoped 🙂

Of course, this doesn’t guarantee all the others are also broodless, but it does give me some confidence that I’d chosen the correct weather to treat.

^†This article, like most on this site, discuss beekeeping issues relevant to temperate climates. It’s important to make this clear now as most of what follows is irrelevant to readers from warmer regions.

^∞Even if there is brood in midwinter, it’s going to be in pretty small amounts. The rate at which this brood emerges is going to be low. The chances of determining what’s going in the colony by ‘reading the tea leaves’ from the debris falling through the mesh floor of the hive is therefore not great. It would probably also require repeated visits to the apiary.

^ßThis needs qualifying … in midseason, when the temperature varies but it’s not generally cold, the nectar flow is probably the rate-limiting step for brood rearing. The June gap is regularly associated with the queen shutting up shop for a while. However, in late autumn and early winter I’m sure the plummeting temperatures is a major influence on egg laying by the queen.

^‡National … Ha! Most are only national if you live within the M25. Anywhere else and you’re usually much better off accessing some data from closer to home. It’s worth noting that the sort of ‘amateur’ weather stations I discuss do vary in data quality. For example, they’re a bit dodgy recording temperatures in full sun (they tend to over-read). However, if you find a local one, check the temperature in comparison to a thermometer in your apiary, you’ll find it’s a useful way to monitor what might be happening in the hives.

^§I don’t routinely generate these graphs – I have a life (!) – but did specifically to illustrate this post. It’s sufficient to simply monitor the average temperature.

Colophon

Whether the weather be fine
Or whether the weather be not,
Whether the weather be cold
Or whether the weather be hot,
We’ll weather the weather
Whatever the weather,
Whether we like it or not.

Anonymous

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The day job

It’s no secret that I have both amateur and professional interests in bees, bee health and beekeeping.

During the weekend I sweat profusely in my beesuit, rushing between my apiaries in Central and Eastern Fife, checking my colonies – about 15 at the autumn census this year – averting swarms, setting up bait hives, queen rearing and carrying bulging supers back for extraction.

Actually, not so much of the latter in 2017 🙁 I did get very wet though, much like all the other beekeepers in Fife.

The BSRC labs …

During the week I sit in front of a large computer screen running (or sometimes running to keep up with) a team of researchers studying the biology of viruses in the Biomedical Sciences Research Complex (BSRC) at the University of St. Andrews. Some of these researchers work on the biology and control of honey bee viruses.

During the winter the beekeeping stops, but the research continues unabated. The apiary visits are replaced with trips in the evenings and weekends to beekeeping associations and conventions to talk about our research … or sometimes to talk about beekeeping.

Or both.

This weekend I’m delighted to be speaking at the South Devon Beekeepers Convention in Totnes on the science that underpins rational and practical Varroa control.

Which came first?

I’ve been a virologist my entire academic career, but I’ve only worked on honey bee viruses for about 6 years. I’ve been a beekeeper for about a decade, so the beekeeping preceded working on the viruses of bees.

However, the two are inextricably entwined. Having a reasonable amount of beekeeping experience provides a unique insight into the problems and practicalities of controlling the virus diseases that bees get.

Being able to “talk beekeeping” with beekeepers has been very useful – both for the communication of our results to a wider audience and in influencing the way we approach our research.

Increasingly, the latter is important. Researchers need to address relevant questions, using their detailed understanding of the science to deliver practical solutions to problems¹. There’s no point in coming up with a solution if there’s no way it’s implementation is compatible with beekeeping.

Deformed wing virus

DWV symptoms

The most important virus for most beekeepers in most years is deformed wing virus (DWV). This virus “does what it says on the tin” because, at high levels, it causes developmental defects in pupae that emerge with shrivelled, stunted wings. There are additional developmental defects which are slightly less obvious, but there are additional (largely invisible) changes which are of greater importance.

DWV reduces the lifespan of worker bees. This is probably not hugely significant in workers destined to live only a few weeks in midsummer. However, the winter bees that get the colony through from September through to March must live for months, not weeks. If these bees are heavily infected with DWV they die at a faster rate. Consequently, the colony dwindles and dies out in midwinter or early Spring. At best, it staggers through to March and then never builds up properly. It’s still effectively a winter loss.

Our research focuses on how Varroa influences the virus population. There’s very good evidence now that DWV transmission by Varroa leads to a significant increase in the amount of virus, and a considerable decrease in the diversity of the virus population.

So what?

Well, this is important because if we want to control the virus (i.e. to reduce DWV-associated disease and colony losses) it must help to know the proper identity of the virus we are trying to control. It will also help us measure how well our control works. We know we’re measuring the right thing.

We’re working with researchers around the world to define the important characteristics of DWV strains that cause disease and, closer to home, with entire beekeeping associations to investigate practical strategies to improve colony health.

Chronic bee paralysis virus

CBPV symptoms

We’re about to start a large collaborative project on the biology and control of chronic bee paralysis virus (CBPV). This virus is becoming a significant problem for many beekeepers and is increasing globally. It’s a particular problem for some bee farmers.

CBPV causes characteristic symptoms of dark, hairless, oily-looking bees that sometimes shiver, dying in large smelly piles at the hive entrance. It typically affects very strong colonies in the middle of the season. It can be devastating. Hives that should be the most productive ones in the apiary fail catastrophically.

Why is a virus we’ve known about for decades apparently increasing in the amount of disease it causes? Are there new virulent strains of the virus circulating? Are there particular beekeeping practices that facilitate it’s spread? We’re working with collaborators in the University of Newcastle to try and address these and related questions.

I’ll write more about CBPV over the next year or so. It won’t be a running dialogue on the research (which would be crushingly dull for most readers), but will provide some background information on what is a really fascinating virus.

At least to a virologist 😉

And perhaps to beekeepers.

Grow your own

As virologists, we approach the disease by studying the virus. Although we maintain an excellent research apiary, we don’t do many experiments in ‘the field’. Almost all the work is done in test tubes in incubators in the laboratory … or in bees we rear in those incubators.

Grow your own …

We can harvest day-old larvae (or even eggs) from a colony and rear them to emergence as adult bees in small plastic dishes in the laboratory. We use an artificial diet of sugar and pollen to do this. It’s time consuming – they need very regular feeding – but it provides a tightly controllable environment in which to do experiments.

Since we can rear the bees, we can therefore easily test the ability of viruses to replicate in the bees. Do all strains of the virus replicate equally well? Do some strains outcompete others? Does the route by which the virus is acquired influence the location(s) in the bee in which the virus replicates? Or the strains it is susceptible to? Or the level of virus that accumulates?

And if our competitors are reading this, the answer to most of those questions is ‘yes’ 😉

We can even ask questions about why and how DWV causes deformed wings.

Again, so what? We suspect that DWV causes deformed wings because it stops the expression of a gene in the bee that’s needed to make ‘good’ wings. If we can identify that gene we might be able to investigate different strains of honey bee for variation in the gene that would render them less susceptible to being ‘turned off’ by DWV. That might be the basis for a selective breeding project.

It’s a simplistic explanation, but it’s this type of molecular interaction that explains susceptibility to a wide range of human, animal and plant diseases.

Bee observant

Bee health is important, and not fundamentally difficult to achieve. There are some basics to attend to … strong hives, good forage, good apiary hygiene etc. However, it primarily requires good powers of observation – does something look odd? Are there lots of mites present? How does the brood look?

If things aren’t right – and often deducing this means comparisons must be made between hives – then many interventions are relatively straightforward.

Not long for this world …

The most widespread problems (though, interestingly, this doesn’t apply to CBPV) are due to high levels of Varroa infestation. There are effective and relatively inexpensive ways to treat these … if they’re used properly.

More correctly, they’re relatively inexpensive whether they’re used properly or not. However, they’re pretty ineffective if not used properly 😉

Regular checks, good record keeping, comparisons between hives and informed observation are what is needed. Don’t just look, instead look for specific things. Can you see bees with overt symptoms of DWV? Are there bees with Varroa riding around on their backs? The photo above has both of these in plain view. Are some hairless bees staggering around the top bars with glossy abdomens, or clinging to the side bars shaking and twitching?

Don’t wait, act

I’ve no doubt that scientists will be able to develop novel treatments to control or prevent virus infections of bees. I would say that … I’m a scientist 😉 However, I’m not sure beekeepers will be able to afford them, or perhaps even want to use them, or that they’d be compatible with honey production or of any use in Warré hives etc.

I’m also not sure how soon these sorts of treatments might become available … so don’t wait.

If there are signs of obvious DWV infection you need to do something. ‘Obvious’ because DWV is always present, but it’s usually harmless or at least tolerated by the bees. My lab have looked at thousands of bees and have yet to find one without detectable levels of DWV. However, healthy bees have only about 1/10,000 the level of DWV present in sick bees … and these are the ones that have obvious symptoms.

I’ve discussed Varroa control elsewhere, and will again.

Unfortunately, if your colony has signs of CBPV disease then Varroa control is not really relevant. The virus is transmitted from bee to bee by direct contact. This probably accounts for the appearance of the disease primarily in very strong colonies.

At the moment there’s little you can do to ‘cure’ a CBPV-afflicted colony. I hope, in 2-3 years we will have a better idea on what interventions might work. We have lots of ideas, but there are a lot of basic questions to be addressed before we can test them.

Field work

Business and pleasure

The half of my lab that don’t work on bee viruses study fundamental mechanisms of virus replication and evolution. They do this using human viruses, some of which are distant relatives of DWV. They work on human viruses as it’s only these that have excellent model systems to facilitate the types of elegant experiments we try to do. They’re also relatively easy to justify in funding applications, and it allows us to tap into a much bigger pot for funding opportunities (human health R&D costs probably total £2 billion/annum, bees might be £2 million/annum).

And no, my lab don’t get anything like that much per year for our research!

Importantly, the two activities on human and honey bee viruses are related. Our experience with the human viruses related to DWV made us well-qualified to tackle the bee virus. They replicate and evolve in very similar ways, we quantify them in the same way and there may be similarities in some ways we could approach to control them.

And with the bee viruses I can mix business with pleasure. If I’m going to the apiary I’ll get to see and handle bees, despite it being officially “work”. It doesn’t happen as much as I’d like as I’m usually sat behind the computer and all of the ‘bee team’ have been trained to work with bees by the ESBA.

However, at least when I talk to collaborators or to the beekeeping groups we’re fortunate to be working with we – inevitably – talk about bees.

And that’s fun 😀

¹Several years ago I delivered an enthusiastic and rather science-heavy talk at a Bee Farmers Association meeting. I thought it had gone reasonably well and they were kind enough to say some nice things to me … and then I got the question from the back of the room which went something like “That’s all very well young man … but what have you made NOW that I can put into my hives to make them healthy?”.

I’m sure my answer was a bit woolly. These days the presentation would have had a bit less science and bit more justification. We’ve also made some progress and it’s possible to now discuss practical strategies to rationally control viruses in the hive. It’s not rocket science … though some of the science it’s based on is reasonably fancy.

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Trick(le) and treat

Tools of the trade

This is the third and final post on why, with what, when and how to minimise mite levels in colonies in midwinter.

In the first post I explained why midwinter mite treatment makes sense. In the second I described how oxalic acid-containing solutions should be prepared and stored.

“Oxalic acid-containing” solutions includes both Api-Bioxal, the VMD approved treatment, and the unadulterated chemical. All three posts focus on trickling or dribbling – I’ve covered sublimation previously and both are essentially equally effective. Sublimation or vaporisation is currently very fashionable … but trickling is simplicity-itself and requires almost no special equipment.

In this post I’ll discuss how to administer the oxalic acid-containing solution.

For readability I’ll use the term OA solution to mean any oxalic acid-containing solution. About 50% of the readers of this site are from outside the UK; local rules may determine what you are or are not allowed to administer to your bees.

Trickling or dribbling

You’ll hear both terms used interchangeably¹. The general principle is that you directly administer 5ml of a 3.2% w/v solution of oxalic acid in thin (1:1) syrup per seam of bees in the colony.

‘Directly‘ because you administer the OA solution to the seam of bees. You don’t count the seams and then simply pour it into the hive. You don’t spread it across the top bars. The idea is that the bees at the top of the seam get coated in the solution and that it dribbles down through the colony, being passed from bee to bee as they feed and groom and move about.

Two seams of bees …

During this process any phoretic mites will also get exposed to the oxalic acid. Since mites are readily damaged by the OA solution they fall off and gradually drop out of the bottom of the cluster. Gradually, as it takes a few days for gravity to deliver all the corpses.

You can therefore determine whether mites were present and killed by placing a Varroa tray underneath the open mesh floor of the hive. Note that this doesn’t tell you how effective the treatment has been … for that you’d need to know the mite infestation level before treatment as well.

When to treat

In many ways this is the critical decision. As described previously, maximal benefit occurs when the colony is broodless. Ideally you want an extended cold period late in the calendar year. The colony will cluster tightly and brood rearing will slow down or stop completely.

If the cold period has lasted 2-3 weeks, even better. This will mean that some or all of the brood present will have emerged. The more sealed brood present, the less effective trickling OA solution is as a means of controlling mites.

Choose a calm, cool or cold day. I usually wait for a day with temperatures between 0 and 5°C. Much warmer than that and the cluster starts to break up or the bees are more likely to fly about as the crownboard is lifted. Windy or wet days disturb the bees (at least when you prise the crownboard off), so it’s best to avoid those.

I prefer to treat before the year end, rather than after, if I can. From a few irregular midwinter peeks into the cluster I think queens start laying earlier than most beekeepers think.

It pays to be prepared …

Trickle 2 – £1

… Aesop (~620-560BC) was right, though he wasn’t talking about beekeeping. Before treating your colonies there is some preparation needed. Do this properly and it’s a doddle.

Purchase a Trickle 2 container from Thorne’s. These are a measly quid each. You’ll only need one.

Practice with the Trickle 2 container (see below).

Gently warm your pre-prepared OA solution to about 25°C. If you made it up in advance and stored it at 4°C in the fridge this will take an hour or two. The easiest way is to stand the container (preferably thin-walled … I use a well-rinsed milk carton) in a basin of warm water.

Pour the pre-warmed OA solution into a well-labelled vacuum flask. You can buy these from Tesco for £2.50 with a capacity of 1 litre. The aim here is to take everything you need ready-prepared to the apiary so the treatments take the minimum time possible.

Remember that OA is toxic. Label everything carefully, make sure children can’t get near it and don’t use it again for food/drink purposes.

That’s it … you’re ready. You’ll need a hive tool, a bee suit, thin gloves (to protect you from the OA, not the bees), your vacuum flask of OA solution and the Trickle 2 bottle. By all means take your smoker, but you shouldn’t need it.

I’ve got a 5 ml (or 25 ml) syringe … won’t that do?

Yes … but no.

A Trickle 2 bottle holds 100ml of prepared OA solution. It takes two hands to fill the bottle, but only one hand to use it. That 100ml is sufficient for 20 seams of bees i.e. two completely full colonies (assuming an 11 frame National box). In midwinter the colony is unlikely to occupy 10 seams. A Trickle 2 bottle is also pretty accurate, reproducibly dispensing about 4.6-4.8ml of liquid. That’s close enough to 5ml.

In contrast, a syringe also takes two hands to fill (and refill). However, unless it’s a 5ml syringe, it’s difficult to accurately and reproducibly dispense liquid without using two hands. A 5ml syringe gives you the necessary accuracy, but needs refilling for every seam of bees. This takes time … during which the crownboard is off and the colony is getting chilled.

I’ve done both and can assure you that the Trickle 2 bottle is much better. Just buy one. It’s only £1 and it’ll last ages if one of your association members doesn’t borrow it … or doesn’t return it.

How to use a Trickle 2 bottle

Remove the cap and fill to the top of the lower chamber with liquid (practice with water).
Replace the cap.
Hold the bottle with your thumb and fingers on opposite sides of the lower chamber, with the external ‘pipe’ to the upper chamber next to your palm.
Undo the spout about a turn.
Gently squeeze the lower chamber. Liquid is forced up the pipe into the upper chamber. Hold it against the light to observe this.
Once the upper chamber is full, stop squeezing. Excess liquid drains back into the lower chamber.
If you are right handed turn the Trickle 2 bottle anti-clockwise² using your wrist and gently squeeze the bottle to dispense the liquid in the upper chamber from the spout. If you’re left handed you need to turn the bottle clockwise.

And in practice

The single-handed operation for the Trickle 2 container really pays dividends when treating a colony. You can gently prize up one side of the crownboard, hold it in one hand, administer the OA solution to each seam with the other hand and gently lower the crownboard back down … all in less time than it took me to write that.

Like this:

This is a reasonably sized colony being treated in the second week of January 3 years ago. The video is 1’45” long, but the crownboard is only open for about 50 seconds. And I was chatting with Mick Smith off camera, so could have perhaps gone a bit faster if I’d concentrated … 😉

Here’s a more detailed view of treating a small colony:

33 seconds of warmed, acidic goodness to slaughter the mites and give the colony the best possible start to the upcoming season.

Cautions and considerations

Discard any OA solution that’s not been used. Warming it will have raised the HMF levels and this may be toxic for your bees. However, read footnote 3 for another way to avoid HMF buildup³.

Wash everything carefully – the Trickle 2 bottle, the vacuum flask, gloves etc. Since the OA solution was in syrup everything gets sticky and gummed up. Clean stuff up, make sure it’s labelled and not going to be used in the kitchen and put it away until next year.

Oxalic acid kills mites, but it’s also toxic for unsealed brood. This is perhaps unsurprising considering it has a pH of 1 (i.e. very acidic) and ‘naked’ larvae aren’t protected by the tough exoskeleton that adult bees have. This is another reason to treat during a broodless period in midwinter.

In summer, swarms can also be treated with trickled oxalic acid-containing solutions before they have sealed brood. If a swarm arrives in bait hive, let it settle and start drawing comb on the foundationless frames. A day or so later treat it with oxalic acid by trickling. When I’ve done this I usually wait until late afternoon or early evening, so most of the bees are in the box. The colony obviously won’t be clustered, but the principle is the same – 5ml of syrup down each seam. Easy peasy. Effective.

Swarms have a significant mite load, so it’s well worth treating them before they rear brood and give the phoretic mites somewhere to breed.

Finally, it’s often recommended that a colony is only treated once per year with oxalic acid by trickling or dribbling. I’m not sure where this advice originates, but it’s probably wise.

‘Vaping’ vs. trickling

The discussion forums are awash with recommendations to ‘vape’ the colony, rather than trickle. Vaporisation, or more correctly sublimation, is a widely used method and has been in use for two decades. It’s currently very fashionable. I’ll write a more substantial comparison sometime in the future, but the following brief notes might be of interest.

Sublimation can be done repeatedly with brood present (though there’s no peer-reviewed evidence of efficacy) and is both well-tolerated by the colony and is not toxic to unsealed brood. It requires specialised and potentially expensive equipment, both for delivery and personal protection. You can build your own vaporiser, but shouldn’t skimp on protection for the operator. With a well designed vaporiser and hive there’s no need to open the colony to administer treatment.

In contrast, trickling requires only the Trickle 2 bottle and vacuum flask described here. Personal protection is a pair of latex gloves. It should only be conducted when the colony is broodless, should probably only be conducted once and does require the hive to be opened (albeit briefly).

You’ll be told that vaporisation is faster. It isn’t. Watch the videos above. Even my Sublimox – probably the fastest ‘active’ vaporiser on the market – takes well over a minute per colony if you take into account sealing the box, moving the generator about, unsealing the hive etc.

There are reports that sublimation is more effective, but the difference is marginal, and possibly not statistically significant. There is also a report that colonies are stronger in the Spring after sublimation, though this may be due to toxicity to open brood by trickled OA solution. If the colony is broodless this shouldn’t be an issue.

I’ve used both many, many times without a problem. Across the UK I suspect more beekeepers trickle OA, rather than ‘vape’ (a word I dislike), though the vocal ones on the discussion forums currently favour vaporisation.

What’s more important than how you deliver the oxalic acid, is that you do treat. Trickling OA solution is so easy and inexpensive that there’s no reason not to … and your colonies will be much healthier for it.

Get dribbling 😉

¹If the beekeeper is of a certain age you’ll hear these terms used in a different context. We’re restricting discussions here to delivering OA 😉

²If you are left handed you need to turn the Trickle 2 bottle clockwise. Actually, to be pedantic, if you are left handed and holding the bottle in your left hand, turn it clockwise. It’ll make sense once you try.

³ In the previous article on preparing oxalic acid solutions Calum posted a comment on preparing the OA in water and only adding and dissolving the required amount of sugar just before use. This has the advantage that there will be no HMF buildup. OA solution in water should be perfectly stable. I’ve not done it this way, but it makes sense and might be worth trying.

Colophon

The title of this article is a twist on the term Trick or treat. This is not entirely inappropriate as Trick or treating is a Halloween (31^st October … just a few days away) custom dating back – in various forms – centuries.

The modern usage, essentially North American, dates back to the 1920’s and refers to children in costumes going house to house threatening to play a trick unless the homeowner provides a treat, usually sweets or toys. In Britain these traditions date back to the 16^th Century, both of children going house-to-house asking for food and of dressing up in costumes at Halloween.

Closer to home, ‘guising‘ – children in Scotland going from door to door in disguise asking for food, coins or chocolate – dates back at least a century.

The term Trick or treat only entered common usage in the UK in the 1980’s.

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