Category Archives: Seasonal

The flow must go on

Except it doesn’t ūüôĀ

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

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

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 ūüôĀ

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 ūüôĀ

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 ūüôĀ ). 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.

  • 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 ūüėČ
  • 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 ūüôā
  • 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 ūüėČ
  • 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 ūüėĮ

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).

Women without men

The title of the post last week was The end is nigh which, looking at the fate of drones this week, was prophetic.

Shallow depth of field

Watch your back mate … !

After the ‘June gap’ ended queens started laying again with gusto. However, there are differences in the pattern of egg laying when compared to the late spring and early summer.

Inspections in mid/late August 1 show clear signs of colonies making preparations for the winter ahead.

For at least a month the amount of drone brood in colonies has been reducing (though the proportions do not change dramatically). As drones emerge the cells are being back-filled with nectar.

Seasonal production of sealed brood in Aberdeen, Scotland.

The data in the graph above was collected over 50 years ago 2. It remains equally valid today with the usual caveats about year-to-year variation, the influence of latitude and local climate.

Drones are valuable …

Drones are vital to the health of the colony.

Honey bees are polyandrous, meaning the queen mates with multiple males so increasing the genetic diversity of the resulting workers.

There are well documented associations between colony fitness and polyandry, including improvements in population growth, weight gain (foraging efficiency) and disease resistance.

The average number of drones mating with a queen is probably somewhere between 12 and 15 under real world conditions. However studies have shown that hyperpolyandry further enhances the benefits of polyandry. Instrumentally inseminated queens “mated” with 30 or 60 drones show greater numbers of brood per bee and reduced levels of¬†Varroa infestation.

Why don’t queens¬†always mate with 30-60 drones then?

Presumably this is a balance between access, predation and availability of drones. For example, more mating would likely necessitate a longer visit to a drone congregation area so increasing the chance of predation.

In addition, increasing the numbers of matings might necessitate increasing the number of drones available for mating 3.

… and expensive

But there’s a cost to increasing the numbers of drones.

Colonies already invest a huge amount in drone rearing. If you consider that this investment is for colony reproduction it is possible to make comparisons with the investment made in workers for reproduction i.e. the swarm that represents the reproductive unit of the colony.

Comparison of the numbers of workers or drones alone is insufficient. As the graph above shows, workers clearly outnumber drones. Remember that drones are significantly bigger than workers. In addition, some workers are not part of the ‘reproductive unit’ (the swarm).

A better comparison is between the dry weight of workers in a swarm and the drones produced by a colony during the season.

It’s worth noting that these comparisons must be made on colonies that make as many drones as they want. Many beekeepers artificially reduce the drone population by only providing worker foundation or culling drone brood (which I will return to later).

In natural colonies the dry weight of workers and drones involved in colony reproduction is just about 1:1 4.

Smaller numbers of drones are produced, but they are individually larger, live a bit longer and need to be fed through this entire period. That is a big investment.

Your days are numbered

And it’s an investment that is no longer needed once the swarming season is over. All those extra mouths that need feeding are a drain on the colony.

Even though the majority of beekeepers see the occasional drone in an overwintering colony, the vast majority of drones are ejected from the hive in late summer or early autumn.

About now in Fife.

In the video above you can see two drones being harassed and evicted. One flies off, the second drops to the ground.

As do many others.

There’s a small, sad pile of dead and dying drones outside the hive entrance at this time of the season. All perfectly normal and not something to worry about 5.

Drones are big, strong bees. These evictions are only possible because the workers have stopped feeding them and they are starved and consequently weakened.

A drone’s life … going out with a bang … or a whimper.

An expense that should be afforded

Some of the original data on colony sex ratios (and absolute numbers) comes from work conducted by Delia Allen in the early 1960’s.

Other colonies in these studies were treated to minimise the numbers of drones reared. Perhaps unexpectedly these colonies did not use the resources (pollen, nectar, bee bread, nurse bee time etc) to rear more worker bees.

In fact, drone-free or low-drone colonies produced more bees overall, a greater weight of bees overall and collected a bit more honey. This strongly suggests that colonies prevented from rearing drones are not able to operate at their maximum potential.

This has interesting implications for our understanding of how resources are divided between drone and worker brood production. It’s obviously not a single ‘pot’ divided according to the numbers of mouths to feed. Rather it suggests that there are independent ‘pots’ dedicated to drone or worker production.

Late season mating and preparations for winter

The summer honey is off and safely in buckets. Colonies are light and a bit lethargic. With little forage about (a bit of balsam and some fireweed perhaps) colonies now need some TLC to prepare them for the winter.

If there’s any reason to delay feeding it’s important that colonies are not allowed to starve. We had a week of bad weather in mid-August. One or two colonies became dangerously light and were given a kilogram of fondant to tide them over until the supers were off all colonies and feeding and treating could begin. I’ll deal with these important activities next week.

In the meantime there are still sufficient drones about to mate with late season queens. The artificial swarm from strong colony in the bee shed was left with a charged, sealed queen cell.

Going by the amount of pollen going in and the fanning workers at the entrance – see the slo-mo movie above – the queen is now mated and the colony will build up sufficiently to overwinter successfully.


Colophon

Men without Women

Men without women was the title of Ernest Hemingway’s second published collection of short stories. They are written in the characteristically pared back, slightly macho and bleak style that Hemingway was famous for.

Many of these stories have a rather unsatisfactory ending.

Not unlike the fate of many of the drones in our colonies.

Women without men is obviously a reworking of the Hemingway title which seemed appropriate considering the gender-balance of colonies going into the winter.

If I’d been restricted to writing using the title¬†Men without Women I’d probably have discussed the wasps that plague our picnics and hives at this time of the year. These are largely males, indulging in an orgy of late-season carbohydrate bingeing.

It doesn’t do them any good … they perish and the hibernating overwintering mated queens single-handedly start a new colony the following spring.

Droning on

This post was supposed to be about¬†Varroa resistance in¬†Apis mellifera – to follow the somewhat controversial ‘Leave and let die’ from a fortnight ago. However, pesky work commitments have prevented me doing it justice so it will have to wait for a future date.

All work and no play …

Instead I’m going to pose some questions (and provide some partial answers) on overwintering mites and the use of drone brood culling to help minimise mite levels early in the season.

Imagine the scenario

A poorly managed colony goes into the winter with very high mite levels. Let’s assume the beekeeper failed to apply a late summer/early autumn treatment early enough and then ignored the advice to treat again in midwinter when the colony is broodless.

Tut, tut …

The queen is laying fewer and fewer eggs as the days shorten and the temperature drops. There are decreasing amounts of the critical 5th instar larvae that the mite must infest to reproduce.

At some point the colony may actually be broodless.

What happens to the mites?

Do they just hang around as phoretic mites waiting for the queen to start laying again?

Presumably, because there is nowhere else they can go … but …

What about the need for nurses?

During the Varroa reproductive cycle newly emerged mites preferentially associate with nurse bees for ~6 days (usually quoted as 4-11 days) before infesting a new 5th instar larva.

Mites that associate with newly emerged bees or bees older than nurse bees exhibit reduced fecundity and fitness i.e. they produce fewer progeny and fewer mature progeny 1 per infested cell.

I’m not aware of studies showing the influence of the physiologically-distinct winter bees on mite fecundity.

Similarly, I’m not sure if there are any studies that have looked at the types of bees phoretic mites associate with during the winter 2, or the numbers of bees in the colony during November to January 3 that might be considered to be similar physiologically to nurse bees.

Whilst we (or at least I) don’t know the answer to these questions, I’m willing to bet – for reasons to be elaborated upon below – that during the winter the fecundity and fitness of mites decreases significantly.

And the number of the little blighters …

Mite longevity

How long does a mite live?

The usual figure quoted for adult female mites is 2-3 reproductive cycles (of ~17 days and ~11 days for the first and subsequent rounds respectively). So perhaps about 40 days in total.

But, in the absence of brood (or if brood is in very short supply) this is probably longer as there is data linking longevity to the number of completed reproductive cycles i.e. if there is no reproduction the mite can live longer.

It is therefore perhaps reasonable to assume that mites should be able to survive through a broodless period of several weeks during midwinter. However, remember that this increases the chance the mite will be removed by grooming or other physical contacts within the cluster, so reducing the overall population.

Spring has sprung

So, going back to the scenario we started with …

What happens in late winter/early spring when the queen starts laying again?

Does that 5cm patch of early worker brood get immediately inundated with hundreds of mites?

If so, the consequences for the early brood are dire. High levels of mite infestation inevitably mean exposure to a large amount of deformed wing virus (DWV) which likely will result in precisely the developmental deformities you’d expect … DWV really “does what it says on the tin”.

Worker bee with DWV symptoms

Worker bee with DWV symptoms

My hives are carefully managed to minimise mite levels. I don’t really have any personal experience to help answer the question. However, in colonies that have higher (or even high) mite levels I don’t think it’s usual to see significant numbers of damaged bees in the very earliest possible inspections of the season 4.

My (un)informed guess …

My guess is that several things probably happen to effectively reduce exposure of this earliest brood to Varroa:

  1. Varroa levels in the colony drop due to the extended winter phoretic phase. More opportunities for grooming or similar physical contact (perhaps even clustering) increase the loss of mites.
  2. Mites that remain may have reduced access to brood simply due to the mathematical chance of the bee they are phoretic on coming into contact with the very small numbers of late stage larvae in the colony.
  3. Mites that do infest brood have reduced fecundity and fitness and may not rear (m)any progeny.

There are a lot of assumptions and guesswork there. Some of these things may be known but discussions I’ve had with some of the leading¬†Varroa researchers suggest that there are still big gaps in our knowledge.

OK, enough droning on, what about drones?

Back to the imagined scenario.

What happens next?

Well, perhaps not next, but soon?

The colony continues to contract (because the daily loss of aged workers still outnumbers the daily gain of new bees) but the laying rate of the queen gradually increases from a few tens, to hundreds to a couple of thousand eggs per day.

And the colony starts to really expand.

And so do the mite numbers …

Pupa (blue) and mite (red) numbers

And at some point, depending upon the expansion rate, the climate and (probably) a host of factors I’ve not thought of or are not known, the colony begins to make early swarm preparations by starting to rear drones.

Drones take 24 days to develop from the egg and a further 12-16 days to reach sexual maturity. If the swarming period starts in the first fortnight of May, the drones that take part were laid as eggs in late March.

And drone larvae are very attractive to Varroa.

9 out of 10 mites prefer drones

Varroa replicates ‘better’ in association with drone pupae. By better I mean that more progeny are produced from each infested cell. This is because the drone replication cycle is longer than that of worker brood.

The replication cycle of Varroa

The replication cycle of Varroa

On average 2.2 new mites are produced in drone cells¬†vs only 1.3 in worker cells 5. From an evolutionary standpoint this is a significant selective pressure and it’s therefore unsurprising that Varroa have evolved to preferentially infest drone brood.

Irrespective of the mite levels, given the choice between worker and drone, Varroa will infest drone brood at 8-11 times the level of worker brood 6.

Significantly, as the amount of drone brood was reduced (typically it’s 5-15% of comb in the hive) the¬†drone cell preference increased by ~50% 7.

I hope you can see where this is now going …

Early drone brood sacrifice

As colony expansion segues into swarm preparation the queen lays small amounts of drone brood. These cells are a very small proportion of the overall brood in the colony but are disproportionately favoured by the mite population.

And the mite population – even in a poorly managed colony – should be less (and less fit) in the Spring than the preceding autumn for reasons elaborated upon above (with the caveat that some of that was informed guesswork).

Therefore, if you make sure you remove the earliest capped drone brood you should also remove a significant proportion of the viable mites in the colony.

Drone brood is usually around the periphery of the brood nest, along the bottom of frames with normal worker foundation, or on the ‘shoulders’ near the lugs. The drone brood is often scattered around the brood nest.

As a consequence, if you want to remove all the earliest capped drone brood you have to rummage through the frames and ‘fork out’ 8 little patches here and there.

It can be a bit of a mess.

Is there an easier way to do this?

Drone cells

Beekeepers who predominantly use foundationless frames will be aware that they usually have significantly more drones (and drone comb) in their colonies than equivalent sized colonies using embossed worker foundation.

Depending upon the type of foundationless frames used the drone comb is drawn out in different positions on the frames.

Horizontally wired foundationless frames can be all drone brood or a mix of drone and worker. However, the demarcation between the brood types is often inconveniently located with regard to support wires.

In contrast, foundationless frames constructed using vertical¬†bamboo supports are often built as ‘panels’ consisting entirely of drone¬†or worker comb.

Drone-worker-drone

Drone-worker-drone …

Which makes slicing out one or more complete panels of recently capped drone brood simplicity itself.

There are no wires in the way.

You can sometimes simply pull it off the starter strip.

Drone brood sacrifice

Check the brood for Varroa 9, feed the pupae to your chickens and/or melt out the wax in your steam wax extractor.

The bees will rapidly rebuild the comb and will not miss a few hundred drones.

They’ll be much healthier without the mites. Importantly, the mites will have been removed from the colony¬†early in the season so preventing them going through repeated rounds of reproduction.

This is the final part of the ‘midseason mite management‘ triptych 10, but I might return to the subject with some more thoughts in the future … for example, continuous culling of drone brood (in contrast to selective culling of the very earliest drone brood in the colony discussed here) is not a particularly effective way of suppressing mite levels in a colony.


 

 

 

 

 

Midseason mite management

The Varroa mite and the potpourri of viruses it transmits are probably the greatest threat to our bees. The number of mites in the colony increases during the spring and summer, feeding and breeding on sealed brood.

Pupa (blue) and mite (red) numbers

In early/mid autumn mite levels reach their peak as the laying rate of the queen decreases. Consequently the number of mites per pupa increases significantly. The bees that are reared at this time of year are the overwintering workers, physiologically-adapted to get the colony through the winter.

The protection of these developing overwintering bees is critical and explains why an early autumn application of a suitable miticide is recommended … or usually¬†essential.

And, although this might appear illogical, if you treat early enough to protect the winter bees you should also treat during a broodless period in midwinter. This is necessary because mite replication goes on into the autumn (while the colony continues to rear brood). If you omit the winter treatment the colony starts with a higher mite load the following season.

And you know what mites mean

Mites in midseason

Under certain circumstances mite levels can increase to dangerous levels 1 much earlier in the season than shown in the graph above.

What circumstances?

I can think of two major reasons 2. Firstly, if the colony starts the season with higher than desirable mite levels (this is why you treat midwinter). Secondly, if the mites are acquired by the colony from other colonies i.e. by infested bees drifting between colonies or by your bees robbing a mite infested colony.

Don’t underestimate the impact these events can have on mite levels. A strong colony robbing out a weak, heavily infested, collapsing colony can acquire dozens of mites a day.

The robbed colony may not be in your apiary. It could be a mile away across the fields in an apiary owned by a treatment-free 3 aficionado or from a pathogen-rich feral colony in the church tower.

How do you identify midseason mite problems?

You need to monitor mite levels, actively and/or passively. The latter includes periodic counts of mites that fall through an open mesh floor onto a Varroa board. The National Bee Unit has a handy Рthough not necessarily accurate Рcalculator to determine the total mite levels in the colony based on the Varroa drop.

Out, damn'd mite ...

Out, damn’d mite …

Don’t rely on the NBU calculator. A host of factors are likely to influence the natural¬†Varroa¬†drop. For example, if the laying rate of the queen is decreasing because there’s no nectar coming in there will be fewer larvae at the right stage to parasitise … consequently the natural drop (which originates from phoretic mites) will increase.

And vice versa.

Active monitoring includes uncapping drone brood or doing a sugar roll or alcohol wash to dislodge phoretic mites.

Overt disease

But in addition to looking for mites you should also keep a close eye on workers during routine inspections. If you see bees showing obvious signs of deformed wing virus (DWV) symptoms then you need to intervene to reduce mite levels.

High levels of DWV

High levels of DWV …

During our studies of DWV we have placed mite-free 4 colonies into a communal apiary. Infested drone cells were identified during routine uncapping within 2 weeks of our colony being introduced. Even more striking, symptomatic workers could be seen in the colony within 11 weeks.

Treatment options

Midseason mite management is more problematic than the late summer/early autumn and midwinter treatments.

Firstly, the colony will (or should) have good levels of sealed brood.

Secondly, there might be a nectar flow on and the colony is hopefully laden with supers.

The combination of these two factors is the issue.

If there is brood in the colony the majority (up to 90%) of mites will be hiding under the protective cappings feasting on sealed pupae.

Of course, exactly the same situation prevails in late summer/early autumn. This is why the majority of approved treatments – Apistan¬†(don’t), Apivar, Apiguard¬†etc. – need to be used for at least 4-6 weeks. This covers multiple brood cycles, so ensuring that the capped¬†Varroa are released and (hopefully) slaughtered.

Which brings us to the second problem. All of those named treatments should not be used when there is a flow on or when there are supers on the hive. This is to avoid tainting (contaminating) the honey.

And, if you think about it, there’s unlikely to be a 4-6 week window between early May and late August during which there is not a nectar flow.

MAQS

The only high-efficacy miticide approved for use when supers are present is MAQS 5.

The active ingredient in MAQS is formic acid which is the only miticide capable of penetrating the cappings to kill Varroa in sealed brood 6. Because MAQS penetrates the cappings the treatment window is only 7 days long.

I have not used MAQS and so cannot comment on its use. The reason I’ve not used it is because of the problems many beekeepers have reported with queen losses or increased bee mortality. The Veterinary Medicines Directorate MAQS¬†Summary of the product characteristics provides advice on how to avoid these problems.

Kill and cure isn’t the option I choose ūüėČ 7

Of course, many beekeepers have used MAQS without problems.

So, what other strategies are available?

Oxalic acid Api-Bioxal

Many beekeepers these days Рif you read the online forums Рwould recommend oxalic acid 8.

I’ve already discussed the oxalic acid-containing treatments extensively.

Importantly, these treatments only target phoretic mites, not those within capped cells.

Trickled oxalic acid is toxic to unsealed brood and so is a poor choice for a brood-rearing colony.

Varroa counts

In contrast, sublimated (vaporised) oxalic acid is tolerated well by the colony and does not harm open brood. Thomas Radetzki demonstrated it continued to be effective for about a week after administration, presumably due to its deposition on all internal surfaces of the hive. My daily mite counts of treated colonies support this conclusion.

Consequently beekeepers have empirically developed methods to treat brooding colonies multiple times with vaporised oxalic acid Api-Bioxal to kill mites released from capped cells.

The first method I’m aware of published for this was by¬†Hivemaker on the Beekeeping Forum. There may well be earlier reports. Hivemaker recommended three or four doses at five day intervals if there is brood present.

This works well 9 but is it compatible with supers on the hive and a honey flow?

What do you mean by compatible?

The VMD Api-Bioxal Summary of product characteristics 10 specifically states “Don‚Äôt treat hives with super in position or during honey flow”.

That is about as definitive as possible.

Another one for the extractor ...

Another one for the extractor …

Some vapoholics (correctly) would argue that honey naturally contains oxalic acid. Untreated honey contains variable amounts of oxalic acid; 8-119 mg/kg in one study 11 or up to 400 mg/kg in a large sample of Italian honeys according to Franco Mutinelli 12.

It should be noted that these levels are significantly less than many vegetables.

In addition, Thomas Radetzki demonstrated that oxalic acid levels in spring honey from OA vaporised colonies (the previous autumn) were not different from those in untreated colonies. 

Therefore surely¬†it’s OK to treat when the supers are present?

Absence of evidence is not evidence of absence

There are a few additional studies that have shown no marked rise in OA concentrations in honey post treatment. One of the problems with these studies is that the delay between treatment and honey testing is not clear and is often not stated 13.

Consider what the minimum potential delay between treatment and honey harvesting would be if it were allowed or recommended.

One day 14.

No one has (yet) tested OA concentrations in honey immediately following treatment, or the (presumable) decline in OA levels in the days, weeks and months after treatment. Is it linear over time? Does it flatline and then drop precipitously or does it drop precipitously and then remain at a very low (background) level?

Oxalic acid levels over time post treatment … it’s anyones guess

How does temperature influence this? What about colony strength and activity?

Frankly, without this information we’re just guessing.

Why risk it?

I try and produce the very best quality honey possible for friends, family and customers.

The last thing I would want to risk is inadvertently producing OA-contaminated honey.

Do I know what this tastes like? 15

No, and I’d prefer not to find out.

Formic acid and thymol have been shown to taint honey and my contention is that thorough studies to properly test this have yet to be conducted for oxalic acid.

Until they are – and unless they are statistically compelling – I will not treat colonies with supers present … and I think those that recommend you do are unwise.

What are the options?

Other than MAQS there are no treatments suitable for use when the honey supers are on. If there’s a good nectar flow and a mite-infested colony you have to make a judgement call.

Will the colony be seriously damaged if you delay treatment further?

Quite possibly.

Which is more valuable 16, the honey or the bees?

One option is to treat, hopefully save the colony and feed the honey back to the bees for winter (nothing wrong with this approach … make sure you label the supers clearly!).

Another approach might be to clear then remove the supers to another colony, then treat the original one.

However, if you choose to delay treatment consider the other colonies in your own or neighbouring apiaries. They are at risk as well.

Finally, prevention is better than cure. Timely application of an effective treatment in late summer and midwinter should be sufficient, particularly if all colonies in a geographic area are coordinately treated to minimise the impact of robbing and drifting.

I’ve got two more articles planned on midseason mite management for when the colony is broodless, or can be engineered to be broodless 17.


 

Ready, Steady … Wait

Since you are reading an internet beekeeping site you are probably aware of the discussion fora like Beesource, BBKA, the Beekeeping Forum and Beemaster Forum.

Several of these have a section for beginners. The idea is that the beginner posts a simple beekeeping question and, hey presto, gets a helpful answer.

Of course, the reality is somewhat different ūüėČ

The question might seem simple (“Should I start colony inspections this week?”), but the answers might well not be.

If there’s more than one answer they will, of course, be contradictory. The standard rule applies …

Opinions expressed = n + 1 (where n is the number of respondents 1)

… but these opinions will be interspersed with petty squabbles, rhetorical questions in return, veiled threats, comments about climate or location, blatant trolling and a long discourse on the benefits of native black bees/Buckfast/Carniolans or¬†Osmia bicornis 2

Finally the thread will peter out and the respondents move to another question …¬†“When should I put the first super on my hive?”

Climate and weather

Although it might not seem helpful at the time, the comment about climate and location refers to an important aspect of beekeeping often overlooked by beginners 3.

Climate and weather are related by time. Weather refers to the short term atmospheric conditions, whereas climate is the average of that weather.

Climate is what you expect, weather is what you get.

Climate and weather have a profound influence on our beekeeping.

We live on a small island bathed in warm water originating from the Gulf Stream. In addition, we are adjacent to a large land mass. The continent and the sea influence both our weather and climate.

For simplicity I’m going to only consider temperature and rainfall. The former influences the flowering period of plants and trees upon which the bees forage.

Mean annual temperature average 1981-2010

Mean annual temperature average 1981-2010

Both temperature and rainfall determine whether the bees can forage – if it’s too cold or wet they stay in the hive.

And adverse weather (strong winds, heavy rain) can make inspections an unpleasant experience for the bees … and the beekeeper 4.

Mean annual average rainfall 1981-2010

Mean annual average rainfall 1981-2010

The North – South divide (and the East – West divide)

Compare the mean temperature in Fife (marked with the red star) with Plymouth (blue star). The average annual temperature is 8-9¬įC in Fife and 10-11¬įC in Plymouth. Although this seems to be a very minor temperature difference it makes a huge difference to the beekeeping season 5.

As I write this (mid-April) I’ve yet to fully inspect a hive but colonies are swarming in the south of England, and have been for at least a week.

When I lived in the Midlands I would often start queen rearing in mid/late April 6 whereas here inspections might not begin until May in some years.

The 6¬į of latitude difference between Plymouth and Fife (~415 miles) is probably equivalent to 3-4 weeks in beekeeping terms.

In contrast to the oft-quoted view that ‘Scotland is wet’, Fife only gets about 66% of the rainfall of Plymouth (800-1000 mm for Fife¬†vs. 1250-1500 mm for Plymouth).

However, there is an East – West divide for rainfall in parts of the country. I’m writing this in Ardnamurchan, the most westerly point of mainland Britain (yellow arrow), where we get about three times the annual rainfall as the arid East coast of Fife.

The rhythm of the seasons

The seasonal duties of the beekeeper are dependent on the weather and the climate. This is because the development of the colony is influenced by how early and how warm the Spring was, how many good foraging days there were in summer, the availability of sunny 20¬įC days for queen mating and the warmth of the autumn for late brood rearing.

And a host of other weather-related things.

All of which vary depending where your bees live.

And vary from year to year.

Which is why it’s impossible to answer the apparently simple question When should I put the first super on my hive?” using a calendar.

“Beekeeping by numbers (or dates)” doesn’t work.

You have to learn the rhythm of the seasons.

Make a note of when early pollen (snowdrop, crocus, hazel, willow) becomes available, when the OSR and rosebay willowherb flowers and when migratory birds return 7. The obvious ones to record are flowers or trees that generate most honey for you, but early- and late-season cues are also useful.

Most useful are the seasonal occurrences that precede key events in the beekeeping year.

Link these together with the recent weather and the development of your colonies. By doing this you will begin to know what to expect and can prepare accordingly. 

If the OSR is just breaking bud 8 start piling the supers on. If cuckoos are first heard a month before the peak of the swarming period in your area make sure you prepare enough new frames for your preferred swarm control method.

And preparation is pretty-much all I’ve been doing so far this year … though I expect to conduct my first full inspections over the Easter weekend.

Degree days

While doing some background reading on climate when preparing this post I came across the concept of heating and cooling degree days. These are used by engineers involved in calculating the energy costs of heating or cooling buildings.

Heating degree days are a measure of how much (in degrees), and for how long (in days), the outside air temperature was below a certain level. 

Conversely, cooling degree days are a measure of how much (in degrees), and for how long (in days), the outside air temperature was above a certain level.

You can read lots more about degree days on the logically-named degreedays.net , which is where the definitions above originated.

From a beekeeping point of view you can use this sort of data to compare seasons or locations.

Most ‘degree days’ calculations use 15.5¬įC as the¬†certain level in the definitions above. This isn’t particularly relevant to beekeeping (but is if you are heating a building). However, degreedays.net (which have a bee on their BizEE Software Ltd. logo ūüôā ) can generate custom degree day information for any location with suitable weather data¬†and you can define the¬†level above or below which the calculation is based.

For convenience I chose 10¬įC. Much lower than this and foraging is limited.

The North – South divide (again)

So, let’s return to swarms in Plymouth and the absence of inspections in Fife … how can we explain this if the average annual temperate is only a couple of degrees different?

Heating and cooling degree days for Plymouth and Fife, April 2018 to March 2019

Heating and cooling degree days for Plymouth and Fife, April 2018 to March 2019

Focus on the dashed lines for the moment. September to November (months 9, 10 and 11) were very similar for both Plymouth (blue) and Fife (red). After that – unsurprisingly – the Fife winter is both colder and longer. From December through to March the Plymouth line rises later, rises less far and falls faster. In Plymouth the winter is less cold, is shorter and – as far as the bees are concerned – the season starts about a month earlier 9.

2018 in Fife was an excellent year for honey. After a cold winter (and the Beast from the East) colonies built up well and I harvested record amounts (for me) of both spring honey (in early June) and summer honey (in late July/early August).

I’ve no idea what 2018 was like for honey yields in Plymouth, but the cooling degree days (solid lines) show that it was warmer earlier, hotter overall and that the season lasted perhaps a month longer (though this tells us nothing about forage availability).

Of course it’s the longer, hotter summers and cooler, shorter winters that – averaged out – mean the average annual temperature difference between Plymouth and Fife is only a couple of degrees Centigrade.

Good years and bad years

As far as honey is concerned the last two years in Fife have been, respectively, sublime and ridiculous.

2018 was great and 2017 was catastrophic.

How do these look when plotted?

The 2017 and 2018 beekeeping season in Fife.

The 2017 and 2018 beekeeping season in Fife.

The onset of summer (solid lines – the cooling degree days – months 4-6) and the preceding winter (dashed lines – the heating degree days – months 9-11) were similar – the lines are nearly superimposed.

The 2016-17 winter was milder and shorter than 2017-18. The latter was extended by arrival of the Beast from the East and Storm Emma which brought blizzards in late February and continued unseasonably cold through March.

However, the harsh 2017-18 winter didn’t hold the bees back and the 2018 season brought bumper honey harvests.

In contrast, the 2017 season was hopeless. It was cooler overall, but the duration of the season was similar to the following year 10. Supers remained resolutely empty and my entire honey crop shared a single batch number ūüôĀ

However, it wasn’t the temperature that was the main problem. It was the abnormally high rainfall during June.

June 2017 rainfall anomaly from 1981-2010

June 2017 rainfall anomaly from 1981-2010 …

Colonies were unable to forage. Some needed feeding. Queen mating was very patchy, with several turning out as drone laying queens later in the season.

Early June 2017 ...

Early June 2017 …

The spring nectar flows were a washout and the colonies weren’t at full strength to exploit the July flows.

Let’s see what 2019 brings …


 

Spring starvation

A very brief post this week to highlight the dangers of unseasonably warm weather early in the season. February 2019 has entered the record books as the first ‘winter’ month in which the temperature exceeded 20¬įC (on at least the 25th and 26th¬†in the UK). It’s also been a record with the daily temperature (highs … we’ve had some hard frosts as well) exceeding the historic average daily temperature on almost every day of the month.

Fife temperatures, February 2019

Fife temperatures, February 2019

Even here in Fife on the East coast of Scotland, the weather has been very warm and sometimes even sunny. The graph above shows the daily maximum temperature compared to the monthly average (dashed line).

The contrast with this time last year is very striking. The big winter storm called Anticyclone Hartmut (aka the Beast from the East) arrived in the last week of February.

The Beast from the East ...

The Beast from the East …

We had six foot deep snow drifts blocking the road to the village and there wasn’t a bee to be seen.

Crocus and snowdrop

Fast forward exactly 12 months and the bees are piling in the pollen and flying well for an extended period. Around here this early pollen probably comes from crocus, snowdrop, hazel and alder, perhaps with a bit of gorse as well which flowers throughout the season.

Brood rearing will have started in earnest. The large amounts of pollen being collected is a pretty good indicator that all is well in the hive, that the queen is starting to ramp up her egg laying rate and the numbers of hungry larvae are increasing.

There’s no need to open the hive to check for brood. Indeed, hive inspections (here at least) are probably at least 6 weeks away.

However, don’t ignore the colonies. The increase in brood rearing is a time when stores levels can quickly get critically low. There’s not a huge range of nectar sources about at the moment and the combination of a warm spell, increasing amounts of brood and a subsequent deterioration in the weather can rapidly result in colonies starving.

Hefting or a sneak peak

If you’ve been regularly hefting the hive to check its weight you should have a reasonable ‘feel’ for what it should be, and whether it’s significantly lighter. More accurately, but also more trouble, you can use luggage scales to record the week-by-week reduction over the winter.

It’s possible to determine whether there are sufficient – or at least some – stores by looking through a perspex crownboard at the tops of the frames.

Emptied bag of fondant

Emptied bag of fondant

Many of my hives went into the winter with the remnants of the autumn-fed fondant still present on the top bars. With a perspex crownboard it’s a trivial task to check if these stores have been used and – if they have – to heft the hive to see if they need more.

Fondant topups

Several hives have already had a fondant topup of about a kilogram placed directly onto the top of the frames. Alternatively, the hives with the Gruyere-like Abelo crownboards 1 get a fondant block slapped directly over the hole above the most concentrated seams of bees.

Fondant absorbs moisture from the atmosphere so you need to protect the faces of the fondant block not accessed by the bees. There are all sorts of ways to do this. A strong plastic bag with a slot or flap cut in the bottom is more than adequate.

Better still is to dole out the fondant into plastic food containers you’ve diligently saved all year. These are reusable, come in a variety of sizes and – ideally – are transparent. You can then easily see when and if the bees need a further topup.

Time for another?

Time for another?

I usually slice up a block of fondant and fill these food containers in midwinter, wrap them in clingfilm and carry them around in the back of the car for my occasional apiary visits. If a hive needs more stores I remove the clingfilm and simply invert the container over the bees.

Do remove the clingfilm! Bees tend to chew it up and drag it down into the brood nest, often embedding it into brace comb. It can be a bit disruptive during cool weather early-season inspections to remove it … hence the suggestion to use a strong plastic bag earlier.

Continued vigilance

Most of my hives will have had at least a kilogram of fondant by the end of February this year. One or two are likely to have had significantly more. I’ll keep a note of these in my records as – all other things being equal – I’d prefer to have frugal bees that don’t need fussing with over the winter.

As the days get longer and the season continues to warm the queen will further increase her laying rate. Until there are both dependable foraging days and good levels of forage there remains the chance of starvation.

Colonies are much more likely to starve in early spring than in the middle of a hard winter. If the latter happens it’s either due to poor winter preparation or possibly disease. However, if they starve in early spring it is probably due to unseasonably warm weather, a lack of available forage, increasing levels of brood and a lack of vigilance by the beekeeper.

Don’t delay!

If a colony is worryingly light don’t wait for a warm sunny day to feed them. Adding a block of fondant as described above takes seconds.

Everynuc fondant topup

Everynuc fondant topup

If a colony needs stores add it as soon as possible.

If it’s cold the bees will be reasonably lethargic and you may not even need to smoke them. I’ve only fired up the smoker once … to topup a colony of psychotic monsters ‘on loan’ from a research collaborator who shall remain nameless.

I managed to add the fondant without using the smoker but they then chased me across the field to thank me ūüôĀ


 

Winter chores

After two weeks of mites, their diets and pedantry we’ll take a break this week for some practical beekeeping.

Or at least as close as you can get to practical beekeeping when it’s been as cold as -8¬įC.

Midwinter is a time to prepare for the season ahead, to stock up on new equipment during the winter sales, build more frames, plan the strategy for swarm control and think about stock improvement.

And – if you’re anything like as disorganised as me – it’s also the time to tidy up after the season just finished.

Which is what we’ll deal with today.

Tidy the shed

The original research apiary and bee shed is now under an access road for a new school. Fortunately, we managed to rescue the shed which has now been re-assembled in the new apiary.

In the longer term these sheds could together accommodate at least a dozen full colonies. However, in the shorter term it has allowed me to rationalise the storage, giving much more space to work with the colonies in the larger shed.

Supers and brood in the storage shed have all been tidied (see below) and are in labelled stacks ready to use. The other side of the store contains stacks of floors, split boards, clearers and roofs.

It’ll get messier as the season progresses, but it’s a good start.

I also spent a couple of weekends making some minor improvements to the bee shed following the experience last season.

The lighting has been increased and repositioned so it is ‘over the shoulder’ when doing inspections. On a dull winter day it is dazzlingly bright 1 but I fear it will still not be enough. I’m looking at creating some reflectors to direct the light better.

I’ve also used a few tubes of exterior sealant to block up all the holes and cracks around the edge of the shed roof. Last season was a bad one for wasps and we were plagued with the little stripy blighters.

Tidy the frames

Two of the most valuable resources a beekeeper has are drawn super frames and capped stores in brood frames.

Look after them!

I often end up uniting colonies late in the season, but then overwinter the bees in a single brood box. This means I can end up with spare frames of sealed stores. These should be protected from wax moth and mice (or anything else) as they are really useful the following year for boosting colonies that are light on stores or making up nucs.

Drawn supers can be used time and time again, year after year. They also need to be protected but – if your extraction is as chaotic as mine – they also usually need to be tidied up so they are ready for the following season.

I load my extractor to balance it properly, rather than just super by super. Inevitably this means the extracted frames are all mixed up. Since frames are also often drawn out unevenly this leaves me with a 250 piece jigsaw with billions of possible permutations, but only a few correct solutions.

Little and large - untidy frames and a breadknife

Little and large – untidy frames and a breadknife

And that’s ignoring all the frames with brace comb that accumulate during a good flow.

So, in midwinter I tidy up all the cleared super frames, levelling off the worst of the waviness with a sharp breadknife, removing the brace comb, scraping down the top bar and arranging them – 9 to 11 at a time 2 – in supers stored neatly in covered stacks.

And, if you’ve got a lot, label them so you know what’s where.

An hour or two of work on a dingy midwinter day can help avoid those irritating moments when – in the middle of a strong flow – you grab a super to find it contains just five ill-fitting frames, one of which has a broken lug.

The wax removed during this tidying up is usually lovely and white. Save it for making soaps, cosmetics or top-quality candles.

Wax extraction

Brood comb has a finite life. After about three years of repeated¬†brood rearing¬†cycles it should be replaced. Old comb contains relatively little wax but what’s there can be recovered using a solar or steam wax extractor. This also allows the cleaned frames to be re-used.

Processing a few dozen brood frames with a solar wax extractor during a Scottish winter is an exercise in futility. For years I’ve used a DIY steam wax extractor which worked pretty well but was starting to fall apart. I therefore recently took advantage of the winter sales and purchased a Thorne’s Easi-steam 3.

The Easi-steam works well and with a little further processing generates a few kilograms of wax for making firelighters or¬†trading in¬†… and a large stack of frames for re-use.

Remember to keep a few old dark brood frames aside for using in bait hives. 

Keep an eye on your bees

In between all these winter chores don’t forget to check on your bees.

There’s not a lot to do, but these checks are important.

Make sure the entrances are clear, that the mouse guards 4 are in place and that the roofs are secure.

Storm Eric brought us 50-60 mph winds and a couple of my¬†hives lost their roofs. These had survived a couple of previous storms, but the wind was from a different direction and lifted the roofs and the bricks stacked on top. I got to them the following day but we’ll have to wait until the season warms up to determine if there’s any harm done.

Fondant top up

Fondant top up

Finally, as the days lengthen and it gets marginally warmer colonies should have started rearing brood again. Make sure they have sufficient stores by regularly ‘hefting‘ the hive. If stores are low, top them up with a block or two of fondant. This should be placed directly over the cluster, either over a hole in the crownboard or on the top bars of the frames.


 

Mites equal viruses

Healthy bees are happy bees ūüôā

Sounds good doesn’t it?

Actually, there’s¬†no evidence that bees display or perceive most of the emotions often attributed to them 1.

Happy? Who knows? But certainly not healthy ...

Happy? Who knows? But certainly not healthy …

A more accurate statement might be¬†“Healthy¬†bees are more¬†productive, they are less likely to die overwinter, less likely to be robbed out by wasps or neighbouring strong colonies and their parasites and pathogens cannot threaten the health of other honey bee colonies or, through so-called-pathogen overspill, the health of other pollinators.”

More accurate?

Yes … but it doesn’t exactly trip off the tongue ūüėČ

Whether it makes the bees happy or not, beekeepers have a responsibility to look after the health of their livestock. This includes controlling Varroa numbers to reduce the levels of pathogenic viruses in the hive.

How well are virus levels controlled if mite levels are reduced?

I’ll get to that in due course …

Midwinter mite massacre

The 2018 autumn was relatively mild through until mid/late November. In the absence of very early frosts colonies continued rearing brood.

We opened colonies in mid-November (for work) and found sealed brood, though it was clear that the laying rate of the queen was much-reduced.

These are ideal conditions for residual mite replication. Any mites that escaped the late summer/early autumn treatment (the ideal time to treat to protect the overwintering bees) continue to replicate, resulting in the colony starting the following season with a disappointingly high level of mites.

I’ve noted before that midwinter mite levels are paradoxically¬†higher if you treat¬†early enough in the autumn to protect the all-important winter bees.

Consequently, to start the year with minimal mite levels, I treat in midwinter with a trickled or vaporised oxalic acid-containing (OA) treatment.

A combination of colder weather (hard frosts in late November) and brood temperature measurements 2 indicated mid-December was a good time to treat.

Midwinter mite massacre

Midwinter mite massacre

18th December

In one of my apiaries ten colonies were treated. Some were definitely broodless (based upon Arnia hive monitoring). Others may have had brood, but colonies were not routinely checked.

Over the four day period after vaporising these ten colonies dropped a total of 92 mites. More than 50% of these were from just one double-brooded colony. Overwintering nucs 3 dropped no mites at all in the 12 days following treatment.

This was very encouraging. These are lower midwinter mite levels than I’ve seen since returning to Scotland in 2015.

The one colony with ‘high’ mite levels received two further treatments (on the 22nd and 27th) in an attempt to minimise the mite levels for the start of the season. Going by the strength of the colony and the debris on the¬†Varroa¬†tray it was presumed that this colony was still rearing brood.

Mite drop following the third treatment was negligible 4.

Why are mite levels so low?

I think it’s a combination of:

  • Luck
  • Use of natural, organic, bee-centric and biodynamic beekeeping methods
  • Varroa-resistant bees
  • Very tight control of mite numbers in the 2017/18 season, primarily by correctly timing the¬†winter¬†and the late-season¬†autumn¬†treatments. This is simply good colony management. Anyone can achieve this.
  • A brood break midseason and/or a broodless period when splitting colonies (both give opportunities for more phoretic mites to be lost through grooming). Undoubtedly beneficial but season-dependent. I’ll be discussing ways to exploit these events in posts next year.
  • A low density of beekeepers in Fife, so relatively little¬†drifting or robbing¬†of poorly managed colonies from neighbouring apiaries. Geography-dependent. Much easier in Fife than Warwickshire … and easier still in Lochaber.

And what do less mites mean?

Varroa is a threat to bee health because it transmits pathogenic viruses when feeding on developing pupae.

The most important of these viruses is deformed wing virus (DWV).

Generally, the higher the level of infestation with mites, the higher the viral load 5. This has been repeatedly demonstrated by studies from researchers working in the UK, Europe and the USA.

It is well-established that colonies with high viral loads have an increased chance of dying overwinter, due to the decreased longevity of bees infected with high levels of virus.

DWV symptoms

DWV symptoms

In our work apiaries we regularly measure DWV levels. For routine screening our limit of detection is around 1,000 viruses per bee.

We don’t actually count the viruses. They’re too small to see without an electron microscope 6.

Instead, we quantify the amount of the virus genetic material present 7, compare it to a set of standards and express it as ‘genome equivalents (GE)’.

Many of the bees tested this year contained ~103 (i.e. 1000) GE, which is extremely low. Bees from Varroa-free regions (e.g. Colonsay) carry similar levels of DWV.

Most of our colonies were at or close to this level of virus much of the 2018 season. This is 100-1,000 times lower than we often see even in apparently perfectly healthy colonies in other years or other apiaries.

For comparison, using the same assay we usually detect about 1010 (ten billion) DWV GE per bee in symptomatic adult bees from heavily mite-infested colonies.

So, less mites means less viruses which means healthier bees ūüôā

And they might even be happier bees ūüėČ

And your point is?

It’s worth remembering that the purpose of treating a colony with miticides is to reduce the transmission of viruses between bees. This transmission results in the amplification of DWV. This is why the¬†timing of treatments is so important.

Yes, it’s always good to slaughter a few (or a few thousand ūüôā ) mites. However, far better massacre them when you need to protect particular populations of bees.

This includes the overwintering bees, raised in September, that get the colony through to the Spring.

Remember also that it ‘takes bees to make bees’¬†i.e.¬†the rearing of new brood requires bees. Therefore strong colony build-up in Spring requires healthy workers rearing healthy brood.

This is why it’s important to minimise mite levels in midwinter when colonies are broodless.

What do most beekeepers do?

Fifteen months ago I published a post on the preparation of oxalic acid solutions for trickling colonies in midwinter.

Whatever the vapoholics on the online forums claim, trickling remains the easiest, quickest and least expensive way to treat colonies in midwinter 8.

The best time to treat in the winter is when the colony is broodless. Here in Fife, and often elsewhere, I believe that this usually occurs¬†earlier in the winter than many beekeepers treat (if it happens at all … or if they treat at all).

I usually treat between the end of the third week in November and mid-December, at the end of the first extended cold period.

Oxalic acid preparation recipe page views

Oxalic acid preparation recipe page views

Looking at the page views for these oxalic acid recipes it looks as though many beekeepers treat after Christmas 9¬†… which may be suboptimal if colonies had a broodless period and now started rearing brood again.

Mine have.

This winter has been quite mild (at least at the time of writing) so there may yet be opportunities to treat really effectively during a broodless period.

Or the chance may have gone …


 

2018 in retrospect

How was 2018 for you?

It was a good year here in Fife, with more of everything; more snow, more colonies, more honey (much more honey ūüôā ), more sheds, more wasps, more swarms and more¬†dead¬†Varroa.

Actually, the ‘more dead mites’¬†isn’t quite correct¬†but I’ll return to that later.

The Beast from the East

There’s not much to say about the winter, but as we moved from February into March Storm Emma (also called the Beast from the East) arrived. The wind whipped the snow across the Howe of Fife (the largely flat centre of the county), dumping large drifts whenever it eddied over hedges or buildings. I had to dig us out of the house and the road from the village was impassable for 2-3 days.

The Beast from the East ...

The Beast from the East …

The colonies were all snug, if not warm, and weathered the storm without mishap. The reality is that if colonies are properly prepared for winter there’s almost nothing to do – or nothing you can do – until the weather picks up again in the Spring.

During the early part of the year I finished preparing our new bee shed. The bees were installed at the very end of March, soon followed by installation of a solar lighting system.

As I write this (early December 2018) the old apiary site has recently been bulldozed flat to make way for a new road. The contractors felled most of the beautiful trees in the well-established arboretum that surrounded the apiary.

All that’s left now is a muddy, ugly scar across the landscape waiting to be tarmac’d.¬†Every time I drive past the line from¬†The Last Resort by The Eagles, Some rich men¬†come and raped the land”, comes to mind.

That’s progress ūüôĀ

On a slightly brighter note, we did save the original shed and it’s recently been reassembled on the new apiary site. This will provide some much needed storage space. The new shed is bigger, but still a bit cramped when used for storage, work and bees.

In like a lion, out like a lamb

Well, almost. March continued cold but the weather had picked up by mid-April. I’d lost just two colonies in the winter, both due to failed queens. By the third week of April I’d started inspections 1 and colonies were all looking pretty good.

The weather got better and better, the oil seed rape (OSR) flowered and the bees started hammering it. Only one of my apiaries had OSR in range and they did really well.

Capped honey super frame ...

Capped honey super frame …

By the middle of June the OSR was over and the honey was all extracted.¬†The high glucose content of OSR nectar means it crystallises fast and very hard. It needs to be extracted before this happens in the frames. Some find OSR honey¬†rather bland¬†or¬†an acquired taste. However, I’ve just processed the first couple of buckets into soft set honey and it’s excellent on toast.

The June gap

In terms of beekeeping it was non-stop. June was frantically busy. Even before the the Spring honey was off the crowded colonies had started to make preparations for swarming.

Just as the bees were preparing to move house I was also busy moving into a new house. It was manic. As fast as I put split boards into colonies more queen cells would appear. I started to run out of frames and brood boxes. I managed to hold some colonies back by slicing out great slabs of drone comb. This takes just a few seconds using foundationless frames and gives the bees something to do rather than make swarm preparations.

And in between all this I was interminably packing, driving and unpacking rental vans doing my own move.

I know I lost a couple of swarms – from about 20 colonies in total 2 – which left me feeling a bit guilty. At least they left with very low¬†Varroa levels so, for a time at least, they would not contribute to the mite levels in the local environment. To ‘compensate’ for colonies that might establish themselves somewhere unwanted I donned my beesuit and destroyed a huge wasps nest in a neighbours roof space.

I also gratefully received a good-sized swarm in a bait hive.

The ‘June gap’ refers to the dearth of nectar that often occurs at this time of year. This year – despite excellent weather – was no exception. I didn’t feed colonies but many around me did. A few were a bit light but were OK until the summer flow started … which it did in late June or early July.

The flow must go on

Lime, blackberry, clover, rosebay willow herb and goodness knows what else. It was excellent. Coupled with continued good weather, hives got taller and taller as more supers were added. I ran out of supers altogether.

With lots of nectar and great weather for inspections it was my best beekeeping year since I moved back to Scotland.

Laden foragers returning ...

Laden foragers returning …

The good weather also aided queen mating which helped with requeening and preparing nucs for overwintering. About 75% of my colonies were requeened this year, almost all through splits of one type of another.

And then it was all over

The flow eventually stopped and the extraction was interminable. Not that I’m complaining. Super after super after super looked like this:

Ready to extract

Ready to extract …

Wasps were a big problem in late summer. I lost a queenless colony and a nuc to the stripey blighters. Amazingly I managed to save the queen from the nuc 3 and she’s now heading a strong colony through the winter.

After a fortnight or so tidying, stock-taking¬†(uniting colonies, cleaning cleared supers, making up a few additional nucs) and ‘final’ inspections it was time to start¬†Varroa treatment and feeding colonies up for winter.

I’ve deliberately finished the season with fewer colonies than I started, but with more overwintering nucleus colonies for sale or making up losses. The absence of a work/life balance means I want to reduce my personal colony numbers by about a third for the next couple of years (to ~10), with another 6-8 overwintering for work. I’ll still be busy ūüôĀ

Mite news

Mite levels have been extraordinarily low this season. For work we uncapped many hundreds to low thousands of individual pupae 4¬†and found no more than half a dozen mites all season. We’ve seen no evidence of DWV symptoms and irregular mite counts on the¬†Varroa trays have yielded very low numbers.

All colonies were treated by sublimation with an oxalic acid-containing treatment in early September, with three applications at five day intervals. The mite drop was so low (<200 from eight colonies in total in one apiary) that I was concerned that the treatment had failed. I therefore followed it up with Apivar strips in half the colonies. One or two additional dead mites appeared, but that was all.

So, not more dead Varroa, but probably a much greater proportion of the mite population were killed.

The Apiarist in 2018

This is the 300th post over the last five years. Yes, I’m surprised as well. I missed only one Friday when my hosting service was either not hosting or not providing a service ūüôĀ

A few weeks ago I moved the site to a cloud-based virtual server (Amazon LightSail) which, to me at least 5 appears faster and more stable. Processor load is 10% what it was and page response times seem much better. Tell me if it isn’t.

Unique visitor numbers and page reads continue to increase year on year with both up ~33% on last year. What is particularly reassuring is that articles I’ve written on disease management now feature as the most read over the course of the year (though several were written in previous years). The ‘top five’ are:

  1. When to treat? Рthe importance of correctly timing the early autumn Varroa treatment.
  2. Feeding fondant – quicker, easier and possibly better for the bees.
  3. Oxalic acid preparation – making Api-Bioxal solution properly for trickle treating.
  4. Vertical splits and making increase – manipulations for swarm control and expansion.
  5. Making soft set honey – making all that OSR honey look good and sell well.
"When to treat" monthly page views

“When to treat” monthly page views (5/2/16 to 13/12/18)

The composite page on ‘Equipment‘ also featured amongst this top five, but takes visitors off to all sorts of articles on bee sheds, DIY and hive reviews.

And the future …

This post is already too long. I’ve just checked and see I have 55 posts with working titles and scrawled notes in my drafts folder 6. That suggests there’s likely to be¬†something written next year.

Until then …¬†Happy New Year¬†


 

Know your enemy

What less appropriate time is there, as we enter the festive season of goodwill, to provide a brief account of the incestuous and disease-riddled life cycle of the Varroa mite?

Happy Christmas ūüôā

Scanning electron micrograph of Varroa destructor

Scanning electron micrograph of Varroa destructor

Varroa is the biggest enemy of bees, beekeepers and beekeeping. During the replication cycle the mite transfers a smorgasbord of viruses to developing pupae. One of these viruses, deformed wing virus (DWV), although well-tolerated in the absence of Varroa 1, replicates to devastatingly high levels and is pathogenic when transferred by the mite.

Without colony management methods to control Varroa, mite and virus replication will eventually kill the colony.

I’ve written extensively on ways to control¬†Varroa. Most of these have focused on early autumn and midwinter treatment regimes. However, next season I’m hoping to discuss some alternative strategies and will need to reference aspects of the life cycle of¬†Varroa … hence this post.

What is Varroa?

Varroa destructor is a distant relative of spiders, both being members of the class¬†Arachnida … the joint-legged invertebrates (arthropods). It was originally (and remains) an external parasite (ectoparasite) of¬†Apis cerana (the Eastern honey bee) and – following cross-species transfer a century or so ago –¬†Apis mellifera, ‘our’ Western honey bee.

Apis cerana, having co-evolved with Varroa, has a number of strategies to minimise the detrimental consequences of being parasitised by the mite.

Apis mellifera¬†doesn’t. Simple as that 2.

One hundred years is the blink of an eye in evolutionary terms and, whilst there are bees that have partial solutions – largely behavioural (small colonies and very swarmy) – they’re probably unable to collect meaningful amounts of honey 3.

Varroa-resistant honey bees will probably evolve (as much as anything is predictable in evolution) but not in my time as a beekeeper … or possibly not until Voyager 2 leaves the Oort Cloud¬†4.

And there’s no guarantee they’ll be any use whatsoever for beekeeping …

The replication cycle of Varroa

Varroa has no free-living stage during the life-cycle. The adult mated female mite exhibits two distinct phases during the life-cycle. It has a phoretic phase on adult bees and a reproductive phase within sealed (‘capped’) worker and drone brood cells. Male mites only ever exist within sealed brood cells.

I’m going to discuss phoretic mites in a separate post. I’ll concentrate here on the replication cycle.

The mated female mite enters a cell 15-50 hours before brood capping. Drone brood is chosen preferentially (at ~10-fold greater rates than worker brood) and entered earlier. Depending upon the time of the season and the levels of mites and brood, up to 70-90% of mites in the colony occupy capped cells.

The first egg is laid ~70 hours after cell capping. This egg is unfertilized and develops into a haploid male mite. Subsequent eggs are fertilised, diploid, and so develop into female mites. These are laid at ~30 hour intervals.

The replication cycle of Varroa

The replication cycle of Varroa

Worker and drone brood take different times to develop. Therefore a typical reproductive cycle involves five eggs being laid in worker brood and six in drone brood. Not all of these eggs mature, their development being curtailed by the bee emerging as an adult.

There are all sorts of developmental stages involved in getting from an egg to a mature unfertilised mite, but these are not important in terms of the overall outcome. Mite-geeks love this sort of detail 5, but we need to cut to the chase …

Keeping it in the family

The foundress ‘mother’ mite and her progeny all share a single feeding hole through the cuticle of the developing pupa.

What a lovely scene of family ‘togetherness’.¬†

Male and female mites take 6.6 and 5.8 days respectively to develop to sexual maturity. Therefore the male mite reaches sexual maturity before the first of his sisters.

He then lurks around the attractive-sounding “faecal accumulation site” and mates with each of the (sister) females in turn.

What a little charmer ūüėČ

Male mites are short lived and the eclosion of the adult worker or drone curtails further mating activity, releasing the foundress mite and the mated mature daughters 6.

Reproductive rate (mites per cell)

The three day difference in the duration of worker and drone development means that more mites are produced from drone cells than worker cells. Depending on conditions the reproductive rate is 1.3 – 1.45 in worker brood and 2.2 – 2.6 in drone brood.

Remember that the foundress is also released from the cell. She can go on to initiate one or two further reproductive cycles (or up to 7 in vitro). Consequently, the average yield of mature, mated female mites from worker and drone cells is a fraction over 2 and 3 respectively.

Before entering a fresh cell containing a late stage (5th instar) larva the newly-mated mites need to mature. They do this during the phoretic phase which lasts 5-11 days. Therefore the full replication cycle of the mite probably takes a minimum of about 17 days.

Exponential growth

Two to three mites per infested cell doesn’t sound very much. However, under ideal conditions this leads to exponential growth of the mite population in the colony. Assuming 10 reproductive cycles in 6 months, a single mite would generate a population of >1,000 in worker brood and >59,000 in drone brood 7.

Fortunately (for our bees, not for the mites), ideal conditions don’t actually occur in reality.

Lots of things contribute to the reduction in reproductive potential. For example, only 60% of male mites achieve sexual maturity due to developmental mortality, drone brood is only available at certain times in the season, brood breaks interrupt the availability of any suitable brood and grooming helps rid adult bees of phoretic mites.

Out, damn'd mite ...

Out, damn’d mite …

However, these reductions aren’t enough. Without proper management mite levels still reach dangerously high levels, threatening the long-term viability of the colony.

In the next few months I will discuss some additional opportunities for reducing the mite population.

In the meantime, as we reach the winter solstice, colonies in temperate regions may well be broodless and – as emphasised last week – this is an ideal time to apply a midwinter oxalic acid-containing treatment. This will effectively reduce mite levels for the start of the coming season.

Happy Christmas … unless you’re a mite ūüėČ


Colophon

Today is the¬†winter solstice in the Northern hemisphere. This is actually the precise¬†time when¬†the Earth’s Northern pole has its maximum tilt away from the Sun. However, the term is usually used for the day with the shortest period of daylight and the longest period of night.¬†In Fife, sunrise is at 08.44 and sunset at 15.37, meaning the day length is 6 hours and 53 minutes long.

With increasing day length queens will start laying again … but there’s a long way to go until winter is over.