Category Archives: Varroa control

Apivar (amitraz) resistance

Apivar is a widely used acaricide (a pesticide that kills mites and ticks) used to control Varroa.

The active ingredient of Apivar 1 is amitraz, a synthetic chemical discovered and developed almost 50 years ago.

Amitraz

Amitraz …

Amitraz has multiple molecular targets. I previously discussed the mechanism of action and summed it up with the words:

Essentially, amitraz binds and activates receptors that are critically important in a range of important aspects of the Varroa activity and behaviour … amitraz changes [this] behaviour and so exhibits miticidal activity. It has additional activities as well … these multiple routes of action may explain why resistance to amitraz is slow to develop.

I made the point in a subsequent post that amitraz resistance was very well documented … in cattle ticks 2 but that there was only anecdotal or incompletely documented evidence of resistance in Varroa in the USA, Argentina and Europe.

Apivar strip – fit and (don’t) forget

Amitraz has been used for mite control in honey bees for over twenty years. Considering its widespread use, the concentrations it is used at, and the relatively high replication rate of Varroa it is surprising that there has not been better evidence of resistance.

But that is no longer the case 🙁

Do you want the good news or the bad news first?

The bad news

A very recent paper 3 has clearly documented amitraz resistant Varroa in several commercial beekeeping operations in the USA.

I’ll discuss the key results of this paper first and then make some general comments on the implications for beekeepers and beekeeping.

The study had three components:

  1. Determine the sensitivity of Varroa never treated with amitraz to the chemical. This forms the baseline sensitivity against which field samples from commercial beekeepers could be tested.
  2. Screen Varroa from hives maintained by commercial beekeepers (with a multi-year history of Apivar usage) for amitraz resistance.
  3. Validate that the reduced efficacy of Apivar correlates with the observed amitraz resistance.

Essentially it involved harvesting live Varroa from colonies by a large-scale dusting with icing sugar 4. The Varroa were then tested to determine whether they showed resistance to amitraz, and the sensitivity was compared with the baseline sample of mites from colonies never treated.

Finally, an Apivar sensitivity test was conducted to determine the proportion of mites killed in a standardised assay in a set time period, again compared with the control (baseline sample).

The results of the study

You should refer to the paper for the primary data if needed.

Not all the apiaries tested yielded sufficient mites to screen for Apivar resistance. This is part of ‘the good news’ which I’ll get to shortly … but first the science.

Of those apiaries that did, Apivar resistance (determined by LC50 – the Lethal Concentration required to kill 50% of the mites) ranged from similar to that seen in the baseline samples to ~20-fold greater than the controls.

Two apiaries had an over 10-fold increase of the resistance ratio (the observed LC50 divided by the baseline LC50), with some individual colonies having high levels of Varroa infestation despite an active application of amitraz.

Apivar kills mites very quickly. Using a known number of mites trapped in a cage with a single small square of Apivar it is possible to ‘count the corpses’ and plot a kill curve over time. Sensitive mites from the control colonies were all killed within 3 hours.

Time course of Apivar efficacy in amitraz-susceptible Varroa

Using this as the baseline control it was then possible to determine the efficacy of Apivar in killing the mites (in the same 3 hour timeframe) from apiaries exhibiting resistance.

Apivar efficacy in commercial beekeeping apiaries.

Two apiaries (B and C, above) contained mites that exhibited high levels of resistance to Apivar, reflected in a low level of Apivar efficacy (above). In these apiaries, an average of less than 80% of mites were killed within the 3 hour assay.

Finally, the author demonstrated a correlation between Apivar efficacy and amitraz resistance. Unsurprising, but a necessary concluding point for the experimental data.

Within apiary variation

It was interesting that the author notes that the range of Apivar efficacy was much greater in colonies from apiaries with clear evidence of amitraz resistance.

For example, apiary B exhibited a range of Apivar efficacy in colonies from 28% to 97%, with an average (plotted above) of 68%. Whilst this is clearly an unacceptably low level, it is interesting that some of the colonies within the same apiary had mites killed at an efficacy similar or better (>90%) to apiaries A2 and A4 in the graph above.

I’ve re-plotted the primary data of Apivar efficacy vs. mite counts from individual colonies to emphasise this point.

Variation of Apivar efficacy vs mite infestation levels in individual colonies from commercial apiaries

Apiaries B and C (red markers) could be considered as ‘failing apiaries’ as the average Apivar efficacy of each was below 80% (see bar chart). Together the average mite load and Apivar efficacy for these two apiaries was 6.75 mites/100 bees and 72% respectively.

However, of the 16 colonies screened from these two apiaries (8 from each):

  • One colony had insufficient detectable mites to be included in the the full analysis.
  • Eight dropped less than 3 mites/100 bees during the sugar dusting analysis (the average over the 63 colonies screened was 5.33 mites/100 bees).
  • Four colonies exhibited ≥90% Apivar efficacy.
  • One colony from apiary B was a clear outlier, with >50 mites/100 bees ( 😯 ) and only ~28% Apivar efficacy. Inevitably this sample skews the averages …

Clearly the average figures presented in the bar chart above hides a very significant level of within-apiary variation.

Weird

I commented recently on the variation in mite levels during midwinter treatment of colonies with OA/Api-Bioxal. I attributed this – with little supporting evidence (!) – to different rates of late-season brood production. Colonies brooding late into the autumn were expected to have higher midwinter mite levels.

However, the variation seen here is different.

With the exception of that one heavily infested colony from apiary B, the mite levels in the ‘failing apiaries’ (B and C) are actually less than the average of the remainder of the study group (3.88 vs. 4.85).

What differs is the efficacy of Apivar treatment, not the resulting mite levels.

Frankly, this is a bit weird … on two counts:

  1. If Apivar treatment had been failing for a long time in apiaries B and C I would have expected much higher than average mite levels.
  2. Considering the amount of drifting and robbing that goes on between juxtaposed colonies I would have also expected Apivar-resistant mites to be very widely distributed within the ‘failing apiaries’.

Caveat on the mite counts – Apiaries in Louisiana, New York and South Dakota were analysed in this study. Louisiana apiaries were sampled in April, the others in July and August. I don’t know enough about the climate or mite-replication kinetics in these states to know how much this would have influenced the mite infestation levels (or prior or ongoing treatment regimes, which would also influence mite numbers). Unfortunately, the locations of the apiaries (A, B, C etc.) are not provided, other than the control apiary which is in Baton Rouge, LA. If the study had been done in the UK mite drops in April and August would have been wildly different depending upon the location.

Idle speculation

Apivar resistance does appear to have arisen in some of these colonies, but it does not appear to have become widely distributed within the apiary.

Why not?

I don’t actually think we have enough information to work with. The paper contains almost no additional background details – Apivar treatment history, use of other treatments, colony loss data etc.

But that won’t stop me speculating a little bit 😉

Do Apivar-resistant mites stop bees from drifting? Probably not, but it would explain why resistance was not widespread in the apiary 5.

More sensibly, perhaps Apivar resistance is detrimental in the absence of selection.

In the colonies in which resistance evolves it gives the mites a significant advantage. The ongoing infestation could encourage prolonged or repeated treatment, so selecting for yet more resistant mites. Eventually the colony succumbs to the resulting high viral load.

In other colonies, treatment is withdrawn (or forgotten … remember, we have zero information here!) and the Apivar-resistant mites are then at a disadvantage to their sisters.

This isn’t unheard of.

Apistan resistance appears to be detrimental in the absence of selection. There are some relatively straightforward molecular explanations for this type of phenotype.

You would have to assume differential colony treatments within apiaries B and C for this to be part of the explanation (and to account for drifting). Let’s hope the colony records are less shambolic than mine many beekeepers keep 😉

Until a clearer picture emerges of the management history of these colonies all we’re left with is the slightly (or very) confusing observation that Apivar resistance is a hive-specific phenomenon.

As the author states:

This colony level resolution suggests that each colony may act an island of resistance with its own distinct Varroa population. Beekeepers have reported inconsistency in amitraz treatment efficacy among colonies within an apiary and this variation seems to support those anecdotal observations.

And the good news?

I think there are two ‘encouraging’ observations in this paper (though of course I’d be happier if there was no resistance).

  1. About half of the commercial apiaries surveyed (5 of 11 that had a long history of Apivar usage) had too few mites detectable to screen for amitraz resistance. Clearly Apivar works, and often works very well indeed.
  2. Apivar resistance is not widespread in the apiaries within which it had arisen. For whatever reason, resistant mite populations appear restricted to individual colonies.

And these, in turn, have implications for practical beekeeping.

Implications for practical beekeeping

How does Apivar resistance evolve? Classically, misuse or overuse of treatments results in their eventual failure. Antibiotics are a good example of this.

I’ve been told by commercial beekeepers that some use a half dose of Apivar midseason to knock mite levels back sufficiently for the late season nectar flows. This is a typical example of misuse. It may not result in the development of resistance and it may not be a strategy used by the beefarmers managing apiaries B and C, but it is not the correct way to use Apivar.

What about overuse? Mites still dropping after 6 weeks of Apivar? Go on, slip another couple of strips in for another month or two. An (expensive) example of overuse.

Used Apivar strips

Or what about the Apivar strip found lying on the bottom of the hive at the first spring inspection? Again, overuse as there are likely to be lingering traces of Apivar present in the colony all winter 6.

So the first implication for practical beekeeping is to use Apivar correctly to help avoid the development of resistance. Don’t overdose or underdose, remove after 6-10 weeks, do not leave in over the winter.

Secondly, use alternate treatments to knock back the mite population. This is again a classic strategy to avoid selecting for resistance.

For example, use Apivar in late summer and Api-Bioxal in midwinter.

The mechanism of action of these two treatments is fundamentally different, so resistance to one will not confer resistance to the other (and there are no documented cases of oxalic acid resistance I’m aware of).

If you don’t treat midwinter (and you probably should 7) then use Apiguard one year and Apivar the next. Again, totally different mechanisms of action.

Finally, do not rely on individual colonies within an apiary being indicative of all colonies. I know some beekeepers who only conduct mite drop counts in one colony as a ‘sentinel’ 8.

If the drop is high then treatment is needed.

Or vice versa … no mites, so no treatment needed.

There’s a lot of colony to colony variation so it’s worth monitoring them all 9. And this is probably even more important with the colony level Apivar resistance reported in this paper.

Just something else to worry about … 🙁


 

Resolutions

It’s that time of the year again. The winter solstice is long passed. Christmas has been and gone. The New Year is here.

Happy New Year 🙂

And New Year is a time to make resolutions (a firm decision to do or not to do something).

There is a long history of making resolutions at the turn of the year. The Babylonians promised to pay their debts and return borrowed objects at their New Year. Of course, their year was based on a lunar calendar and started with the first crescent moon in March/April, but the principle was the same.

Many New Year’s resolutions have religious origins … though the more recent trend to resolve to “drink less alcohol” or “lose weight are somewhat more secular.

About 50% of people in the western world make New Year’s resolutions. This figure is up from ~25% in the 1930’s. Perhaps success increases uptake?

Popular resolutions include improvement to: health (stop smoking, get fit, lose weight), finance or career (reduce debt, get a better job, more education, save more), helpfulness (volunteer more, give more to charity) or self (be less grumpy, less stressed, more friendly) etc.

But since this is a beekeeping website it is perhaps logical to consider what resolutions would lead to improvements in our beekeeping.

Beekeeping resolutions

The short winter days and long, dark nights are an ideal time to develop all sorts of fanciful plans for the season ahead.

How often are these promptly forgotten in the stifling heat of a long June afternoon as your second colony swarms in front of you?

The beekeeping season starts slowly, but very quickly gathers pace. It doesn’t take long before there’s not enough time for what must be done, let alone what you’d like (or had planned) to do.

And then there are all those pesky ‘real life’ things like family holidays, mowing the lawn or visiting relatives etc. that get in the way of essential beekeeping.

So, if you are going to make beekeeping resolutions, it might be best to choose some that allow you to be more proactive rather than reactive. To anticipate what’s about to happen so you’re either ready for it, or can prevent it 1.

Keep better records

I’ve seen all sorts of very complex record keeping – spreadsheets, databases, “inspection to a page” notepads, audio and even video recordings.

Complex isn’t necessarily the same as ‘better’, though I’ve no doubt that proponents of each use them because they suit their particular type of beekeeping.

Objective and subjective notes

My notes are very straightforward. I want them to:

  • Be available. They are in the bee bag and so with me (back of the car, at home or in the apiary) all the time. If I need to refer to them I can 2. They are just printed sheets of A4 paper, stuffed into a plastic envelope. I usually write them up there and then unless I forget a pen, it’s raining and/or very windy or I’m doing detailed inspections of every colony in the apiary. In these cases I use a small dictation machine and transcribe them later that evening.
  • Keep track of colonies and queens. I record the key qualitative features that are important to me – health, temper, steadiness on the comb etc. – using a simple numerical scoring system. Added supers are recorded (+1, +1, -2 etc) and there’s a freeform section for an additional line or two of notes. Colonies and queens are uniquely numbered, so I know what I’m referring to even if I move them between apiaries, unite them or switch from a nuc box to a full hive.
  • Allow season-long comparisons ‘at a glance’. With just a line or two per inspection I can view a complete season on one page. Colonies consistently underperforming towards the bottom of the page usually end up being united in late August/early September.
  • Include seasonal or environmental jottingsMay 4th – first swift of the year”, “June 7th – OSR finished”, “no rain for a fortnight”. These are the notes that, over time, will help relate the status of the colony to the local environment and climate. If the house martins, swallows and swifts are late and it’s rained for a month then swarming will likely be delayed. Gradually I’m learning what to expect and when, so I’m better prepared.

Monitor mites

Varroa remains the near-certain threat that beekeepers have to deal with every season. But you can only deal with them properly if you have an idea of the level of infestation.

Varroa levels in the colony depend upon a number of factors including the rate of brood rearing, the proportion of drone to worker brood and the acquisition of exogenous mites (those acquired through the processes of drifting and robbing).

Pupa (blue) and mite (red) numbers

In turn, these factors vary from colony to colony and from season to season. As I discussed recently, adjacent colonies in the same apiary can have very different levels of mite infestation.

Additional variation can be introduced depending upon the genetically-determined grooming or hygienic activity of the colony, both of which rid the hive of mites.

Since the combined influence of these factors cannot be (easily or accurately) predicted it makes sense to monitor mite levels. If they are too high you can then intervene in a timely and appropriate manner.

Quick and effective ways to monitor mite levels

Any monitoring is better than none.

Easy counting ...

Easy counting …

There are a variety of ways of doing this, some more accurate than others:

  1. Place a Correx tray under the open mesh floor (OMF) and count the natural mite drop over a week or so. Stick the counts into the National Bee Unit’s (appropriately named) Varroa calculator and see what they advise. There are quite a few variables – drone brood amounts, length of season etc – that need to be taken into account and their recommendation comes with some caveats 3. But it’s a lot better than doing nothing.
  2. Uncap drone brood and count the percentage of pupae parasitised by mites. The NBU’s Varroa calculator can use these figures to determine the overall infestation level. The same caveats apply.
  3. Determine phoretic mite levels by performing a sugar roll or alcohol wash. A known number of workers (often ~300) are placed in a jar and the phoretic mites displaced using icing sugar or alcohol (car screenwash is often used). After filtering the sugar or alcohol the mites can be counted. Sugar-treated bees can be returned to the colony 4. Infestation levels of 2-3% (depending upon the time of season) indicate that intervention is required 5.

Does what it says on the tin.

Overwinter nucs

If you keep livestock you can expect dead stock.

Unfortunately colony losses are an inevitability of beekeeping.

They occur through disease, queen failure and simple accidents.

Most losses are avoidable:

  • Monitor mites and intervene before virus levels threaten survival of the colony.
  • Check regularly for poorly mated or failing queens (drone layers) and unite the colony before it dwindles or is targeted by wasps or other robbers.
  • Make sure you close the apiary gate to prevent stock getting in and tipping over hives … or any number of other (D’oh! Slaps forehead 🙄 ) beekeeper-mediated accidents).

But they will occur.

Corpses

Corpses …

And most will occur overwinter. This means that as the new season starts you might be missing one or two hives.

Which could be all of your colonies if you only have a two 6.

Replacing these in April/May is both expensive and too late to ensure a spring honey crop.

Winter colony losses are the gift that keeps on giving taking.

However, if you overwinter an additional 10-25% of your colonies as 5 frame nucs (with a minimum of one), you can easily avoid disaster.

Here's one I prepared earlier

Here’s one I prepared earlier

If you lose a colony you can quickly expand the nuc to a full hive (usually well before a commercially-purchased colony would be ready … or perhaps even available).

And if you don’t lose a colony you can sell the nuc or expand your colony numbers.

Sustainable beekeeping

If you’ve not watched Michael Palmer’s The Sustainable Apiary at the National Honey Show I can recommend it as an entertaining and informative hour for a winter evening.

Michael keeps bees in Vermont … a different country and climate to those of us in the UK. However, his principles of sustainable beekeeping without reliance on bought-in colonies is equally valid.

Overwintering nucs requires a small investment of time and money. The former in providing a little more care and attention in preparation for winter, and the latter in good quality nucleus hives.

I reviewed a range of nuc boxes six years ago. Several of these models have been discontinued or revised, but the general design features to look for remain unchanged.

Here's three I prepared earlier ...

Everynuc poly nucs

Buy dense poly nucs for insulation, make sure the roof isn’t too thin and flimsy and choose one with an entrance that can be readily reduced to a “bee width” 7. Choice (and quality) has improved over the last 5-6 years but I still almost exclusively use Thorne’s Everynuc. I bought 20 a few seasons ago and remain pleased with them, despite a few design weaknesses.

Beekeeping benefits

I do all of the above.

Having learned (often the hard way) that my beekeeping benefits, these habits are now ingrained.

I had about 20 colonies going into the 2019/20 winter, including ~20% nucs. All continue to look good, but it won’t be until late April that I’ll know what my winter losses are.

In the meantime I can review the hive notes from last season and plan for 2020. Some colonies are overwintering with very substandard queens (generally poor temper) because they’re research colonies being monitored for changes in the virus population 8. They will all be requeened or united by mid/late May.

My notes mean I can plan my queen rearing and identify the colonies for requeening. I know which colonies can be used to source larvae from and which will likely be the cell raisers. The timing of all this will be influenced by the state of the colonies and the environmental ‘clues’ I’ve noted in previous years.

Capped queen cells

Capped queen cells

Of course, things might go awry before then, but at least I have a plan to revise rather than making it up on the spur of the moment.

I learned the importance of mite monitoring the hard way. Colonies unexpectedly crashing in early autumn, captured swarms riddled with mites that were then generously distributed to others in the same apiary. Monitoring involves little effort, 2-3 times a season.

So these three things don’t need to be on my New Year’s resolution list.

Be resolute

More people make New Year’s resolutions now than 90 years ago.

However, increasing participation unfortunately does not mean that they are a successful way to achieve your goals.

Richard Wiseman showed that only 12% of those surveyed achieved their goal(s) despite over 50% being confident of doing so at the beginning of the year.

Interestingly, success in males and females was influenced by different things. For men, incremental goal-setting increased the success rate 9 (I will write hive notes on every apiary visit, rather than Keep better notes). For women, the peer pressure resulting from telling friends and family increased success by 10%.

More generally, increased success in achieving the goals resulted from:

  • Making only one New Year’s resolution – so perhaps the three things above is overly ambitious?
  • Setting specific goals and avoiding resolutions you’re previously failed at.

My New Year’s (beekeeping) resolutions?

Since I’m a man, the chance of achieving my goals is not influenced by peer pressure so I’m not publishing them. We’ll have to see in 12 months whether I’m in the 12% that succeed … or the 88% that fail 😉


 

2019 in retrospect

The winter solstice, the shortest day of the year, is tomorrow. It will be a long time until there’s any active beekeeping, but at least the days are getting longer again 🙂 

The queens in your colonies will soon – or may already – be laying again.

What better time to look back over the past season? How did the bees do? How did you do as a beekeeper? What could be done better next time?

Were there any catastrophic errors that really must not be repeated?

Overview of the season

Overall, in my part of Scotland, it was about average.

But that, of course, obscures all sorts of detail.

Spring was warm and swarming started early. I hived my first swarm before the end of April and my last in early July. This is about twice the length of the usual swarming season I’ve come to expect in Scotland. However, it wasn’t all frantic swarm management as there was a prolonged ‘June gap’ during which colonies were much more subdued.

The summer nectar, particularly the lime, was helped by some rain, but the season was effectively over by mid-August. I don’t take my colonies to the heather. Overall, the honey crop was 50-60% that of the (exceptional) 2018 season.

Looking at the yields from different apiaries for spring and summer it’s clear that – despite the warm spring – colonies did less well on the early season nectar (~40% that of 2018). I suspect this is due to their being less oil seed rape (OSR) grown within range of my apiaries. The colonies were strong, but the OSR just wasn’t close enough to be fully exploited..

Over recent years the area of OSR grown has reduced, a trend that is likely to continue.

Winter oil seed rape – the potential is not obvious

The winter rape is already sitting soggily in the fields; I’ve chatted to a couple of the local farmers and will move some hives onto these fields if colonies are strong enough and the weather looks promising.

Bait hives

Every year I’ve been back in Scotland I’ve put a bait hive in the garden.

Every year it has attracted a swarm.

This year – with the extended swarming season – it led to the capture of three swarms in about 10 days. As the June gap ended the weather got quite hot and sultry 1 and the first swarm arrived near the end of that month.

One week after the first swarm arrived there was lots more scout bee activity. There were also quite a few dead or dying bees littering the ground underneath the bait hive. It turned out that these were the walking wounded (or worse) scout bees from two different hives fighting.

Gone but not forgotten

Within 48 hours another swarm arrived and I was fortunate enough to watch it descend.

Incoming!

I moved the hive that evening, placing another bait hive on the same spot. By the following morning there were yet more scout bees checking the entrance and a third swarm – by far the biggest of the three – arrived later that day.

Each was a prime swarm and none were from my own hives which are in the only apiary 2 within a mile of the bait hive.

Watching the scout bees check out a bait hive is always interesting. There’s a fuller account of the observations and lessons learnt – of which there were several – written in the post titled BOGOF (buy one get one free 😉 ).

Swarm prevention

My swarm prevention this year either used the nucleus method or vertical splits (with an occasional Demaree for good measure) for most hives. All prevented the loss of swarms and queen mating went about as well – or badly – as it usually does i.e. never as fast as I’d like, but (eventually) all were successful.

Split board

Split board …

I did miss a couple of swarms. One relocated underneath the OMF of the hive it originated from because the queen was clipped and, having fallen ignominiously to the ground, she just clambered up the hive stand again.

The second swarm was also not lost as I inadvertently trapped the queen on the wrong side of the queen excluder. D’oh! In my defence, I’ve had a rather busy year at work 3 and it’s little short of a miracle that I got any beekeeping – let alone swarm control – done at all.

Mites

Considering the extended June gap, which resulted in a brood break for some colonies, mite levels were appreciably higher this year than last. I think this can largely be attributed to the warm Spring which allowed colonies to build up fast. Several colonies were strong enough to swarm in late April.

I do a limited amount of mite counting during the season but also monitor virus loads in emerging bees in our research colonies. In most colonies these stayed resolutely low and no production colonies needed any mid-season interventions for mite control.

Poly Varroa tray from Thorne's Everynuc with visible mites.

Gotcha! …

Newly-arrived swarms were treated as were some broodless splits. The former because many swarms carry a larger than expected mite population 4 and the latter because it’s an ideal opportunity to target mites as – in the absence of brood – all will be phoretic.

All colonies were treated with Apivar immediately after the summer honey came off. At the same time they were fed copious amount of fondant in preparation for the winter ahead.

In late November most colonies were broodless and were treated with a vaporised OA-containing miticide.

What worked well

In what was a pretty tough year for non-beekeeping reasons even small beekeeping successes have assumed a significance out of all proportion to the effort expended on them.

In my first year or two of beekeeping honey extraction was an unbridled pleasure. As hive numbers increased it because more of a chore. An electric extractor marginally improved things.

However, there was still the never-ending juggling of frames trying to balance the extractor and jiggling of the unbalanced machine as it sashayed across the floor.

Rubber-wheeled castor with brake

Two years ago I purchased some rubber braked wheels to add to the extractor legs.

This year I finally got round to fitting them.

The jiggle-free revolutions were a revelation 🙂

I know some beekeepers who stand their extractors on foam pads. Others who have them bolted to a triangular wooden platform. I can’t imagine either solution works better than these castors, which also make moving the extractor to and from storage much easier.

I changed my hive numbering system this season. I’d previously referred to hives by position or with a number written on the box. This caused some issues with the (sometimes shambolic) way I do my beekeeping.

If the hive moves and it’s numbered by position then its number should change. Manageable, but a bit of a pain.

If the position does not change but they’re expanded from a nuc to a full brood box do they get a new number or retain the old one? A problem if it’s written on the box.

And what happens when you move queens about in the apiary (which we sometimes need to do for work)?

Numbers for hives and queens

Numbers for hives and queens

All hives and queens were assigned a number – small red discs for the queen and big, bold numbers for the box. They stay with the colony or the queen … and the records 😉

This has worked very well. As colonies expand the numbers move, if queens are moved I know from and to where (and keep a separate record of queen performance). When colonies are united the queenless component loses both the queen number and the colony number.

The numbering has been a great success. The numbers themselves less so. Most of the red discs have faded very badly and a few of the hive numbers have cracked and/or blown away.

Numbered nuc and production colonies.

Never mind … the system works as intended and it has significantly improved my record keeping. I now know which hive and queen I’m referring to 😉

The Apiarist in 2019

I might squeeze in a more thorough overview of funny search terms and page accesses before the New Year. Briefly … there are significantly more subscribers and an increase of ~20% in overall page reads.

This year marks the sixth full season of The Apiarist which still surprises me. There still seem to be things to write about. Post length continues to increase, though the overall number of posts remain almost exactly one a week. Amazingly I’ve written nearly 95,000 words this year.

Words, words, words …

We had some server issues but most of these appear to have been resolved. Spam remains a problem and the machine auto-filters several hundred messages a day to keep my inbox only unmanageably overflowing. It has meant I’ve had to add some “I am not a robot” CAPTCHA trickery to the contact and/or comment forms. I’m aware that this has caused some problems making contact but can’t find an alternative solution that doesn’t swamp me in adverts for fake sunglasses, Bitcoins or Russian brides.

I live in Scotland and have no use for any of these things 😉 5

The year ahead

There are three main items on the ‘to do’ list for 2020 6.

The first is to start queen rearing again. Pressure of work has prevented this from happening over the last couple of seasons and I’m missing both the huge satisfaction it brings and the improved control over stock improvement. I’ve done lots of queen rearing in the past, but work has muscled its way in to too many weekends and evenings recently 7.

3 day old QCs ...

3 day old QCs …

I now have some perfectly adequate bees.

Actually, although they’re far from ‘perfect’ they are also far better than ‘adequate’.

I’ve got a couple of lines that have too much chalkbrood and almost all of them are less stable on the comb than I’d like. They don’t fall in wriggling gloops off the corner of the frame as some do, but they’re more active than I’d prefer. It’s a trait that has crept into some stocks over the last couple of years and I need to try and get rid of it.

The second is to provide better information on the provenance of my honey to potential and actual purchasers. There’s increasing interest in sourcing high quality local food and, as I’ve discussed recently on honey pricing, we should be aiming to provide a premium product (at a premium price 😉 ). The public are also increasingly aware that some of the major supermarkets have been reported to be selling adulterated honey. Providing details of the batch, the apiary and the area in which it was produced should help define it as a quality local product.

And generate repeat business.

Local honey

Finally, I’m planting up a new apiary on the west coast with dozens of pollen-bearing trees before I start beekeeping there. This has been a long and protracted process as it has involved clearing large areas of invasive rhododendron. The first 125+ native trees go in this winter – a mix of alder, loads of willow, hazel, blackthorn and wild cherry. More will follow if I manage to stop the deer eating them all.

Only another few acres of rhododendron to clear 🙁

The new apiary is in a Varroa-free region so I will not be moving my current bees there, but instead sourcing them from other areas fortunate enough to be mite-free. This is a long-term project.

Bee shed #3 … bigger and better.

The trees will need a few years to mature but the bee shed (bigger than all that have gone before 🙂 ) foundations are finished and the shed will be assembled sometime in March.

Holibobs

The holiday period is almost here. Many beekeepers will be thinking about fondant top-ups and oxalic acid mite treatment. I’ve done the latter already and – if your colonies are also broodless – hope you’ve done the same. All my hives remain reassuringly heavy but as the weather warms and brood rearing gears up I’ll have some fondant ready ‘just in case’.

I’ve covered last-minute beekeeping gifts in previous years. I think the (digital edition) American Bee Journal remains good value and provides a different perspective for UK beekeepers of what happens in the US.

And with that I’ll pour another glass of mead red wine 8 and wish you all Happy Christmas/Holidays (delete as appropriate).

David


 

Rinse and repeat

Midwinter mite treatment is no substitute for a properly applied late summer treatment that protects your all important winter bees. However, you also need to control mites in the winter or there is a good chance their numbers will reach damaging levels the following season 1.

Mid September

Late summer treatment and no winter treatment – mite levels in red.

OA (oxalic acid-containing) treatments are the ones to use in midwinter (e.g. Api-Bioxal). These can be trickled in syrup onto each seam of bees or they can be vaporised (sublimated), effectively coating everything in the hive with a very fine dusting of crystals.

Trickling damages open brood whereas sublimation is exceedingly well-tolerated by the colony.

If you are certain the colony is broodless then trickling is faster 2 and – because you don’t need power or any more PPE 3 than a pair of gloves – much easier.

If the ambient temperature is consistently below ~6°C and I know the colony is broodless I usually trickle. If the temperature is higher and/or I’m uncertain about whether there is brood present I usually vaporise.

I watch the weather and treat after the first prolonged cold spell of the winter.

Experience over the last few years suggests this is when colonies are most likely to be broodless.

Most likely is not the same as certain 🙁

Count the corpses

After treating I closely monitor the mite drop over several days. I use white Correx Varroa trays that slide underneath the open mesh of my kewl floors.

Easy counting ...

Easy counting …

I don’t count the mites every day, but I do try and count the day after treatment and 2-4 days later. I record the mite drop per hive and, over time, look for two things:

  1. The cumulative mite drop. This indicates the original infestation level of the hive. Usually it’s in the range 10-75 mites (total) for my colonies in midwinter, but – as you’ll see – it can be much higher.
  2. The speed with which the daily mite drop falls to a low single-digit average. OA treatment is very effective at killing phoretic mites. If there’s a continuing high level of mite drop it suggests that more are getting exposed over time.

In my experience, vaporised OA often results in a greater mite drop 24-48 hours post-treatment rather than in the first 24 hours 4. After that I expect (hope) the daily mite drop tails off very quickly.

Vaporised OA remains effective in the hive for several days. Randy Oliver reports studies by Radetzki who claims it remains effective for up to three weeks. I think this is an overestimate but I’m sure it continues working well for four to five days.

OA, whether vaporised or trickled, on broodless colonies is 90-95% effective i.e. if there were 100 mites in the colony you should expect as few as 5 remain after treatment.

Four to five days after the initial treatment I eyeball the numbers across all the hives in an apiary and look at the profile of the mite drop.

Mite drop profiles

I couldn’t think of a better term for this. Essentially, it’s the shape of a graph of mites dropped per day after treatment.

I don’t usually draw the graph – I have a life – but I do look carefully at the numbers.

Here are a couple of sketched graphs showing what I mean. Days are on the horizontal (X) axis, dead mites per day are on the vertical (Y) axis. Treatment applied on day 0. No count (yet) on day 6.

Mite drop profile – this is what you want

In the graph above there are high(er) levels of dropped mites on the first day or two after treatment, but levels thereafter drop to a basal level of perhaps 1-4 mites per day.

Each time I count the mites I clean the Varroa tray (the rinse in the title of the post).

Assuming the day 5 mite drop is very low, the profile above is what I’m looking for. It shows that treatment has worked and no repeat is necessary.

The profile below is much less promising 5.

Mite drop profile – this suggests additional treatment is needed

In this graph (above) the mite drop remains high every day after treatment. Sometimes they even increase over time.

If you assume treatment is equally effective – say 90%+ – on the five days after treatment 6 this must mean that there are mites being killed on days 4 and 5 that were not exposed to treatment on the earlier days.

How can this be?

The most likely explanation is that the colony had some sealed brood that has emerged in the days following treatment, exposing previously ‘hidden’ mites to the miticide.

It’s good that they’ve perished, but are there more hiding? How do you tell?

Enough of my hand drawn idealised graphs with no real numbers … what about some actual data?

Real world data

The graph below shows data for seven colonies in a single apiary. All were treated with Apivar in late summer. All were treated with a vaporised oxalic acid-containing treatment on the 28th of November. 

Mite drop profiles – real world data

I counted the mite drops on the 29th (T+1), the 2nd (T+4) and 3rd (T+5). The figures for 30th to the 2nd were averaged, which is why the bars are all the same height.

  • Colonies 3 and 6 had very low mite levels. Though not the lowest in the apiary 🙂
  • Colonies 2 and 7 had pretty good mite drop profiles, with low single-digit numbers on day T+5. None of these four colonies (2, 3, 6, 7) need treating again.
  • Colonies 1 and 5 have high mite levels 7 and – despite the pretty good levels on T+5 in colony 1 – were both re-treated.
  • Colony 4 was also treated again as the profile was flat and I suspected they had low levels of mites but were rearing brood..

And repeat

Note: The instructions for Api-Bioxal specifically state that the maximal dose of 2.3g/hive should be made in a single administrations with only one treatment per yearPrior to the VMD licensing and approval of Api-Bioxal there was effectively tacit approval for beekeepers to use unadulterated oxalic acid by trickling or vaporisation, without any particular limitations on frequency of usage.

It’s worth stressing that you should not repeat oxalic acid trickling 8.

Here is some real data for repeat treatments of another colony in the same apiary.

Repeat treatment for brood-rearing colony

The average mite drop per day over the first 5 days was ~60. This justified an additional treatment. Over the next 6 days 9 the average drop was ~20. I considered a third application was needed after which the mite drop per day was in the low single digits.

And again

Repeated treatment is needed if there is sealed brood in the colony.

The likelihood is that two additional treatments will be required.

Why two?

Here’s a reminder of the development cycle of the Varroa mite in developing worker or drone brood.

Repeated oxalic acid vaporisation treatment regime.

Worker brood occupies capped cells for 12 days (days 10 – 21 of development, shown above). Vaporised oxalic acid-containing treatments show a drop in efficacy after 4-5 days 10.

Therefore, to cover a complete cycle of capped brood, you need 3 x 5 day treatments to be sure no mites emerge without them being greeted with a lethal dose of something really, really unpleasant 😉

There should be no drone brood in your winter hives 11 but, if there was, 3 x 5 day treatments should just be enough to cover the complete cycle of capped drone brood as well. However, a fourth treatment might be needed.

Note (again): The instructions for Api-Bioxal specifically state that the maximal dose of 2.3g/hive should be made in a single administrations with only one treatment per year

Not all hives are equal

There are 15 hives in the apiary containing the bee shed. Colony 1 had just about the highest mite levels. However, as shown in one of the graphs above, adjacent colonies can have markedly different mite levels.

There is no clear correlation between mite drop after treatment and colony size. Colony 1 is a double brood monster, but the others in the bee shed are all single brood 10 and 11 frame Nationals 12.

Some colonies need repeated treatment, others did not.

To maximise efficient treatment and minimise unnecessary miticide usage it is necessary to monitor all the colonies.

It’s also worth noting that monitoring only a single hive in an apiary may be misleading; compare colonies 1 and 6 above in the graph of real data from the bee shed.

This monitoring takes just a few minutes. I usually do it after work. In the bee shed this is easy as I now have LED lighting and it’s nice and dry.

Easy conditions to count mites

In my out apiaries I have to do it by headtorch … under an umbrella if it’s raining 🙁

Checking mite drop by torchlight

That’s the last job of the winter completed … time now to review the season just gone and plan for next year.


Colophon

Rinse and repeat

Rinse and repeat is a truncation of instructions often found on the side of shampoo bottles – Lather, rinse and repeat. Other than potentially resulting in an endless loop of hair washing, it also means that a process is (or needs to be) repeated.

In The Plagiarist by Benjamin Cheever, a marketing executive becomes an industry legend by adding one word – REPEAT – to shampoo bottles. He doubles sales overnight.

For Varroa treatment the instructions should be amended to Repeat if necessary … and note again the instructions on Api-Bioxal which, at the time of writing, is the only oxalic-acid containing VMD approved miticide that can be administered by vaporisation.

 

Midwinter, no; mites, yes

There’s a certain irony that the more conscientious you are in protecting your winter bees from the ravages of Varroa in late summer, the more necessary it is to apply a miticide in the winter.

Winter bees are the ones that are in your hives now 1.

They have a very different physiology to the midsummer foragers that fill your supers with nectar. Winter bees have low levels of juvenile hormone and high levels of vitellogenin. They are long-lived – up to 8 months – and they form an efficient thermoregulating cluster when the external temperature plummets.

Winter bees production

In the temperate northern hemisphere, winter bees are reared from late summer/early autumn onwards. The combination of reductions in the photoperiod (day length), temperature and forage availability triggers changes in brood and forager pheromones.

Factors that influence winter bee production

Together these induce the production of winter bees.

For more details see Overwintering honey bees: biology and management by Döke et al., (2010).

Day length reduces predictably as summer changes to autumn. In contrast, temperature and forage availability (which itself is influenced by temperature and rainfall … and day length) are much more variable (so less predictable).

All of which means that you cannot be sure when the winter bees are produced.

If there’s an “Indian summer“, with warm temperatures stretching into late October, the bees will be out working the ivy and rearing good amounts of brood late into the year. The busy foragers and high(er) levels of brood pheromone will then delay the production of winter bees.

Conversely, low temperatures and early frosts reduce foraging and brood production, so bringing forward winter bee production.

It’s an inexact science.

You cannot be sure when the winter bees will be produced, but you can be sure that they will be reared.

Protect your winter bees

And if they are being reared, you must protect them from Varroa and the viral payload it delivers to developing pupae. Most important of these viruses is deformed wing virus (DWV).

Worker bee with DWV symptoms

Worker bee with DWV symptoms

Aside from “doing what it says on the tin” i.e. causing wing deformities and other developmental defects in some brood, DWV also reduces the longevity of winter bees.

And that’s a problem.

If they die sooner than they should they cannot help in thermoregulating the winter cluster.

And that results in the cluster having to work harder to keep warm as it gets smaller … and smaller … and smaller …

Until it’s so small it cannot reach its food reserves (isolation starvation) or freezes to death 2.

So, to protect your winter bees, you need to treat with an appropriate miticide in late summer. This reduces the mite load in the hive by up to 95% and so gives the winter bees a very good chance of leading a long and happy life 😉

Time of treatment and mite numbers

Time of treatment and mite numbers

I discussed this in excruciating detail in 2016 in a post titled When to treat?.

The figure above was taken from that post and is described more fully there. The arrow indicates when winter bees are produced and the variously coloured solid lines indicate mite numbers when treated in mid-July to mid-November.

The earlier you treat (indicated by the sudden drop in the mite count) the lower the peak mite numbers when the winter bees are being reared.

Note that the mite numbers indicated on the right hand vertical axis are not ‘real’ figures. They depend on the number present at the start of the year. In the figure above I “primed” the in silico modelled colony with just 20 mites. This will become very important in a few paragraphs.

Late season brood rearing

Compare the blue line (mid-August treatment) with the cyan line 3 (mid-October treatment) in the figure above.

The mid-October treatment really hammers the mite number down and they remain low until the end of the year 4.

The reason the mite numbers remain low after a mid-October treatment is that there is little or no brood being reared in the colony during this period.

Mites need brood, and specifically sealed brood, to reproduce on.

In the absence of brood the mites ‘colony surf‘, riding around as phoretic mites on nurse bees (or any bees if there aren’t the nurse bees they prefer).

And that late season brood rearing is the reason the end-of-year mite number for the colony treated in mid-August (the blue line) remains significantly higher.

Mites that survive the miticide in August simply carry on with their sordid little destructive lives, infesting the ample brood available (which could even include some highly mite-attractive and productive drone brood) and reproducing busily.

So, the earlier you treat, the more mites remain in the hive at the end of the year.

Weird, but true.

Early season brood rearing

The winter bees don’t ‘just’ get the colony through the winter.

As the day length increases and the temperature rises the colony starts rearing brood again. Depending upon your latitude it might never stop, but the rate at which it rears brood certainly increases in early spring.

Or, more correctly, in mid- to late-winter.

And it’s the winter bees that do this brood rearing. As Grozinger and colleagues state Once brood rearing re-initiates in late winter/early spring, the division of labor resumes among overwintered worker bees.”

Some winter bees revert to nurse bee activity, to rear the next generation of bees.

And this is another reason why strong colonies overwinter better … not because they (also) survive the cold better 5, but because there are more bees available to take on these brood rearing activities.

Strong, healthy colonies build up better in early spring.

Colonies that are weak in spring and stagger through the first few months of the year, never getting close to swarming, are of little use for honey production, more likely to get robbed out and may not build up enough for the following winter.

Midwinter mite treatments

Which brings us back to the need for miticide treatment in midwinter.

The BEEHAVE modelled colony shown in the graph above was ‘primed’ at the beginning of the season with 20 mites. These reproduced and generated almost 800 mites over the next 10-11 months.

What do you think would happen if you start the year with 200 mites, rather than 20?

Like the 200 remaining at the year end when you treat in mid-August?

Lots of mites … probably approaching 8000 … that’s almost as many mites as bees by the end of the season.

So, one reason to treat in the middle of winter is to reduce mite levels later in the season. The smaller the number you start with, the less you have later.

Vapour leaks out ...

Vaporisation … oxalic acid vapour leaks out …

But at the beginning of the season these elevated levels of mites could cause problems. High levels of mites and low levels of brood is not a good mix.

There’s the potential for those tiny patches of brood to become mite-infested very early in the season … this helps the mites but hinders the bees.

Logically, the more mites present at the start of brood rearing, the more likely it is that colony build up will be retarded.

So that’s two reasons to treat with miticides – usually an oxalic-acid containing treatment – in midwinter.

Midwinter? Or earlier?

When does the colony start brood rearing again in earnest?

This is important as the ‘midwinter’ treatment should be timed for a period before this when the colony is broodless. This is to ensure that all the mites are phoretic and ‘easy to reach’ with a well-timed dribble of Api-Bioxal.

In studies over 30 years ago Seeley and Visscher demonstrated that colonies have to start brood rearing in midwinter to build up enough to have the opportunity to swarm in late spring. These were colonies in cold climates, but the conditions – and season length – aren’t dramatically different to much of the UK.

Low temperatures regularly extend into January or February. The temperature is also variable year on year. It therefore seems (to me) that the most likely trigger for new brood rearing is increasing day length 6.

The apiary in winter ...

The apiary in winter …

I therefore assume that colonies may well be rearing brood very soon after the winter solstice.

I’m also aware that my colonies are almost always broodless earlier in the winter … or even what is still technically late autumn.

This is from experience of both direct (opening hives) or indirect (fresh brood mappings on the Varroa tray) observation.

Hence the “Midwinter, no” title of this post.

Don’t delay

I therefore treat with a dribbled or vaporised oxalic acid-containing miticide in late November or early December. In 2016 and 2017 it was the first week in December. Last year it was a week  later because we had heavy snow.

This year it was today … the 28th of November. With another apiary destined for treatment this weekend.

If colonies are broodless there is nothing to be gained by delaying treatment until later in the winter.

Most beekeepers treat between Christmas and New Year. It’s convenient. They’re probably on holiday and it is a good excuse to escape the family/mince pies/rubbish on the TV (delete as appropriate).

But it might be too late … don’t delay.

If colonies are broodless treat them now.

If you don’t and they start rearing brood the mites will hide away and be unreachable … but their daughters and granddaughters will cause you and your bees problems later in the season.

Finally, it’s worth noting that there’s no need to coordinate winter treatments. The bees aren’t flying and the possibility of mites being transferred – through robbing or drifting – from treated to untreated colonies is minimal.


 

Beekeeping economics

You are not going to make a million being a beekeeper. Or even a fraction of that.

I know a couple of beekeepers who have all the trappings of wealth … the big house, the big car with the personal number plate, the holiday place in France and the beesuit with no smoker-induced holes in the veil.

Neither of them made their money beekeeping.

Anyone aboard Murray?

I’ve met a few of the large commercial beekeepers here and abroad, operations with 500 to 1000 times the number of hives I’ve got.

None of them seemed to have yachts or Ferraris.

Or any free time to enjoy them if they had 😉

If you want to have a lot of money when you finally lose your last hive tool you probably need to start with lots more 1.

But the vast majority of beekeepers aren’t commercial. Most are hobbyists.

A hobby that (sometimes) makes a profit

In the UK there are ~25,000 beekeepers. Of these, the Bee Farmers Association represent the interests of the ~400 commercial beekeeping businesses.

Over 98% of UK beekeepers therefore do not consider themselves as commercial. These amateur or hobby beekeepers have on average 3-5 hives each, according to relatively recent surveys. Most probably have just one or two, with a few having more 2.

It’s worth emphasising (again) that it is always better to have more than one colony. The small increase in work involved – the apiary visits, the inspections, extracting all that honey 😉 – is more than justified by the experience and resilience it brings to your beekeeping.

Two are better than one …

For the remainder of the post I’m going to consider a (hypothetical) beekeeper with four colonies.

What are the costs involved in running four colonies and how much ‘profit’ might be expected?

Inevitably, this is going to be very, very approximate.

I’m going to make a load of assumptions, some loosely based on real data. I’ll discuss some of the more important assumptions where appropriate.

I’m also going to ignore a load of variables that would be little more than guesstimates anyway e.g. petrol costs to get to your apiary 3, the purchase of additional hive hardware or rent for the apiary.

Why four hives?

I’ve chosen four hives for a number of reasons.

Firstly, it’s a small enough number you could house them in a small(ish) suburban garden and, wherever they’re sited, they will not exploit all the forage in range.

Abelo poly hives

Abelo poly hives on wooden pallets

Secondly, it’s a manageable number for one beekeeper with a full time job and lots of other commitments. However, it’s not so many you have to buy an electric extractor or build a honey-processing room 4.

Finally, some expenses are for items sold in multiples e.g. frames or miticides, and it saves me having to slice’n’dice every outgoing cost too much.

This hypothetical four hive beekeeper also, very sensibly, belongs to her local association. She therefore has access to the shared equipment (e.g. a honey extractor) that the association owns.

The costs of starting beekeeping

I’ve covered this before and will just summarise it here.

I reckon the minimum outlay is a bit less than £500. This covers the purchase of two hives (Thorne’s Bees on a Budget @ £160 for a complete hive, two supers, frames, foundation etc.), a good quality beesuit (perhaps another £100) together with the peripheral, but nevertheless essential, smoker, hive tool and gloves. It does not cover the cost of bees.

Two hives really should be considered the minimum. Even if you only start with one colony, swarm control or colony splits in your second year will necessitate the purchase of a second hive.

So, for the purpose of these back of an envelope calculations I’ll assume our hypothetical beekeeper has already spent about £1000 on starting up and then doubling up the numbers of hives.

Cedar or polystyrene hives should last more than 25 years. I’m not going to work out the depreciation on this initial outlay 5.

So, let’s get back on track.

In an average year, what is the expenditure and potential income from these four hives.

Expenditure

The outgoing costs are associated with maintaining a good environment for the bees, minimising disease and ensuring they have sufficient food for the winter (or during a nectar dearth).

Yet more frames ...

Yet more frames …

The first annual expense is the replacement of ~30% of the brood comb every season. This is necessary to reduce the pathogen load in the hive and to replace the old, black comb with fresh new comb.

Frames and the foundation to go in them are generally bought in 10’s or 50’s. With four hives (assuming Nationals) that means you need a fraction over 13 new frames a season. First quality frames bought in 10’s, together with premium quality foundation 6, work out at £2.99 each i.e. ~£40 for the year.

To control mites you need to use miticides 7. For the purpose of this exercise we’ll assume our beekeeper chooses to use Apivar in the autumn. This costs £31 for 5 hive treatments 8 and is required once per year. In midwinter our beekeeper wisely chooses to use an oxalic acid trickle as well, knowing that – while the colony is broodless – the mites are easier to slay. £13 buys you a ten-hive (35 g) pack of Api-Bioxal 9 which has a shelf-life of more than a year, so for one year the expense is £6.50 (which for convenience I’ve rounded up to £7).

Food is essentially sugar in some form or another. A single colony needs 10-20 kg of stores for the winter (depending – very much – upon the strain of bee, the harshness of the winter etc.). You therefore need to feed about 12.5 litres of heavy syrup (2:1 by weight, sugar to water) which weighs about 16kg (and finally generates ~14 kg of stores) and contains about 10 kg of sugar. Tesco sell granulated sugar for 64p per kilogram. So, for four colonies, our beekeeper needs to purchase ~£26 of granulated sugar.

Remember two of those figures in particular – 14 kg of stores and the 10 kg of sugar that needs to be purchased to make them 10.

Expenditure totals

In total, four hives are likely to cost about £104 to maintain per year.

Yes, I know I’ve omitted all sorts of things such as stimulative feeding in the spring, replacement super frames and hive tools. I’ve not costed in the honey buckets or any number of other ‘odds and sods’ like replacement Posca pens for queen marking. Let’s keep this simple 🙂

The essentials work out at a little over £25 per hive.

But wait … there is something I’ve omitted.

Not expenditure per se, but losses that have to be made good to ensure that our beekeeper still has 4 colonies in subsequent seasons.

Isolation starvation ...

Isolation starvation …

These are the ‘losses’ due to colonies dying overwinter or during the season. I think these should be included because they are the reality for most beekeepers. On average ~20-25% of colonies are lost each season. Not by everyone (which I’ll cover in a follow-up article on economies in beekeeping) of course, but winter losses are so common for most beekeepers that they need to be factored in – either by making increase or by avoiding losing them in the first place.

Enough on these hidden costs, what about the the income?

Products of the hive

Bees, as well as providing critical ecosystem services (pollination) and being fascinating animals, also produce very valuable products.

The best known and most obvious product is of course honey. However, the products of the hive also includes wax, propolis and Royal Jelly.

Local honey

I’m going to ignore everything but the honey. Royal Jelly and propolis are too specialised for the sort of ‘average beekeeper’ we’re considering and four hives produce relatively small amounts of wax each year.

There’s an additional product of the hive … bees. Don’t forget these as they can be the most valuable product made in any quantity.

You can sell complete hives, small nucleus colonies (nucs) and mated queen bees 11. For convenience I’m going to assume the only ‘live’ product of the hive our beekeeper might sell is a five frame nuc if they have one spare. What’s more, I’m going to assume that our beekeeper either recoups the cost of the box or has it returned (but pays £15 for the frames and foundation in the nuc).

So, how much honey and how many bees?

Income from honey

The average honey yield in 2018 in the UK was ~31 lb per hive.

2018 was a very good season.

The annual BBKA survey of 2017 showed the average that year was ~24 lb per hive.

Yields vary year by year and according to where you keep bees. The 2010 figure was ~31 lb, 2012 was a measly 8 lb per hive and 2014 was ~31 lb. I can’t find a record of the 2016 figure (but haven’t looked too hard).

Yields are higher in the south and lower in the north.

I’m going to err on the slightly generous side and assume that the honey yield per hive is 25 lb and that our hypothetical beekeeper therefore generates 100 lb of honey per year.

More local honey

As we saw last week, honey prices vary considerably across the country.  For the purposes of these calculations we can use the BBKA survey which showed that ~56% of beekeepers sold honey at an average price of £5.49 per lb (cf. £5.67 in 2017).

And here’s the first dilemma … did the 44% of beekeepers who did not sell honey not have any honey to sell?

How does this affect the average per hive?

Or did they simply give everything away?

Or just eat it themselves 😉

The annual BBKA surveys are not ideal datasets to base these calculations on. They are voluntary and self-selecting. Perhaps the 23,000 beekeepers who did not complete the survey 12 produced 150 lb per colony.

No, I don’t think so either.

I’m going to make the assumption that the average yield per hive was 25 lb and that our beekeeper chooses to sell her honey at an average price of £5.50.

So the gross income from honey is £550 13.

However, selling this honey requires packaging – jars, labels etc. Like everything else, costs vary, but 12 oz hexagonal honey jars plus lids from C Wynne Jones cost ~39p each, with a standard custom label and a plain anti-tamper label adding a further 10p per jar.  Therefore to sell that 100 lb of honey our beekeeper will have an outlay of £63, reducing the net income to £487.

Income from bees

A strong hive in a good year should be able to produce both bees and honey. With good beekeeping, good forage and good weather it is possible to generate a super or two of honey and a nuc colony for sale or to make increase.

However, you can’t produce large amounts of both from a single hive … it’s an either or situation if you want to maximise your production of honey or nucs.

I’m not aware of any good statistics on nuc production by amateur beekeepers (or even poor statistics). My assumption – justified below – is that the majority of beekeepers produce few, if any, surplus nucs.

Everynuc

Everynuc …

Why do I think that?

Firstly, nuc and package imports from overseas are very high. Demand is enormous and is clearly not met by local supply 14. Secondly, winter losses (25%, discussed above) need to be made good. I presume that this is what many/most nucs are used for.

If they’re produced at all.

There are some major gaps in the available information meaning that the next bit is a guesstimate with a capital G.

For the purpose of this exercise I’m going to assume that our hypothetical beekeeper produces one nuc per year that it is used to compensate for overwintering losses, thereby keeping colony numbers stable.

In addition, she generates one surplus nuc every four years for sale.

I’ve chosen four years as it’s approximately every four years that there is a ‘good bee season’ giving high yields of honey and the opportunity for good queen mating and surplus nuc production.

This surplus nuc is sold locally for £175 which, after subtraction of £15 for the frames, leaves an annual profit from bees of £40 (£160 every 4 years).

Income totals and overall ‘profit’

That was all a bit turgid wasn’t it?

Here are the final figures. Remember, this is for a four hive apiary, per annum (4 year average).

Item Expenditure (£) Income (£)
Frames and foundation 40.00
Miticides 38.00
Food 26.00
Honey (jars/labelling) and gross 63.00 550.00
Nucleus colony 15.00 40.00
Sub totals 182.00 590.00
Profit 408.00

Experienced beekeepers reading this far 15 will appreciate some of the assumptions that have been made. There are many.

They’ll also probably disagree with half of the figures quoted, considering them too high.

And with the other half, considering them too low.

They’ll certainly consider the average ‘profit’ per hive per year is underestimated.

Mid-May ... 45,000 bees, 17 frames of brood, one queen ... now marked

Mid-May … 45,000 bees, 17 frames of brood, one queen … now marked and clipped

But remember, our hypothetical beekeeper is based upon the average productivity and number of hives reported in the BBKA annual surveys.

As you will probably realise, a limited amount of travel to and from the apiary, or to shops/markets to sell honey, very quickly eats into the rather measly £102 “profit” per hive.

Observations

I think there are two key things worth noting immediately:

  1. Miticide treatments cost ~£7.50 per hive per annum. Even at the rather derisory £5.50/lb honey price quoted, this is still less than one and a half jars of honey. It is false economy to not treat colonies for Varroa infestation. If you compare the cost of the treatment vs. the ‘value’ of a replacement nuc to make up losses (£175) it further emphasises how unwise it is to ignore the mites.
  2. Some beekeepers leave a super or two at the end of the season ‘for the bees’. This is also false economy if you want to have any profit. The ~14 kg of stores (honey) needed will be replaced with a heavy syrup feed containing 10 kg of granulated sugar. At £5.50 per pound this honey could be sold for ~£170 16. The granulated sugar costs about £6.40. Do the maths, as they say. There is no compelling (or even vaguely convincing) evidence that bees overwinter more successfully on honey rather than after a granulated sugar feed. None 17.

Summary

This article highlights some of the major expenses involved in beekeeping. Where possible I’ve based the figures on a hypothetical ‘average’ beekeeper with an average number of hives.

I’ve assumed that all outgoing costs were at list price from large suppliers (and excluded shipping costs).

I’ve left out the almost invaluable pleasure you get from working with the bees to produce lovely delicious local honey (or wax, or propolis, or bees or queens).

Do not underestimate this 🙂 Many – and I’m one – would keep some bees simply for this pleasure and the odd jar of honey.

No one is going to get rich quickly on £100 per hive per year 18. However, the purpose of this post was to provide a framework to consider where potential cost savings can be made. In addition, it will allow me to emphasise the benefits, to the bees and the beekeeper (and potentially her bank balance), of strong, healthy, highly productive colonies rather than the ‘average’ 25% colony losses per autumn with less than a full super per hive honey … which is then sold for less than it’s worth.

But that’s for another time …


Colophon

Beekeeping economics as in “The management of private or domestic finances; (also) financial position.” which is distinct from economy in beekeeping (which I will cover in a later post) meaning “The careful management of resources; sparingness”.

Cabinet reshuffle

Don’t worry, this isn’t a post about the totally dysfunctional state of British politics at the moment 1.

Once the honey supers are removed there’s seemingly little to do in the apiary. There is a temptation to catch up on all those other jobs postponed because I was “just off to the bees”.

Well, maybe temptation is a bit strong. After all, like all good procrastinators, I can usually find an excuse to postpone until next week something that could be left until at least tomorrow.

However, as I said last week, preparations for winter are very important and should not be delayed.

I covered feeding and the all-important late summer mite treatments in that post. Here I’m going to briefly discuss the various late season hive rearrangements that might be needed.

Clearing additional supers

I use very simple clearer boards to get the bees out of my supers. However, there are a couple of instances when not all the supers end up being removed:

  1. If some frames are empty or fail the ‘shake test’ I’ll rearrange these into the bottom super 2. I then clear the bees down into the bottom super and leave it for the bees.
  2. If the colony is really strong and is unlikely to fit into the brood box(es) I’ll often add a super above the queen excluder to clear the bees down into. Sometimes the bees will add a few dribbles of nectar to this … not enough to ever extract, and I’d prefer they put it in the brood box instead.

In both these situations I’ll want to remove the additional super before winter. I don’t want the bees to have a cold empty space above their heads.

Feed & clear together

I usually do this at the same time that I feed the bees.

I rearrange the boxes so that the ‘leftover’ super is above a crownboard on top of the super that is providing the headspace to accommodate the fondant blocks.

Since access to this top super is through a small hole the bees consider it is ‘outside’ the hive and so empty the remaining nectar and bring it down to the brood box 3.

If there are sealed stores in any of these super frames I bruise 4 the cappings with a hive tool and they’ll then move the stores down.

Substandard colonies

A very good piece of advice to all beekeepers is to “take your winter losses in the autumn”. This means assess colonies in the late summer/early autumn and get rid of those that are weak or substandard 5.

Substandard might mean those with a poor temper.

This is the colony which you put up with all season (despite their yobbo tendencies) because you believe that aggressive bees are productive bees’.

Were they?

Was that one half-filled super of partially-capped honey really worth the grief they gave you all summer?

Unless substandard (not just aggression … running, following, insufficiently frugal in winter etc.) colonies are replaced the overall standard of your bees will never improve.

I’ll discuss how to ‘remove’ them in a few paragraphs.

It’s probably a reasonable estimate to suggest that the ‘best’ third of your colonies should be used to rear more queens and the ‘worst’ third should be re-queened with these 6.

Over time 7 the quality will improve.

Of course, a substandard colony might well make it through the winter perfectly successfully. The same cannot be said for weak colonies.

TLC or tough love?

At the end of the summer colonies should be strong. If they are not then there is probably something wrong. A poorly mated queen, an old and failing queen, disease?

The exception might be a recently requeened colony or a new 5 frame nuc.

Everynuc

Everynuc …

Colonies that are weak at this stage of the season for no obvious reason need attention. Without it they are likely to succumb during the winter. And they’ll do this after you’ve gone to the trouble and expense of feeding and treating them … 8

There are essentially two choices:

  1. Mollycoddle them and hope they pick up. Boosting them with a frame or two of emerging brood may help (but make sure you don’t weaken the donor colony significantly). Moving them from a full hive to a nuc – preferably poly to provide better insulation – may also be beneficial. In a nuc they have less dead space to heat. An analogous strategy is to fill the space in the brood box with ‘fat dummies‘ or – low-tech but just as effective – a big wodge of bubble wrap with a standard dummy board to hold it in place.
  2. Sacrifice the queen from the weak hive and unite them with a strong colony.

Sentimentalism

Of the two I’d almost always recommend uniting colonies.

It’s less work. There’s no potentially wasted outlay on food and miticides. Most importantly, it’s much more likely to result in a strong colony the following spring.

However, we all get attached to our bees. It’s not unusual to give a fading favourite old queen ‘one more chance’ in the hope that next year will be her last hurrah.

Uniting notes

I’ve covered uniting before and so will only add some additional notes here …

Uniting a nuc with a full colony

Uniting a nuc with a full colony …

  • You cannot generate a strong colony by uniting two weak colonies. They’re weak for a reason. Whether they’re weak for the same or different reasons uniting them is unlikely to help.
  • Never unite a colony with signs of disease. All you do is jeopardise the healthy colony.
  • Find the queen and permanently remove her from the weak or poor quality (substandard) colony.
  • If you can’t find the queen unite them with a queen excluder between the colonies. In my limited experience (I usually manage to find the unwanted queen) the bees usually do away with a failing queen when offered a better one, but best to check in a week or so.
  • I generally move the de-queened colony and put it on top of the strong queenright colony.
  • Unite over newspaper and don’t interfere with the hive for at least another week.
  • You can unite one strong colony and two weak colonies simultaneously.
  • Uniting and feeding at the same time is possible.
  • You can unite and treat with a miticide like Amitraz simultaneously. You will have to make a judgement call on whether both boxes need miticide treatment, depending on the strength of the weak colony.
  • If you’re uniting a strong substandard colony and a strong good colony you will need to use an amount of miticide appropriate for a double brood colony (four strips in the case of Amitraz).
Successful uniting ...

Successful uniting …

Season of mists and mellow fruitfulness

The goal of all of the above is to go into autumn with strong, healthy, well-fed colonies that will survive the winter and build up strongly again in the spring.

A very small or weak colony 9 in autumn may survive, but it’s unlikely to flourish the following spring.

“It takes bees to make bees.”

And a weak colony in spring lacks bees, so cannot build up fast.

In contrast, an overwintered strong colony can often yield a nuc in May the following year. You’ve regained your colony numbers, but have a new, young queen in one hive with most of the season ahead for her to prove her worth.

I’ve merged three topics here – clearing supers, stock improvement and getting rid of weak colonies before winter – because all involve some sort of hive manipulation in the early autumn. I usually complete this in late September or early October, with the intention of overwintering strong colonies in single brood boxes packed with bees and stores.


Colophon

The heading of the final paragraph is the opening line of To Autumn by John Keats (1795-1821). Keats wrote To Autumn exactly two hundred years ago (September 1819, his last poem) while gradually succumbing to tuberculosis. Despite this, and his doomed relationship with Fanny Brawne, the poem is not about sadness at the end of summer but instead revels in the ripeness and bounteousness of the season.

Of course, all beekeepers know that the first stanza of To Autumn closes with a reference to bees.

Season of mists and mellow fruitfulness,
  Close bosom-friend of the maturing sun;
Conspiring with him how to load and bless
  With fruit the vines that round the thatch-eves run;
To bend with apples the moss’d cottage-trees,
  And fill all fruit with ripeness to the core;
    To swell the gourd, and plump the hazel shells
  With a sweet kernel; to set budding more,
And still more, later flowers for the bees,
Until they think warm days will never cease,
    For summer has o’er-brimm’d their clammy cells.

 

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

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 🙁

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.

  • 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).

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.


 

 

 

 

 

Window of opportunity

I’ve recently discussed problems faced by beekeepers trying to control high Varroa levels in colonies during the ‘body’ of the beekeeping season. Essentially the problems are two-fold:

  • Many miticides need to be used for several weeks to target mites in capped cells.
  • The soft or hard chemicals used for Varroa control are – with the exception of the formic acid in MAQS – incompatible with honey production.

This type of midseason mite management should not be needed if parasite levels are controlled in late summer and midwinter.

If it is needed it suggests that the treatment(s) failed or that mites are being acquired through robbing or drifting from other colonies in the neighbourhood (either your own, a nearby apiary or a feral colony).

Opportunity knocks

However, all is not lost. Most seasons offer at least one opportunity to intervene and control mite levels.

Knowing when and how to exploit it requires an appreciation of the development cycle of the bee.

Honey bee development

Honey bee development

The important numbers are the 21 and 24 day development cycle of workers and drones respectively, the 16 day development cycle of the queen and the time it takes for eggs to hatch, grow as larvae and pupate in capped cells.

Not shown is the maturation period after emergence for the queen (5 to 6 days) before she goes on a mating flight, or the delay after returning before she starts laying (2-3 days) 1.

Swarms

The easiest scenario to discuss is when the colony swarms.

Consider the swarm first. A prime swarm is broodless, contains a mated queen and ~35% of the mites that were present in the issuing colony. All the mites will be phoretic. Assuming there’s drawn comb available the queen will start laying soon after the swarm is hived (or conveniently moves into your bait hive).

Eight days later the first eggs will have hatched, the larvae grown and the brood will be capped.

At which point the majority of the mites will start to become inaccessible again.

However, during those 8 days it’s ‘open season’ for those phoretic mites.

It is sensible to quarantine swarms from an unknown source and treat for mites in the first 8 days if needed.

If the swarm is a cast with an unmated queen you’ve got a bit more time. The virgin queen needs to get out and mate, mature and start laying. This tends to happen in just a few days if the weather is accommodating, so don’t leave things too long.

The swarmed colony

Now consider what’s left in the colony that swarmed 2. There will be sealed and unsealed brood and – notwithstanding the reduced egg laying by the queen as she’s slimmed down in preparation for swarming – there are also likely to be some eggs.

There will also be a sealed queen cell (and, in a strong colony, several sealed and unsealed queen cells).

Queen cells ...

Queen cells …

Without intervention the queen(s) will start emerging about 9 days later. If you intervene, knocking down all the sealed cells and leaving just one good charged open cell 3, it will be a couple more days before the queen emerges.

Weather permitting it will be a further 8 days before the newly mated queen starts laying. In reality, this is the absolute minimum and is rarely achieved in a full hive 4.

Simultaneously, in the requeening hive, the open brood is maturing and being capped and the capped brood is emerging (releasing more mites).

About eight days after the swarm leaves all the worker brood in the hive will be capped.

Twenty one (or 24 in the case of drone brood) days after the last egg was laid by the queen all the brood will have emerged.

Consequently all the mites in the colony will be phoretic.

The window of opportunity

So, if you need to treat 5 the window of opportunity is between the last of the brood from the old queen emerging and the first of the larvae from the new queen being capped.

You can determine when this is likely to be based upon the known activities of the old and new queen during the swarming period.

The window of opportunity

The diagram above makes a number of assumptions. As presented, all minimise the duration of the minimum broodless period:

  • The old queen continues laying until the day she swarms
  • The colony swarms on the day the queen cell is sealed
  • The beekeeper does not intervene to leave an open, charged cell of a known age
  • The new queen takes the minimum amount of time to mature, go on a mating flight and start laying

It should be self-evident that more realistic timings applied to these will only increase the length of the minimum broodless period.

For example, the weather will have a significant impact. Swarming may be delayed due to adverse conditions. During this time the slimmed-down queen will probably lay very few eggs.

Similarly, only 8 days are shown for maturing, mating and starting to lay. Mating flights are very weather-dependent and this period could easily take a week longer (or more).

Splits and artificial swarms

If you practice swarm control using the nucleus method, vertical splits or the classic Pagden artificial swarm the same types of calculations apply.

These three methods all share two features:

  • They involve the physical separation of the box with the old queen and the new developing queen
  • The old queen is isolated with a very small amount of brood – either open brood or emerging brood

The queenright component of the split (whether nuc box or new brood box left on the old site) will follow the right hand part of the diagram above i.e. everything to the right of the vertical red line labelled laying. Here it is expanded a bit:

Queenright splits and the window(s) of opportunity

The queen should start laying almost immediately if drawn comb is provided meaning this new brood will be sealed in a further 8-9 days. The timing and duration of the minimum broodless period depends upon whether you prime the queenright split with a small amount of open or emerging brood.

  • Open brood will be capped within about 6 days of the eggs hatching. If the frame contains nothing older than 3rd instar larvae (about mid-size) you will only have about 3 days before the cells are capped – indicated by bracketed region labelled (A) above, with capped pupae shown by the dark shaded arrow.
  • Emerging brood offers a bit more flexibility. If all the brood emerges in the first 2-3 days after the split (shown with the pale shaded arrow) then the duration of the broodless period, shown in (B) above, lasts about 5 days.

Queenless colonies after splitting

The queenless part of the split will behave like the swarmed colony in the upper line diagram. All capped worker brood will have emerged 21 days after the split (drones after 24 days).

Capped brood arising from eggs laid by the new queen in this colony will depend upon the origin of the queen.

If the colony is left to rear its own queen then the timing will be similar to the upper line diagram plus the additional time required to create a capped queen cell (which rather depends upon the state of the colony when split).

However, if you add a mature queen cell a day off emergence you will reduce the time to the appearance of new capped brood by ~8 days. Consequently the colony will probably never go through a phase with no capped brood present. This is the same, but even more so, if you requeen the colony with a mated queen.

The miticide of choice

Of all the (rather limited range of) miticides available, an oxalic acid-containing treatment is the most appropriate. Oxalic acid (OA) is well-tolerated and, if used on a colony that lacks capped brood, over 90% effective. In addition, and critical for treatment in a narrow window of opportunity, only one treatment is required.

OA can be administered by trickling or sublimation. I’ve covered both methods in detail previously so won’t repeat what’s required, or the recipes, here.

Note that in many cases although the colony will have no capped brood it will not be broodless. For example, larvae from eggs laid by the new queen will be present but uncapped.

This is important because trickled oxalic acid-containing treatments are toxic to open brood. Under these conditions the treatment of choice would be sublimated oxalic acid.

Sublimox vaporiser

Sublimox vaporiser …

Finally, note that if you are going to sublimate Api-Bioxal you’ll either have to spend ages cleaning the pan of the vaporiser, or line it with aluminium foil in advance.

The treatments outlined here are not intended for routine use. They should be used only if needed based upon mite counts or overt signs of DWV-mediated disease.

However, if you do need to treat make sure you do it when the treatment will be most effective.