Tag Archives: mite monitoring

OA Q&A

The post last week on the preparation of oxalic acid (OA; the active ingredient in the commercially available and VMD approved product Api-Bioxal) generated a slew questions. Inevitably, some of these drifted off topic … at least as far as the specific content of the post was concerned.

This partly reflects the deficiency of a weekly blog as a means of communicating.

It may also reflect the inadequacy of the indexing system 1.

Comprehensive coverage of subject, and peripherally related topics, would require a post so long that most readers 2 would give up halfway through.

And it would take so long to write that the weekly post format would have to be abandoned.

The resultingĀ magnum opus would be a masterpiece of bad punctuation, littered with poor puns and would leave me nothing to write the following week …

This week I’ve attempted to address a series of oxalic acid-related points that should have been mentioned before, that I’ve received questions about, or I think justify a question (and answer).

Should I trickle treat or vaporise?

One of the key features of approved miticides is that, used according to the instructions and at the appropriate time, they are very effective.

Conversely, use them incorrectly or at the wrong time and they will be, at best, pretty hopeless.

In the case of OA, both trickle treating (dribbling) or vaporisation (sublimation) can achieve 90% or more reduction in the levels of phoretic mites.

Therefore, the choice between them is not on the grounds of efficacy but should be on their ease of us, convenience, safety or other factors.

Trickle treating is fast, requires a minimum amount of specialised equipment and only limited PPE (personal protection equipment).

I’d strongly recommend using a Trickle 2 bottle from Thorne’s to administer the solution. It is infinitely better than a syringe, which requires the use of at least two hands.

If you hold the crownboard up at an angle with one hand you can administer the OA solution using the other. Wear gloves and your bee suit. It takes as long to read as it does to do.

With a Trickle 2 bottle and some pre-warmed OA-containing solution it should be possible to open, treat and close a colony in well under two minutes. Like this …

On a cold day very few bees will be disturbed. The OA will dribble down through the clustered colony and the mites will get what they deserve šŸ™‚

Temperature and treatment choice

It’s usually the temperature that determines whether I trickle or vaporise. I prefer to trickle when the colony is clustered, but would usually treat by sublimation on a warmer day.

At what temperature does cold become warm? About 8-9Ā°C … i.e. about the temperature at which the bees start to cluster.

Partly this is to reduce the number of bees that might be disturbed – I can vaporise a colony without opening the box.

However, my crashingly unscientific opinion – based entirely on gut feeling and guesswork 3 – is that the OA vapour perfuses through loose clustersĀ  better, whereas the solution is more likely to come into contact with the mites when dribbling down through the cluster.

I have no data to support this –Ā don’t say you weren’t warned!

Through choice I’d not treat (unless I had to) if the temperature was much below 3-4Ā°C. The bees get rapidly chilled should something goes wrong – you drop the bottle, get a bee in your veil or whatever.

Single use ...

Caramel coated Sublimox vaporiser pan

Of course, if you haven’t got a vaporiser your choice is limited to trickle treating. Likewise, if you don’t enjoy scouring caramelised glucose from the pan of your vaporiser you should probably stick to trickling Api-Bioxal solution.

The only additional thing to consider is whether there’s brood present in the hive – I discuss this in more detail below.

How can I use a vaporiser and an Abelo poly floor?

I use a lot of Abelo poly hives. Mine are all the ‘old design‘ with the floor that features a long landing board and an ill-fitting Varroa tray. The new ones don’t look fundamentally different from the website 4.

Abelo poly National hives ...

Abelo poly National hives …

My storage shed has a shoulder-high stack of unused Abelo floors as I prefer my own homemade ‘kewl’ floors.

However, inevitably some Abelo floors get pressed into use during the season and – through idleness, disorganisation and a global virus pandemic – remain in use during the winter šŸ™

I’ve now worked out how to vaporise colonies using these floors. Please remember, my vaporiser is a Sublimox which has a brass (?) nozzle through which the vapour is expelled. The nozzle gets very hot and melts polystyrene.

Don’t ask me how I know šŸ™

The underside of the open mesh floor can be sealed by inverting theĀ Varroa tray and wedging a block of foam underneath at the back. I didn’t think this would work until I tried it, and was pleasantly impressed.

Abelo poly floor set up for OA vaporisation

This is important as it significantly reduces the loss of OA vapour.Ā Any vapour that escapes is OA that will not be killing mites.

The Sublimox can be simultaneously inserted and inverted through the front entrance. This takes some deft ‘wrist action’ but results in minimal loss of OA vapour.

To protect the poly I use a piece of cardboard. You simply rest the nozzle on this.

As soon as the vaporiser is removed the bees will start to come out, so use the cardboard to block the entrance for a few minutes, by which time they will have settled.

No expense spared cardboard ‘protector’ for poly floor

The gaffer tape in the photo above is sealing the ventilation holes in the entrance block, again keeping valuable OA vapour inside the hive.

And on a related point …

My favoured nuc is the Everynuc. This is a Langstroth-sized box with a removable floor and an integral feeder that more-or-less converts the box to take National frames. It’s well-insulated, robust, easy to paint and – in my view – a more flexible design that the all-in-one single moulded boxes (like the offering from Maisemores).

However, the entrance of the Everynuc is too big.

Everynuc entrance

Open wide …

The disadvantage of this is that a DIY entrance reducer is needed if the nuc is weak and at risk from robbing.

Conversely, the large entrance and short (~2cm) “landing board” is preferable during OA vaporisation. I carry a nuc-width strip of wood, 2 cm thick, with a central 7 mm hole.

With this balanced on the landing board, the vaporiser can be inserted and inverted without loss of vapour or risk of melting the poly. It’s a quick and dirty fix that I discovered several years ago and have never got round to improving.

How do I know if the colony is broodless?

Oxalic acid is a single-use treatment, remaining active in the hive for significantly less time than a brood cycle (see mite counts below). Therefore, the ‘appropriate time’ to use it is when the colony is broodless.

An additional consideration is that open brood is very sensitive and responds unfavourably to a warm acid bath in OA i.e. it dies 5.

In contrast, sealed brood is impervious to OA vapour or solution.

So, how can you tell if the colony is broodless or not?

The easiestĀ way to determine whether the colony has sealed brood is – on a slightly better day – to open the box and have a look.

Done quickly and calmly I suspect this is more distressing for the beekeeper than it is for the colony. YouĀ think the bees will be aggressive or distressed. In reality they’re usually pretty lethargic and often very few fly at all.

You only need to look at the frame in the centre of the cluster. If there’s brood present it will be where the bees are most concentrated. You will probably well see the queen nearby.

Gently, gently, quicky peeky

Remove the roof and insulation and lift one corner of the crownboard. Give them a gentle puff of smoke under the crownboard 6. Wait 30 seconds or so and gently remove the crownboard.

There will be bees on the underside of the crownboard. Stand it carefully to the side out of the breeze. The bees will probably crawl to the upper edge, remember to shake them off into the hive rather than crush them when you place it back on the hive.

The colony is likely to be clustered if the weather is 8Ā°C or cooler. Remove the outer frame furthest from the cluster. If it’s late autumn or early winter this should still be heavy with stores. Here’s one I pulled out last week.

Outer frame from a colony in early winter

Now you have space to work. Viewed from above the cluster will often be spread over several frames and shaped approximately like a rugby ball.

In the hive shown above they occupied the front five seams 7 with a few stragglers between frames 6 and 7.

Early winter cluster

I used my hive tool between frames 3 and 4 to split the colony, just levering them a centimetre or so apart, so I could then separate frame 3 from 2 and lift it out.

The queen was on the far side of frame 3.

It looks like magic to inexperienced beekeepers, but it really isn’t …

The top of the frame was filled with sealed stores, the lower part of the frame was almost full of uncapped stores.

There was no sealed brood and no eggs or larvae that I could see 8. An adjacent hive looked very similar. Again, the queen was on the reverse side of the first frame I checked. The bees were barely disturbed. Almost none flew and the boxes were carefully sealed up again.

No brood, so ready to treat šŸ™‚

Can I determine if there’s brood present without opening the hive?

Possibly.

You should be able to tell if brood is emerging by the appearance of the characteristic biscuit-coloured wax crumbs on the Varroa tray.

Think digestive rather than Fox’s Party Rings

Not this colour of biscuit

To see this evidence you need to start with a clean Varroa tray. In addition, the underside of the open mesh floor must be sufficiently draught-free that the cappings aren’t blown around, or accessible to slugs.

Cleaned Varroa tray

Remember that there might be only a very small amount of brood emerging. They may also be uncapping stores (which will have much paler cappings).

Leave the tray in place for a few days and check for darker stripes of crumbs/cappings under the centre of the cluster.

Biscuit-coloured cappings on Varroa tray

Note that the photograph above was taken in mid-February. A late autumn colony would almost certainly have significantly less brood cappings present on the tray. The brood cappings are the two and a bit distinct horizontal stripes concentrated just above centre. The stores cappings are the white crumbs forming the just discernible stripes the full width of the tray.

You cannot use this method to infer anything about whether there’s unsealed brood present. At least, not with any certainty. If, in successive weeks, the amount of brood cappings increases there’s almost certainly unsealed brood present. Conversely, if brood cappings are reducing there may not be unsealed brood if the queen is just shutting down.

While you’re staring at the tray …

Look forĀ Varroa.

It’s useful to have an idea of the mite drop in the few days before OA treatment.

If it’s high then treatment is clearly needed.

If it’s low (1-2 per day) you have a useful baseline to compare the number that fall after treatment.

You may well be surprised (or perhaps disappointed) at the number that appear from a colony that has already had an autumn treatment.

It’s worth remembering that 9 there will be more mites present in the winter if you treated early enough in the autumn toĀ protect the winter bees (blue line).

Mite numbers after early and late autumn treatment

Conversely, if you get little or no mite drop with an OA treatment in the winter it indicates theĀ  bees have not been rearing brood in the intervening period. That means the diutinus winter bees were rearedĀ before or during the last treatment, meaning they will have been exposed to high mite levels (red line).

This is not a good thingā„¢.

In my experience the daily mite drop is highest 24-48 hours after treatment. I usually try and monitor it over 5-7 days by which time the drop has reached a basal level, presumably because the OA has disappeared or stopped being effective.

Finally, the ambient temperature has an influence on theĀ Varroa drop. I’ll write about this sometime in the future, but it’s worth looking out for.


 

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 šŸ™‚

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” orĀ “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.Ā It doesn’t take long before there’s not enough time for what must be done, let alone what you’dĀ 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.Ā 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 thanĀ 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 combĀ etc. – using a simple numerical scoring system. Added supers are recorded (+1, +1, -2Ā 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 jottings.Ā May 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)Ā Varroa calculator and see what they advise. There are quite a few variables – drone brood amounts, length of seasonĀ 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 expectĀ 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!Ā Slaps forehead šŸ™„ ) 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 beĀ 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’sĀ 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,Ā 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 everyĀ apiary visit, rather thanĀ 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 šŸ˜‰