I’ve been using a Sublimox sublimator (vaporiser) since late 2014. In that time it’s worked faultlessly. There have been only two things that have needed any attention. These are the screws that hold the heat shield in place and replacement of the ‘O’ rings on the nylon cup you load with oxalic acid.
Actually, the other thing that needed attention was the heating chamber that became coated with caramelised glucose when I first used Api-Bioxal … but I’ve posted on that separately.
The heat shield protects the operator and your easy-to-melt poly hives from the metal heating chamber within which the oxalic acid is vaporised. It’s made out of folded, perforated metal and is held in place with two small retaining screws on the underside.
The heat shield can get a bit of a battering. The sublimator rests on it when the machine is laying on the side. More significantly it can get twisted or pulled if it gets caught on the edge of the hive when inverting it to deliver the oxalic acid. Inevitably, it is also subjected to repeated cycles of heating and cooling.
All of this tends to mean that the grub screws work loose over time. If the machine is cool they can be finger-tightened, but they’ll eventually loosen off again.
Retaining screws …
To rectify this and prevent their permanent loss in the apiary mud I gave them each a dab of Loctite 243 and tightened them up properly 1. This appears to have done the trick and they’ve remained in place without loosening.
The nylon cup you preload with oxalic acid has an O ring seated in a groove. This provides a gas-tight seal with the metal chamber in which the OA is vaporised.
It’s a tough life being an O ring.
It is subjected to a very harsh environment consisting of both high acidity and high temperatures. With repeated use the O rings become less able to form the gas-tight seal. They get thinner, crack and/or stiffen. Eventually they fail completely.
Once they have failed there’s a significant risk of vaporised oxalic acid escaping. Aside from potentially increasing operator exposure this also means that all that mite-destroying goodness is not being delivered where it does most harm (to the mites in the hive).
Here’s two I wrecked earlier …
Replacement O rings can be purchased from the various suppliers of the Sublimox. Icko used to list them on their website but they appear to have disappeared for the moment. Abelo list them at £2 each.
As an alternative I’ve purchased and am testing some Viton O rings from eBay. Viton 75 is a “DuPont-manufactured fluorocarbon elastomer that exhibit excellent resistance to high temperature and many organic solvents and chemicals over a temperature range of -25°F to +400°F”.
Which sounds ideal for something that needs to work with oxalic acid at a temperature of about 160°C. The documentation from Dupont indicates that Viton has excellent resistance to oxalic acid.
Sublimox nylon cups and O rings …
I’ll post on how well these work sometime in the future.
Essential accessories …
Although not really a “spare or repair” it’s worth noting here that the Sublimox requires a 240V supply and so should always be used with an RCD (residual current device). This is particularly important since the apiary in winter is probably a damp (or worse) environment. An RCD, together with a bottle of water for cleaning the vaporiser, can just about be squeezed into the carry case. It’s therefore available whether you use a portable generator or an extension lead to the mains voltage supply.
Spring (or late winter) vigilance
As the season slowly starts, colonies will begin rearing more brood. You don’t need to open the colony up to determine this. Instead, insert a Varroa tray under the open mesh floor and look for thin rows of “biscuit crumbs” that are the cappings from emerging brood.
All is well …
And, while you’re looking at this evidence that the long winter will soon be over, look carefully for any Varroa that have dropped from the colony. Mite drops should be very low if your autumn and midwinter treatment regime was effective.
You need to monitor for at least a week. With low mite numbers in the colony and small amounts of sealed brood the drop can fluctuate a bit.
If the mite drop is not low or non-existent there’s probably no need to treat immediately 2. However, make a note to monitor the colony at regular intervals – both for mites and overt DWV disease – and intervene if necessary.
I wonder how many beekeepers have one of these on their wish list for Santa?
Sublimox vaporiser …
From being a bit of an imported oddity (I had to import mine from Icko Apiculture in France three years ago) they’re now becoming mainstream … over the last year or so they’ve been sold by an independent importer, then Abelo and – just this month – the ‘Big Daddy’ of UK beekeeping suppliers, E. M. Thorne (Rebecca at Thorne’s kindly asked if they could include links in their December newsletter to previous posts here on the Sublimox and vaporising Api-Bioxal).
The Sublimox is also now being discussed more widely on the online forums, with much of this discussion emphasising the price (they are expensive). Aside from this disadvantage, I think there are a number of significant advantages of this design of sublimator (vaporiser) which are worth emphasising.
The general principle of active and passive sublimators
Sublimators (vaporisers) are designed to heat oxalic acid (OA) crystals sufficiently that they sublimate i.e. go through a phase transition from a solid into a gas without an intervening liquid phase. As readers of this site should know, oxalic acid is highly effective against the Varroa mite – both by sublimation and trickling in solution, which has recently been covered in excruciating detail so won’t be elaborated on here.
Many sublimators (vaporisers) are passive. You add the OA to a pan, slide it into the hive entrance, apply a current to heat the pan, allow the OA to sublimate, withdraw the pan and start again. You usually need to cool the pan in water before addition of the next dose. This heat, rinse and repeat cycle takes time, but is very effective and the pan-type vaporisers are relatively inexpensive (£35-£100).
The Varrox vaporiser is one of the original and best known models, though there are any number of much less expensive copies sold by beekeeping suppliers and on eBay. Most require a 12V supply of some kind.
In contrast to these, the Sublimox is ‘active’, as is the US equivalent machine, the ProVap 110. In these the pan is pre-heated, the OA is ‘dropped’ into the pan in such a way that the vapour is generated in an enclosed space which it then escapes under pressure through a nozzle.
Probably the best sublimator in the world …
In terms of speed, convenience and ease of use I’d argue that the Sublimox is hard to beat.
Delivery of a single dose takes no more than 45 seconds from inserting the Sublimox nozzle into the hive. It’s appreciably faster than the pan-type passive sublimators. There’s a preliminary warming up period before use, as the machine reaches operating temperature. After that it’s simply treat, refill, treat, refill ad infinitum. The rate-limiting step is sealing the hive and refilling the small plastic ‘cartridge’ with OA.
For one person, a hive-a-minute is just about possible – if you have 10-20 closely spaced hives, sufficient entrance blocks and buy additional white plastic cartridges. But, to achieve this you’ll be rushing about like a mad thing and it’s not realistically achievable1.
But speed isn’t the major benefit.
It’s convenient because you can ‘squirt’ the gas through a small hole in hive. You don’t need to open the hive and so it works with any hive type or entrance. My favoured kewl floors cannot be used with a sublimator that needs to be pushed through the entrance. Instead, all my hives have a neat 6mm hole drilled through the sidewall of the floor which is usually plugged with a small foam bung or twist of grass2. Vapour quickly permeates throughout the hive, ensuring all surfaces are reached.
The only exception are the all-poly hives, such as the garishly coloured Abelo’s I’ve been using for work this season. The nozzle of the Sublimox gets hot and melts polystyrene (been there, done that 🙁 ). With poly hives I usually use a simple shallow eke with a Sublimox nozzle-sized hole in one side. In this case you do need to remove the roof and crownboard, add the eke, replace the roof (upside down), treat and then close up the hive.
Foam bung …
The alternative is to simply squirt the gas through the open entrance. This isn’t ideal as some of the gas will escape, potentially exposing the beekeeper and definitely not exposing the bees/mites. One way to avoid this loss of gas is to use a wooden block with a small hole through the middle held over the poly hive entrance.
It’s important to have a clear space into which the gas is ‘squirted’. If you don’t the OA tends to not permeate through the hive properly.
The Abelo hives have a hole in one face of the brood box. This is usually plugged. I think it’s intended as an upper entrance. I’ve yet to try poking the Sublimox nozzle through this hole to deliver the OA … this might not work as it may be too close to the frame, so impeding the spread of gas through the box. Time will tell†.
There’s an additional benefit of the way the Sublimox is used. Operator exposure to OA should be minimised. The gas isn’t generated until the machine is inserted and inverted and takes no more than ~45s to deliver. If the hive is sealed properly there’s very little exposure to the gas.
… but all this comes at a cost
The Sublimox is three-times the price of a Varrox vaporiser. Is it worth it? That’s up to the purchaser to decide, based on the number of hives to be treated, the depth of their pockets, the perceived benefits of the speed, ease of use, convenience and safety etc.
Many will baulk at the cost. Some build their own. Others don’t bother vaporising, but solely dribble OA solution in midwinter. This is the cheapest and fastest way to treat colonies. I estimate it costs about 0.5p/hive to trickle treat if you buy OA in 25kg bags. Dribbling is probably even faster than using the Sublimox. However, dribbling is really only practical for broodless colonies – swarms and for midwinter use – and should only be done once per season. In contrast, repeated sublimation is tolerated well by colonies.
Would I buy another one?
Before you splash the cash
Be aware … the Sublimox requires a 240V supply. One of my apiaries has mains power which is the best solution, but unlikely in the corner of a farmers field. You can use an inverter from a car battery which is fine if you can get your car close enough to the hives. Alternatively – and this is what I do – you can use a portable generator. I’ve got an 700W Impax one from Screwfix which works perfectly.
But that’s another £190 🙁
You’ll also need to periodically buy replacement sealing rings for the OA “cassette”. These wear out or perish rather fast. Icko sell them for a daft price, but they’re now available in the UK.
Single use …
You should also be aware that Api-Bioxal, the VMD-approved oxalic acid-containing miticide, has glucose in it which caramelises in the pan of the Sublimox (and other vaporisers) and is a bit of a nightmare to clean out properly. I’d go further and suggest that Api-Bioxal is unsuitable to use with a Sublimox. If the nozzle is blocked the gas has to escape and there could be inadvertent exposure of the operator.
I’ve touched on safety above. However, just because OA vapour is generated for a very short and well defined time doesn’t make it safe. There are still exposure risks which must be taken seriously.
You’ll need PPE – personal protection equipment – to prevent exposure to the OA vapour when treating colonies. This includes eye protection and a suitable vapour mask. Don’t skimp on this and assume you’ll just stand downwind. If the hive is poorly sealed, swirling gusts of wind will expose you to vapour and it’s – at best – very, very unpleasant.
Entrance block …
Unlike passive vaporisers, the Sublimox generates a very large volume of gas immediately the OA is added. There’s no opportunity to ‘stand well back’ as the pan warms up as you can with the passive machines. You have to be holding the Sublimox to invert it and drop the OA into the pan. You’ll be bent over the hive and unable to avoid the swirling fog of acidic vapour if it escapes. To help minimise this seal the hive thoroughly. I use a full-width entrance block and tightly fitting Varroa tray. Even then, particularly on ageing cedar hives, there are all sorts of little gaps from which the OA vapour can be seen escaping.
Entrance block in use …
Finally, as if gassing yourself with an evil smelling acidic cloud of OA wasn’t enough, remember you’re using a 240V supply outside, probably on damp grass … or possibly even in the rain. Don’t get electrocuted. Make sure you use an RCD (residual current device) that’s been tested and you know works.
Share the costs
At the time of writing the Sublimox costs over £300. Perhaps competition will force the price down a bit? When you consider that these machines are used relatively infrequently during the season it makes sense to consider purchasing them as an Association item (or with a group of friends), in the same way that some associations have extraction equipment available.
Of course, like an extractor, everyone needs it at about the same time of the season (at least in midwinter). However, unlike an extractor, it’s generally needed for a relatively short period, is easy to transport and easy clean after use. There should be no reason it couldn’t be shared by association members.
I appreciate that many associations don’t have shared equipment, or many beekeepers don’t belong to their local association. All I’m doing is suggesting a way in which a good quality and highly effective piece of equipment could be purchased so that many can benefit.
Whether you’ve got one of these on your list for Santa or not …
… Happy Christmas!
1 The rate-limiting step is probably having enough entrance blocks. If removed too soon you’ll lose lots of vaporised OA goodness. Leave it a good 5 minutes if at all possible, which is easily enough time to treat another 5 hives. See what I mean?
2 When treating a hive for the first time I’ve even drilled this hole through an occupied hive.
† Actually, this hole isn’t suitable. It opens onto the face (rather than end) of a frame, and the vapour is therefore restricting from spreading. Don’t bother.
‡ I’ve regularly treated colonies in the dark. Sometimes the only time I can get to the apiary is after work. The bees are all ‘at home’ but you can easily seal the hive up and treat them. Use a headtorch with a red bulb. Since bees can’t see red, any that escape won’t directly target your head and you can probably work safely without a veil.
If Carlsberg did … is one of the most recognisable advertising campaigns of all time. Originally created in 1973 it has achieved near-universal recognition and remains in daily use, though predominantly these days as internet memes. The opening three words of the adverts were as recognisable as the closing seven … probably the best lager in the world.
There are any number of comedic If Carlsberg did ‘advertising’ campaigns, including some from Carlsberg itself … Probably the best poster in the world, featured the distinctive swirly underscore, colour scheme and font, together with a real tap dispensing lager installed in Londons Brick Lane.
Anyone reading the beekeepingforum.co.uk will be aware that there are a number of contributors there that enthusiastically recommend the treatment of colonies with vaporised (or, perhaps more accurately, sublimated) oxalic acid to reduce Varroa levels.
There goes a few pence …
Although vaporised oxalic acid (OA) has been used by some for many years, the speed with which it has recently been embraced by many UK beekeepers (at least those that contribute to discussion forums and, perhaps to a lesser extent, those I speak to in associations over the winter) probably reflects two or three things:
an awareness of just how effective oxalic acid is as a treatment
the increased availability of commercial oxalic acid vaporisers (or Heath Robinson-like plans to build-your-own)
There are almost as many homegrown or imported vaporisers as there are treatment regimes to hammer down the mite levels. Of course, there’s the contentious point that oxalic acid is not approved by the VMD (Veterinary Medicines Directorate), despite having been in routine use for decades. Api-Bioxal is, but is probably unsuitable for sublimation due to the inert (as far as Varroa are concerned) additives it contains. Api-Bioxal can be vaporised but leaves a caramelised residue in the vaporiser pan that is hard to clean.
Out, damn’d mite …
‘Vaping’ is also popular in the US. Randy Oliver has covered it extensively on his scientificbeekeeping.com site and it’s also regularly discussed on Beesource. OxaVap make/supply a vaporiser that appears very similar to the Sublimox I use. The OxaVap model has a useful temperature display that I would find much easier to read than the red/green diodes on the Sublimox … I’m red/green colourblind.
Active and passive vaporisers
The Sublimox and OxaVap vaporisers are ‘active’ … they blow out a dense cloud of OA-containing vapour through a relatively narrow diameter nozzle (the video below uses water to demonstrate this process). This provides advantages both in terms of ease and speed of delivery. These vaporisers simply need a 7mm hole drilled through the sidewall of the floor (see photo at the top of the page), or through an eke placed over the colony. The OA-containing vapour is ‘squirted’ in, permeates all corners of the hive within seconds and you can then move on to the next hive. The vaporiser doesn’t need cooling between treatments and the dose administered is tightly controlled.
However, OA dosage isn’t critical. It has been shown to be well-tolerated by bees in studies from groups in the UK and Germany. If the dose isn’t critical and speed really is important then perhaps consider the vmVaporizer. At $3600 it’s about ten times the price of a Sublimox.
The manufacturers claim you can treat 300 hives an hour with one of these … one every 12 seconds. For comparison, the Sublimox takes 20-30 seconds per hive. However, what takes the time is sealing the hive, moving the generator about, unsealing the hive etc. so you’d need a team of (well protected) helpers and some closely spaced hives to achieve a similar rate. The vmVaporizer is mains (110V) powered so would also need a generator or inverter.
The video above demonstrates the vmVaporizer in action. It produces copious amounts of oxalic acid vapour, albeit less ‘forcefully’ than the Sublimox. It seems the only way to control how much is delivered is by changing the duration the hive is exposed for.
Undoubtedly this is overkill for the majority of readers of this site, but it’s interesting to see what the commercial beekeeping community are using (much like browsing the decapping or bottling machines in the Swienty catalogue). There’s at least one satisfied UK-based beekeeper quoted on the vmVaporizer site so … Mark, if you happen to read this I’d be interested in how well the machine works and whether you can achieve the quoted hive treatment every 12 seconds?
There’s a saying that goes something like “Ask three beekeepers an opinion on … and you’ll get five answers”. And if it isn’t a saying, then it should be. Have a look at the online forums and you’ll see numerous threads with multiple – often wildly contradictory – answers. This can be a problem for experienced beekeepers and is a total nightmare for new beekeepers.
Inevitably, beekeeping is an inexact science. There are too many variables to be dogmatic about things – the weather, colony strength, available forage, parasite levels, time, beekeeping ability etc†.
Compatibility, standardisation and efficiency
However, one thing that most beekeepers should agree on is that compatibility of equipment is important. For efficiency, your equipment needs to be compatible e.g. using a roof that fits any of your hives. Without compatibility you will inevitably experience the frustration of trying to make incompatible equipment ‘fit’ together, or have to make repeated trips to the apiary with the correct kit.
Been there, done that 🙁
Compatibility is best achieved by standardisation i.e. all hives are of the same size and design, built to an agreed specification or standard, ideally by a single manufacturer. I suggest ‘single manufacturer’ as some don’t adhere to the standards as closely as others. Unless you are, and intend to stay, a single hive owner (and there are very good reasons why you shouldn’t) this is an ideal that is rarely achieved.
If you have more than one apiary you’re likely to be moving hives between them. Again, compatibility is important. Finally, if you are being mentored, acting as a mentor to others or intending to sell nucleus colonies, it helps if your hive equipment is compatible with others.
This compatibility starts with the frame size – and therefore defines the brood/super dimensions – and the frame spacing (e.g. Hoffman/Manley), but extends to whether the hives are bottom or top bee space, the types of floors, entrance blocks, clearer boards, split or division boards, feeders etc.
We’re spoilt for choice in the UK … literally.
Compare the hive types sold by some of the largest suppliers of beekeeping equipment in the UK and USA e.g. Thorne’s and Dadant. Thorne’s list about eight removable-frame hives (National, WBC, Langstroth, Commercial, Dadant, Smith, Rose and Dartington). Dadant list just one (Langstroth, albeit in 8 or 10 frame widths). I know that some hives use the same frame sizes∏, but have also simplified things by ignoring the range of frame depths offered – 14×12’s, shallows, mediums, deeps etc. In this post I’m only really concerned with box compatibility.
No wonder many starting beekeeping ask “Which hive should I buy?”. They’re probably advised to get whatever is in use locally, often Nationals, but increasingly Langstroths in some places or Smiths in parts of Scotland. The recommendation to start with whatever is used locally is both logical and pragmatic. The beginner is likely to have to source a nucleus colony to start with and (hopefully) this will have been purchased locally, from a more experienced beekeeper (their mentor?) with gentle bees of known provenance, adapted to the local climate and inspected before purchase‡.
In the overall scheme of things I don’t think the choice of hive type is particularly important. None are inherently better than others, though a few are perhaps worse. The bees, Apis mellifera, are the same and certainly don’t care. Far more important is that the equipment acquired is compatible – with what is already owned, with what might be purchased, built or inherited in the future, and with what others use.
Running out of kit
A universal truth about beekeeping is that, sooner or later, you’ll run out of equipment. For beginners it’s during their first swarm season when they suddenly find they need a complete additional hive to undertake the classic Pagden ‘artificial swarm’ method. Alternatively, or perhaps simultaneously, they capture a swarm and have to house that. It’s not unusual for all this to happen in the same week of the same month of the first year of beekeeping.
It can be a little chaotic 🙂
Gaffer tape apiary …
There are two or three obvious ways to reduce the equipment crisis. Firstly, use a version of the vertical split rather than a Pagden artificial swarm, thereby reducing the need for an additional floor and roof for starters. Secondly, bodge a solution … use stacked supers as a makeshift broodbox, build roofs out of Correx (abandoned For Sale signs should always be repurposed) or use an upturned plant tray or piece of polythene-covered plywood. Finally, borrow suitable kit from a friendly local beekeeper … which brings us back to compatibility again.
Don’t for a moment think that a dozen colonies and a decade’s experience stops a beekeeper running out of equipment. A couple of years ago we had a bumper summer and I ran out of supers. Most colonies had 2-3 supers on already and there seemed to be no end in sight to the nectar flow. It was fantastic. A generous friend loaned me a dozen supers to buy me enough time to remove the first fully capped supers, extract the honey and recycle the boxes. Without this act of generosity – only possible as my friend was downsizing – my hives would have become packed with nectar and the colonies might have swarmed.
It’s at these times that equipment compatibility becomes paramount. I could borrow and use those supers as my friend also ran Nationals. The beginner can of course borrow any type of kit, but if the artificially swarmed colony needs to subsequently be united with the original box then it’s much easier if the equipment is compatible (note the thin shim in use in the picture below, between the incompatible poly boxes on top and standard cedars). As it turned out, the supers I borrowed weren’t 100% compatible as my friend used top bee space whereas mine were bottom bee space … the bees and I coped.
This need to mix’n’match equipment happens every season. You might want to move frames about to boost particular colonies, to mix frames removed from several strong colonies to make up nucs for overwintering, to unite nucleus colonies after using the newly mated queen from one of them, or merge two very uneven strength colonies for overwintering. It even happens when trying to efficiently ‘use up’ two- or three-frame nucs used for queen mating at the end of the season – it’s far easier to simply drop these into full-size hives than do the same thing with brood and bees from mini-nucs.
Uniting with newspaper …
Not only the big box items
Equipment standardisation and compatibility also extends to things other than frames and boxes. There’s a host of other items where it’s beneficial to have one type only, and for that type to be compatible with your other equipment. Floors are a good example; if they’re all made to the same design and dimensions then the removable Correx Varroa trays, the entrance reducers and the travel screens/entrance blocks are perfectly interchangeable. Both crownboards and roofs should also be broadly standardised and compatible. For example, all my colonies have year-round insulation in the crownboard and all the roofs are uninsulated. I previously had some insulated roofs and some uninsulated crownboards. Inevitably, moving or uniting hives resulted in the odd colony lacking insulation altogether. D’oh!
Correx in the frost …
The dreaded overhang …
Varroa tray …
I’ve slowly achieved a reasonable level of standardisation and compatibility across my apiaries. I’m hoping that this will be improved further in 2017. After using a range of hives – purchased, borrowed and homemade, I’m settling on:
Standard depth, bottom bee space, Nationals in cedar or poly but – critically – these boxes must be interchangeable. To this end I’m using standard cedar broods and supers, or Swienty poly equivalents. These have the same external dimensions (18″/46cm), so can be stacked as required, and the interface between boxes is completely flat.
Just two floor designs. One has a fully sealed Varroa tray – built by Pete Little – and is used exclusively in the bee shed. The entrance reducer is fitted permanently to these floors. The second type are the so-called ‘kewl’ floors with a Dartington-inspired underfloor entrance. All my kewl floors are homemade. Despite this (and my amateur DIY skills), they take the same size Correx Varroa tray, all have holes drilled in the correct places to a) attach luggage scales for winter ‘hefting’, and b) deliver vaporised miticides. In addition, all take the same size and design entrance block for transport or other operations when the entrance needs to be sealed (vaporisation, vertical splits or Bailey comb changes).
Roofs are all uninsulated, interchangeable and either standard wood/metal or simple sheets of folded Correx. They serve no other purpose than weatherporoofing. I gave away all my insulated roofs when I moved North.
All crownboards are insulated, either with inbuilt Kingspan blocks or by the addition of an 18″ square block on top. None have feeder holes. Almost all are reversible and I’ve got ekes to achieve the same separation when I need space to feed fondant.
All nucleus hives are Thorne’s Everynucs. This design has a removable floor, so two bodies can be stacked for uniting.
But … if I were to start again from scratch I’d probably use Langstroths. I use Nationals because I’ve invested in Nationals, not because I think they’re inherently better.
Exceptions to the rule
Or compromises …
All of my bait hives are MB/Paradise poly Nationals (or stacked supers from the same manufacturer). All have simple Correx floors and roofs, or those supplied at purchase. Almost none of these items – floors, boxes or roofs – are readily compatible with production hives. This poly hive design has an infuriating lip/overhang that makes them incompatible with standard National equipment (see images above). Bait hives tend to get lugged about a bit more than production hives so their low weight is a bonus. My continued use of these hives is a perfect example of meanness and generosity … I’m too mean to get rid of them and I’m too generous to palm them off on an unsuspecting beginner.
My Everynucs are not directly (i.e. box to box) compatible with National hives though of course the frames are. I therefore can’t stack nucs onto standard brood boxes – for uniting, for overwintering or for certain types of queen rearing operations. This is a compromise I have to make due to a) the finances and time I have invested in these poly nucs, and b) their overall benefits and quality, both of which I remain convinced about. I have a few lovely cedar nuc boxes built by Pete Little that can be used for the queenright queen rearing method developed by Steve Rose if needed.
I have a few Paynes 8-frame nuc boxes used solely to capture swarms (or for dire emergencies). These are lightweight boxes with flimsy lids and no removable floor … ideal for use in one hand at the top of a ladder.
Paynes nuc box …
Outstanding improvements to compatibility
Outstanding as in ‘not yet achieved’ that is. Sorry if you were expecting some brilliant insights here 😉 Regular readers are unlikely to have been mislead.
The entrance holes through the bee shed wall are of two sizes and the larger ones will be replaced (reduced) at some point. When I first built them I overestimated the size needed. The oversized entrances are too big for a weak colony to defend and the different sizes means I need two types of foam entrance blocks when vaporising.
Secondly, I have to decide on a standard way to block/reduce the entrance of the poly Everynucs. I’ve previously used a hotchpotch collection of wire mesh, foam or wooden blocks. The entrance on these nucs is ridiculously large and I’ve been dabbling with a few simple designs over the winter. I need a simple and inexpensive ‘fix’ as I have a lot of these boxes … as usual, Correx is my friend!
Reduced entrance …
Finally, I’ve recently purchased a stack of Abelo poly hives for work and will be interested to see how these perform this season. These boxes are ‘Nationals’, but ever so slightly different from the Swienty and cedar boxes. However, the dimensions and interfaces of broods and supers are definitely compatible, so they should mix’n’match OK. This purchase was a perfect example of how beekeepers end up with a wide range of different gear … they are supplied ready-painted, so save time, and they were cheap as chips in the Abelo sale 😉
† Of course, the widely divergent views expressed on some of the discussions forums simply reflects a bad case of midwinter cabin fever and the contrariness of some contributors.
∏ And irritatingly, some take the same frame sizes, but with either short or long lugs. Grrr.
There has been a prolonged spell of cold weather in Eastern Scotland. Temperatures have rarely risen above 5°C, with hard frosts overnight. However, a warm front moved in on Tuesday night and the last few days have been significantly warmer†. The lack of activity at the hive entrances and a quick peek under the insulation through the perspex crownboards (where fitted) indicated the bees were all tightly clustered during the cold spell. Furthermore, the absence of debris on the removable Varroa monitoring trays fitted to many of the open mesh floors, suggested that little or no brood was being reared.
Ridiculous to the sublime
Varroa trays …
There was another clue that the colonies are likely broodless. I had been recording the natural Varroa drop of a few colonies over the last month. I did this by simply counting Varroa at each visit, calculated on a mites/day basis. Although generally low (and very low in a few colonies), it had been steadily increasing. This is a good indication there were more phoretic mites in the colony … again, presumably due to the absence of suitable brood for them to parasitise.
It’s worth noting that the natural mite drop is a notoriously unreliable method of accurately determining mite levels in a colony. For example, it’s dependent upon the amount of sealed brood in the colony. With no sealed brood all mites must be phoretic. In contrast, with limitless sealed brood 80-90% of the mites are within cells. However, although estimates from mite drop are not hugely accurate, they are a lot better than doing nothing. The National Bee Unit has published a Varroa calculator. This allows you to use a combination of the mite drop per day, the time of year, length of season and level of drone brood to predict the total numbers of mites in the colony. For some inexplicable reason this asks for the level of drone brood in December … with 0% not being an available option 🙁
Time to treat
With little or no brood in the colonies, now is a perfect time to treat with an oxalic acid-containing preparation to hammer down the remaining mite population. I’ve previously discussed the importance of this midwinter treatment (see Two treatments … a double whammy). In many ways it’s preparation for the season ahead, rather than for the protection of the bees already present in the colony. The lower the mite levels are at the beginning of the season, the longer it will take for the mite population to reach dangerously high levels.
You can model these events using BEEHAVE. This is an interesting in silico model of a beehive. With mite numbers of ~10 at the beginning of the year, maximum levels reached are low to mid-hundreds by late summer, reducing to a couple of hundred the following winter. This assumes no intervening treatment and runs the model using all the default settings. In contrast, using the same parameters but starting the year with ~100 mites, levels peak at between 3000 and 4000 mites, returning to about 1800 in December.
Remember that the National Bee Unit recommends mite levels should not exceed 1000 or there is a risk of “significant adverse effects on the colony”. Therefore, the midwinter treatment is an important preparation for the year ahead, delaying the point at which these dangerously high mite levels are achieved.
Have your hives got less than 100 mites in them now?
Remember also that, with no sealed brood, midwinter is also the ideal time to expose as many mites as possible to the treatment. With the exception of prolonged treatment with hard chemicals like Apistan or Apivar, it’s probably the only time you’ll achieve greater than 95% reduction in mite numbers. With little or no brood present there’s nowhere for the mites to hide.
Dribbling or vaporisation?
An oxalic acid-containing treatment is recommended in midwinter. This can be delivered by dribbling or sublimation (vaporisation). Under optimal conditions, efficacy of the two methods is broadly similar (90%+) though there is some evidence that dribbled oxalic acid is slightly detrimental to colonies (when compared with sublimation, but not when compared to doing nothing).
Sublimox in use …
Api-Bioxal is the VMD-approved oxalic acid-containing treatment. If used for dribbling be aware that the suggested concentration on the side of the packet is higher than conventionally used in the UK. It’s also worth noting that it’s not available pre-mixed so has to be made up from powder. In this regard it’s a less useful product than the pre-mixed oxalic acid solution that Thorne’s (and possibly other suppliers) sold each winter. The one- or two-hive beekeeper needs to weigh out very small amounts accurately, or get together with others to make a large batch. Hardly what I’d call progress. Furthermore, the inclusion of glucose and powdered silica (as an anti-caking agent) in Api-Bioxal means it leaves a caramelised mess if used for vaporisation. Although a scouring pad and elbow grease will get rid of this mess, it’s another example of how the “approved” commercial product is actually less good – and no more effective – than the oxalic acid dihydrate that beekeepers have been using for 20 years or more.
Notwithstanding these negative comments, Api-Bioxal works well and is less expensive (per treatment) than most of the other VMD-approved Varroa treatments.
Don’t delay, get out and get dribbling …
The forecast for the next 7-10 days is for significantly warmer temperatures. This means that the queen – if she was having a break from egg-laying – will start laying again. There will be open brood by this weekend and sealed brood in your colonies by about the 15th of December‡. Dribbled oxalic acid is detrimental to – and may kill – open brood so if this is your preferred method of treatment then don’t delay. If you sublimate you’ve got a few days leeway, but don’t delay any longer than that.
Here are a couple of old videos showing trickling (dribbling) oxalic acid onto a large and small colony in the middle of winter. The Trickle bottle from Thorne’s makes administering the treatment very quick and easy.
Of course, sublimation using an active vaporiser like a Sublimox is even faster and doesn’t involve opening the colony. Here’s an example showing treatment of a recently hived swarm in midsummer … I could have removed the Sublimox after about 30 seconds.
The Daily Mail may be predicting the coldest winter since the last ice age (so perhaps there will be another broodless period§) but I wouldn’t rely on them to influence something as important as the midwinter treatment for reducing Varroa levels.
† Here’s a perfect example of the problems encountered by the ‘topical blogger’. I wanted to write about midwinter Varroa treatment in the middle of winter, at a time when others – particular new beekeepers – should be treating their own colonies. Typically these treatments are made in late December or early January. However, the long-range (10 day) forecast in late November suggested the second week of December might be suitable. Some of this was therefore written in very late November, the Varroa drop comments added once I’d completed counting around the 4th to the 6th, and the post finished off the following day once I’d treated my own colonies.
‡ This assumes that the queen started laying on the 7th, the first full day with elevated temperatures.
§ I didn’t open any colonies to confirm they were broodless. I was happy enough to take the clues from the increased mite drop on the Varroa trays and the absence of debris indicating uncapping of brood cells. However, I was told by friends that other colonies they opened on the 7th were broodless.
Today was very mild, slightly damp and breezy after a prolonged cold spell (at least here in Scotland). The long, cold spell means that colonies are broodless†. Now is an ideal time to apply your midwinter Varroa treatment. Don’t wait until the Christmas holidays, don’t wait until the weekend after next … colonies will probably have sealed brood again by then. For maximum effect treat while the colony is broodless and decimate the phoretic mite population.
I treated all my colonies late this afternoon and evening. I finished the last using a headtorch for illumination and tidied up under bright moonlight. The bees looked good and it was great to be doing some beekeeping again, if only briefly.
† A longer post justifying why the colonies were considered broodless and why it is so important to treat when they are broodless will appear this Friday.
The rather weak title is a variant of Shakespeare’s “Out, damned spot” from the play Macbeth. Thewords are spoken by the sleepwalking Lady Macbeth who is going insane with guilt after her husband killed Duncan (the King of Scotland). The spot refers to Duncan’s blood. Mites on the Varroa tray look like tiny spots of blood …
If you haven’t yet treated your colonies to reduce Varroa levels before the winter arrives it may well be too late†. High Varroa levels are known to result in the transmission of virulent strains of deformed wing virus (DWV). These replicate to very high levels and reduce the lifespan of bees. If this happens to the ‘winter bees’ raised in late summer/early autumn there’s a significant chance that the colony will die during the winter.
Mite levels in most of my colonies have been very low this year. Partly due to thorough Varroa management in the 2015/16 winter (the only thing I can take credit for), partly due to the relative sparsity of beekeepers in Fife, partly due to the late Spring and consequent slow build-up of colonies and partly due to an extended mid-season brood break when requeening. Most colonies yielded only a small number of mites (<50) during and after a 3 x 5 day treatment regime (to be discussed in detail in a later post) by sublimation.
The low mite drop definitely wasn’t due to operator error or vaporiser malfunction. At the same time I treated a swarm that had moved into a bait hive in early June …
Out, damn’d mite …
This is ~20% of the Varroa tray. Have a guess at the number of mites in this view only. Click on the image to read the full legend which includes the mite count.
The image above was taken on the 18th of September, a day or two after starting the second round of 3 x 5 day treatments. The colony really was riddled. When a colony swarms 35% of the mites in the colony leave with the swarm (or, in this case, arrives with it). For this reason the swarm was treated for mites shortly after it arrived in June. It did have a reasonably high mite load but subsequently built up very quickly and didn’t experience the mid-season brood break my other colonies benefitted from.
The colony now has an acceptable mite drop (<1 per day). Similar colonies are still rearing brood – I’ve not checked this one, but they are bringing in some pollen from somewhere – so there’s a possibility the majority of the remaining mites are tucked away in sealed cells. I’ll keep a close eye on this colony through the next few weeks and will be treating again midwinter to further reduce the parasite burden.
Treat ’em right
If you are treating this late in the season make sure you use a miticide that is appropriate for the conditions. Apiguard (a thymol-containing treatment) is almost certainly unsuitable unless you’re living in southern France as it needs a temperature of 15°C to be effective. MAQS has a recommended temperature minimum of 10°C which may be achievable.
Hard chemicals such as Apivar and Apistan can be used at lower temperatures but there’s little point in treating with Apistan unless you’re certain all your mites are sensitive. They almost certainly are not as Apistan/Bayvarol resistance is very widespread in the UK mite population. Just because you get an increased mite drop in the presence of Apistan does not mean treatment has been effective. Perhaps all you’ve done is killed the sensitive mites in the population, leaving the remainder untroubled. This is what’s known as a bad idea … both for your bees next season and for your neighbours.
† I’m posting this now due to the large number of searches for, and visits to, pages on use of Apiguard or other Varroa treatments. These are currently running second to ‘fondant‘ in one form or another.
The last colonies to be treated for Varroa this late summer (early autumn?) are those in the bee shed†. These have had consistently low levels of mites all season … levels were so low that we uncapped two full frames of drone brood (individually) from one of them in June without finding a single mite.
reduced queen laying at this time of year means mites have fewer pupae to target resulting in elevated infestation levels in the critical winter bees (and why this is important). In recent sampling of pupae we’ve seen an increase in the number of mites in capped in cells which we assume is due to this.
we need to keep these colonies with the lowest practical mite levels.
… they were treated anyway. I’m reasonably confident that sublimated oxalic acid (which is the active ingredient in Api-Bioxal) does little or no harm to the colony, and am sure that the mite reduction is always beneficial. I’d therefore prefer to treat than regret not treating at a later stage in the winter or early next season.
Expose the bees to the vapour … not the beekeeper
There’s nothing fundamentally different about treating colonies in the bee shed than those outside. Using a Sublimox vaporiser is very straightforward. However, two points need a little more care than normal.
The first is the sealing of the colony. To be effective the vapour must be evenly spread throughout the hive. Because of the ‘tunnel-like’ entrances there are more potential gaps from which the vapour can escape. I therefore do my best to push the hive tightly against the entrance tunnel after sealing the latter with a block of foam. The floors on these hives were built by Pete Little and have a commendably leakproof Varroa tray, making them ideal for sealing the open mesh floor. As an aside, don’t try squirting the vapour in from the entrance … direct inspection through the Perspex crownboard suggests that (at least in my setup) the vapour only poorly permeates the hive if administered like this. Been there, done that. The goal is to get the oxalic acid crystals spread evenly and thoroughly throughout the hive, ensuring maximum exposure to the mites, and maximising the duration of activity against,
Vapour spreads well …
Vapour leaks out …
The second point relates to the ‘leakiness’ of the hive and the fact that it’s in an enclosed space (the shed). There’s therefore no chance of standing upwind and allowing escaping vapour to drift away safely. Operator protection is particularly important as the shed is liable to fill with oxalic acid vapour. Eye protection and a suitable particle mask rated for acid particulates are essential. It’s a case of “lighting the blue touch paper and retiring to a safe distance”. With a Sublimox you can simply invert the machine – into the ‘delivery’ mode – and leave it hanging out of a hole through the sidewall of the floor (see photo above right). There’s a couple of seconds before sublimation starts which you can use to step out into the fresh air, only returning once the vapour has cleared.
Finally, if you run your vaporiser off a generator it should also be left outside the shed. Don’t gas the bees when you’re gassing the bees 😉
† Plus a recalcitrant swarm that’s on it’s second round of treatment due to the stubbornly high mite levels. Grrrr.
Vaporising Api-Bioxal leaves a burnt caramelised residue in the vaporiser. This is difficult to clean. Does this damage the vaporiser or make it work less efficiently?
Forget it …
I remortgaged the house, took my kids out of university and cancelled both trips to Mauritius later this year, all so I could afford some Api-Bioxal (a snip at £10.99 for 35g from Thorne’s). Api-Bioxal is the VMD-approved oxalic acid-containing miticide. Only ‘containing’ as – according to the manufacturers instructions – only 88.9% of the dodgy-looking white crystalline powder is actually oxalic acid (OA). The remaining ~11% is a mixture of glucose and powdered silica (VMD documentation [MS Word]) . As cutting agents go, these are relatively harmless. Nevertheless, some have expressed concern that the presence of glucose might leave a horrible gunky mess (a widely accepted technical term) in the bottom of the vaporiser. Let’s see …
Since I’d promised to help a friend with vaporising a few hives that were disappointingly Varroa-riddled when treated earlier in the winter, this seemed a good opportunity to do a side-by-side comparison of Api-Bioxal and OA vaporisation – in terms of residues, not efficacy¹. My vaporiser is an ‘active’ model (made by Sublimox) in which the vaporised oxalic acid is forced out through a small nozzle in about 20-30 seconds (see video). In use, the OA crystals are dropped into a preheated pan – by inverting the Sublimox – so the temperature change from ambient to 157ºC happens more or less instantaneously. Any comments below therefore might not apply to the passive vaporisers like the “Varrox”, or the plethora of home-grown ones² on the forums or variants listed on eBay. In the majority of these types the powder is added to a pan which is then heated to the sublimation temperature³.
At the start of the trial the pan of the Sublimox was clean, contained no residues and was only slightly tarnished (from historical use). This machine has been used dozens of times previously and in each case has been washed out with clean water after use as instructed by the manufacturers.
After a single colony was treated with 1.6g of Api-Bioxal the pan of the Sublimox contained an obvious charred residue.
Single use …
We treated one further hive with Api-Bioxal and took another photograph of the vaporiser ‘pan’ which now contained an even more obvious charred caramelised deposit, bubbled and lumpy in places. This wasn’t a loose flaky deposit, it was burnt onto the base and lower sidewalls of the vaporiser ‘pan’.
Two treatments …
In use the ‘collar’ around the plastic (delrin?) cups used to deliver the OA/Api-Bioxal usually have slight traces of the powder left around them. These were particularly obvious when using Api-Bioxal though I’m not sure any greater amount of powder was left here … it just looked a lot worse. It was also more difficult to clean off than ‘pure’ OA.
Plastic cup …
The caramelised charred residues remaining in the vaporiser after two Api-Bioxal treatments needed a combination of scraping with a knife and repeated rinsing with boiling water to remove it. This took several minutes and would clearly be impractical (and irritating) to do between treatments, meaning that the residues would build up quickly over time. Compare the first and second image in the series above to see how much residue builds up at each use (and see the note below regarding the amount vaporised).
Cleaned vaporiser …
I then added 1.6g of standard oxalic acid dihydrate (Thorne’s) and vaporised it before immediately photographing the unwashed pan and cup. The photo below should therefore be compared directly with the first in this series. You can see the traces of OA powder at the end of the nozzle of the vaporiser, but the pan is completely clean and contains no additional charred and caramelised residues. This vaporisation was done ‘in the open’ (i.e. not into a hive) and it was interesting to see how long it took the extensive cloud of crystals – perhaps 5 x 2 x 2m in extent – to dissipate as it gently drifted away downwind.
Single OA use …
But it gets worse …
I actually used much less Api-Bioxal per hive than the manufacturers recommended 2.3g per colony (this is partly because there is published evidence that ~1.4g is sufficient and double that amount provides no increase in mite killing). I didn’t weigh the Api-Bioxal but used one measuring scoop that – from previous tests – is known to contain ~1.6g of OA when full. Had I used the full recommended dose of Api-Bioxal I would have therefore expected the residue build up to be about 50% worse than shown above. On a vaguely brighter note, the powdered Api-Bioxal pours easily and smoothly, presumably because of the anti-caking agents it contains.
What are the implications of this?
I am very disappointed with the amount of residues left in the vaporiser after using even a single (less than recommended) dose of Api-Bioxal. I’m also disappointed with how difficult these are to clean out of the vaporiser. Might these residues damage the vaporiser, for example by blocking the nozzle, or reduce the effectiveness of vaporisation, for example by not allowing the pan to heat as evenly or quickly? I think both of these are a distinct possibility. An advantage of vaporisation is the ease and speed with which OA can be administered. If the vaporiser needs to be cleaned between every (or even every few) hives it would significantly reduce the attractiveness of this type of Varroa treatment. Remember, if you take your PPE seriously – which you should when vaporising oxalic acid – you’ll be wearing gloves, a respirator/mask and goggles throughout this entire procedure, including cleaning out the residues from the hot vaporiser.
Update … 22/2/16
Chris Strudwick kindly sent me before and after photographs of a Bioenoxal vaporiser that had been used once with Api-Bioxal. The ‘before’ image (left) shows the machine after vaporising 1.6g of Api-Bioxal. The ‘after’ shows the “result of 5 minutes with a nylon pan scourer and water after an initial scraping with a hive tool” … so the gunk can be cleaned off, but it takes time.
Many thanks Chris
¹This would have entailed treating hives with a known Varroa-load with either Api-Bioxal or OA. This was not done.
²Some of the DIY vaporisers are either spectacularly dangerous or have been designed without an appreciation of the temperature control required to vaporise oxalic acid.
³If you have a “Varrox”-type vaporiser I’d be interested to hear your experience with using Api-Bioxal.
Many beekeepers use oxalic acid (OA) to control Varroa numbers, by trickling a low percentage (w/v) solution over colonies in winter, or by vaporisation/sublimation. Oxalic acid dihydrate (a white crystalline powder) has been sold by most of the large beekeeping suppliers for years, and the BBKA have provided instructions on its use as a ‘cleanser’. Until recently OA has not been licensed by the UK’s Veterinary Medicines Directorate (VMD) for use as a Varroa control (hence use of the term ‘cleanser’ by the BBKA) but was available under the EU Cascade Scheme as the product Api-Bioxal from Italy, where it was licensed. Api-Bioxal was licensed by the UK VMD in September 2015.
Librae,solidi,denarii … pounds, shillings and pence
Assuming the largest quantity available is the most economic way to purchase OA (which may or may not be correct) then Api-Bioxal currently costs about £0.21/g from E.M. Thorne. The same supplier are selling generic OA crystals for £0.016/g. The recommended dose for Api-Bioxal vaporisation is 2.3g/colony (stated on the product label), though the size of the colony isn’t indicated. Aside from the problem of weighing out 2.3g in the apiary, this makes single treatments with Api-Bioxal cost about 50p a shot. My Sublimox vaporiser was provided with a small scoop which dollops out 1.5g at a time of OA (confirmed on a laboratory balance), which is about all that can be conveniently loaded into the white plastic thingy (my poor translation from the original Italian … see the photo right) from which it drops into the heating pan. That’s the amount I use for one treatment of a single brood National hive. Thomas Radetzki has looked at the efficacy of 1.4g and 2.8g doses – most conveniently found in this graph from Randy Oliver’s Scientific Beekeeping website – which are effectively indistinguishable, so I choose to use the lesser amount. Therefore, using generic OA supplied by E.M. Thorne makes treatments cost less than 2.5p each. Quite a difference.
OA is available from other suppliers as well, and is also widely available as a boat deck cleanser … and if you’ve got a large enough yacht you can probably justify buying 25 kg of the stuff for less than £70. Or a lot of hives … at that price it works out at less than 0.5p/treatment 🙂
Time to stock up?
This is why we treat …
The licensing of Api-Bioxal as the first approved OA miticide in the UK is to be welcomed if it encourages beekeepers to reduce mite levels in their colonies. It is, after all, the viral payload the mite transfers between bees, that causes significant levels of overwintering colony losses for beekeepers. I’ve no doubt that the licensing (and the associated testing needed for getting this approval), the packaging and the marketing have added significantly to the costs of the oxalic acid dihydrate. However, at about 20 times the price of the generic powder from the same beekeeping suppliers, there are some who will consider this profiteering.
Over the next few months and years it will be interesting to see whether generic OA disappears from beekeeping suppliers because their customers have all switched to using Api-Bioxal, which they meticulously record in their hive notes under ‘medicines’ … or whether Api-Bioxal fails to succeed because beekeepers continue using the same stuff, admittedly unapproved and unlicensed, they been using for many years without any problems.