Oxalic acid and LSD

Api-Bioxal has recently been approved by the UK Veterinary Medicines Directorate and is available from the usual suspects. At a price.

Oxalic acid ...

Oxalic acid …

OA crystals on bee ...

OA crystals on bee …

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

Sublimox vaporiser

Sublimox vaporiser

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 ...

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.

* and you thought MAQS was expensive?

9 thoughts on “Oxalic acid and LSD

  1. Emily

    This is a bit of a pain in the butt! It looks like Thornes are not selling a pre-mixed Api-Bioxal syrup solution, which is how I’m used to using oxalic acid. So I would have to use my kitchen equipment to make up the syrup, weigh the correct amount of Api-Bioxal out and mix it together. And I can’t stock up on pre-mixed oxalic acid as Thornes say it deteoriates quickly and only lasts two months 🙁

    1. David Post author

      Pre-mixed OA does go off pretty quickly … I’m not sure quite how fast but the HMF levels build up and I always chucked it out after a couple of weeks. Better to be safe than sorry. This was homemade rather than purchased and I’m sure I was being overly-cautious. Chemicals Laif – the manufacturers (packagers?) of Api-Bioxal – clearly expect end users to mix their own. If you bought the smallest packet and carefully calculated the amount of syrup needed you wouldnt need to weigh anything – just tip the entire packet in and mix well. So your kitchen would remain uncontaminated …

      Alternatively, if you found a suitable measuring scoop (perhaps a 1 tsp measure) and weighed the OA it would hold – just once – you could then use it, or multiples of it, to prepare your own trickling mix. That way you could prepare small amounts to treat swarms or shook swarms as needed. The powder keeps for ages if kept well sealed … which is fortunate for those who purchase kilograms at a time (to clean their yacht decks 😉 )

  2. Tim

    Having looked at this product at the honey show recently, this is the same oxalic acid we have been using before just packaged in a nice bag. I have to agree that this is profiteering and from some of the info I have seen, the NBU say they will prosecute those found using other oxalic acid not under the cascade system, proving and policing it will be difficult I think.

    1. David Post author

      The package leaflet/labelling for Api-Bioxal claims 88.6% is ‘oxalic acid dihydrate’, so I’m not sure what the remaining 11.4% is … possibly some sort of inert carrier or stuff to prevent clumping. In contrast, the oxalic acid dihydrate routinely available online is often 99% pure. With OA available so widely – not just from beekeeping suppliers – I also think it will be difficult (and due to extensive custom and practice, very unpopular) to enforce. We’ll see …

      STOP PRESS [edited 12/11/15] – there’s an interesting thread on the BBKA forum that discusses the ‘other’ 11% in Api-Bioxal, suggesting it is a mix of glucose and anti-caking agents (though the source of this information isn’t cited). The glucose might not work well in a vaporiser …

      STOP PRESS [edited 30/1/16] – Vaporising Api-Bioxal makes leaves a horrible gunky mess in your vaporiser … I know, ‘cos I tested it 🙁

  3. Madasafish

    Lots and Lots of oxalic acid on ebay – for cleaning things..

    Cheaper than any other suppliers.

    I have a boat to clean – it’s always underwater so you cannot see it.

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