New LASI oxalic acid research published

A comment by the lovely Amelia from on my last post led me to look at the University of Sussex’s Laboratory of Apiculture and Social Insects (LASI) website.

I was dismayed to see a new press release, ‘Scientists determine how to control parasite without harming bees‘, which advises beekeepers not to use the trickling or spraying oxalic acid method (which is what most beekeepers I know use). Instead sublimation (also known as vaporisation) is recommended.

“Professor Francis Ratnieks, head of LASI, says that beekeepers should cease using the other two methods (“trickling” and “spraying”, in which a solution of oxalic acid is used) as they are harmful to the bees and less effective at killing Varroa.”

Research accompanying the press release was due to be published today (Tuesday 5 January 2016) in the Journal of Apicultural Research, but unfortunately this journal is not publicly accessible to non-subscribers. I’ll try to see if I can access it through work as I would like to read the research study – it’s called ‘Towards integrated control of varroa: comparing application methods and doses of oxalic acid on the mortality of phoretic Varroa destructor mites and their honey bee hosts’ by Hasan Al Toufailia, Luciano Scandian and Francis Ratnieks.

The press release says the trickling and spraying methods “cause harm to bee colonies, resulting in reduced winter survival”. I wonder why harm is caused, how great the harm is, and whether it outweighs the harm caused by not treating for varroa at all. Emma and I have never had any colony losses following oxalic acid trickling and I cannot recall other beekeepers having experienced this either, but perhaps LASI have found colonies to be weakened by it afterwards.

Hopefully Beecraft and BBKA News will mention the study in their February issues.

EDIT 29/02/16: The research has now been published and I’m grateful to the Journal of Apicultural Research for generously making it freely available to the public: Towards integrated control of varroa

Treating with oxalic acid. Courtesy The Food and Environment Research Agency (Fera), Crown Copyright.

Treating with oxalic acid. Courtesy The Food and Environment Research Agency (Fera), Crown Copyright.

About Emily Scott

I am a UK beekeeper who has recently moved from London to windswept, wet Cornwall. I first started keeping bees in the Ealing Beekeepers Association’s local apiary in 2008, when I created this blog as a record for myself of my various beekeeping related disasters and - hopefully! - future successes.
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22 Responses to New LASI oxalic acid research published

  1. Erik says:

    I know a lot of US beekeepers swear by vaporization. Be interesting to see the results when they are more widely available.


  2. Emily, I believe on the Randy Oliver site there is credible reference to the fact that the wet application method for OA causes weaker colonies in spring due to some larval mortality, presumably after being fed OA by nurse bees. Vapour treatment is safer and more thorough for the bees, but more dangerous for the beekeeper (full face mask should be used). IMHO, the focus needs to shift to eradication of Varroa rather than “control”, but of course business R&D can only justify research that results in a marketable treatment….preferably one that has to be repeated as often as beekeepers can afford. Only non-commercial interests will be pushing for research aimed at eradication. Meanwhile we need better treatment regimes, safer regimes, and some control of off-label use of treatments by large commercial beekeepers, which is driving resistance and producing more virulent pests and diseases (which drift to the rest of us). And you are right, the only thing worse than treating for Varroa is NOT treating for Varroa! That puts bees and beekeepers in a really unhappy place.


    • Emily Scott says:

      Thanks, will check out what Randy says. I wondered whether LASI could be referring to larval mortality, but the press release does not have a caveat such as ‘on colonies which are not broodless’, which makes it sound like trickling could be harmful to even adult bees. But press releases do not tell the whole story so I hope I can read the research.

      Eradication is difficult in a densely populated area like London, even if I did manage to create a ‘hygienic’ queen, or buy one in, without resorting to artificial insemination her genes would be diluted within a couple of generations by all the drones here from other beekeepers’ hives. Hopefully the bees will sort it out and adapt themselves eventually but that will take a few decades at least and meanwhile I would like my current colonies to say alive!


  3. This latest press release without full facts could come across as a confused message Emily but I think what they are saying out of the three methods of applying oxalic sublimation is now considered to be the best one for the bees. That’s not to say that trickle is not a good treatment if it’s necessary to treat. As you know I don’t use oxalic, I would if I had to but am happy that I have reduced the varroa to low levels come the winter so as not to disturb the bees and if my calculations are out I have a number of options come the spring. Winter oxalic is just another treatment but it’s often wrongly in my opinion thought of as compulsory. I doubt any treatment is without risk to the bees and we have to ballance the damage a treatment may cause over the good it does.


  4. I think Kourosh will treat with HiveClean with three successive treatments and check the fall. If the rain stops! Amelia

    Liked by 1 person

    • Emily Scott says:

      The rain is such a pain! Especially with working five days a week and having the bees away from home, it feels like every time I finally get an opportunity to go and see the hives it’s raining. Will be interested to hear how Kourosh gets on with the HiveClean.

      Liked by 1 person

  5. The Apiarist says:

    Hi Emily, it’s a pity this paper wasn’t published “open access” so anyone can read it without a subscription to JAR. I suspect it would get quite a lot of attention from beekeepers. However publishing like this (if JAR even allows it) usually costs £1000-2500 depending on the journal, so it’s not always possible.

    It’s not clear what this paper adds to the very extensive studies done a few years ago by Thomas Radetski that are cited by Randy Oliver’s ScientificBeekeeping blog ( – mentioned above). OA dribbling has long been known to damage unsealed brood, though whether this alone accounts for the 20% reduction in colony strength is unclear. Vaporisation is certainly well tolerated … colonies settle within minutes of treatment and it can often be done without opening the hive at all (

    I’ve repeatedly treated colonies last year – not continuously (though others have done this) – but multiple times before and after the main flow. The colonies went into the winter with very low mite levels and presumably very low levels of the detrimental strains of DWV. We’re checking this.

    I don’t think eradication is possible, but I do think there are more rationale ways to treat colonies and have written a little about factors that need to be considered recently ( and have an article in the Scottish Beekeeper with Alan Bowman and Fiona Highet in December 2015. OA or Api-Bioxal as a Varroa treatment has a huge amount going for it – no resistance, very cheap (even the latter is only abou 50p per treatment), extremely well tolerated if vaporised, highly effective and with no long term build up of residues in wax or honey.

    Liked by 1 person

    • Emily Scott says:

      I can understand why they wouldn’t make it open access, as the journal has to make money and it’s not a charity. It may be possible for me to get the article at a lower cost through my local library.

      I asked Karin Alton (who works at LASI) on Facebook how harmful trickling is and she said “It really depends on the dose, Emily. If you stick to the recommended dose, the bees should be fine.” This wasn’t really explained in the press release, which just says trickling is harmful to bees without adding any extra explanation.


      • The Apiarist says:

        Hi Emily … I wasn’t clear, sorry. The authors could have chosen to make it open access by paying a fee. Doing so guarantees that everyone and anyone can read the paper. As it is currently, fewer people can read it and the journal – that contributed nothing to the funding of the study presumably – makes the money. There are big changes in academic publishing and more and more things will be available open access.
        The concentration comment is interesting … particularly when you consider that the concentration of Api-Bioxal made up as recommended by the manufacturers is stronger than that routinely used and recommended in the UK.


        • Emily Scott says:

          Ah I see. Perhaps Sussex uni would not have approved of them spending money on that. Would be good if more research was open access though.

          The move towards Api-Bioxal seems more likely to lead to beekeeper mistakes to me, as it can’t be bought pre-mixed. I liked buying it pre-mixed as it meant I didn’t need to worry about mixing it up correctly and using home equipment to do so… it’s an extra job now.


  6. Can I suggest you email Francis Ratnieks asking for a pdf of the paper. Here is his home page with address:
    Most academics are quite happy (and flattered) to be asked for their papers and your blog would be a great place to disseminate the findings more widely.

    Liked by 1 person

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  8. theresagreen says:

    I’m beginning to believe that keeping bees healthy is harder work than it is children! Hope you sort it out and that the bees have a happy and healthy New Year – you too of course!


  9. donna213 says:

    Really interesting. I hope you find out if the method most use is detrimental to hive health. We need EVERY bee now a days and they have far too many obstacles they face daily.


  10. honeymedic says:

    Interesting research.Emma,
    On the general subject of Varroa and DVW (Deformed wing Virus) my friend Professor Reichhart of University of Strasbourg has sent me a link to a very interesting illustrated article about what is happening to Honey bees and bumble bees which you may find interesting in your studies:- INSIGHTS The mite that jumped, the Bee that travelled, the Disease which followed.
    if you gave me an email I could forward it privately.


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