Oxalic acid is an effective treatment against varroa. It burns the feet and tongues of the varroa mites so that they fall off the bees! The treatment is only given in winter when the mites are living on adult bees and there is no brood for the acid to damage.
This weekend the apiary gave the hives oxalic acid as a way of saying ‘Happy New Year’ to our bees. The bees were not pleased, as they do not like their cosy cluster being disturbed in winter, and flew up as soon as the crown board was lifted. John Chapple, who is rarely seen behind a veil, observed that even he wears a bee suit when giving oxalic acid to the bees. Although the bees were not pleased, Emily and I enjoyed saying hello to our ladies again, and both hives looked healthy and strong.
The treatment is given as a pre-mixed solution of 3% oxalic acid in sugar syrup and warmed slightly so that it won’t chill the bees. About 5ml of solution is dribbled in-between each gap in the frames where the bees are clustered, called seams of bees. The British Beekeepers Association (BBKA) have a good advisory leaflet on oxalic acid cleansing. It is a simple treatment to do, but it is critical to get the dosage right as over-dosing will harm the bees.
Lavender’s ladies were quiet and well behaved for their treatment, while Rosemary’s ladies were livelier. Believe it or not, our bees are much calmer than this in the summer! My first video, I hope to do more this year, shows Emily treating Rosemary’s hive:
Look how disgusted our bees are that we tore apart the sticky propolis insulating the hive! Sadly one bee was squashed as we closed the hive, but we rescued stragglers who had got cold and slow in the roof and carried them around to the entrance of the hives. It was fun to watch them climb in and re-join their sisters.
The BBKA say that oxalic acid is an important part of varroa management alongside other treatments and methods to keep varroa ‘below a level that damages the colony’. As varroa levels at the apiary increased in late autumn, it is hoped that the oxalic acid will help all the hives to stay healthy until spring. There is some talk among beekeepers about replacing treatments like oxalic acid and fumidil with ‘natural’ treatments, but I will write about this in another post in 2012 alongside a re-launch of my blog coming soon.
Happy New Year to bees, beekeepers, everyone and world!
Note: If you have not given oxalic acid to bees before, Glyn Davies of the Devon Beekeepers Association demonstrates the method very well. Emily has more videos of our apiary receiving oxalic acid treatment that are less shaky than my shots!
Mrs Apis Mellifera 
Great post. My dribbling wasn’t as professional as Pat’s! Need some practice I think. Hope I didn’t put too much on them. Great to see how lively the colony was.
We forgot to record doing the treatment and to put our varroa monitoring boards in. Oh well, can do that next week!
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I thought your dribbling was expert and I think John was watching so the bees should be ok 😮 Good to remember hive records and varroa boards next week – one of my New Year resolutions is to be a better beekeeper!
And just thought, we’ll have to practise our frame-making soon for spring. Think we should video our next frame-making workshop at the apiary 😛
Arrgh, is it really frame-making time again? Please no videos of my embarrassing efforts!
I rather like making frames :p and need to practise for the basic assessment in the summer – you could do the videoing as I think your camera skills are better than mine!
Very informative post .Till now , I used to know only the side affects of Oxalic acid in human bodies . But this is awesome that Oxalic acid is also used to trash Varroa . So , it also helps people from different aspects . Nice video but quite risky to shoot .I have previous experience of bee-bite .In India , there is a forest by name ‘Sundarban’ which is one of the main sources of honey in entire India . However , the collected honey is also exported to various countries . That is a quite remote area .Perhaps , they also face the same problem due to Varroa . I wish the farmers or the honey-collectors could read your blog post .thnX again.
Welcome, I’d love to read posts by the beekeepers in India too – sorry that they are also having a problem with varroa. Feel free to share!
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I loved your decorated hive! Happy Christmas and a bee-ful 2013.
Ooh, just spotted this comment! Thanks, I think the bees enjoyed their Christmas.
You may want to try and vaporize OA. Alot easier and don’t have to open the hive and can do it at anytime.
We finally got our first batch of honey last summer and the effort was worth it! The honey is far superior to any you can get on the commercial market. We got another batch last fall. The bees appear to be wintering well.
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