Varroa Mites – Oxalic Vapour Treatment

I had to come to a hard decision to treat my bees. The hive had reached a daily Varroa drop count of nearly 100. The writing was on the wall, I either did something or I would lose my bees and have to start again next year. My long term strategy is to breed bees that can handle Varroa themselves and to regress my bees to impede the varroa life-cycle. But the hard truth is I’m just not there yet.

I was unable to fully regress the bees this year because of the late season start, nor was I able to do a split. So I am left with one hive and no real options other than to treat to get them through the winter in reasonable shape. Next year I hope to both regress all my bees and to go into the following winter with at least 3-4 hives. If I had that number of hives – I would probably not treat and just let nature select the strongest bees. But this winter, the bees just need to live, so they can fight another day.

The method I have chosen is Oxalic Vaporization. This uses a small heater to vaporize oxalic acid crystals into a gas. This gas fills the hive with then recrystalises into tiny oxalic acid crystals that coat the inside of the hive. The Oxalic acid crystals are deadly to the mites but the bees seem to tolerate with little ill effect. Whilst I would not call this treatment in any way “natural”, oxalic acid is an “organic” acid and present in low dosages in the hive and many common foods. Research into the effects of this treatment have indicated no build up within the wax or the hive and no negative effects on the bees or pupae (if present).

I did my first treatment this morning, it took about 15 minutes and the bees seem to be getting on fine. I have not opened up the hive but it is likely that there is still some brood present as pollen is still going in. I may therefore do a follow-up treatment in a weeks time. The best time to treat is when there is no brood because varroa within a capped brood cell is protected from the initial effects of the treatment. Below is a video from Varrox who make the vaporizer I used.

Bottom Board 2 days after oxalic acid vapor treatment

Bottom Board 2 days after oxalic acid vapor treatment

Update 11th Oct 2013:  Below is a picture of the bottom board some 36 hours later. An approximate count gives a mite drop of around 1000 mites. The white powder is unburnt oxalilic acid. I had to insert the vaporizer through the rear bottom board entrance as the hive entrance was too small. I am concerned that I did not get a complete burn because of the amount of oxalic acid that was left around the vaporizer seemed high. I will treat again in a week.

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