Oxalic Acid Treatment
Oxalic Acid is labelled as a poison and may be fatal if swallowed. It causes severe irritation to skin, eyes and the respiratory tract.
With the dangers in mind, I think its best to purchase a ready made solution of Oxalic Acid ready rather than mixing the Oxalic Acid crystals with sugar and water. Also – when you buy ready made Oxalic Acid there is less risk of killing the bees due to too incorrect concentrations.
The literature says this treatment can remove 90% of varroa mites in a colony. There will be a big mite fall on the first day and they will continue to fall for about two weeks after treatment.
When I applied Oxalic Acid in December 2013 I got a 40% reduction in Varroa (Post: Acid-Resistant Bugs).
The acid will kill varroa providing they are not in a capped cell. When there is brood in the hive normally only about 15% of the mites are found on the bees. The rest are in the brood. So treat when colony is broodless. Another reason to ensure colony is broodless is that oxalic acid will kill open brood.
It is difficult to judge when the hive is broodless. Most colonies stop raising brood when the temperature remains below 5C. After 3 weeks at temperatures below 5C the hive will be broodless. Hence, the beekeeper has to judge when they believe the longest sub-5C spell has come to an end and then treat.
In the UK research has shown that between 10-25 December is the optimal time for applying Oxalic Acid with December 21/22 (Winter solstice) often often quoted as the best date. Typically, the Queen will start laying again in early January.
Oxalic acid can be used on both natural and artificial swarms during their broodless period.
- Wear your bee suit, washing-up gloves and goggles.
- Trickle 5ml per seam of bees (a seam is the gap between 2 brood frames) using a syringe.
- Do it as quickly as possible and its probably best with a bee buddy.
Here I am applying Oxalic Acid:
This method is less safe and more time consuming. There is the risk of inhaling Oxalic Acid fumes. I am not going to describe or recommend this technique.
If you have found this guide helpful, please use the “like” buttons below. If you want me to let you know when I have created new guides, then please follow this blog.
These how-to guides are provided for general interest and information only. No liability is accepted for any injury or loss arising out of the contents of these pages.