Fight against Varroa: Treatment with oxalic acid, a promising alternative

The fight against Varroa destructor, a formidable parasite of bees, is a major challenge for the health of colonies and the survival of beekeeping. Among the various treatment methods available, the use of oxalic acid stands out as a promising alternative, offering a natural and effective solution to control varroa infestation. In this article, we will examine more closely the properties of oxalic acid, its mode of action, and the application methods to combat Varroa.

Oxalic acid: a natural organic acid

Oxalic acid is an organic acid present in many plants, particularly sorrel, spinach, and rhubarb. It is also naturally produced by bees in small quantities. Oxalic acid is known for its acaricidal properties, meaning it is capable of killing mites, such as varroa mites.

Mode of action of oxalic acid against Varroa

Oxalic acid acts by disrupting the nervous system of varroa mites, causing their paralysis and death. It is particularly effective against phoretic varroa mites, that is, those found on the bodies of adult bees. However, it is not effective against varroa mites present in the capped cells of the brood.

Application methods of oxalic acid

There are two main methods for applying oxalic acid in hives: sublimation and the drip method.


Sublimation is the most commonly used method for applying oxalic acid in hives. This technique involves vaporizing oxalic acid in the form of crystals using a special device called a sublimator. The crystals then transform into gas, which spreads throughout the hive and comes into contact with the varroa mites present on adult bees.

Sublimation of oxalic acid offers several advantages. First, it allows for uniform distribution of the product in the hive, ensuring optimal effectiveness. Moreover, it reduces the risk of contamination of honey and other hive products, as oxalic acid degrades rapidly in the presence of moisture.

Drip method

The drip method involves mixing oxalic acid with a sugar syrup and applying this mixture directly onto the bees by dripping it between the frames of the hive. This method is less common than sublimation, as it presents certain disadvantages, such as less uniform distribution of the product and an increased risk of honey contamination.

Advantages of oxalic acid:

  • Natural and biodegradable: Environmentally friendly and compatible with organic beekeeping.
  • High effectiveness: Allows for significant reduction of varroa mite populations.
  • Relatively low toxicity for bees: When used properly, it presents a low risk for the colony.
  • Affordable: An accessible solution for small-scale beekeepers.

Precautions and recommendations

The use of oxalic acid to combat Varroa should be carried out with caution and while respecting certain recommendations. First, it is essential to use appropriate protective equipment, such as gloves and safety glasses, to avoid contact with the skin or eyes. Next, it is important to respect the recommended doses and not to treat hives too frequently, in order to avoid weakening bee colonies.

Treatment with oxalic acid is generally recommended during broodless periods, that is, when bees are not producing larvae, as it is not effective against varroa mites present in capped cells. This period typically corresponds to the end of autumn or the beginning of winter, depending on the region and climate conditions.

Stop Varroa: An oxalic acid-based treatment

The Stop Varroa treatment is organic and easy to use. It's the only treatment to eliminate 100% of varroa mites. It can also be used in organic beekeeping. Stop Varroa is safe for bees and does not poison your honey. To use it, simply lift the frames one by one and spray both sides with the treatment. The varroa mite colony will be completely destroyed within 24 hours.


Treatment with oxalic acid is a promising alternative for combating Varroa destructor, offering a natural and effective solution to control varroa mite infestation in hives. By using this method responsibly and following recommendations, beekeepers can help preserve the health of their bee colonies and ensure the sustainability of beekeeping.