Organic acids in the treatment of Varroa: instructions for use

The fight against Varroa, this formidable parasitic mite on bee colonies, is a constant challenge for beekeepers. Among the authorized and recommended treatment methods, organic acids such as oxalic acid or formic acid offer many advantages. Discover in this article our detailed instructions for effectively using these natural products against Varroa.

Formic acid

Formic acid is widely recognized for its ability to penetrate the brood and kill Varroa mites, including those hiding inside the sealed cells. Its application must be carried out carefully to avoid harming the bees. The outdoor temperature should be between 10°C and 29.5°C during treatment to ensure effectiveness and minimize risks. The dosages and application method vary depending on the available products, but a common approach is to use formic acid-soaked strips placed inside the hive for gradual release.

Oxalic acid

Oxalic acid is particularly effective during periods when colonies are broodless, such as in winter, as it does not penetrate sealed cells. It can be applied in several ways, including by sublimation (heating oxalic acid to create a vapor), by direct spraying on the bees, or by using sugar solutions that the bees ingest. Precision in dosage and application is crucial to avoid any damage to the bees.

Lactic acid

Although less commonly used than the previous two, lactic acid has the advantage of being extremely safe for bees. It is generally applied in the form of an aqueous solution, directly on the frames and bees. Its effectiveness is maximized when the colony has little or no brood.

Understanding the mode of action of organic acids

Short-chain organic acids such as oxalic acid and formic acid are molecules naturally present in honey. At high concentrations, they become lethal to Varroa mites without significantly affecting the bees. Their mode of action differs depending on the form in which they are applied:

- In gaseous release (formic acid): the vapors penetrate the hive and kill Varroa mites present on the bees and capped brood.

- By sublimation (oxalic acid): the crystals vaporize when heated and destroy the phoretic Varroa mites on the bees during cluster formation.

Choosing the right organic acid according to the season

In beekeeping, the timing of Varroa treatment is crucial. Each acid has an optimal period of use:

- Formic acid: ideal in summer when the colony is strong to combat the peak infestation.

- Oxalic acid: more suitable during periods of reduced feeding and brood rearing (beginning/end of winter) to treat residual bees.

Applying acids safely

Although of natural origin, concentrated organic acids require precautions for use:

- Wear personal protective equipment (gloves, goggles, coveralls)

- Prepare precise doses according to the product instructions

- Preferably carry out treatments in the evening to minimize damage to the brood

- Ventilate the hive well after treatment

By carefully following these recommendations, you will explore the full potential of organic acids to save your colonies from Varroa!

Using the Stop Varroa Treatment

Among the many organic acid-based products, the Stop Varroa solution stands out for its remarkable effectiveness. This treatment is said to eliminate 100% of Varroa mites present in the hive. Its formula certified for organic beekeeping ensures a risk-free fight for the bees and no residue in the harvested honey.

Its application is claimed to be very simple: just gently lift the frames one by one, and spray both sides with the Stop Varroa product. Within 24 hours only, the colony would be completely rid of the parasitic mites. This rapid action is a valuable asset for beekeepers wishing to stop a Varroa infestation before it becomes too severe.


Organic acids are a healthy, natural and economical alternative to chemical treatments against Varroa. By mastering their use according to the right periods and dosages, you will effectively contribute to preserving the health of your foraging bees. Do not hesitate to contact us for any additional information!