Formic acid or thymol
Both formic acid and thymol treatment are meant to be so-called long period treatments. This means that all the capped bee brood will hatch once during the treatment. Worker bees will remain capped pupae for 12 days, which is why the treatment period is normally two weeks long. The mites inside the pupae will then gradually come out and also be exposed to either formic acid or thymol during the treatment.
- In Finland, thymol is mainly used for varroa control in August after harvesting in the beginning of winter feeding.
- In Dalsland, Sweden, only oxalic acid gas by Oxamat is used for varroa treatment.