THYMOVAR is a product to control the Varroa mite (Varroa destructor) on bees (Apis mellifera) and contains the essential oil thymol. THYMOVAR contains thymol, a volatile substance which sublimates in the air depending on temperature. On release, thymol vapour concentrations build up in the treated beehive. These vapours are highly toxic to varroa mites but concentrations are not high enough to harm the honey bees. For optimal control, appropriate concentrations of thymol vapour must be maintained for six to eight weeks.