Chemistry of terpenes that kill Varroa but not the honey bees

Monoterpenoids and certain plant essential oils can be used for control of Varroa mites in bee hives. Thymol, a monoterpenoid from thyme oil can be used for that purpose as well. Menthol, a monoterpenoid from peppermint oil, can be used for control of tracheal mites in the honey bees. A comparative toxicity study was conducted testing a series of structurally diverse monoterpenoids for efficacy against the Varroa mites and for safety to honey bees. Among all of the types of functional groups evaluated, one subclass of the monoterpenoids showed a high degree of selectivity against the mite and in favor of the bees. The natural monoterpenoids and some synthetic analogs demonstrated better efficacy than thymol and were safer to the bees.