BeeVital brand VarroMed (oxalic acid dihydrate & formic acid) is a veterinary medicine used to treat varroosis in honeybee colonies. Varroosis is a disease caused by the Varroa mite, a parasite that weakens and can even kill honeybee colonies. VarroMed is a ready-to-use, liquid dispersion that is applied directly into the hive to kill the mites. An EU Authorised medicine.