Varroa destructor (Varroa mite) is an external parasitic mite that attacks the honey bees Apis cerana and Apis mellifera.  It is the most severe threat to beekeeping in recent years in the US.  We use Integrated pest management (IPM), also known as integrated pest control (IPC) which is a broad-based approach that integrates practices for economic control of pests. IPM aims to suppress pest populations below the economic injury level (EIL).  We do this using an organic acid found commonly in spinach, starfruit, chard and beet greens and is called oxalic acid.  When necessary, we treat using a fuming or dribble method whenever our hives are broodless, usually once in the early winter and never when honey is being produced for harvest.  Based on IPM standards, we may also use Thymol (from the spice thyme, and also organic).  Neither of these contaminant our top quality honey.