May: A daily mite fall of more than 3 mites in the last week of May is hazardous. It is worth considering a treatment with formic acid 85% immediately after harvesting the spring honey flow.
Daily natural mite fall above 30 mites needs action without delay in anytime of the year.
Next counting will be in the last week of June.
Thank you very much for your cooperation.
Romée van der ZeeNetherlands Centre Bee Research