First, we’ll be giving these definitions: when we talk about varroa in phoretic stage, it means that the female varroas are outside the cells, looking for another cells to get into in order to continue with the reproductive cycle. In contrast, the non-phoretic stage means the presence of the mites inside the cell, where the bee is in pre-pupa stage.
Every health treatment is developed based on the study and comprehension of the disease that is trying to be controlled. As we saw, the reproductive stage of the varroa takes place in a non-phoretic way. When the varroa is in this stage, almost all treatments won’t have any effect because they’re not in contact. Because of that, the best moment to treat is when the varroa goes out of the cells to get into other cells, that means, in phoretic stage.
This means that, whereas the queen keeps laying eggs, the disease spreads and it’s necessary to work on varroa control and treat the hive. When? When a substantial amount of phoretic varroa is found in order to interrupt its reproductive cycle in the most appropriate way. If a low presence of varroa is found, it means that the majority of varroa is in non-phoretic state or not developed enough to justify an immediate treatment.