It has been indicated that Varroa can be controlled by providing hives with drone comb and getting a few frames of drones reared in the hive. Varroa seems to prefer drone larvae, and will seek out those combs. Once the drone brood is sealed, it can be taken from the hive and dealt with (e.g. treated so as to kill the Varroa and the larvae). It can be replaced in the hives, the bees will clean it up, and re-used. My guess is that this is rather labour intensive, and perhaps others would comment on the practicality of this means of control by sanitation management. I am just re-iterating what I have heard.