Can I add one more possible myth? Drone brood is a Varroa factory.
Yes Varroa are attracted to drone brood in preference to worker brood and yes they do have longer as pupae for an extra daughter mite to survive. However I have reared drones in my colonies for years and there is no surge in Varroa. My observations are that mite drop falls almost to zero during May and June when drones are reared but then increases in August and September when there is no drone brood. I know it sounds counter intuitive but maybe rearing drones actually helps control Varroa. Small numbers of drone cells could be invaded by too many Varroa resulting in the death of both. I have found dead drone pupae and newly emerged drones with DWV on the landing board and mite drops go right down. Before Nigel posts that mite counts don't work, I confirmed the very low mite levels with sugar dusting over the whole brood box.
Yes Varroa are attracted to drone brood in preference to worker brood and yes they do have longer as pupae for an extra daughter mite to survive. However I have reared drones in my colonies for years and there is no surge in Varroa. My observations are that mite drop falls almost to zero during May and June when drones are reared but then increases in August and September when there is no drone brood. I know it sounds counter intuitive but maybe rearing drones actually helps control Varroa. Small numbers of drone cells could be invaded by too many Varroa resulting in the death of both. I have found dead drone pupae and newly emerged drones with DWV on the landing board and mite drops go right down. Before Nigel posts that mite counts don't work, I confirmed the very low mite levels with sugar dusting over the whole brood box.