In response to Jim Moore: It wouldn't be accurate to say that drones are the primary vectors of Varroa mites in Apis mellifera. Varroa reproduces in both the drone and worker brood in the European bee, unlike in its original host, Apis cerana. Furthermore, it is the workers that are more responsible for the spread of the mite, both within and between hives, due to the workers' greater numbers. It can be argued that the fall is the better time to treat in cooler areas, simply because there is less brood of any type, thus less mite reproduction. In addition, a greater proportion of the mites in the hive at that time are on the adults and more susceptible to chemical treatment. Regards, Paul Gatien