And back to the OP. For a considerable time I had a rather defensive hive and I did nothing, and now they are not defensive. I mentioned this to the old beekeeper at my club and he said that it is not only the queens that can breed defensiveness. When the queen mates, she mates with up to twenty drones which can come from different hives and if one or more of those drones come from defensive hives then for that period of egg laying using that particular sperm then those bees can be defensive. Once the queen moves onto the next lot and the first lot of bees die out then the hive calms down again. I can't confirm this is the case but give it time, you never know.