Burleybee, I have already started with OAV. Hitting them once per week for three weeks and then wait three weeks to keep the numbers low. If you have a high mite count now, you should treat every five days for three weeks or until only a few mites drop. Where I live, it is important to treat regularly throughout the fall as many mites will be coming in from the hives of those that do not treat or non-resistant feral bees (escaped swarms from packages). Like Tim, I treat again at Thanksgiving and Christmas with single doses as there is little foraging activity and the hives are broodless.