OA sublimated on 11th December - temp climbed up to around 7C locally and that loosened up the cluster thus making OA treatment more effective. My 2 colonies were treated, 2 colonies belonging to one friend, 8 belonging to another plus a few others. No mite fall from one of my hives so far - no doubt someone will tell me that means I didn't need to treat - and the other colony produced a grand total of 32 dead mites over the course of 7 days.
Did mine ,fed fondant.
Not happy about it but can't afford to let nature run riot especially when the odds are stacked in favour of the varroa mite .
Next year I hope to follow HMs routine which involoves IPM but no OA treatments . Formic acid if absolutely necessary .
If Pete makes it work you can bet he's worked it out by observation and practice rather than following advice blindly !
I usually treat between Christmas and New Year, however as we have had 4 weeks of very cold weather I think there will be very little/no sealed brood. As the temperature yesterday recovered to 7C They were dosed yesterday. I will monitor mite drop for the next 7 days to see how effective it has been.