For my girls, once we get nto August, the summer is over. In that I mean that the supers come off – after the blackberry has flowered – and treatment for varroa starts. Yes I know that we have the whole of the month of August as summer, but forage can be variable or poor and any honey the bees gather is for them. We need to ensure that they are healthy and well-stocked for winter. There are often discussions about treating for varroa in Spetember or even later. However once the varroa are killed, the colony is not, at that point, up to optimal strength. It still has to clear the viruses that were vectored by varroa. And that takes time – say a couple of brood cycles. Also, as the brood numbers reduce, the proportion of varroa to brood increases rapidly so parasitic mite syndrome is a real threat and colony collapse possible. Better to treat sooner rather than later.