I've been doing quite a lot of monitoring this year - far more than the four times recommended by Fera's Managing Varroa. MV also suggests that that an infestation of 1000 mites is the critical point and that as numbers approach this point, treatments should be undertaken.
Every time I've done a mite monitor, I've used the Beebase Varroa Calculator to find out the calculated number of mites in the colony. In one of my two colonies, total estimated mites increased from 130 in early July to 290 a week ago. Whilst this is nowhere near the 1000 critical figure but it was bad enough to trigger action from me - I put on Hivemaker's Thymol treatment three days ago and in two days have had a drop of 175 mites - over half of the estimated number of mites in the colony. I intend to leave that treatment in place for 14 days and place the second treatment in the colony and monitor daily. If the temperatures hold up but no mites drop, I'll withdraw the treatment.
My aim is to reduce the numbers of mites to a low level but not necessarily to kill all of them - I think it's important the bees have the opportunity to learn mite-grooming traits and if there are no mites, they cannot learn that. I've noticed over the summer that as the number of mites has increased, the percentage of live mites on the monitoring tray has increased - something like 15 - 20 % were alive on the last monitoring. I regard live mites on the monitoring board as a good sign - it seems to me to mean that the bees are grooming mites off themselves or other bees rather than mites dying of natural causes and "dropping off the perch".
Every beekeeper must manage his or her bees using methods that make sense to them - I urge new beekeepers to avoid the "it's September so I'll treat with Thymol" and "It's January, so I must treat with Oxalic" method of mite control. It's important to Monitor regularly so you know what's happening inside the hive.
CVB
was that from your crystal ball
