Originally Posted by
fatshark
I wasn't commenting on whether we should be rummaging around in colonies at this time, just that if they were broodless (which you'd discovered because there were doubts about the queen or whatever) then I'd treat. I've got several colonies I've not looked in since the first week of August.
GG and I had cause to go through some colonies with vanishingly (desperately?) low levels of brood a few days ago which, under other circumstances, were ideal for treatment.
Here's another thought, and possibly one for GG ...
A broodless colony in midwinter has the highest (100%) proportion of phoretic mites. If the colony starts rearing brood, do they get heavily infested with mites? In relative terms there are lots of mites in the colony per late stage larva. Or are the mites "not very fit"?
If they do get heavily infested, it has potentially dire consequences for the very early season build-up of the colony ...