PLB said>I was always under the impression that disturbing a winter cluster was a very bad idea and should be avoided at all costs.


I sublimate OA each year in early winter and try to time the application for when the colony first becomes broodless. I've done it hundreds of times and never noticed that the disturbance was harmful only that it killed the phoretic mites. I do hear the colony begin a low hum while they temporally break cluster as things heat up for a moment, but that subsides quickly and they go on to winter normally. I don't actually know if the treatment is harmful, and in some way, I suppose it is, but mites feeding on winter bees and invading early brood is also harmful. In trying to control mites with active treatments we always seem to be making the same choice between doing harm and what we perceive as a greater good.  It would be beneficial to have some science specifically about winter sublimation, and the harm to bees versus the benefit of killing the late season phoretics. 

Since I've never outright killed a colony with this procedure and have no records of related queen loss, my experience is that it's probably safe, and it sure feels good to see those dead mites on the drop boards. 

Bill Hesbach
Cheshire CT

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