>>...when there's an influx of mites in autumn, too late  for the bees to raise a generation of unparasitised workers to overwinter. 

On the other hand, if they are not broodless for most of your mild UK winter then they should start raising healthy bees following the OA treatment and recover their numbers by the end of April.

I find that any colony that is on the smaller side going into the winter will continue raising more brood and longer that the larger colonies.  [This is not in all cases but there is that general trend in my colonies.]  I think bees have a clear concept of what they should maintain as a minimum critical mass cluster size and will strive to make adjustments by raising more brood in the winter given sufficient stores.

I hear what Dee says about the potential loss of beneficial microorganism to acids.  I have not read anything that said OA killed such organisms beyond recovery or what these organisms are.  Anyone know of any online references to this?  Are these microorganisms found exclusively in the hives or can they be re-introduced into the hives with the spring pollen?

Thank you.

Waldemar

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