So if we all stopped treating for varroa would the ones with DWV type A die, leaving only those with type B?

I guess this would not happen instantly (nothing is ever that easy!) as there would be drifting and re-invasion, but is this the way to go?

I have also been reading the transcript of a lecture given by Prof. Stephen Martin and Dr Ricky Kather to the Central Association of Beekeepers (http://www.cabk.org.uk) "Social Insect Recognition: telling friends from foes and how parasites like varroa fit in" in which they explain how varroa become invisible to bees by acquiring colony odour (within 3-9 hours) and that colonies that uncap brood containing varroa probably do so because they have detected damaged brood rather than the varroa mites.

This suggests to me that there is great merit in selecting for hygienic colonies as an aid to varroa control (as well as the benefits for reducing foulbrood).

Best wishes

Peter 
52°14'44.44"N, 1°50'35"W

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