>Or perhaps a continuous control during this invasion period.

I couldn’t agree more. The advantage of continuous control during this period is that it lessens the chance that incoming mites will get to feed on winter-bee pupae. Also, it's a transitory time in the mites quest for a new host when they are most vulnerable. IMO this is the perfect time for a slow release OA/glycerine treatment that kills mites as they enter and that lasts over the entire invasion period.  To restate the obvious, no matter what we've done to keep our mite numbers in check all season, an early swarm, hived in some unknown location, has likely become a mite lure, and the same is true for other area colonies allowed to host large numbers of mites.

I've often thought of mites as existing in two populations, one we can deal with as a resident parasite and the other suspended in the environment beyond our control. It's the suspended population that will kill a host and will invariably find their way back to a healthy colony.  If we kill those mites that naturally quest out of a dying colony, it seems to me that we apply selection pressure for a mite that is less virulent.   


Bill Hesbach
Cheshire CT

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