> It's not so much the mite load on the adult bees that's the problem--it's
> the percentage of the pupae that are infested.  Once the pupal infestation
> rate exceeds ~25%, the colony is "walking dead."  This rate is generally
> reached in autumn as the declining bee pop concentrates the mites in the
> remaining brood.
>

Thanks Randy. Very clearly stated and is an Occam's razor solution to the
"sudden" collapse of strong hives in the fall from robbing..

Only other thing I would add is the mites from the robbed hive will also
probably carry a higher viral load compounding the problem.

Bill Truesdell
Bath, Maine

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html