At 02:37 PM 10/20/99 -0400, you wrote:

We have done some work in Montana.  Our varroa infested hives collapsed in
the fall after removal of the honey crop when outside temperatures dropped
to 20 degrees F.  Most of these colonies died within a week of each other.
Bee populations were large, with plenty of food.  Losses occurred in Oct.,
the few survivors (out of 48 colonies) dropped out before April.

It appeared that the bees did not cluster for warmth.  I talked to Ed
Southwick just before he died from cancer.  Ed said that he had observed
the same behavior in his environmental chambers - the mite seemed to have
altered the bees response to low temperatures.  In our case, they did not
cluster properly and they did not move to available food (and I mean they
didn't creep up the frames they were on, I don't mean they didn't move
between frames).  So, some appeared to have starved within a fraction of an
inch of readily available food in relatively mild temperatures.

Cheers