>  As I winter more than 250 four frame nucs, and some singles, and some
> tiny mating nucs with four half sized combs above production colonies, I
> should add some comments.




>That's right, and putting one hive on top of another makes checking the
>bottom hive difficult,


That depends upon how you set the hives up. Once the bottom colony is
prepared for winter, there isn't any checking anyway. I wrap with a
standard wrap for the bottom hive, and a shorter "nuc" wrap for the top.
The nuc can be removed without unwraping the bottom hive. When spring
comes, the nucs are moved to a holding yard, and the bottom hives can be
checked.



>plus it means that the bottom hive gets no top
>insulation


I don't see how this effects the bottom hive. The nuc box on top acts as
the insulation for the bottom. The bottom still has its upper entrance, and
from what I've seen winters equally well as colonies with no nuc box and
standard insulation...2" foam.


>Moreover, bees will tend to drift up to the top hive in spring, sometimes
>depleting it somewhat.


The unit(s) above have their entrances on the sides or back. The bottom
hive has its entrances on the front. There really isn't any drift.


In  my opinion any real boost the top hive gets is from being up, off the
cold ground --


I agree. While the top colonies must receive some heat through the inner
cover of the bottom colony...solid inner with closed escape hole...I don't
think it much. The fact that the top colonies are high and dry is probably
why such tiny colonies will survive the winter.

Mike
>