Madeleine asked Keith: " Do you overwinter nucs? I was told there wasn't
enough brood, feed or warm
> > space in a 5-frame nuc to survive a winter. If a nuc can survive an
Alaskan winter, it could survive even here in NJ! How do you do it?"
While we wait for Keith to reply , perhaps a few comments on theory may
help.

Madeleine mentions brood, food and space but omits the most important - the
right amount of young bees.
Bees form a hollow cluster in winter with an outer crust that can get as
dense as 25 bees per cubic inch - I have not checked the books, but there
are many on the list who love to correct details if wrong. The crust
insulates the open space in the middle where the queen and nurses are free
to move - so bees can re-start brood rearing in mid-winter. Now bees on the
outside of the crust must not fall below 6 degrees centrigrade (?) or they
become moribund and unable to move. However, the temperature in the hollow
centre must not rise above about 35 degrees centigrade or the bees
de-hydrate too quickly and their lives are shortened. So u have a situation
that can be studied by physics - given the two outer limits for temperature,
what range does that create for the insulation value of the crust, and what
thickness is needed? Then u have to consider the heat produced at the centre
(and throughout the crust) by consumption of honey that has to balance the
heat lost from the outside of the cluster due to temperature difference
between the minimum for bees and the (variable) weather temperature, and u
can then test the effectiveness of various sizes of cluster ie total numbers
of bees in the nuc. Where this gets u - speaking from memory - is that
(surprisingly) a cluster can be too big, especially in temperate zones, as
the internal temperature gets forced too high. Medium sized clusters winter
better. In very cold zones however, I presume a larger number of bees will
be needed to form the thicker/denser crust. So if I was experimenting, I
would start with 5 or 6 frame nucs on very tall combs (Eastern Europeans
have used combs 12 inches wide by 14 inches deep), after calculaing how much
fuel the nuc is going to need and checking that the 60-80 pounds needed can
be accomodated above the early winter cluster. Then I would crowd the nuc
with YOUNG bees, sufficient to form the crust, and young enough not to die
out too quickly in spring (which causes spring dwindling). To get the young
bees, I would initiate feeding in autumn late enough that bees do not age
thru foraging, but early enough for say two brood cycles, - and I would use
honey for breeding but sugar+pollen for the final feed that will take the
cluster thru the inactive period.

All very theoetical. The best ref I know on the physics is E B Wedmore,
Ventilation of Bee-hives, 1947 - 115 pages. There are brains on this list
which rev nicely on problems in physics - perhaps they will expand.
Robin Dartington.

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