I think radiat heat is very important for wintering beecolonies in my
cold winter climate, as I stated before.
It has been mentioned
"insulation will stop most of this radiant heat", "wrapping a hive
insulates from two directions normally."
This holds true if you insulate EMPTY beehives for the winter.  You are
forgetting a very important fact.  The bee generate a termendous
amount of heat inside the hive.
Just loosely off the top of my head, a honeybee colony will generate up
to 25-35Joules of heat while in cluster.  I wrap my hives to conserve
some of that heat that is lost through the hive top and sidewalls, lets
say 5-10J heat loss depending on temp.  That heat loss will be
significantly reduced when you factor in the suns radiant heat.  If it
happens to be a -25degreeC sunny day, the sun will have warmed the
pack due to the black felt paper, your hives heat loss will be
significantly lower than if they were not wraped or wrapped in a
reflective pack.
The disadvantage is it also keeps them warmer during winter warm
spells and will increase food consumption.  Rairely do we have sutch
long warm spells to induce mid winter brood rearing.  I think in such
conditions, the premature brood rearing would happen in either case,
wrap or no wrap.  I'm not sure what your hives consume through the
winter.  I'm sure to have my colonies at least 170-180lbs going into
winter.  Not very often do I have hungery hives in the spring.
I have yet to hear of a beekeeper who doesn't wrap their hives in cold
winter conditions.  In our climate, either you wrap your hives, move
them inside, or to warmer areas of the countrey.  I'm limited to
wrapping becasue of the capital involved in the other two, and I cant
afford to loose my hives due to an extreemly harsh winter, like last
year.


Ian

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