Much discussion on this subject recently and it is clear that no one is
certain of the best method, if there is one.  A lot or a little, half way,
top,bottomor both, beekeepers try them all and most of the time the bees
survive.  When one considers the range of climate from the tropics to the
Arctic there can hardly be one best method for all.
 
Some years ago a well known beekeeper, Bernard Mobus, NDB and Beekeeping
Adviser for Scotland, wrote a series of articles titled Damp, Condensation
and Ventilation in the Beekeepers Annual for 1988,89,90.  These covered some
32 pages of small text and I was so impressed I wrote to him suggesting he
made it into a book because ventilation was such an argumentative subject.
Unfortunately he declined and shortly after retired to France.
 
We all know that in nature bees do not approve of top ventilation and this
was how beekeepers kept them for hundreds of years.  Only with the arrival
of the modern hive did beekeepers start thinking about it.  With the
approach of winter bees  seal down the cover board with propolis and if any
feed holes are covered with gauze that is quickly sealed as well.  They are
telling us quite clearly they do not want it.  In spite of that we see the
advice to raise the cover board by one eighth of an inch or make holes or
slots in other ways.  That gap all round a Langstroth hive, 16.25 by 20
inches, tots up to a chimney of three inches diameter.  A little arithmetic
will show that this is equivalent to a hole in our bedroom ceiling some
three feet by three feet,open to atmosphere.  Extra blankets needed.  In any
hive exposed to winter gales, assuming a bottom entrance, such a chimney
must cause a lot of heat loss, so increased food consumption.
Back to Mr Mobus.  His researches and those of others led him to the
following conclusions.  In a climate such as in Britain with a distinct
winter where the queen stopped laying and the bees clustered for long
periods there was an optimum sized cluster, 9000 to14000 bees for successful
wintering.  Large stocks and small ones had extra problems.  No top
ventilation but the cover board should have extra insulation.  Plenty of
bottom ventilation, preferably a hole in the floorboard around a foot square
with suitable screening against predators.
 
With regard to the last point I have vague memories of some experiments many
years ago where it was shown that bees wintered quite happily without
floorboards as long as the hole was suitably screened.  Personally I have
not yet got around to cutting holes in my floors.  Hampshire has a more
gentle climate than Scotland.  All my bees have no top ventilation.  Those
outside have full width entrances, but with anti-mice screening, 16 or18
inches by one inch.  Those in the beehouse have around 27 square inches.
They all seem quite happy with it.
  Happy New Year to all and thanks to all those regular contributors.  May
the letters keep coming.               Regards                  Sid P.
_________________________________________________________________
Sid Pullinger                    Email :  [log in to unmask]
36, Grange Rd                Compuserve:  [log in to unmask]
Alresford
Hants SO24 9HF
England