There has been some discussions about inner covers and top ventilation
on the
list lately. We had the same topic here about a year ago, and will
undoubtedly
see more of it.
 
It seem to be the common practice in some parts of the world to always
leave
a hole at the top of the hive to provide ventilation through the hive.
Others
state that there should only be ventilation in the bottom.
 
I have styrofoam hives with no top vent. The entrance is 8 mm high, and
there is
a hole 250 by 250 mm in the center of the bottom board with a steel mesh
to provide
ventilation.
 
I have been thinking of making a test one winter but never got around to
do it.
Last year however, a woodpecker decided it was time to check it out.
Now Woody didn't seem to care much for the scientific value of his work,
the
shapes and sizes of his holes were a bit irregular. Most of the holes
were in
the upper box, some boxes had up to 3 holes. He choosed about 20 hives
for the
test.
 
We had a long and cold winter here with temps down to -20 C for several
months.
The entrances were closed with ice for 2 months on the hives without the
extra ventilation, only ventilation left was the hole in the bottom
board. As dead bees
fell down on the mesh during winter, the circulation of fresh air in the
hives would decrease. On Woody's hives the entrance didn't freeze
completely, the air flow
through the hives kept it open.
 
So, did I see any difference between the hives with extra ventilation
and
those without after winter? The answer is no. Both groups had wet and
dry
hives. And there didn't seem to be any difference in food consumption
either.
 
--
Regards
 
P-O Gustafsson, Sweden
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