If the proper temperature is maintained in the cellar there will be
little need of ventilation, for in almost all cases there will be
sufficient interchange of air to keep the bees in good condition.
If the temperature is as low as 45° F., a little ventilation will be
needed, although most of the bee cellars that have been built have
had too much ventilation, and as a result it has been impossible
to maintain a correct temperature within them. In cold weather the
tendency toward an interchange of air is greatest, and at such times
the ventilators may be entirely closed. In mild weather it makes no
difference if large ventilators are open, unless this results in too
great a rise in temperature.
In a well-insulated cellar it should not be necessary to ventilate at
night at the approach of spring to cool the air inside, for the bees
will not get so warm from their own activity as will bees in a cellar
that is or has been too cold. The greatest problem in most cellars is
to maintain the right temperature during the spring just before the
bees are to be removed. The trouble is that in most cellars--those
which are too cold in winter--the bees generate heat constantly
during the winter and as a result have an accumulation of feces in
the intestines, resulting in a condition known as dysentery. For this
reason they become excited easily, and beekeepers have thought it
necessary to ventilate the cellar at night freely in order to remedy
this trouble. The proper method, of course, is to prevent it by keeping
the temperature higher during the winter, but if the temperature has
fallen too low during the winter ventilation at night seems to help
somewhat. It is safe, however, to say that a cellar in which this
happens is not satisfactory as a place to keep bees during the winter,
and steps should be taken to insulate it more completely before bees
are put into it again. If the bees are wintering on stores that are
not of the best quality the tendency to accumulate feces will be far
greater, even with the right temperatures inside the hives, and if
there is dysentery it may be relieved somewhat by ventilation, although
this is simply reducing a symptom and is not removing the cause of the
trouble.