The Care bf Bees in Winter 347 
undisturbed broodless bees generate virtually no heat 
between 57° and G9° F. (Fig. 141). When the temperature 
of the air about the bees falls below 57° the bees form a 
cluster and raise the temperature, often almost to blood 
heat. It follows that when the temperature of the bees 
is above 57° and below 69° F. they do less work than at 
other temperatures and their energies are thereby conserved. 
However, to raise the outer temperature to 57° F. often so 
reduces the relative humidity of the surrounding air as to 
create excitement in the cluster and thereby to destroy the 
desirable condition. Other factors not yet worked out 
probably have a bearing on this problem. The majority 
of beekeepers consider 40° to 45° F. as the best cellar tem¬ 
perature, but it is clear that the temperature can usually 
be raised to at least 50° F. with beneficial results. Humidity 
and ventilation are so intimately connected with tempera¬ 
ture that one cannot be investigated separate from the 
others. 
Disturbance. 
Any factor which induces undue activity in the winter 
must be considered as a disturbing factor. For example, 
low temperature, improper humidity, poor food or insuffi¬ 
cient ventilation create an undue excitement which should 
be avoided. Disturbance is usually considered, however, as 
applying to manipulation of the colony or to jarring while 
the colony is clustered. Any such circumstance causes the 
colony to raise the temperature, which may not again become 
normal for many hours. All manipulation or handling is 
to be avoided, therefore, especially in cold weather or in 
the cellar. Colonies sometimes begin brood-rearing in 
winter, usually induced by some improper outside condi¬ 
tion. The care of the brood then causes a high temperature 
and corresponding excessive activity which decimates the 
colony. Brood-rearing should so far as possible be avoided 
until the bees can fly freely. 
In this connection it will be recalled that breeding often 
