OUTDOOR WINTERING OF BEES. 7 
CONSERVATION OF HEAT AND REDUCTION OF EXPENDITURE OF 
ENERGY. 
In outside wintering the heat produced by the bees is conserved 
by the insulation of the cluster itself and also by the insulation of the 
hive and packing. In the cellar there is less insulation near the clus- 
ter, but the cellar itself replaces the packing, and is in reality simply 
an insulation. The insulation of the individual hive, of several hives 
packed together, or of bees in a cellar serves solely to reduce the loss 
of heat generated by the bees. 
The amount of packing that should be used obviously varies with 
the climate and it is impossible to make definite general statements in 
a bulletin intended for all parts of the United States. There is one 
general statement which can be made with safety: The majority of 
beekeepers do not give sufficient insulation and no beekeeper ever 
gave a colony too much. For example, in the relatively mild climate 
of Washington, most beekeepers winter their bees in single-walled 
hives. The authors have used a large packing case holding four 
hives, two facing east and two west, close together. This case was 
constructed so as to hold 3 inches of packing below, 5 inches on the 
ends, 6 inches on ‘the sides, and 8 to 12 inches on top. Colonies 
wintered in such a case in Philadelphia in 1913-14, and in the apiary 
of the Bureau of Entomology at Drummond, Md., near Washington, 
in 1914-15, were in much better condition than colonies left un- 
protected, and cases of this general type are being constructed for 
the entire apiary at Drummond, except for such colonies as are used 
in other wintering experiments. The dimensions here stated should 
by no means be accepted as best for other localities, especially those 
farther north, where the protection should be heavier, but in this 
particular packing case the temperature of the air within the hive 
but outside the cluster usually stood at about 55° to 57° F., except 
for a reduction in temperature under one condition to be discussed 
on the next page. The aim of the beekeeper should be to keep 
the air about the bees at about 57° F., at which temperature there 
is no condensation of moisture within the hive, even on the inside 
of the cover, where it first appears. It might be inferred that if 
double the amount of packing had been used the temperature of the 
air about the bees would have been too high. This is not the case, 
for bees cease heat-generation when the temperature reaches 57° F., 
(or even sooner when the surrounding temperature is rising'), and 
the temperature will not exceed 57° F. unless that of the outer air 
remains higher than that for a considerable period. 
Bees well protected and with good stores do not fly from the hive 
because of the warmth within when the outer air is too cold for them 
1 See Department Bulletin No. 95. 
