4 FARMERS’ BULLETIN 695. 
tion necessary. It is obvious, however, that winter protection is 
beneficial throughout practically the entire United States. 
Necessity of having young bees.—Bees may be compared with 
minute dry batteries, in so far as their vital energy is concerned. 
They emerge as adult bees with a certain amount of vital energy, and 
when this is exhausted they die, not having power to recover lost 
vitality as human beings have. To withstand the hardships of 
winter under usual conditions, a colony must have many young bees, 
capable of prolonged muscular work. Obviously the better the 
wintering conditions, the less necessary it becomes to provide young 
bees, but even with the most perfect wintering it is desirable that 
there be plenty of young bees in the fall, so that they will be available 
for extensive brood-rearing in the spring. This calls for prolonged 
brood-rearing in late summer. Old bees, which have been worn out 
earlier and are ready to die, soon succumb from the work of heat- 
generation. 
Danger of weak colonies.—In a strong colony many bees in the 
center of the cluster may be engaged in heat-generation, and there 
will still remain many bees to serve as insulators. A weak colony, 
on the other hand, has less reserves for insulation, and, since heat is 
rapidly lost, the bees on the inside must generate excessive heat in 
order that the outermost bees may always be at a temperature of 
over 50° F. Since the surface of a spherical cluster is proportionate 
to the square of the diameter, while the volume is proportionate to 
the cube of the diameter, it follows that a large colony cluster has 
a relatively smaller surface for radiation of heat than does a small 
one. Below about 50° F. individual bees become numb, and so long 
as the cluster remains active the authors have never found normal 
bees at a temperature lower than the critical temperature, 57° F. In 
a small colony the inner temperature is often many degrees warmer 
than that of a neighboring strong colony, which doubtless explains 
the prolonged brocd-rearing of weak colonies in the fall. Most 
colonies which die of excessive heat-generation are rushed to their 
doom by the temperature being high enough to start brood-rearing, 
which is perhaps one of the most unfortunate circumstances which a 
colony can experience in winter. By all means a colony should be so 
protected that brood-rearing will not be begun until frequent flights 
are possible. 
Since weak colonies so frequently succumb in winter, it is obvious that 
a too rapid increase in the number of colonies in summer is unwise. 
Beekeepers have learned that swarming is to be avoided because of 
the resulting reduction in the honey crop, and the loss in winter is 
additional argument against allowing the bees to exercise this in- 
stinct freely. It is a common saying among beekeepers that a rapid 
increase is usually followed by a rapid decrease. It is impossible to 
