2 FARMERS’ BULLETIN 695. 
enough, the decrease in all parts of the United States is due to the 
same causes in varying degree. 
For the past three winters the authors have made a study of the 
activity of bees during the winter and of the effects of various 
environmental factors on the colony. This bulletin does not include 
the results of this work, but gives the methods of outside wintering 
which have proved best in commercial apiaries, all the statements 
here made having been substantiated by the results of the more de- 
tailed studies which are to be reported’in other form. There are 
many factors which require still more study and the doubtful points 
are not here discussed. It seems best not to include a discussion of 
the wintering of bees in cellars, concerning which there are many 
more points in dispute which can be settled only by detailed scien- . 
tific studies. This omission should not be interpreted as indicating 
that the authors condemn cellar wintering; in fact, they are inclined 
to believe that when preperly worked out this method will be found 
superior in northern localities. 
Beekeepers usually report the results of wintering by giving the 
percentage of colonies in which all the bees die, Just as was done in 
the first paragraph of this bulletin. This is a convenient method 
but is misleading. If every individual bee that goes into winter 
quarters remained alive in the spring with no loss of vitality, we 
should have perfect wintering, but such success is impossible. If 
out of 100 colonies only 2 die and the remainder are only half as 
strong in numbers as they were in the fall, most beekeepers would 
consider this rather good wintering, while in fact it is poor. The 
criterion of success is to save the greatest possible number of indi- 
vidual bees and to have them capable of prolonged activity in the 
spring. Beekeepers sorely need a new point of view as to success 
with this vital problem. 
Frequently in beekeeping literature mention is made of the 
“winter sleep” of bees. Bees can not hibernate as do most. insects. 
While the bees on the outside of the winter cluster are usually 
quiet, there is incessant movement in the center during cold weather: 
in fact, the colder the surrounding air, the greater the activity of 
the colony after a cluster is formed. The phrase “ winter sleep” is 
therefore erroneous and should be dropped from the literature, as 
it misleads beekeepers. 
CAUSES OF WINTER LOSS. 
The causes of the death of individual bees or of a colony of bees 
in winter, barring unusual accidents, are only two in number: (1) 
1¥Wor a preliminary report of this work see Phillips and Demuth, 1914. The tempera- 
ture of the honeybee cluster in winter, Bul. 93, U. 8. Dept. Agr., 16 p. 
