PREFACE. 
Bees, like many other members of the animal kingdom, are 
known to suffer from diseases. Simultaneously with the good work 
that has been done during the last half century toward the deter- 
mination of the causes of the various diseases of man and animals, 
there has been some work done on the causes of bee diseases. This 
work has caused considerable literature to be written on the subject. 
Although this literature contains much that is valuable, it abounds 
in statements that are erroneous and in conclusions that seem 
unjustifiable. Many of the inaccurate statements and conclusions 
have been frequently copied in the past and they are still too often 
copied into the current literature on bee diseases. The bee keeper, 
therefore, in reading is often at a loss to know what is true and 
what is untrue; what is actually known and what is not known. 
For the purpose of aiding the bee keepers with this literature, 
we have reviewed here portions ot several original papers dealing 
with the causes of bee diseases. It is hoped that this bulletin may 
serve aS a means whereby the bee keeper may solve for himself 
some of the apparent mysteries found in beekeeping literature. 
In selecting the papers for review, for the most part, those were 
chosen which were written by men who had worked more or less 
on the causes of bee diseases. The reviews that have been made 
contain the more important beliefs concerning the causes of these 
diseases that were entertained by the authors of the different papers 
at the time they wrote. The classification of the diseases of bees as 
understood by these different men is also frequently included. The 
original papers naturally contain much that has not been mentioned 
in these brief reviews, and therefore the reader is urged, if oppor- 
tunity permits, to read the papers cited in this bulletin rather than 
the reviews. lt is probable that the papers here considered might 
with profit have been more completely reviewed and that other papers 
might with profit have been considered, but if either had been done 
it is probable that the length of the bulletin would have defeated its 
object. : 
It is hoped that the readers of bee-disease literature will learn, so 
far as possible, to judge correctly an article that discusses in any 
way the causes of bee diseases. To do this, one should first of all 
learn who are actually doing work on the causes of these diseases. 
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