192 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 9 



cordance with his best judgment and in an earnest effort to help bee- 

 keepers. If this section can provide a safer basis for judgment it 

 will be conferring a great benefit on beekeepers who are suffering from 

 neglect. 



SOME DIFFICULTIES IN GROSS DIAGNOSIS OF THE 

 INFECTIOUS BROOD DISEASES OF BEES 



By Arthur H. McCrat, M. D., ApicuUvral Assistant, Bureau of Entomology, 

 U. S. Department of Agriculture. 



The beginner in diagnosis rarely appreciates the difficulties in rec- 

 ognizing and differentiating disease, consequently many mistakes are 

 made and there results a lack of confidence in his own ability. Cer- 

 tainly this is deplorable. In this paper it is aimed to point out certain 

 difficulties in the gross diagnosis of the infectious brood diseases of bees 

 in such manner that the inexperienced inspector may profit thereby 

 and it is hoped that those of greater experience may find something 

 of value in the recital of some of the difficulties which have been en- 

 countered in the examination of over 4,500 different specimens of bee 

 comb and brood representing every section of the United States. 



Dead, Not Living, Laev^ Must Be Studied 

 The few published characteristics of living diseased larvse are not 

 readily applicable to gross diagnosis, especiallj^n the field, consequently 

 attention must be directed for the present almost exclusively to dead 

 larvae. 



Variations in the Same Disease 

 The various factors entering into a description of the dead brood in 

 any one of the three known infectious brood diseases of bees are not 

 constant, thus resulting in different appearances in different cases of the 

 same disease. It is this variation that makes a differential gross 

 diagnosis at times difficult or even impossible so that laboratory aid 

 must be sought. 



Consideration of the Variations at Length 

 It will be well to consider some of the more striking 

 variations at greater length. Many lay great stress upon the 

 value of odor in American foulbrood and European foulbrood. 

 There is no doubt that most of the cases of American foulbrood, 

 probably all, have at some time in the course of the disease a 

 characteristic odor. The same cannot be said of European foulbrood 

 for the odor here seems accidental and is not always present, more- 



