2 BULLETIN 671, U. S. DEPARTMENT OF AGRICULTURE. 



For the understanding and application of the methods herein out- 

 lined, a preliminary training in general bacteriology, supplemented 

 by a special knowledge of the pathogenic bacteria and the methods 

 pursued in the diagnosis of diseases in general, is essential. As effi- 

 ciency depends largely upon a knowledge of pathology, too much 

 emphasis can not be given to it. With such general and special train- 

 ing as a basis, and with a knowledge of the bee diseases, the acquisi- 

 tion of the special methods necessary for a laboratory diagnosis of 

 them becomes a comparatively simple matter. 



One of the authors (White) began his investigations on the dis- 

 eases of bees in 1902, and from this date to 1909 examined and 

 diagnosed about 500 samples of suspected material and during the 

 period developed the laboratory methods as given in the present 

 paper. Since 1909 the senior author (McCray) has carried on the 

 work of diagnosing the samples received by the Bureau of Ento- 

 mology and up to the present time has examined and diagnosed 

 about 5,000 of them. 



LABORATORY METHODS. 



OBTAINING THE SAMPLES. 



For a satisfactory diagnosis of suspected brood the material at 

 hand should be adequate. The size of the comb containing the af- 

 fected larvae should be ample. A piece about 5 inches square is suit- 

 able, provided it contains a sufficient number of larvse. All samples, 

 no matter how far sent or how long in transit, should be inclosed in 

 wooden boxes to prevent crushing during transportation. Paste- 

 board boxes are apt to allow the sample to be crushed, while samples 

 inclosed in tin boxes are often covered with a rich fungous growth 

 when received. Both the crushing of the sample and the fungous 

 growth obscure the gross features which form an important part of 

 the examination. The sample should not be wrapped in cloth or 

 paper, as this will tend to retain moisture and further encourage 

 fungous growth. If thin paper is used, it frequently adheres so 

 closely that its complete removal is difficult. The sample should con- 

 tain no honey, as a small amount of it in a comb is sometimes suffi- 

 cient to cause an unsightly mass, owing to leakage through the pack- 

 age in transit. As complete a history as can be obtained should 

 accompany each suspected specimen as an aid to diagnosis. The 

 Bureau of Entomology for several years past has sent out a printed 

 question card with blank spaces for answers by the beekeeper sending 

 the suspected brood. Some of the more important of these questions 

 are as follows: 



1. Is there any bee disease in your neighborhood? 



2. If so, what disease? 



3. Have you brought colonies from a distance? If so, give source. 



