DIAGNOSIS OF BEE DISEASES. 11 



color may be light yellow, light gray, or light brown. The lighter 

 shades soon deepen to the darker ones. 



(/) Consistency. — ^The consistency is characteristic. The cuticular 

 portion of the body wall of an affected larva is decidedly resistant so 

 that the larva may be grasped with forceps and removed from the 

 cell intact. After removal from the cell the larva has the appear- 

 ance of a small closed sac. When the sac is ruptured the contents 

 will be seen to be watery. Suspended in the waterlike fluid will be 

 noted numerous fine brown granules. 



{g) Odor. — There is no distinctive odor to sacbrood combs. 



{h) Kind of hrood. — The greatest ravages occur in the worker- 

 brood. Affected drone-brood may be encountered. 



{i) Scales. — The scales when dried down are quite black and the 

 surface appears somewhat roughened. They separate readily from 

 the cell wall and may be lifted out intact by means of forceps. 



MICKOSCOPIC FINDINGS. 



The striking feature of the microscopic examination is the absence 

 of microorganisms. Rarely a few rods may be observed. A large 

 amount of detritus is always in evidence, consisting of the brown 

 granular material seen on gross examination after rupturing the 

 body wall of the larva. These granules are in a large part the re- 

 sult of the disintegration of the fat body of the larva. 



CTJLTUBES. 



As might be expected from the microscopic examination, agar 

 plates inoculated with infected material are practically always nega- 

 tive as to bacterial growth. Even the presence of organisms of the 

 vulgatus group is rare. No other growth occurs unless from chance 

 contamination. 



OTHER ABNORMAL CONDITIONS OF THE BROOD. 



There are noninfectious abnormal conditions of the brood of bees 

 which have been confused with one or more of the infectious diseases. 

 Among the more important of these may be mentioned chilled brood, 

 starved brood, overheated brood, drone-brood resulting from laying 

 workers, and brood dying after removal from the hive. The names 

 given to most of the foregoing conditions are sufficient to indicate in 

 a general way the probable cause of death. These conditions are less 

 likely to be confused with American foulbrood than with either one 

 of the other two infectious brood diseases of bees. The specimens 

 that resemble European foulbrood in the gross consist of soft, easily 

 ruptured, gray, yellow, and light-brown larvae. The irregularity of 

 the brood, the age, the color, and sometimes the scales bear a strik- 

 ing resemblance to many cases of the disease. 



On microscopical examination of the affected larvae the smear 

 often discloses microorganisms, yet they lack the definite, clear-cut. 



