FUNGOUS DISEASES OP THE HONEYBEE 6 



The affected bees become much weakened, are capable of only feeble, 

 trembling movements, and finally die. As in the case of the brood 

 killed by the " pickled brood " disease, the fungus was not observed on 

 or within the tissues of the infected bees, but when cultures were pre- 

 pared from the alimentary canals of these bees, A. ■pollmi developed 

 constantly to the exclusion of all other fungi. 



It appears probable, therefore, that Howard may have observed 

 one or more species of Aspergillus on brood combs and succeeded in 

 culturing these, or other species, from the alimentary canals of 

 adult bees. His technical descriptions of AspergUIm pollini are 

 entirely too meager to make it possible to determine which of the 

 numerous species of Aspergillus were observed. If they are patho- 

 genic for bees, it is evident that he either did not observe a true 

 mycosis of bees or confused the condition with other disturbances. 



Diseases of bees caused by fungi have not been reported from 

 North America since then. This may probably be attributed to the 

 fact that fungous diseases of bees appear less destructive than the 

 common bacterial diseases of bees and seldom become epidemic. 



In Europe, on the other hand, two species of fungi, AspefrgiUuS 

 flavies Link and Pericystis apis Maassen, are widely recognized as 

 the causative organisms of diseases of brood and adult bees. Of 

 these, A. ■flav%us is considered of the greater economic importance, 

 since it attacks worker brood and adult bees, whereas P apis usually 

 attacks only drone brood. The two brood diseases stone brood 

 (Steinbrut), caused by A. flaims, and chalk brood (Kalkbrut), 

 caused by P. apis, have received more attention from European 

 beekeepers and investigators than has the disease of adult bees caused 

 by A. flanms. This might readily be expected as a direct result of 

 the nature of the diseases and the reaction of infected adult bees. 

 Pericystis mycosis is mentioned by Claussen (■?), Bahr (^), and 

 Morgenthaler, Kessling, and Hunselmann (in communications with 

 Claussen) . Claussen describes it as benign and transient rather than 

 malignant, affecting capped as well as uncapped drone brood and 

 passing over to worker brood in severe or exceptional cases. He 

 states that dead and diseased larvae may be thrown out of the hive 

 by the bees or allowed to remain in the brood combs, where they 

 become mummified after they are overgrown with white mycelium. 

 The bees, however, usually allow any brood killed by A. fiavvs to 

 remain in the combs for a considerable length of time, or at most 

 only partially remove it, since destruction of the cell walls is often 

 necessary for complete removal. 



Slight infection among the brood quickly attracts the attention of 

 an observing beekeeper, whereas he may completely overlook a con- 

 siderable number of adult bees dead of this disease, owing to the fact 

 that during the active season worn-out field bees die normally in 

 considerable numbers about the hive. The writer, therefore, believes 

 that the importance of Aspergillus mycosis as a brood disease may 

 have been overestimated in comparison with its importance as a 

 disease of adult bees. 



Eecent research in Europe seems to indicate that other fungi than 

 the foregoing may under favorable conditions infect and kill bees 

 and their brood. Fielitz (10), working with three fungi, Tricho- 

 derma lignorvmi Tode, Mwcor nmcedo Linne, and PeniHlUwin glaucuTn 



