DISEASES OF BEES 11 



such a nucleus normal sealed brood soon appeared, following the 

 introduction of a healthy queen. It seems that the disease is not 

 necessarily one of old queens, for queens mated in 1936 have 

 been foimd to produce Addled brood. One experiment has shown 

 that drone as well as worker pupae are affected ; this might be 

 taken to indicate that the queen is directly responsible for the 

 trouble and that the drone plays no part. The fact that eggs and 

 very young larvae, when inserted in an affected colony, have been 

 observed to develop normally, supports the idea that the queen 

 causes the malady and that it is not due to lack of attention of the 

 larvae by the nurse bees. 



Though the superficial cause of the disease is a defective queen, 

 the fundamental cause remains to be determined. The defect may 

 be hereditary, the queen possessing some " lethal factor," or the 

 queen may suffer from some infectious disease or from some abstruse 

 pathological abnormality. This remains to be determined. Since 

 further experiments on the control of this disease are needed, it is 

 hoped that beekeepers who experience the complaint will try 

 requeening affected stocks and will notify this Station of the result. 

 The importance of continued investigation can readily be foreseen, 

 especially in view of the fact that the queen breeder must at all 

 costs eradicate the disease from his apiaries. 



European foul brood 



At present it appears that this disease is not widespread in 

 England, but the fact that it does occur, that it is highly contagious, 

 that it causes more trouble than American foul brood in Switzerland, 

 and that its cause has been in doubt has made it advisable to 

 investigate it thoroughly. If more is known about it, then it will 

 be easier to employ measures to prevent its spread should it again 

 show signs of increasing. 



Larvae affected with European foul brood, imlike those dead of 

 American foul brood, exhibit a very varied bacterial flora, and this 

 fact has greatly complicated the determination of the cause of 

 the disease. The remarkable confusion which has existed with 

 reference to its etiology, has been referred to in a number of publica- 

 tions. The results of preliminary experiments carried out here, led 

 to the suggestion that European foul brood might not be a single 

 disease, but that it was, perhaps, a mixed bacteria] infection of the 

 brood of weak stocks of bees. Further experiments carried out 

 during the past season have shown that this hypothesis was 

 erroneous, and that the disease is, in fact, a single one in which 

 various modifications may occur. 



White (1912-1920) working at the United States Department 

 of Agriculture, concluded, on the basis of a large number of 

 experiments, that European foul brood was a single disease caused 

 by a lanceolate-shaped coccus organism which he termed Bacillus 

 pluton. He was unable to cultivate this organism on any laboratory 



