2 BULLETIN 92 ? U. S. DEPARTMENT OF AGRICULTURE. 



or Nosema disease, healthy colonies of bees must be inoculated in 

 making the test in case of these diseases. This is done by feeding the 

 bees the heated germ-containing material in sirup. If the disease is 

 produced by this feeding, naturally the infecting agent has not been 

 destroyed by the heating; but if the disease is not produced, it vir- 

 tually has been destroyed by it. By repeated experiments of this kind 

 in which the temperature used in the heating is varied, the minimum 

 temperature at which any virus is killed can be determined. As will 

 be seen from the tables, 13 experiments for European foul brood, 

 22 for sacbrood, and 20 for Nosema disease were made in which healthy 

 colonies were inoculated with heated germ-containing material 

 from these three diseases, respectively. In the last disease the 

 stomachs from diseased bees furnished the germ-containing material 

 for heating and feeding. In these experiments the temperature was 

 maintained for 10 minutes as a rule. 



DISEASES OF THE BROOD OF BEES. 



Nearly a century and a half ago the name "foul brood" was used 

 for a destructive brood disorder of bees, and for almost a century 

 later it was apparently the custom to diagnose as foul brood any 

 destructive disease of the brood. About half a century ago bee- 

 keepers began to note that all of the brood diseases are not the same. 

 They began, therefore, to write of different forms of foul brood. 

 At the present time it is known that there are at least three infectious 

 diseases of the brood of bees. All of these diseases are more or less 

 destructive, and it is quite likely that each of them has now and then 

 been diagnosed as foul brood. In America these brood diseases are 

 now known as European foul brood, American foul brood, and sac- 

 brood. 



EUROPEAN FOUL BROOD. 



In European foul brood death occurs early, the larvae dying usually 

 before the time for cell capping. There is no viscidity (ropiness) to 

 the decaying larvae as a rule, and no pronounced odor present. 



Numerous samples of this disease have been examined from the 

 United States, and some from Canada. Its presence also in England, 

 Germany, Switzerland, and Denmark is strongly suggested by written 

 reports from these countries. It is very probable that the disease 

 has a much wider geographical distribution than these facts indicate. 



Two years ago the fact was demonstrated that the germ causing 

 European foul brood is the microorganism to which the name Bacillus 

 pluton is given. In a paper x announcing the fact it was stated that 

 the studies then made indicated that the germ is easily killed by heat. 

 This belief has been confirmed by further experiments. 



i White, G. F., 1912. The Cause of European Foul Brood. U. S. Dept. Agriculture, Bureau of Ento- 

 mology, Cir. No. 157. 



