4 BULLETIN 92, U. S. DEPARTMENT OF AGKICULTURE. 



germ causing the disease is the one to which the name Bacillus larvse 

 is given. 



The facts obtained to date are too meager to justify anything 

 more than a general statement regarding the minimum amount of 

 heating that can be employed in rendering material containing the 

 germ of American foul brood noninfectious. Taking rather wide 

 limits, it may safely be said that the minimum temperature at which 

 this can be done, if the temperature is applied for 10 minutes, lies 

 somewhere between 90° C. (194° F.) and 100° C. (212° F.). It seems 

 quite probable, indeed, that a temperature less than 98° C. (208.4° F.) 

 will suffice if applied for 10 minutes. When 100° C. was used the 

 spores of Bacillus larvse were killed in less than five minutes. 



SACBROOD. 



Observant beekeepers have for many years noted the presence of 

 dead brood which seemed to them to be different from that dead of 

 foul brood. Some were inclined to believe that the disease was 

 an infectious one; a larger number apparently were disposed to 

 ascribe the trouble to such causes as an unsatisfactory queen, starva- 

 tion, and the like. This brood disease has been recently demonstrated 

 to be an infectious one, and the name "sacbrood" has been given to it. 

 Larvse that die of this disease do so almost invariably after the time 

 of cell capping. The most characteristic symptom of the disease is 

 the saclike appearance of the dead larvae when they are removed from 

 the cell. This fact suggested the name "sacbrood " for the disease. 



Sacbrood is frequently met with. Its presence has been diagnosed 

 by Dr. A. H. McCray and the writer in 367 samples received from 44 

 States of the Union and in 13 samples received from Canada. Reports 

 from England, Switzerland, and Australia indicate strongly that this 

 disease exists in these countries also. It is very probable that it has 

 a much wider geographical distribution than is shown by these facts. 



More than a year ago it was again the writer's fortune to determine 

 the cause of another brood disease. Unlike the cause of either 

 European foul brood or American foul brood, the infecting agent 

 causing sacbrood has not yet been seen. It was demonstrated, 

 however, that the infecting agent in this disease passes through the 

 pores of earthenware filters. For this reason the cause of sacbrood 

 is spoken of as a filterable virus. 



In a paper 1 announcing the cause of sacbrood the statement is 

 made that the germ causing the disease is destroyed by a com- 

 paratively small amount of heat. This belief is confirmed by the 

 results of the experiments summarized in Table II. 



i White, G. F., 1913. Sacbrood, a Disease of Bees. U. S. Dept. of Agriculture, Bureau of Entomology, 

 Cir. No. 169. 



