DESTRUCTION OF GERMS OP BEE DISEASES BY HEATING. 3 



Table I gives a brief summary of 13 inoculation experiments per- 

 formed for the purpose of determining approximately the amount of 

 heating necessary to destroy the germ of European foul brood. 



Table I.- — A summary of the experiments made to determine approximately the minimum 

 amount of heating necessary to destroy the germ causing European foul brood. 



Dates of inocu- 

 lation. 



Tempera- 

 ture. 



Time of 

 heating. 



Results of inoculation. 



Sept. 12,1912 

 Do 



Sept. 23, 1912 

 Oct. 12,1912 

 Oct. 1, 1912 

 Oct. 8, 1912 

 Oct. 10,1912 

 Oct. 4, 1912 

 Aug. 8, 1913 

 Sept. 3,1912 

 Sept. 20, 1912 

 Sept. 28, 1912 

 Sept. 20, 1912 



°C. 

 75 to 80 

 65 to 70 

 64 to 66 

 64 to 65 

 62 to 63 

 62 to 63 

 62 to 63 

 61 to 62 

 60 

 60 

 58 to 60 

 57 to 60 

 55 to 56 



Min. 

 10 

 10 

 10 

 10 

 10 



No disease produced. 



Do. 



Do. 



Do. 



Do. 



Do. 

 Disease produced. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



10 

 10 

 20 

 10 

 10 

 20 

 10 



It will be observed by an inspection of Table I that European foul 

 brood was produced in every instance where healthy colonies were 

 fed disease material which had been heated for 10 minutes at tempera- 

 tures below 63° C. (145.4° F.), but that no disease was produced when 

 temperatures higher than 63° C. (145.4° F.) were used for the same 

 length of time. The minimum temperature that can be used, there- 

 fore, in destroying the germ of European foul brood, if it is applied 

 for 10 minutes, lies somewhere between 60° C. (140° F.) and 65° C. 

 (149° F.), being near 63° C. (145.4° F.). 



AMERICAN FOUL BROOD. 



American foul brood is the disease of the brood of bees that is best 

 known to beekeepers and is the one the presence of which they have 

 been able to recognize most easily. In this disease the larvse usually 

 die after the cells containing them are capped. The disease is charac- 

 terized especially by the marked viscidity (ropiness) manifested by the 

 decaying larvse that are dead of the disease. The pronounced odor 

 noticeable within hives housing colonies affected by this disease, espe- 

 cially in its later stages, is another well-known characteristic. 



This disease is very widely distributed geographically. Samples 

 of it have been received from many localities in the United States, 

 from Switzerland, New Zealand, Germany, England, and France, and 

 it is very probable that it has a much wider geographical distribution 

 even than is indicated by these facts. 



Until seven years ago the cause 1 of American foul brood was not 

 known. At that time the fact was demonstrated positively that the 



i White, G. F., 1907. 

 mology, Cir. No. 94. 



The Cause of American Foul Brood. U.S. Dept. of Agriculture, Bureau of Ento- 



