26 Department Circular 284, U. S. Depl. of Agriculture 



under treatment, indicate that little if any actual liquid enters cells 

 where the capping is intact and more or less impermeable. It is 

 probable that when such sealed cells are sterilized the disinfection is 

 brought about by the passage through the capping of gas and 

 vapor liberated from the solution. 



The perforation of brood cappings adds to the efficiency of the dis- 

 infectant solutions, both alcoholic and water; but, aside from the 

 difficulty of doing this in a practical wa} r , the sterilization of such 

 cells is not always uniformly complete, even after a treatment of 

 48 hours. 



To obtain uniformly complete sterilization of all infected cells in 

 American foulbrood combs, no matter what solution is used, all cap- 

 pings, covering both brood and honey, should be carefully removed 

 before the combs are immersed in the solution. This can be easily 

 done if care is used, with a hot, sharp, uncapping knife, and adds 

 little to the labor costs. 



The sterilization of combs infected with American foulbrood, 

 when all the cells are uncapped and alcohol-formalin solution is 

 used, requires, if complete from the standpoint of the cultural re- 

 sults obtained, more than a 24-hour treatment. A treatment of 48 

 hours would give a margin of safety. 



The sterilization of combs infected with American foulbrood, 

 when all the cells are uncapped and a 20 per cent solution of for- 

 malin in water is used, if complete from the standpoint of the cul- 

 tural results obtained, requires treatment for 24 hours at least. A 

 somewhat longer period would give a greater margin of safety. 



The washing of combs in water, to prevent the formation of a 

 residue of paraformaldehyde after treatment with disinfectants con- 

 taining 20 per cent of formalin, should not be attempted unless the 

 combs have been treated at least 48 hours in the solution. A some- 

 what longer period would give a greater margin of safety, particu- 

 larly with the alcohol-formalin solution. 



To reduce the chance of missing any cells that have not been 

 completely sterilized, when testing the efficiency of any disinfectant 

 solution, a sufficiently large number of cells should be cultured. The 

 proportion should be approximately from 3 to 5 per cent of the cells 

 of each class, open and closed, so distributed as to represent fairly all 

 the cells treated. 



In view of the cultural results obtained, a 20 per cent solution of 

 formalin in water was found the most satisfactory disinfectant for 

 use in sterilizing combs infected with American foulbrood, with re- 

 gard to both germicidal action and low cost, provided the proper 

 precautions are taken. All honey should be extracted, all brood 

 cappings should be completely removed, and the combs should be 

 treated at least 24 hours, or 48 hours if it is found desirable to wash 

 them in water after treatment. Before such a procedure can be rec- 

 ommended unreservedly exhaustive tests must be carried out under 

 apiary conditions. 



Care must be taken not only with the process of disinfecting combs 

 infected with American foulbrood, no matter what solution or 

 method is used, but equal or greater care must be exercised in the 

 treatment of the diseased colonies themselves to eliminate the danger 

 of recurrence of disease from that source. The successful steriliza- 

 tion of the combs will otherwise be of little avail. 



