24 Department Circular 28k, U. S. Dept. of Agriculture 



The uncapping of all brood cells eliminates the necessity for a 

 solution with low surface tension. The much less expensive water- 

 formalin solution will be found to enter the open cells sufficiently 

 to soften, loosen, and sterilize the scales as effectively as an alcoholic 

 solution, although the entrance may not be quite so rapid. The 

 slower entrance into the cells is more than counterbalanced by the 

 greater germicidal efficiency of formalin in the presence of water as 

 compared with that of the same disinfectant in an alcoholic solution. 

 The water-formalin solution readily softens and penetrates the 

 masses of pollen in cells, since stored pollen is held together by small 

 amounts of honey, readily soluble in water. Aside from the count- 

 less spores contained in the diseased remains and those in the infected 

 honey or pollen, practically the only other spores that might in any 

 way get to healthy larvae and cause disease are not in masses, but are 

 scattered individually over the surfaces of the comb, having acci- 

 dentally been carried there by the bees in their work. 



White (£7, p. 32) has shown that spores suspended in a 20 per 

 cent formalin solution would be killed inside of a few hours; it 

 follows that when individual spores on combs come in direct contact 

 with the disinfectant they must be killed in a comparatively short 

 time. If, as was found to be the case in the laboratory experiments, 

 soaking for 24 hours of scales of American foulbrood in open cells 

 kills all spores embedded in them, probably immersion for only a 

 few hours is necessary to kill these spores on the comb surfaces, 

 as would be the case with dry extracting combs that have been 

 in diseased colonies but have contained no dead brood. The few 

 spores that might become embedded in propolis are as negligible as 

 those in the w T ax. 



The uncapping of all brood cells, as well as of any sealed cells of 

 honey in diseased brood combs, naturally adds somewhat to the 

 labor cost of treating these combs; but if results in the apiary com- 

 pare at all with the results in the laboratory, the lowering of the 

 cost by elimination of the alcohol, using only formalin in water, will 

 more than offset the slight additional labor cost. However, before 

 treatment it is almost always necessary to uncap some sealed honey 

 in combs from diseased colonies; if the brood is uncapped at the 

 same time, comparatively little extra effort or time will be required. 

 The washing of combs, when necessary after treatment for 48 hours 

 in the water-formalin solution, also adds to the labor costs; but in 

 this case again the extra labor should be repaid b}^ the results. 



The data presented indicate that a 20 per cent solution of formalin 

 in water is the most efficient as well as the most economical disin- 

 fectant so far found for the sterilization of combs infected with 

 American foulbrood. provided the cappings are all completely re- 

 moved. It is hoped that apiary tests will be made to determine the 

 practicability of these results. Naturally, even with the most re- 

 liable process, carelessness in handling the combs, and more particu- 

 larly carelessness in the treatment of the diseased colonies from which 

 the combs are taken, will be fatal to success in gaining control 

 over this disease which has thus far caused such great losses. The 

 must approved methods for the treatment of American foulbrood 

 have been discussed elsewhere. 3 



8 Methods of treatment and control of American foulbrood are discussed in United 

 States Department of Agriculture Farmers' Bulletin 1084. 



