32 



BULLETIN 809, U. S. DEPARTMENT OF AGRICULTURE. 



and sealed. After different intervals of time the suspension was 

 cultured, using brood-filtrate-egg-yolk-suspension agar. 



The results show that spores of American foulbrood were alive 

 after being in suspension in 1, 2J, and 5 per cent aqueous solutions 

 of carbolic acid (commercial) for months at room, outdoor, and ice- 

 box temperatures, respectively. The maximum period 

 during which any suspension was kept at ice-box 

 temperature was 32 months. At incubator temper- 

 ature the period during which the spores remain alive 

 in 5 per cent carbolic acid is better reckoned in weeks 

 than months. In 5 and 10 per cent solutions, re- 

 spectively, of formalin (37 per cent formaldehyde) it 

 was found that they were viable after 6 hours, and in a 

 20 per cent solution they were alive after 30 minutes. 

 While the spores were alive in the formalin suspensions 

 after these periods, the evidences obtained indicate 

 that the chemical death point was being reached. 

 Mercuric chlorid was resisted for days in 1 to 1000 and 

 1 to 500 solutions, respectively. 



Inasmuch as the spores of American foulbrood resist 

 the action of carbolic acid for more than a month 

 under fairly favorable conditions for their destruction, 

 this agent could scarcely be used with profit in prac- 

 tical apiculture. As the destruction of the spores with 

 formalin is a question of hours only, it is possible in 

 well-selected cases that use could be made of this 

 agent. Since mercuric chlorid in strengths ordinarily 

 used is resisted by the spores for days and furthermore 

 is such a violent poison, its value as a disinfectant in 

 American foulbrood is evidently limited. The general 

 fig.9 -capsule used conclusion in regard to chemicals as disinfectants is, 

 in determining the therefore, that they offer very little promise as a 

 to^hemlca/disin- practical means for the destruction of the spores of 

 fectants. American foulbrood. 



EFFECT OF DRUGS ON AMERICAN FOULBROOD 



Divers experiences have been reported by beekeepers relative to 

 the value of drugs in the treatment of the bee diseases. The fact 

 that the spores of Bacillus larvae possess a marked resistance to chem- 

 ical disinfectants tends to discourage hope that such substances 

 would be of much therapeutic value when employed as drugs in 

 American foulbrood. Such a conclusion, naturally, would not follow 

 necessarily. Some data relative to the effects of drugs on this disease 

 have been obtained through experimental inoculations using beta- 

 naphthol, U. S. P.; carbolic acid (phenol), C. P.; oil of eucalyptus, 



