8 FAEMEES' BtTLLETIH" 9^5. 



(3) The disease disappears later in the summer unless the colony 

 has become so badly weakened that it can not remove the dead larvae. 

 Such weakened colonies usually die in winter or in a time of dearth. 

 Colonies do not as a rule die as a direct result of European foul- 

 brood. There may still remain some dead larvae in the combs, show- 

 ing that the bees have not been able to remove all of them, but in any 

 but the worst cases even these disappear. If conditions which com- 

 monly prevail in early summer again appear there may be a recur- 

 rence of the disease the same season. 



(4) This disappearance of the disease usually accompanies the 

 beginning of the honey flow. At this time, unless the colony has 

 already reached maximum strength, there is a rapid increase in 

 brood rearing and the colony increases in strength, bringing about 

 conditions unfavorable for the development of the disease. • If the 

 honey flow fails, the disease may continue and under such condi- 

 tions is at its worst. It should be noted that in regions where the 

 early honey flows are uncertain or usually lacking European foul- 

 brood has done the most damage, for in years of failure the disease 

 spreads with such rapidity that the entire region becomes badly 

 infected. European foulbrood is rarely observed in regions where 

 an early honey flow is certain. 



(5) The .earliest brood of the year usually escapes with little loss. 

 This important fact has been overlooked in previous discussions of 

 this disease, but it is evident from Table I. The scarcity of Euro- 

 pean foulbrood in the early spring was mentioned in the earliest 

 accounts of its prevalence in New York. This in all probability is 

 due to the fact that the colonies have been able to remove most of 

 the disease dui'ing the previous summer and there has been left only 

 a little of the infecting material. 



(6) Some bees resist the disease more successfully than others. It 

 has been found through the experience of beekeepers generally that 

 the three-banded Italian bees are best for this purpose. These bees 

 have a further advantage in that they give excellent results in all 

 lines of beekeeping activity, and it is therefore safe to recommend 

 them as the best. This does not at all indicate that other races of 

 bees would not give as good results, as far as European foulbrood 

 control is concerned, but that it is easier to get good three-banded 

 Italian than good bees of any other race. The resistance appears to 

 be either a form of immunity or a greater ability to remove the dead 

 larvse completely. 



(7) European foulbrood is an infectious disease. This was clearly 

 shown by the experience of beekeepers before the disease was investi- 

 gated from a bacteriological standpoint, and these investigations have 

 supported the observations of the beekeeper. The bacteriological 



