CONTROL OF EUROPEAN FOULBROOD. 7 



times with startling rapidity, much more rapidly than American 

 foulbrood. 



(11) Variability. — In all its symptoms European foulbrood is 

 more variable than is American foulbrood. Color is perhaps the 

 most constant symptom. 



BASIS OF TREATMENT. 



The confusion in the treatment of the disease is due to a failure to 

 analyze the factors forming the basis of treatment. Various treat- 

 ments have been described in the beekeeping journals as distinct 

 when they were simply modifications of the same treatment. 



(1) European foulbrood is a disease of weak colonies. While at 

 times one may observe larvae dead of this disease in strong colonies, 

 usually .they are removed before the disease can do much harm. It 

 should be pointed out, further, that it is the colony which is failing 

 to increase in strength in the spring which is most seriously affected, 

 for a small colony which is rich in young and vigorous bees and 

 which is increasing in strength is often able to overcome the disease. 

 It is therefore a disease of weak rather than small colonies. 



(2) The disease is prevalent in the spring and early summer. 

 While at times it is observed at other periods of the year, this is not 

 usual. Samples of European foulbrood have been received by the 

 Bureau of Entomology in every month of the year, but, as will be 

 seen from Table I, they are far more commonly received in the early 

 part of the active season. These samples are listed according to the 

 date of receipt at the bureau laboratory. The highest number is re- 

 ceived in June and the average date for the removal of these samples 

 from the hives is probably a few days previous to June 15, perhaps 

 June 10. The earliest samples received are regularly those from 

 California, where the season opens early. There is a sudden increase 

 in May and June and almost as rapid- a decline later. The few sam- 

 ples received from October to April may be largely disregarded, as 

 they are almost without exception dried material of unknown age. 



Table I. — Distril)Ution of European foulbrood by months, including all posi- 

 tively diagnosed samples received by the Bureau of Entomology from 1908 

 to December, 1917. 



Month. 



New 

 York. 



January... 

 February. . 



March 



April 



May 



June 



July 



August 



September 

 October... 

 November. 

 December. 















2 



23 



50 



41 



20 



8 



3 



1 







