Apr. 12, 1924 Development of AmeHcan Foulbrood 131 



disease attacks drone and queen larvse nearly as quickly as those of the workers . 

 The tendency of this disease to attack queen larvse is a serious drawback in treat- 

 ment. Frequently bees of a diseased colony attempt to supersede their queen 

 but the larvffl in the queen cells often die, leaving the colony hopelessly queenless. 

 The colony is thus depleted rapidly." 



In American foulbrood, according to PhiUips (39), "Usually the disease attacks 

 only worker brood, but rare cases are found in which queen and drone brood are 

 diseased." White (BS) states, however: "That worker, drone, and queen larvae 

 are all susceptible to the disease has been demonstrated during these [White's] 

 studies. Affected drone brood is encountered less often in the diagnosis of this 

 disease than in that of European foulbrood. The writer has encountered queen 

 larvsB affected by American foulbrood in experimental colonies only, although 

 very probably diseased queen larvse do occur in nature also." A few samples of 

 diseased brood containing American foulbrood sent to the Bee Culture Labora- 

 tory for diagnosis have been found to contain affected drone larvse as well as one 

 or two cases of diseased queen larvse. Although beekeepers believe that in 

 American foulbrood drone brood is so seldom affected that the absence of dis- 

 eased drone brood is a diagnostic character, the fact that occasionally drone larvse 

 do die of the disease makes it possible that some other factor than nonsuscepti- 

 bility of sex is concerned. No accurate data are available on this subject. The 

 work of this paper is concerned only with worker brood, because the great pre- 

 ponderance of worker brood affected gives slight importance to the comparatively 

 few drone larvae in the average colony. 



AGE 



The general characteristic difference in age between larvae dying of American 

 foulbrood and those dying of European foulbrood, mentioned at the beginning 

 of this paper, has been one of the chief factors in the differentiation between the 

 two diseases. Originally there was considered to be only one disease, "foul- 

 brood." Although beekeepers have long known that brood of various ages is 

 attacked by brood disease, it seems not to have been until about 1880 that the 

 difference in age at the time of attack was used to separate foulbrood into two 

 distinct forms, one "easily curable" and the other "virulent." Dzierzon (SI) 

 was the first thus to differentiate definitely into two types of disease, according to 

 the difference in symptoms and age a|t time of attack. He stated that in the 

 curable disease, " More of the larvse die still unsealed, while they are still coiled 

 in the bottom of the cell * * *. xhe brood which does not die before sealing 

 mostly attains to perfection * * *. This is exactly the reverse in the malig- 

 nant kind of foulbrood. In this the Jarvae do not generallydie before they have 

 raised themselves from the bottom of the cell, have been sealed and begun to 

 change into nymphs." 



Cheshire {13) who probably was the first to investigate the bacteria associated 

 with what, in the light of present knowledge, is known as European foulbrood, 

 was inclined to agree at first with the distinctions made by Dzierzon. He soon 

 stated (,14), however, that Dzierzon was in error and that there is only the one 

 disease, foulbrood, which he supposed was caused by an organism to which he 

 gave the name Bacillus alvei. Cheshire and Cheyne (15) described Bacillus alvei 

 as a spore-forming bacillus which they constantly found associated with a dis- 

 eased condition of the brood and recognized only as "foulbrood." The results 

 of this work caused considerable confusion to beekeepers and investigators, both 

 in this country and abroad, for more than a decade. 



In this country some time after 1890 it became evident to certain beekeepers , 

 particularly in New York State, that they were dealing with two distinct dis- 

 eases. The newly recognized form, which was found to attack the coiled larvse. 



