Apr. 12, 1924 
Development of American Foulbrood 
131 
disease attacks drone and queen larvse nearly as quickly as those of the workers. 
The tendency of this disease to attack queen larvae is a serious drawback in treat, 
ment. Frequently bees of a diseased colony attempt to supersede their queen 
but the larvae in the queen cells often die, leaving the colony hopelessly queenless. 
The colony is thus depleted rapidly.” 
In American foulbrood, according to Phillips ( 39 ), “Usually the disease attacks 
only worker brood, but rare cases are found in which queen and drone brood are 
diseased.” White (55) 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 
larvae affected by American foulbrood in experimental colonies only, although 
very probably diseased queen larvae 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 larvae as well as one 
or two cases of diseased queen larvae. 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 larvae 
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 (21) 
was the first thus to differentiate definitely into two types of disease, according to 
the difference in symptoms and age at 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 * * *. The 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 larvae do not generally die 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, 
88286—24-4 
