Bee Disease Control 



American Foulbrood 



The date when the differences in the two diseases were posi- 

 tively recognized is obscure, but the work of Dzierzon in 1882 

 is the first which appears at all reliable. 



American foulbrood is an infectious disease of the larvae of 

 the honey bee, caused by Bacillus larvce White*. The majority 

 of the larvse are killed by this disease about the time they are 

 normally sealed. For this reason the initial stages of the disease 

 are seldom seen in a colony only recently attacked. As the 

 disease progresses the larvae lose their plump form and pearly 

 white color, sink down in the cell and the color becomes at first 

 a light brown, changing to a dark brown in the last stages of 

 the disease. Finally, the dried down larva forms a scale on the 

 lower side wall with the head toward the mouth of the cell and 

 the posterior end slightly turned up against the cell base. These 

 scales adhere tightly to the cell wall and are removed only with 

 difficulty by the beekeeper and practically not at all by the bees. 



There is a pronounced odor accompanying this disease which 

 has been likened to that from poor glue when heated.- It also 

 resembles somewhat the odor from decaying animal skins. This 

 odor while pronounced is usually not intense. If a comb con- 

 taining advanced stages of this disease is removed from the 

 hive and kept in a warm place, the odor increases for a time, 

 then gradually becomes less. 



The first symptoms which attract the apiarist's attention upon 

 opening a hive infected with American foulbrood are the scat- 

 tered appearance of the brood, and sunken and perforated cap- 

 pings over the diseased brood. The disease causes death in the 

 majority of cases after the larvae are sealed. This is particularly 

 true in a colony which has been infected a short time. The bees, 

 finding the brood does not emerge as it should, make holes in 

 the cuppings varying in size from a mere perforation to the 

 removal of the entire capping. 



The color of the capping over diseased larvae is darker than 

 that covering healthy brood. The cappings become sunken and 



*White, G. F. 1907. The cause of American foulbrood. U. S. Dept. 

 Agr. Bur. Ent. Cir. 94. 



