6 Department of Agriculture 



also look as though they were saturated with grease, whereas 

 the cappmgs over healthy larvas have a porous appearance some- 

 what resembling coarse paper. « 



At that stage of the progress of the disease, when the larva 

 has sunk down in the cell, the color has become a pronounced 

 brown and the larva is still moist. If a small stick is inserted in 

 the dead larva and withdrawn, a part of the decaying mass will 

 adhere to the stick and be drawn out in a thread sometimes 

 several inches in length. 



In the final stages of the disease the dried-down larvae are 

 found, with rare exceptions, on the lower cell wall. 



In advanced cases many larva; die before the sealing stage, but 

 usually there are in such cases a sufficient number of the char- 

 acteristic scales to make it evident that American foulbrood is 

 the invader. Death sometimes does not occur until pupation 

 has begun, and occasionally the dried-down pupa is found with 

 the tongue extended across the mouth of the cell. 



Usually only worker larvae are attacked by this disease, al- 

 though drone and queen larvae are sometimes affected. 



Contrary to experience vvith European foulbrood, American 

 foulbrood shows no sharp increase or decrease in relation to any 

 particular part of the active season, neither has there been found 

 a race of bees which have shown definite resistance to its 

 attacks. 



In an apiary where this disease is present, usually a small 

 percentage of colonies are found affected unless the disease has 

 been much neglected. The spread of this disease in an infected 

 colony is much slower than is the case in a colony infected with 

 European foulbrood. 



European Foulbrood 



This form of foulbrood is caused by Bacillus pluton White^ 

 The majority of the larvae affected die before the time for seal- 

 ing ; in advanced cases, many do not get beyond the stage when 

 they are curled up in the bottom of the cell. Some are sealed 

 before death occurs. There is a loss of form of the larva. The 



