EUROPEAN FOULBROOD. 31 



Sacbrood is recognized by the death of larvse after capping, by the 

 saclike appearance, the watery granular consistency of the larval 

 remains, and the absence of viscidity. The absence of microorgan- 

 isms characterizes the microscopic picture in sacbrood. 



OTHER CONDITIONS 



Conditions referred to as chilled brood, overheated brood, and 

 starved brood must be differentiated from European foulbrood. This 

 can usually be done with little difficulty by a comparison of the symp- 

 toms present with those of European foulbrood. The history of 

 the case is of much value. Brood dying after being removed from 

 the hive and before examination is made shows often an interest- 

 ing similarity to European foulbrood. B. alvei and B. pluton are not 

 found in these conditions. The absence of bacteria, or their presence 

 in small numbers only, and a lack of uniformity of the species when 

 present, characterize the bacteriological findings in these cases. 



PROGNOSIS 



There is no uniformity in the prognosis in European foulbrood. 

 The diseased colony may recover completely from the infection, suf- 

 fering only a slight loss in strength as a result of it ; the colony may 

 recover but sustain considerable loss ; or it may die out entirely, as a 

 result of the disease. The infection may spread only slightly to other 

 colonies of the apiary or the entire apiary may become infected. The 

 losses sustained vary from slight to total. The tendency for Euro- 

 pean foulbrood to disappear is greater after midsummer than before. 



Whether a larva once infected ever recovers from this disease is 

 not known, but the evidence at hand indicates that it may. This 

 seems to be especially probable when the infection takes place during 

 the latter part of the feeding period of the larva. Queen larvse are 

 susceptible to infection, but sufficient data are wanting from which 

 to estimate the extent to which queenlessness may result from the 

 disease. In experimental colonies queens have been reared in the 

 presence of a considerable amount of European foulbrood infection. 



The prognosis for the colony in the case of European foulbrood 

 may be said, therefore, to vary from very good to very grave, many 

 recovering entirely from the infection without treatment and without 

 appreciable losses, while others rapidly decline and finally die out. 



SUMMARY AND CONCLUSIONS 



The following -is a brief summary of facts regarding European 

 foulbrood, together with some conclusions based upon them: 

 1. European foulbrood is an infectious brood disease of bees caused 

 by Bacillus plwton. 



