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and survival of the colony and this is controlled by 

 various factors of which the development of broods of 

 mites with the coincident pathology in certain individual 

 bees may not be the dominant one. Whilst these factors 

 are considered separately it will be understood that there 

 is an interacting influence where they are present 

 together. 



Multiple Infestation from Outside Sources. 



The commencement of infestation in a stock, may be 

 due to the entrance to the colony of a single or of a 

 limited number of infested bees. In such cases the 

 spread of disease within the colony may be very slow 

 or it may fail. On the other hand there may be within 

 a limited time, repeated fresh infestations from outside 

 sources. 



Under certain circumstances, of which probably the 

 most dangerous is robbing, infestation is conveyed by 

 the robbing bees to their own colony. In this case it is 

 started not from one or from a few centres within the 

 hive, but more likely from hundreds. And this may 

 take place in the course of a single day. Further, it 

 may be repeated over a considerable period of time. 



Under such circumstances a stock of bees, although 

 otherwise most favourably situated, may be expected 

 to show within a comparatively short period a well 

 established infestation. 



I have quoted robbing as a chief source of multiple 

 infestations. Another will be found in the case where 

 there are already affected stocks in the same apiary or 

 in the immediate neighbourhood. Under such circum- 

 stances multiple infestations may be conveyed — apart 

 from robbing — by the other means already enumerated, 

 viz : drones, drifting bees, or casual visitors entering 

 the wrong hive. 



Effect of Numbers of Bees. 



The larger the community, i.e., the greater the 

 number of worker bees, the longer time will elapse 

 before the presence of the disease will become apparent 

 to the observer or significant to the stock. We do not 

 know how long a period elapses before a single bee 



