235 



III.— FACTORS AFFECTING THE COURSE OF 

 THE DISEASE WITHIN A COLONY. 



There exists a very general impression that a stock, 

 once affected by Acarine disease is inevitably doomed 

 to extinction. The impression doubtless originated in 

 the fact that until recently it was not possible to 

 recognise the presence of the disease until it had become 

 securely established in the colony. When this stage has 

 been reached, it is quite true, it has rarely been possible 

 to save the stock. Whilst this is so, it is equally note- 

 worthy that the course followed by the disease shows 

 in different cases great variation in its rate of progress 

 as well as definite fluctuations in its incidence upon the 

 stock. It is now also clear that in a proportion of 

 cases, where there is a combination of favourable cir- 

 cumstances, the infection may be shed and the stock 

 become free of the disease. 



In the belief that an understanding of the main con- 

 tributing factors affecting the course of the disease is 

 essential to its successful management, the following 

 effort to make these clear is submitted. It is some- 

 what surprising that probably most beekeepers have 

 failed to grasp the simple but really fundamentally 

 significant fact that the problem is one which concerns 

 the spread of an infestation in a continuously changing 

 community rather than the progress of a disease in an 

 individual. To make comparisons of this and other 

 bee diseases with human infectious diseases leads only 

 to confused thinking, unless the obvious distinction 

 between the progress of these diseases within a com- 

 munity and their manifestations in suffering individuals 

 is recognised. 



There is no doubt that the progress of the disease in 

 the individual bee is a very important feature in the 

 main problem, and this matter is dealt with elsewhere 

 (pp. 3 & 32). But it is not directly proportional to the 

 spread of the disease in the colony, which is governed, 

 as we shall see, by a number of independent factors. 

 The beekeeper is primarily concerned with the increase 



