OR ABUNDANCE OF VARIOUS SPECIES 109 



the effects of mildew produced by wet, but there 

 is often no apparent reason why a well established 

 colony should migrate to quite new pastures. 

 Sometimes the proximity of new buildings or 

 the digging up of ground may disturb them, 

 but I know of colonies that have gone from where 

 I knew them a comparatively few years ago, 

 and where I can detect no change likely to have 

 affected them. On the other hand there are 

 colonies which one has known all one's life and 

 which still go on as strongly or more strongly 

 than ever the case quoted under Anthophora, 

 p. 63, shows what persistence there can be in some. 



