87 



more normal case of the atrophy of organs that are no longer 

 required. 



The mode of dispersal of these species of moths with wingless 

 females has been the subject of discussion. It has been suggested 

 that they are carried about by the males when paired, but positive 

 confirmation of this theory by actual observation is strangely 

 lacking. Indeed I know of only one case (22) in which it has 

 been observed, and then only when the insects were disturbed. 

 Alternative modes would be presumably (i.) by the wandering of 

 the 5 after emergence before finding a suitable tree or shrub to 

 climb up ; in view of the active way in which they can run they 

 might be expected to cover very considerable distances ; (ii.) by 

 the wandering of the larvae either when seeking a suitable spot for 

 pupation or earlier. Considering the readiness with which they drop 

 from the taller vegetation and the frequency with which some of 

 them may be found crawling about on low-growing plants, it 

 seems likely that this method forms no inconsiderable factor in the 

 dispersal of these species. 



We have already seen that one of the principal directions in 

 which insect life is affected by the conditions of winter is in conse- 

 quence of the fall of the leaf and the dying down of many of the 

 summer plants. But in the almost infinite variety of insect life 

 there are, of course, a large number of insects whose food supply is 

 not thus cut off, so that among these we may look for species which 

 feed through the winter, or at any rate during the large portion of 

 it when the weather remains mild and open. 



Many predaceous insects, such as beetles of the families 

 Carabiihe, Staj>liyliniihc, etc., remain more or less active throughout 

 the winter, subsisting upon hibernating insects, larvae, eggs, and 

 so forth. 



Aquatic insects are in this respect perhaps more highly favoured 

 than most. In anything but the smallest pools the temperature 

 practically never falls below freezing point, so that the denizens of 

 our ponds and rivers are favoured with a much more equable 

 temperature all the year round than have the aerial insects, and 

 pond life continues, at a somewhat slower speed it is true, but 

 otherwise scarcely altered, throughout the winter. Many of the 

 aquatic insects are, of course, air breathers, obtaining their air 

 supplies direct from the atmosphere at the surface of the water. 

 This is to some extent interfered with when the ponds are frozen 

 over, but sufficient oxygen for their reduced needs is usually held in 



