346 



Aquatic Societies 



those that dry up in summer. The commonest beetles 

 are small members of the families Hydrophilidae, 

 Dytiscidae and Haliplidae. The most characteristic of 



the bugs is the slen- 

 der little marsh- 

 treader, Limno- 

 bates. Swale-flies, 

 mosquitoes, crane- 

 flies and ubiqui- 

 tous midges abun- 

 dantly represent 

 the aquatic Dip- 

 tera. 



There are, of 

 course, many in- 

 sects dependent 

 upon particular 

 plants. Such are 

 the tineid moth, 

 Limnacea phragm i- 

 tella, that burrows 

 when a larva in 

 the Typha fruit 

 spike, and the wee- 

 vil, Sphenophorus, 

 that burrows in the 

 Typha crown; the 

 leaf -beetle, Dona- 

 tio, emerginata, 

 whose larva feeds 

 on the submerged roots of the bur-reed, etc. Here are 

 also a number of characteristic spiders, such as the 

 diving spider, Dolomedes. 



Doubtless the lower groups of animals possess species 

 that are addicted to dwelling in marshes, and fitted to 

 the peculiar conditions such places impose, but these 



Fig. 204. A damselfly. Lestes uncatus. 



