68 



Pond Insects. 



Certain pond insects are found swimming or running on 

 the surface of the water, others swimming in the water, and 

 still others live habitually crawling or slowly swimming over and 

 thru the soft mud and organic detritus at the bottom of the pool 

 or pond. 



WATER-STRIDKRS AND WHIRLIGIG BEETLES. Running 

 quickly about on the surface of almost any pond or quiet brook 

 pool, may be seen numerous rather large, blackish, narrow- bodied 

 long legged insects (fig. 41), the water-striders, or pond skaters, 



as they are sometimes called. 

 The water-striders run or leap 

 quickly over the water's surface 

 when disturbed; when at rest 

 they have the two hinder pairs 

 of long, thread-like legs out- 

 stretched, while the front pair 

 ~~ of shorter, stouter legs is held 

 projecting forwards close to the 

 head, ready tor grasping and 

 holding smaller insects which 

 are the prey of the water-striders. 

 For these insects are predaceous, 



Fig. 41. A Water-strider (Hygrotrechus.) living On the blood of Other 



insects which come up from be- 

 low to breathe, or the flying insects which may happen to fall 

 into the pool. 



The water-striders may be observed on the surface of their 

 own pool, or they may be brought to the school- room and readily 

 kept and watched in the quiet water aquarium. (A glass jar half 

 filled with water.) A few house flies or other non-swimming insects 

 should be thrown on the water to serve as food for the water- 

 triders. The surface of the water should not be too near the 



