186 



NATURE STUDY REVIEW [8 :o— May, 1913 



swimmers, dragon fly and may fly nymphs, and sometimes their 

 own young. They also attack snails and young fish. Collect 

 and fed them in the same way as described for the Large Giant 

 Water Bug. If young ones of different sizes are put into the 

 same aquarium, the smaller ones will be eaten up. It is easy to 

 keep them in an aquarium and to see much of their very interest- 

 ing life history. 



The Predaceous Diving Beetles (Fig. 12). 



Both the adult beetles and their larvae can be found at almost 

 any time and in almost any weedy pool of stagnant or standing 

 water. By approaching one of these -pools very quietly, these 

 dark, oval, flattened beetles can be seen hanging head down with 

 the tip of the abdomen at the surface of the water. If disturbed, 



10 



ri 



12 



Adult Insects. — 9, Larger Giant Water Bug; 10, Smaller 

 Giant Water Bug; 11, Water Scavenger Beetle; 12, 

 Diving Beetle. 



they dive and may conceal themselves at the bottom, but in time 

 they will appear at the surface again. These beetles and their 

 larvae (Fig. 21) are the most blood-thirsty of all the water beetles 

 and are a terror to the smaller water insects as well as to young 

 fish and tadpoles. In fact, the larvae are even more fierce than 

 the adults, and are constantly feeding on almost every living 

 form which they can capture. To collect the larvae or the adults, 

 go very quietly to the edge of some suitable pool and when they 

 come to the surface for air, put the net gently under them when 

 they dive. Since these insects often hide in the partly submerged 

 vegetation near the shore they can be collected by sweeping the 



