158 GOLDFISH VAEIETIES A^D 



make a very sudden leap towards a victim. The "mask" shown in Figure 

 102 when not in use is folded before and under the head. Dragon Fly 

 larvae are strictly carnivorous at all periods and will attack any pond 

 creature reasonably near its own size. If given enough time a single 

 individual will destroy an entire hatching of fishes, growing by what it 

 feeds upon so as to be able to devour the remaining fishes which are also 

 becoming larger. 



Water Boatmen and Back Swimmers (Corixidcu and Notonectidce) 

 are found everywhere in still or slow-moving water. They are especially 

 plentiful in ponds containing vegetal decomposition and filth, not because 



Fig. 103. Water Boatman (Slightly enlarged) 



they like these, but because such conditions are favorable to the growth 

 of other creatures making good food for themselves. In daphnia pools 

 from midsummer until the end of the season Water Boatmen are fre- 

 quently found. Care should be exercised in picking them out of a net, 

 as their bite is very severe, the sensation being described as akin to the 

 sting of a hornet. Young fishes fall easy prey to these predatory insects. 

 They are usually easy to see on account of their jerky, jumping move- 

 ments, which are produced by use of their oar-like swimming legs. They 

 are obliged to occasionally come to the surface of the water to take air, 

 which gives an opportunity of seeing them. Both Water Boatmen and 

 Back Swimmers fly clumsily at night, and are often attracted to electric 

 lights. In some Southern climates they occur in enormous numbers. 

 They are gathered by the natives, dried and sold as fishfood under the 

 name of "African Flies." 



Fig. 104. Predaceous Diving Beetle (Life size) 



Predaceous Diving Beetle (Dytisciis). Fortunately this beetle is of 

 such size that it can scarcely escape notice, especially as it is obliged to 

 come to the surface for air, which it takes at the end of the abdomen. 



