98 FISH ENEMIES 



of propulsion through the water is peculiar, being brought about by a 

 series of expulsions of water from the rear end. This enables them to 

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

 Figure 74, 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 their 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. 



Predaceous Diving Beetle (Dytiscus). Fortunately this beetle is 

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



Fig. 75. Predaceous Diving Beetle (Life size) 



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

 It is rapacious in extreme degree and is a good swimmer. A large 

 specimen was once placed in an aquarium for observation. It so quickly 

 attacked a goldfish that the scales fell in a small shower and the fish 

 died before it could be rescued. They are usually of such a dark brown as 

 to appear black, but are sometimes bordered with yellow. 



Water Scavenger Beetle (Hydrophilidce). We mention this beetle 

 here because of its resemblance to the large predaceous diving beetle. 



Fig. 76. Water Scavenger Beetle (Life size) 



It swims differently, using its legs alternately, while the diving beetle 

 moves opposite pairs together. The Scavenger Beetle is also different 

 in that it breathes at the surface from the mouth. Instead of long 

 antennas, they have palpi looking like club-shaped antennae. This beetle 

 lives chiefly on decomposing vegetal and animal matter, although taking 

 soft living plants such as Nitella. It has been claimed to be predaceous, 



