FISH ENEMIES 



97 



which it sucks enough blood to kill its victim and then wantonly goes 

 after another. In this way a single individual may kill an entire 

 hatching of fish over night. This larva can usually be recognized by its 

 spindle-shaped body ; flat, strong head ; pale translucent brown color and 

 a steady progress through the water, coming to the surface frequently to 

 breathe a moment through the rear end. Although growing to a length 

 of 2Y2. inches, at which time it attacks larger fishes and any small aquatic 

 animals, it is the smaller sizes with which we are principally concerned. 

 From a length of l /\ to 1 inch they are not so easily seen, but are capable 

 of doing great mischief. 



Spearmouth. While not quite so common as the Water Tiger, its 

 habits are similar and it grows to an even larger size, reaching 3 inches. 



Fig. 72. Spearmouth (Life Size) 



The body is thicker and the mandibles are shorter. From the aquarist's 

 standpoint both these larvae could be classed as one. The Spearmouth 

 is the larva of the large Water Scavenger Beetle (Hydrophilus). 



Dragon-Fly Larvae. Almost everyone who raises fish outdoors is 

 familiar with these unpleasant individuals. There are two reasons why 

 they are difficult to altogether avoid. When newly hatched they are 

 very small and will go through the same strainer as daphnia ; furthermore, 

 the mother Dragon Fly (Odonata) is an excellent flier and may deposit 

 her eggs in any body of water that provides proper facilities for her 

 needs. These larvae live more by their cunning than by any agility as 



Fig. 73. 

 Nymph of Dragon Fly 



Fig. 74. 

 Dragon Fly Larva Catching Young Fish (Life size) 



swimmers. Waiting on a dirty pond-bottom or attached to sticks, aquatic 

 grass or other object, they mark time until a victim comes within close 

 reach. Then they quickly pounce forward, extending a vicious, pincher-like 

 organ called the "mask," rarely missing the object of attack. The method 



