144 



FISH ENEMIES 



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 2yi 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 ^ 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. The body is thicker and the mandibles are shorter. From 



Fig. 135. Spearmouth (Life size) 



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 



Fig. 136 

 Nymph of Dragon Fly 



Fig. 137. Dragon Fly Larva Catching Young Fish 

 (Life size) 



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

 furthermore, the mother Dragon Fly (Odoiiafa) is an excellent flier and 

 may deposit her eggs in any body of water that provides proper facili- 

 ties for her needs. These larvae live more by their cunning than by 

 any agility as 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, extend- 



