FISH CONTROL 



191 



larva-protecting plants or else to treat them in such manner as to 

 make them obnoxious to the larvae. 



The first consideration is to get rid of the shore vegetation, 

 which frequently is thickest in the shallow areas where mos- 

 quitoes are most apt to breed. This, generally, can be done very 

 effectively with a hoe or shovel, the idea being to leave a clean 

 edge, devoid of grass, brush and other debris which may conceal 

 the larvae from the fish. 





(Photo by E. B. Johnson, C. E.) 



Fig. 135. — Breeding in this stream is controlled by means of larva- 

 destroying fish. Note the clean edges and the cow helping to keep 

 them clean. 



In some cases, this cleaning of the edges may be accomplished 

 more cheaply by lowering the water level from 6 inches to a foot. 

 If the water has stood at its former level for some time, the new 

 shore line probably will be quite clean. 



Often, there will be some shallow coves or other areas thickly 

 covered with algae or other aquatic growths or debris, most of 

 which will be beyond the reach of the man with the hoe or shovel. 

 In such cases, it may be sufficient to oil these areas very liberally 

 once every week or ten days. It should be borne in mind, how- 

 ever, that application of oil probably will drive away the fish, 

 thus making it necessary to rely solely on the use of oil to control 

 the area. 



