FISH CONTROL 



187 



This aid must take the form of removing or otherwise eliminat- 

 ing vegetation and other floating matter, which serve to conceal 

 the larvae from the fishes and to prevent the fishes from reaching 



Fig. 130. — This formidable looking mosquito breeding-place offered quite a 

 problem. To have cleaned all the circumference, so as to make fish control 

 practicable, would have cost a lot of money. Instead, it was drained into a 

 large abandoned gravel pit nearby, the edges of which were already clean. In 

 this way, complete and permanent fish control was obtained at slight cost. 



Fig. 131. — Too much vegetation in this pool for effective fish control. 



the larvae, even though the larvae be visible. Just how impor- 

 tant this matter is is shown by the following observation of 

 Hildebrand: 1 



1 "Fishes in Relation to Mosquito Control in" Ponds," U. S. Bureau of 

 Fisheries,_1919. 



