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MALARIA 



it cannot be irrigation as such. The matter simply 

 resolves itself to relative abundance of water; where 

 this is abundant, it is used unsparingly and without 

 regard to leaky ditches (Fig. 29) and great waste, 

 thus forming the ideal swamp areas (Fig. 30) for the 

 propagation of the Anopheles mosquito. On the other 



Fig. 30. Showing the results of a "leaky" irrigation ditch. Field Agent placing flag 

 in position to mark place where Anopheles mosquito larvae were found. 



hand, where there is little rainfall and water is expen- 

 sive, with greater evaporation throughout the year, 

 the water is husbanded, with the result that leaky 

 ditches, and consequent swamps, are practically un- 

 known, and therefore the Anopheles mosquito has not 

 obtained a foothold. 



The farmers of northern California in general must 

 pay more attention to the improvement of their irri- 

 gation methods. In irrigating, the water should not 



