Anopheles Propagation Areas 65 



bed. Then vegetation grows around the edges 

 in shallow water giving the desired protection. 

 As the water is shallow, it becomes warmer and 

 this assists the rapid development of algae. 



The larvEe can penetrate the algae but small 

 fish cannot. AlgEe containing larvae may be 

 detached and floated downstream. Fish swim 

 to and fro around it, and follow it, trying to seize 

 the larvae, but they seldom appear to succeed. 

 Where the slope of the river bank is gradual, and 

 the water at the edges shallow, with gravel or 

 stone at the bottom. Anopheles larvae are often 

 found, providing other nearby and better pro- 

 tected breeding places do not exist. With the 

 first heavy floods of the rainy season most of these 

 river production areas are promptly eradicated. 



SEEPAGE 



Seepage water is water that flows underground 

 along an impervious stratum and reaches the 

 ground surface when that stratum becomes exposed 

 at the surface, or approaches it. Or it may come 

 through a stratum that is more or less porous and 

 water bearing. The places where the water 

 appears at the surface are called seepage out- 

 crops. They are frequently found on benches, hill- 

 sides, and in small valleys. In areas where they 



