150 The Control of Mosquitoes 



cause silt, etc., to be deposited, but decreases the 

 surface velocity near the banks in the wider section, 

 and in such places algae will grow and mosquito 

 larvae thrive. Near Empire the topography was 

 suitable for the temporary impounding of water, 

 and by placing a gate at the entrance to a culvert, 

 sufficient water was obtained to thoroughly flush 

 the ditch below it and remove all mosquito larvae 

 whenever desired. 



