> 



CHAPTER VIII 

 OILING 



PLACE OF OILING IN ANTI-MOSQUITO WORK 



Oiling of water surfaces should be considered as merely supple- 

 mentary to drainage and other measures of mosquito control. 

 While oiling alone might, under certain circumstances, suffice, 

 the expense, over a term of years, would be excessive. For 

 these reasons, oiling is usually confined to areas which it is 

 impracticable to drain, stock with fish or otherwise eliminate as 

 sources of mosquito-breeding, or else is used temporarily, pending 

 application of other measures. 



The purpose of oiling is to cover the surface of the water with a 

 film of oil, which kills larvae already present in the water and 

 prevents further deposition of eggs, so long as the film retains its 

 strength. The larvae are suffocated, through inability to pene- 

 trate the film with their breathing tubes. 



The necessity of oiling as a mosquito control measure will vary, 

 of course, with temperature, topography, aquatic plant growth, 

 presence of larva-destroying fish, the nature of the breeding 

 areas, etc. 



WHERE OILING IS APPLICABLE 



The greatest virtue of oiling, perhaps, is its applicability to 

 treating small rain-water pools, too numerous to drain and too 

 transient to stock with fish, yet often lasting long enough to 

 produce a brood of mosquitoes. There seems to be no other 

 method so effective as oiling for dealing with these. Streams, 

 ponds, swamps etc., may be treated by drainage methods or by 

 means of fish; breeding in artificial containers about homes may 

 be eliminated by removing the containers or, where necessary, 

 screening them; but neither of these methods is suitable for deal- 

 ing with rain-water pools. 



Another large use of oiling is to handle production areas while 

 steps are being taken to control them by other means. Thus, 

 the edges of ponds may be oiled, while the process of removing 



158 



