158 The Control of Mosquitoes 



These difficulties have been partially overcome 

 by using the following drips : 



The simplest form of drip is a vessel with a small 

 hole punched in the bottom. This form is still 

 much used in places where the installation is 

 temporary, as on temporary ditches that are wet 



^7zl 



Obttoa 



'Bottom of on Oan 



on Drip made by 



Insertins Nail in 



Bottom of Container 



A simple form of oil drip. 



for relatively short periods, small pools shortly to 

 be drained, etc. A five-gallon kerosene can is 

 commonly used, having a hole punched in it by a 

 nail. A small quantity of cotton waste is wound 

 around the nail just below its head. The nail is 

 then pushed through the small hole from the inside 

 of the can. The quantity of oil allowed to drip 

 through the opening is regulated by pushing the 

 nail point upward or pulling the nail downward. 



