Exterminating Mosquitoes 



NEXT to ilraining, the best way to 

 abolish mosquito breeding places 

 is to treat the water so as to kill 

 the mosquito larvae and while main- 

 substances have been tried for this 

 purpose, nothinij has given sucli good 

 results as petroleum, according to ex- 

 l)erts of the United States Department 

 of Agriculture. Common kerosene of 

 low grade is most satisfactory as regards 

 I ihciency and price. 



It has been found that spraying with a 

 portable pump is the best way to use 

 the oil. Small jionds, however, can be 

 sprinkled out of an ordinary watering- 

 pot with a rose nozzle, or for that matter 

 pouring it out of a dipper or cup will be 

 satisfactory. In larger ponds pumps with 

 a straight nozzle may • be used. A 

 straight stream will sink and then rise 

 and the oil will spread until the whole 

 surface of the water can be covered 

 without waste. 



In choosing the grtide of oil to be used 



two factors must be considered; it 



should spread rapidly and should not 



evaporate too quickh". 



^M^^ Heavier grades of oil 



^^^^B will be apt to gather in 



spots and the coaling will be neces- 

 sarily thick. It has been found that one 

 ounce of kerosene is sufficient to cover 

 fifteen scpiare feet of surface, and in the 

 absence of wind, such a film will remain 

 persistent for ten days. Even after the 

 iridescent scum apparently disappears 

 there is still an odor of kerosene about 

 the water. A mixture of crude oil and 

 kerosene has lieen found to be effective 

 in killing mosquito larvae. It has one 

 very decided advantage over pure kero- 

 sene which is that it does not evaporate 

 so quicklv'. 



Special attention should be paid to 

 little pockets of water that form around 

 the edges of ponds, for it is in such places 

 where the water is not disturbed by 

 wind or otherwise that the larvae breed 

 in greatest numbers. Larvae do not 

 Ijreed in open stretches of water where 

 the surface is rippled by the wind. 



In the fight against the mosquito in 

 Panama, the government experts found 

 that a larvicide composed of carbolic 

 acid, rosin and caustic soda was very 

 effective and thousands of gallons of it 

 were used. Crude oil was employed in 

 streams having a fair velocity. 



Covering the Surfaces of Ponds and Other Breeding Places with Petroleum, According to 

 Experts of the Department of Agriculture. Is the Best Move Against Mosquito Larvae. 

 The Illustration Shows a Pond Being Sprinkled with Petroleum from a Portable Pump 



367 



