REMEDIES AGAINST 3I0SQUIT0ES 193 



lish language as spoken by Englishmen, who invariably 

 term it paraffine or paraffine oil. To the Italians we are 

 indebted for a useful expression, which we might just as 

 well adopt, namely to ^^ pelrolhx^' meaning to treat waters 

 with kerosene. Example : The %jet7'olization of mosquito- 

 breeding pools is one of the most important measures to 

 be undertaken in the warfare against mosquitoes. 



Many of the small-scale experiments which have been 

 made, notably by the Italians, with a small number of 

 mosquito larviB in small jars or puddles, are not so in- 

 dicative of the results to be ex^iected as are more natural 

 and large-scale conditions. Mr. Matheson tells me that 

 he once took twenty-five larvae in a quart jar and cov- 

 ered it with a thin film of common kerosene oil and no- 

 ticed that in less than fifteen minutes all larvae were dead. 

 At the same time he put a film of oil on the surface of a 

 thirty-gallon tank, and at the end of an hour there were 

 still some few larvie wriggling. He questions whether 

 kerosene is as swift a larvicide if put on the surface of 

 deep i^onds, as it is on the surface of experimental jars. 

 In my own work I discovered that where the oil was not 

 distributed equally the larvae clustered in the free places 

 and were able to support life for hours. 



Otlier Stilstances Af/ainsf the Earhj Stages of 

 Jlosqnitoes. 



The last paragraph indicates plainly the fact that 

 laboratory experiments with other substances must not 

 be accepted as conclusive until the substances used are 



