196 MOSQUITOES 



it free from organic matter for tliirty days, at a cost of 25 cents ; 

 tliat with care a whole state may be kept free of insect pests at a 

 small cost. An efficacious method is to scatter a few crystals 

 widely apart. A single pinch of permanganate has killed all the 

 germs in a 1,000-gallon tank. 



The item is so obviously ridiculous upon its face that 

 it would hardly seem worth while to make any attempt to 

 refute its statements. Nevertheless, it has been so widely 

 read that definite experimentation seems necessary to set 

 the matter at rest. The unknown author's ig-norance of 

 the life history of mosquitoes in the openin^^ sentence 

 need not necessarily imply that he would not know a good 

 remed}^ if he found one. Careful experiments were under- 

 taken by the writer in July, 1898, Avith various strengths 

 of permang-anate of potash, in water containing" mosquito 

 larvse from one to six days old. It was found that small 

 amounts of the chemical had no effect whatever upon the 

 larvae, which Avere, however, killed hy using amounts 

 so large that, instead of using a " handful to a ten-acre 

 swamp," at least a wagon-load would have to be used 

 to accomplish any result. Moreover, after the use of 

 tliis large amount and after the larvae were killed, the 

 same water, twenty-four hours later, sustained freshly 

 hatched mosquito larvae perfectly, so that even were a 

 person to go to the prohibitive expense of killing mos- 

 quito larvae in the swamp with permanganate of potash, 

 the same task would have to be done over again two days 

 later. 



The same conclusion was subsequently reached, after 

 careful experiment, by Dr. Lederle, of the New York 



