A NOTE ON THE TOXICITY OF ACIDS FOR 

 MOSQUITO LARVAE. 



JOSEPH HALL BODINE, 

 ZOOLOGICAL LABORATORY, UNIVERSITY OF PENNSYLVANIA. 



Interest in the resistance of mosquito larvae to various physical 

 and chemical reagents has been largely, if not solely, directed 

 toward the discovery of practical methods for the eradication of 

 the mosquito. A large amount of literature dealing with this 

 phase of the subject is now available. The effects of various 

 solutions of salts on mosquito larvae have also been rather ex- 

 tensively investigated and it has been found that the animals are 

 able to withstand rather high concentrations of pure salt solutions 

 (Mac Fie (i), Chidester (2), Sen (3), Sharma (4), etc.). It has 

 recently been pointed out by MacGregor (5) that mosquito 

 larvae are able to live and develop in extremely high concentra- 

 tions of acid, e.g., acid of P H = 44- In view of these last mentioned 

 observations, it was thought advisable to test the toxicity of a 

 series of acids of different concentrations for mosquito larvae 

 and the present paper embodies results obtained from such ex- 

 periments. 



The larvae used in all experiments, Culex pipiens, were obtained 

 in large numbers from 'small, stagnant pools usually found in 

 uncovered containers. The entire culture as found was brought 

 into the laboratory and tests carried out at the same time and 

 with the same group of animals, all of which had presumably 

 been under identical conditions. Both young and old larvae 

 were used and differences due to age noted. The animals were 

 removed from the cultures by means of a wide-mouth pipette and 

 transferred to a Syracuse watch glass with as little of the culture 

 medium as. possible. In this way a large number of larvae could 

 easily be obtained for use in each experiment. Fifty to sixty 

 animals were used in testing the effect of any concentration of 

 reagents. The chemicals used (10 c.c.) were put into covered 

 Syracuse watch glasses; the larvae were quickly injected into the 

 solution and then observed until dead under a binocular micro- 



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