REPORT ON MOSOUITOES. 



vDD 



conditions were unchang-ed except that the water in Jars 7 and 

 8 was much clearer than the others and the experiment was 

 closed. 



In all the experiments it is to be observed that the killino- of 

 the larvce was gradual and irregular and hence the action of the 

 copper sulphate upon them must be indirect rather than direct; 

 by killing off the food organism and possibly by acting through 

 the digestive system. A few larvcT of Ciilex pipieiis succumbed 

 to one part of copper sulphate in 53.500 of water in sixteen 

 hours: others survived one part^of copper sulphate in 3,300 of 

 water for seventy-two hours, while one survived one part of 

 copper sulphate in 219 of water for over ninety-six hours. Small 

 larvae of Ciilex pipiens in fresh water succumbed to one part of 

 copper sulphate in 53,500 of water in seventy-two hours and to 

 one part of copper sulphate in 1,(872 of water in eighteen hours. 

 One part of copper sulphate in 4.400 of water killed in forty- 

 eight hours, while in another case two examples survived one 

 part of copper sulphate in 30S of w'ater for twenty-four hours. 



The pupae did not appear to be affected by the copper sulphate 

 even in the large amounts except that it hastened development to 

 the adult condition and in fully mature larvae hastened the change 

 to the pupal stage. In every case development was much more 

 rapid in the experiment jars than in the check jars. Owing to 

 this tendency to force development and to the irregular effect 

 produced it is evident that the copper sulphate cannot serve as 

 a practical larvicide. 



It was noted that when a sufficient quantity of the copper sul- 

 phate was used, the water, both fresh and salt, was cleared up 

 and a green precipitate formed at the bottom. 



As the activity of the copper sulphate seemed greater in salt 

 water, a solution to which sodium chloride — common salt — was 

 added, was also tested. This was prepared by adding one ounce 

 of sodium chloride to 120 cc of the copper sulphate solution used 

 in the preceding experiments. 



Bxperiuicnt 8: with larvae of all sizes and pupcC of Cidcx pi- 

 piens from pail cultures at New Brunswick. These were dis- 

 tributed in three jars of city water to which the combined solution 

 was added as follows : 



Jar I — I part of copper sulphate in 4400 of water. 

 Jar 2 — I " " '■ " " 2200 



Jar 3—1 " " " " " 1400 " 



Changes to pupa and the development of adults continued un- 

 checked and seventv-two hours after the solution had been added 



