REPORT ON MOSQUITOES. 131 



It puts the material, which costs about thirty cents a gallon, 

 on a par with the fuel oil, which costs only one-third as much, 

 and has the advantage of not killing the beetles and other insects 

 that live beneath the surface. 



Sulphate of Copper in simple solution and combined with 

 lime to form the "Bordeaux mixture," has been found by the 

 United States Department of Agriculture (Bull 64, Bureau of 

 Plant Industry) to be wonderfully effective as against certain 

 forms of algae and other microscopic animal and vegetable life. 

 Its effectiveness against moscjuito larvae is only incidentally 

 referred to; but the popular accounts translated that into a more 

 positive statement than was, perhaps, intended, and I had Mr. 

 Dicker son make a series of experiments to test the effectiveness 

 of the material as against both fresh and salt water species. 



Mr. Dickerson's experiments and the conclusions he draws 

 from them may be given in some detail to answer questions that 

 have been frecjuently asked and will be certain to come up again 

 when mosquito campaigns become more general. 



As a preliminary experiment of my own I placed a number of 

 pupte of Ctilex pipiens in a bottle of the concentrated copper solu- 

 tion at 4:30 P. M., and before evening adults began to emerge. 

 Eighteen hours later another adult emerged and one very lively 

 pupa was present after twenty-four hours. The remainder of the 

 pupse, less than 50 per cent, of the whole, w^ere dead. 



At the same time, a few larvae of C. rcstnons of various sizes 

 were placed in another bottle of the concentrate. Half an hour 

 later the smallest larvae were dead and early next morning all 

 were dead. It is interesting to know that even the concentrated 

 solution failed to prevent the development of the adult from the 

 fully matured pupa, though no larvae reached the pupal stage in 

 the solution. 



Mr. Dickerson's report is as follows : 



Bxpci'iuicnts -witJi Copper Sulphate Solution on Culex LarvcB. 



Copper sulphate was used in varying amounts on several lots 

 of Culex larvae and pupae to test its killing properties. The solu- 

 tion used in these experiments was prepared by adding half a 

 pound or 3,500 grains of copper sulphate to 1,275 ^^ ^^ w^ater, 

 thus giving 2.74509 grains of copper sulphate for each cc of the 

 solution used. In each case the amount of water in the experi- 

 ment jars was weighed, and thus the proportions by weight of 

 water and copper sulphate were obtained. 



Experiment i: with very small larvae of Culex pipiens, 

 breeding in pails at New Brunswick. They were placed, together 



