THE PRELIMINARY SURVEY 131 



mosquito act, and also that the County Health Officer 

 be given funds to put the legislation into effect. 



10. Automatic oiling of ditches and creeks is of 

 doubtful value under the conditions here, but the 

 automatic application of copper sulphate solution to 

 the ditches to prevent or kill the growth of algae, on 

 which the mosquito larvae feed, may be found useful. 

 It should not be used in excess of one part per million 

 of water. 



