Mosquito Remedies and Enemies 129 



Woodland swamps are best drained, unless densely 

 overgrown with tall vegetation. The open areas har- 

 bour danger, if partly filled with reeds, lilies, and such 

 plants, because fish cannot well go through such spots. 

 If these places cannot be drained, they should be 

 cleared of vegetation, the edges depressed, and fish 

 introduced. The material removed may be used for 

 filling. Oils do not readily spread among the grasses, 

 and are ineffective in such places, while the chemicals 

 supposed to mix with water cannot, as a rule, be used 

 in sufficient quantity. 



Anopheles frequently breeds in the grasses along 

 the edges of slow streams, or in overflow pools on 

 their margins. Such streams should be cleaned, or 

 the bed deepened and the edges filled. Oil is quickly 

 carried away, even in a sluggish stream. 



Old mill-ponds, or pools with boggy margins, are 

 also menaces. Around the margins of these the im- 

 prints of cattle hoofs remain, collecting enough water 

 to breed many mosquitoes, especially^ nopJieles. Such 

 ponds should be drained, or the margins cleaned and 

 deepened to at least eighteen inches and a stock of 

 fish put in. 



Graders frequently dig up the sides of roads to 

 mend the centres, thus producing places for puddles. 

 When a soft spot exists in the road it is often a good 

 plan to give it a chance to harden by throwing upon 

 it grass and weeds cut from the roadside. 



Mosquito Enemies. — Dr. Dupree writes on this 

 subject as follows : — 



" Most if not all insects have their natural enemies, a 



9 



