DESTROYING AND REPELLING MOSQUITOES 99 



A word should be said regarding the kind of screens to 

 use. In the first place, the wire should be galvanized 

 and should have at least fourteen meshes to the inch, 

 and better sixteen. For protection against the yellow 

 fever mosquito, eighteen meshes to the inch are necessary. 



The most efficient window screens are those that cover 

 the whole window (Fig. 33). Such a screen is fitted inside 



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Fig. 33. — Screen covering 

 whole window. 



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Fig. 34. — Screen over lower 

 half of window. 



the casing on the outside of the window and is held on by 

 buttons, as shown in the illustration. The screen can 

 be quickly removed in the autumn and easily replaced 

 in the spring. Of course, this type of screen is suitable 

 only where there are no shutters. The next best type of 

 screen is one covering the lower half of the window and 

 fitted inside of the casing (Fig. 34). This screen has a 



