Screening and Destruction 207 



17 mesh and 18 mesh will exclude this species. 

 16 mesh will exclude Anopheles. 



1 6 mesh — Area of aperture 0.00235 square inch. 



Wire No. 28 B. W. G.— Diameter 0.014 



inch. 

 Weight per square foot 0.2224 Ih. 

 It is twice as strong as 18 mesh. 

 60.16% of open space. 

 95% increase in area over No. 31 B. W. G. 



17 mesh — ^Area of aperture 0.00219 square inch. 



Wire No. 30 B. W. G. — Diameter 0.012 



inch. 

 Weight per square foot 0.17339 lb. 

 It is 50% stronger than 18 mesh. 

 63% of open space. 

 43% increase in area over No. 31 B. W. G. 



18 mesh — Area of aperture 0.00208 square inch. 



Wire No. 31 B. W. G. — Diameter o.oi 



inch. 

 Weight per square foot 0.12835 lb. 

 67-39% of open space. 



All copper alloy used in screening should contain 

 not less than ninety per cent, copper and less than 

 one half of one per cent, of iron. 



DESTRUCTION OF ADULT ANOPHELES 



In addition to the screening, a further decrease in 

 the possibility of infected mosquitoes transmitting 

 malaria can be accomplished by daily destroying 



