io8 The Control of Mosquitoes 



the area covered by, heavy flights. The appara- 

 tus is here shown. It consists of four glass plates 

 set in a metal frame; the latter mounted on a 



tripod. The 

 plates are set in 

 two vertical 

 planes at right 

 angles to each 

 other. The in- 

 struments can be 

 set up so that 

 the plates point 

 north, south, 

 east, and west. 

 The glass was 

 painted with a 

 mixture of resin 

 and castor oil 

 giving a practi- 

 cally transparent 



A device for showing flight direction of coating Capable 

 Anopheles ^^ j^^^^^g ^^y 



mosquitoes that came into contact with it. The 

 solution was made by adding small quantities of 

 pulverized resin to heated castor oil; constant 

 stirring was necessary. The proportions used 

 were one quarter pound of resin to a pint of castor 



