i86 The Control of Mosquitoes 



DESTRUCTION OF ADULT ANOPHELES 



Spiders are useful as destroyers of mosquitoes. 

 Because mosquitoes prefer to rest on dark sur- 

 faces, a black band two feet wide was painted on 

 the walls of the barracks at Balboa between three 

 and five feet from the floor that they might collect 

 where they could easily be reached by the men 

 employed to catch mosquitoes. The walls above 

 and below this band were white. It was noted that 

 after the black band was applied spiders collected 

 on it while they were not to be seen on the white 

 paint. 



Certain insects are caught and held fast when 

 they rest on spider webs, but it is not definitely 

 known that Anopheles and other mosquitoes on 

 the Isthmus are destroyed in this way. They 

 may be caught by spiders while at rest on or near 

 the webs. 



Anopheles appear to have no difficulty in leav- 

 ing the strand of a spider web which they have 

 selected for a resting place. Thousands of spiders 

 and millions of ants are to be seen on tall grass 

 and weeds growing in shallow water on the 

 Isthmus and they probably destroy many newly 

 emerged mosquitoes. 



The small lizards of different colored markings, 



