98 The Control of Mosquitoes 



outside are numerous, they will try to force their 

 way through incredibly small cracks or defects in 

 the screen. Many cases have been noted where 

 they have become tightly wedged in their efforts 

 to pass through openings that were too small, and 

 then were unable to free themselves. While this 

 experimental work was being done it was found 

 that although the breeding of Anopheles pseudo- 

 punctipennis and Anopheles malefactor was taking 

 place much nearer to the buildings at Corozal than 

 Anopheles albimanus, mosquitoes of the former 

 species were not found at Corozal camp. It is 

 evident, from the long-distance flights described 

 above, that in some instances it was essential to 

 locate and control the principal source or sources 

 of Anopheles, which although more distant than 

 other propagation areas located relatively near, 

 may be, and in the two instances above mentioned 

 actually were, the source of malaria-carrying 

 Anopheles that reached the houses. 



Gatun, about seven miles south of Colon, is one 

 of the largest settlements in the Canal Zone. 

 Above five thousand canal employees live there. 

 Between January and March, 1913, more mos- 

 quitoes were found there than had been found in 

 any settlement since work began on the canal. 

 The weekly catch of the Anopheles that gained 



