I W — ( rl '■4»-Vv^:^4; 



'^\Ar'' 



.OKUL 





% ^ 



^^ niii). '.oHi 









United States Public Health Service 



DECLINE OF MALARIAL AREAS 



The systematic elimination of breeding places has re- 

 moved the mosquito from many areas, and at the same 

 time malaria has declined, in some cases to absolute 

 zero 



624 



cans and other possible 

 containers for water 

 where the female mos- 

 quito can reach them. 

 Without such breeding- 

 places one year would 

 see the end of all mos- 

 quitoes in all co-opera- 

 tive communities. In 

 larger bodies of water 

 where there are fish, 

 these will usually de- 

 stroy the larvae. In the 

 shallow margins, how- 

 ever, where the fish can- 

 not reach them, the 

 mosquitoes have things 

 their own way. It is 

 necessary to keep the 

 borders of ponds clear 

 of weeds, sedges, etc. 



The practical effect of 

 exterminating the mos- 

 quito is shown by the 

 decrease of malaria and 

 yellow fever (see maps). 

 For decades French engi- 

 neers had made repeated 

 attempts to construct 

 the Panama Canal. Each 

 time the "fever" made 

 it impossible to continue 

 the work. When the 

 United States took over 

 the enterprise, the first 

 step was to establish san- 

 itary conditions. And 

 the largest part of the 

 problem was to extermi- 

 nate mosquitoes by elim- 

 inating their breeding- 

 places. 



