INSECTS AND DISEASES 



403 



stifles the larvae and pupae and also destroys many of the 

 adults which come to lay eggs. To be most effective this 

 must be applied frequently, as the film is easily destroyed 

 by rain or wind. 



Successful campaigns 

 against the mosquito. 

 Mosquitoes can be con- 

 trolled and the injury 

 they do largely prevented 

 by the intelligent cooper- 

 ation of the people of a 

 community. There are 

 numerous cases where 

 efforts of this kind have 

 met with remarkable 

 success. Two of the 

 most successful cases 

 were those under charge 

 of the United States gov- 

 ernment in Cuba and 

 Panama. At the close 

 of the Spanish War, the 

 American soldiers under 

 charge of Colonel Gorgas 

 made a campaign against 

 the mosquito in Havana 

 and the immediate vicin- 

 ity. As a result of this 

 work, yellow fever was 

 wiped out in Havana and 

 the number of deaths 

 from malaria was re- 

 duced to one half the 

 first year and to one 

 quarter the second year, 



FIG. 159. Showing death rate from yellow 

 fever in Havana before and after the dis- 

 covery that mosquitoes carried the disease. 





