THE ECONOMIC IMPORTANCE OF ANIMALS 219 



upon the larvae in the water where the mosquitoes breed will do 

 much to free a neighborhood from this pest. Draining swamps 

 or low land which holds water after a rain is another method of 

 extermination. Some of the mosquito-infested districts around 

 New York City have been almost freed from mosquitoes by 

 draining the salt marshes where they breed. Long shallow 

 trenches are so built as to tap and drain off any standing water in 

 which the eggs might be laid. In this way the mosquito has 

 been almost exterminated 

 along some parts of our 

 New England coast. 



Since the beginning of 

 historical times, malaria 

 has been prevalent in 

 regions infested by mos- 

 quitoes. The ancient city 

 of Rome was so greatly 

 troubled by periodic out- 

 breaks of malarial fever 

 that a goddess of fever 

 came to be worshiped in 

 order to lessen the severity 

 of what the inhabitants 

 believed to be a divine visitation. At the present time the 

 malaria of Italy is being successfully fought and conquered by 

 the draining of the mosquito-breeding marshes. By a little care- 

 fully directed oiling of water a few boys may make an almost 

 uninhabitable region absolutely safe to live in. Why not try it 

 if there are mosquitoes in your neighborhood ? 



Yellow Fever and Mosquitoes. — Another disease carried by 

 mosquitoes is yellow fever. In the year 1878 there were 125,000 

 cases and 12,000 deaths in the United States, mostly in Alabama, 

 Louisiana, and Mississippi. During the French occupation of the 

 Panama Canal zone the work was at a standstill part of the time 

 because of the ravages of yellow fever. Before the war with Spain 

 thousands of people were ill in Cuba. But to-day this is changed, 

 and yellow fever is under almost complete control, both here and 



Swamps are drained and all standing water 

 covered with a film of oil in order to ex- 

 terminate mosquitoes. Why is the oil 

 placed on the surface of the water ? 



