1 88 JUNGLE ISLAND 



The natives were careless, but the Americans 

 knew that they must make the whole Canal Zone 

 safe. They cleaned the rain barrel of the poorest 

 negro as energetically as the cistern of the Bishop 

 of Panama. In the thickly built-up city of 

 Panama, men inspected all houses and yards at 

 least every six days, as fast as a new crop of 

 mosquitoes could come on, and whenever mosquito 

 wrigglers were found they were killed and the 

 water that held them emptied. 



With such hard and thorough work it was not 

 many months before the Canal Zone saw the last 

 of yellow fever. Aedes mosquitoes could still be 

 found back in the country, although very few of 

 any kind in the towns, but there were no longer 

 yellow fever patients for them to bite, and so 

 there was no yellow fever to carry. 



The men in the sanitary division did not grow 

 careless on that account, because they knew that 

 some one suffering from yellow fever might come 

 into port on a ship at any time and start a fresh 

 epidemic. Nowadays they go ahead ditching 

 ponds and swamps so that stagnant water can 

 run off (Fig. 8i). They see that screens are 

 mended and that water is not left standing in 

 open containers. Many American cities have 

 more mosquitoes than the Canal Zone towns. 



Malaria has been much harder to wipe out, 

 and the task is not yet done. Many of the natives 

 have malaria in so light a form that it does not 



