298 The Control of Mosquitoes 



concentrate the newly arriving Americans at La 

 Boca, Ancon, Culebra, and Gorgona, a strong 

 effort was made to control the Aedes calopus 

 production at these villages as rapidly as possible. 

 It was expected that the employees quartered 

 in these settlements would visit the terminal 

 cities, and that some of them would contract the 

 fever. Every effort was made to prevent trans- 

 mission of yellow fever from any of those who 

 might have become infected in Panama or Colon, 

 to others living at the villages mentioned. The 

 first cases of yellow fever in the Canal Zone de- 

 veloped at Culebra, Balboa, and Corozal. All 

 Americans living at Corozal worked in the city 

 of Panama and none of the residences of the 

 employees were screened when yellow fever first 

 appeared. When the first cases occurred, the 

 history of every patient was rapidly obtained. 

 All places visited by them since their infection, 

 and where they might have become infected, were 

 fumigated with sulphur, as were also all adjacent 

 houses. The patients whenever possible were 

 removed to the yellow fever wards at Ancon 

 Hospital. 



The fumigation was at first a difficult task to 

 accomplish. The sanitary department was allowed 

 to pay only the lowest rate of wages current, and 



