3o8 The Control of Mosquitoes 



calopus. Such traveling containers can do much 

 harm, as they may release mosqiiitoes at many 

 places in a relatively short period. Many types 

 of barges and canal boats contain and retain rain 

 water. On one or two occasions they were known 

 to have transported Aedes calopus twenty miles 

 down the coast, from Colon to Porto Bello; adults 

 appeared in large numbers in the settlement 

 adjacent to the wharf to which the barge was 

 tied, and in which this species had been absent 

 for a long period. 



Although every precaution is taken to keep 

 yellow fever out, it is always assumed that a case 

 may enter at any time without the knowledge of 

 the health authorities, and precautions are taken 

 accordingly. The light cases known as "walking- 

 cases" are the most dangerous type. 



In order to keep a record of everyone coming from 

 possibly infected areas, the chief sanitary officer 

 keeps in touch with all infected seaports north 

 and south of the Isthmus. Boarding houses and 

 hotels are- compelled to keep a correct register of 

 guests, showing port of departure, and date of 

 arrival of each, so that the history of any case 

 may be rapidly obtained, and non-immunes 

 associated with a case located at once and kept 

 under observation. 



