8 The Control of Mosquitoes 



It was found that the bottom of these wells became 

 clogged with clay and silt, but that the sides 

 supplied sufficient absorbent surface to give 

 satisfactory results. Fish were used to keep some 

 of the wells free from mosquito life ; in others, that 

 frequently became dry, oil was used. Sometimes 

 it was necessary to scrape well walls several times 

 during the wet season to increase absorption. 



The limited funds available did not permit the 

 permanent lining of ditches, although in many 

 cases it would have been more economical than 

 treating and maintaining them for an indefinite 

 length of time. 



Anopheles production in wet areas caused by 

 seepage occurs in Cuba, and one case near Havana 

 was especially interesting. In 1900, a few houses 

 were located near the top of the hill known as 

 Jesus del Monte. Malaria prevailed among the 

 tenants, and several deaths from pernicious malaria 

 occurred there immediately before the undertaking 

 of anti-malaria work. The hill appeared to be 

 dry, and was well above the elevation of the sur- 

 rounding ground. Many inspections were made to 

 locate the source of Anopheles with negative results. 

 It was supposed that they came from a distance, 

 but an extended inspection of the surrounding 

 country disproved this conclusion. 



