290 The Control of Mosquitoes 



inspect. Eventually they were all removed. The 

 tinajas are still used, but as water costs much 

 less than formerly, they are emptied more fre- 

 quently, and are less dangerous. 



In localities where there is no available water 

 supply other than rain water collected by roofs 

 of buildings, it may be absolutely essential to use 

 eave-troughs to obtain all the water possible for 

 storage and future use. 



If eave-troughs are used for that purpose they 

 should be made of galvanized iron of sufficient 

 thickness to prevent sagging, have a good slope, 

 and be securely attached to the roof. It is neces- 

 sary to have the points of support as close together 

 as possible. They should be arranged to permit 

 inspection without leaning heavy ladders against 

 them. Eave-troughs are convenient but nearly 

 all towns where the yellow fever mosquito is 

 found cotild do without them. 



In an anti-yellow fever campaign, it is not safe 

 to rely on fumigation only, for we cannot be sure 

 that all the places in which infected mosquitoes 

 exist have been fumigated. It is only possible 

 to accomplish a certain amount of fumigation in 

 one day, and meanwhile mosquitoes in the adja- 

 cent unfumigated buildings may return. It .is 

 evident that fumigating on a wholesale scale, i.e., 



