140 Insects and Disease 



immunity of the people native to the endemic 

 regions is supposed to be due to their having had 

 mild attacks of the fever during childhood, for the 

 children in these regions are subject to certain 

 fevers which are probably very mild forms of 

 yellow fever. 



Now if we kill practically all of the Stegomyia 

 so that these children do not have this fever there 

 will be developed, in due time, a population most 

 of whom are non-immune. 



This freedom from the disease for some time 

 will allow us to grow careless in regard to fighting 

 the mosquitoes. They will be allowed to increase 

 and by some chance the yellow fever will again be 

 introduced and there will then be very grave danger 

 of most extensive and destructive epidemics. 



DANGER OF THE DISEASE IN THE PACIFIC 

 ISLANDS 



I have already referred once or twice to the con- 

 ditions in many of the Pacific tropical islands. 

 In some of these various species of Stegomyia are 

 abundant, and in some Stegomyia calopus is the 

 most abundant and troublesome form. All the 

 natives of these islands are non-immune because 

 there has never been any yellow fever there. Un- 

 less extraordinary care is taken the disease will be 



