242 INSECTS AND DISEASE 



and (3) twelve clays must elapse before the mosquito 

 is able to infect another person. The parasite thus 

 resembles that of malaria in that it completes certain 

 stages of its development in a secondary host, the 

 mosquito. 



Remedial Measures. — It was perfectly evident to 

 every clear-thinking individual that when the mosquito 

 was shown to be responsible for the transmission of ma- 

 laria and yellow fever these insects should be exter- 

 minated. Theoretically this was a relatively simple 

 matter. All that appeared to be necessary was to drain 

 the marshes or pour oil on the water and thus smother 

 the young aquatic " wrigglers." In reality the task 

 was and continues to be one of gigantic proportions. 

 IVIany districts, such as the valley of the Amazon, are 

 too large to be drained or oil-coated. In other regions 

 the ignorance and indifference of the people has proved 

 to be an almost insurmountable obstacle. Nevertheless 

 there are enlightened communities where millions of 

 dollars have been spent for drainage, house to house 

 inspection of possible breeding places, the introduction 

 of mosquito-devouring fishes and other remedial meas- 

 ures. The results amply justify all of the expense of 

 time and labor. Today yellow fever is practically wiped 

 out from the larger seaports in the Western Hemisphere 

 where formerly its ravages were most severe. Malaria 

 is more stealthy in its attack, and the general public is 

 more inclined to take it as a matter of course and allow 

 the mosquito to carry on its deadly warfare. It is im- 

 portant to note, however, that annually not less than 

 10,000 people die from this disease in the United States 

 alone, and the yearly monetary loss due to the reckiced 

 efficiency of suffering workers amounts to many millions 

 of dollars. When these facts are generally known, and 

 the part the mosquito plays in the grim tragedy is under- 

 stood, it is safe to say that malaria will become as rare 

 as yellow fever. 



