14 MOSQUITO ERADICATION 



"The filarial larvae soon escape from their sheaths in the thickened 

 blood within the stomach of the mosquito. They pierce the stomach 

 wall, enter the thoracic muscles of the insect, pass through a metamor- 

 phosis which takes from 16 to 20 days (longer or shorter, according to 

 atmospheric temperature) ; they now quit the thorax and a few find their 

 way to the abdomen; the vast majority, however, pass forward through 

 the prothorax and neck and, en ering the head, coil themselves up close 

 to the base of the proboscis and beneath the pharynx and under surface 

 of the cephalic ganglia." 



It is not yet definitely known whether Culex fatigans is the only 

 species of mosquito which transmits filariasis; for this reason, 

 anti-mosquito work for the prevention of filariasis should be 

 directed against all the mosquitoes in the vicinity. 



Filariasis occurs throughout the tropics and sub-tropics 

 generally, and the total morbidity from this infection undoubt- 

 edly is large. In the United States, occasional cases are reported 

 in the Southeast, the endemic area reaching as far north as 

 Charleston, S. C. 



ECONOMIC SIGNIFICANCE OF YELLOW FEVER, DENGUE AND 



FILARIASIS 



While none of these diseases are widely prevalent in the 

 United States, the impairment of working capacity which the 

 last two entail — -which probably corresponds in a large measure 

 with that caused by malaria — no doubt amounts to a not incon- 

 siderable sum annually. 



In the tropical regions, however, where these diseases are much 

 more common, it is clear that their economic significance must be 

 very large. The inefficiency of tropical labor has been noted by 

 virtually all persons who have visited those parts, and it is 

 apparent that this inefficiency is due largely to malaria, yellow 

 fever, dengue and filariasis — preventible, mosquito-borne diseases. 



THE MOSQUITO AS AN ANNOYANCE; EFFECTS UPON HEALTH 



Little need be said as to this phase of the mosquito's activities 

 and its effects upon the comfort and health of the community, 

 as anyone who has lived in vicinities that the mosquito frequents 

 knows how much discomfort it causes. 



Not only do they make life miserable for their victims, but, 

 merely as an annoyance alone, they have a very pernicious effect 

 upon the health. The illness caused by loss of rest and sleep, by 



