PUBLIC HEALTH 19 



Filariasis is most common in equatorial regions, but ex- 

 tends less commonly into the subtropics. The parasites 

 themselves do not ordinarily cause great inconvenience, but 

 their presence in the lymphatics may clog these vessels and 

 large swellings developing in the limbs or other parts of the 

 body are thought to be sequelae. 



Less directly detrimental to public health are other mos- 

 quitoes not associated with any human disease, but making 

 life miserable at some season of the year for human beings 

 in practically all parts of the world. Although the United 

 States supports an extensive mosquito fauna, a very few 

 species aside from those already mentioned make up the bulk 

 of those annoying man. Two in particular are widespread, 

 abundant, and on account of their strikingly different habits, 

 perhaps worthy of mention in this connection. The first of 

 these is the house mosquito, Culex pipiens, a palearctic 

 species, now common throughout the eastern states, that 

 breeds in rain barrels, cesspools, sewer catch-basins, puddles, 

 or practically anywhere, no matter how foul the water. The 

 other, Aedes sollicitans, the salt-marsh or "Jersey" mos- 

 quito, breeds only along the coast in salt marshes. Broods 

 of this mosquito follow the lunar calendar, developing after 

 the high tides flood the meadows and fill the pools in which 

 the larvae live. The eggs of this form are laid on the mud and 

 hatch quickly when submerged in water. It is generally be- 

 lieved that all the eggs laid by this mosquito must pass the 

 winter before hatching and that the successive broods are 

 only installments of eggs induced suddenly to hatch in turn 

 by successive wettings. This is a true migratory mosquito, 

 which invades the country for many miles adjacent to the 

 salt marshes. Such incursions follow the appearance of each 

 brood. 



Much attention has been given to the control of this mos- 

 quito in New Jersey and the territory surrounding Long 

 Island Sound, and its numbers have been marvelously les- 

 sened through the drainage of marshes by ditching. In the 

 case of this species reforms have been easier than with the 



