1920] Notes on the Mosquito Fauna of North Carolina 87 



little creatures quiet waters not violently agitated by storms and rapid 

 currents, are most favorable to them. This often means stagnant 

 water, but not necessarily so. Completing its larval life within a 

 week or longer, it changes to a pupa, which stage lasts for a day or 

 longer, when it emerges as an adult, winged mosquito. The length 

 of life of the adult is indefinite, — some live over winter, some species 

 have been kept alive in summer for two months or more. Adult mos- 

 quitoes usually fly for distances of less than a mile, — but some species 

 are more migratory, and with favorable light winds may travel much 

 longer distances. 



The chief features of mosquito control can be briefly outlined as 

 follows: (1) Drainage of stagnant or standing water when practi- 

 cable; (2) straightening and clearing of drains to secure prompt 

 disposal of the flow; (3) oiling of such waters as may still serve as 

 breeding places; (4) stocking with small insect-eating fishes of such 

 waters as cannot be guarded by other means; (5) screening of houses; 

 (6) use of smudges, lotions, perfumes, etc. Accepting one mile as the 

 general limit of flight, the Public Health Service extends the drainage 

 work for one mile beyond the limits of the camp, yard, town or other 

 particular area to be guarded. 



Most rules have exceptions,^ — and although mosquitoes adhere 

 quite closely to the general principles just laid down, yet there are 

 certain species which are exceptional in certain particulars and unless 

 we know something about these exceptions, and how to allow for 

 them, — we are liable to unpleasant and disappointing surprises, — and 

 the public, often inclined to snap judgment, may criticise and even 

 abandon control work which is really well done, because of the inter- 

 vention of exceptional circumstances. Thus the control work in vicin- 

 ity of Wilmington might be ever so well done, — it might almost, it 

 might entirely eliminate malaria, — yet a favoring breeze might bring 

 into that city countless thousands of mosqutoes of the species Aedes 

 sollicitans which breed in the salt marshes of the coast ten to twenty 

 miles away, and which is known to migrate for long distances. Such 

 an invasion, temporary though it may be, might arouse much criti- 

 cism. A house may be "screened," yet small species of mosquitoes 

 may easily crawl through the meshes of an ordinary fly-screen. A 

 pool may be oiled and yet the mosquito Mansonia perturbans may 

 breed from it, because the larva of this species does not come to the 

 surface for air but lives in the saturated mud about the roots of 

 aquatic plants. 



