310 



APPLIED ENTOMOLOGY 



to, water in houses or near by, it having apparently become a " wholly 

 domesticated" species. The eggs hatch in from 10 hr. to about 3 days, 

 and the larvae hang downward from the surface. After a week or 10 

 days in this stage, they pupate for 2 or 3 days before the emergence of the 

 adult. Feeding by the adult appears to be mainly during the warmer 

 hours of sunny days though extending somewhat into the evening. 



Repeated investigations show that the unknown germ or organism 

 producing Yellow Fever is conveyed to man only by the attacks of this 

 insect. Apparently about 12 days is required after feeding on a Yellow 

 Fever patient before the mosquito is able to transmit the organism caus- 

 ing the disease, but from that time on it can do 

 this for well over a month. 



Dengue and Filariasis, two other important 

 diseases of man in tropical and subtropical 

 regions, are also known to be carried by 

 mosquitoes. 



Control of Mosquitoes. There are many 

 ways by which mosquitoes can be more or less 

 effectively controlled. The thorough screening 

 of houses to keep them out is a desirable prac- 

 tice and is also of value as a protection against 

 house-flies. Nettings over beds for the same 

 purpose are often used where entire houses are 

 unscreened. Out-of-doors, veils covering the 

 head, and gloves for the hands are often necessary 

 in places where these insects are extremely 

 abundant. Protective materials rubbed on ex- 

 posed parts of the body are also often used and 

 various substances have proved of value for this purpose. Among these 

 are spirits of camphor, oil of pennyroyal and oil of citronella which seem 

 to be the favorite substances used in this way. Smudges will keep away 

 mosquitoes where the smoke is, and burning insect powder in a room 

 stupifies the insects so that they fall to the floor and can be swept up. 

 Other materials for use in a similar way are also available. 



Destruction of the larvae, pupae and eggs is the most direct way in 

 which to control mosquitoes in large numbers, and many methods for 

 accomplishing this have been tried. As mosquitoes develop only in 

 water, the removal of the places where they can breed, such as the drain- 

 age of marsh land, filling up small pools, hollows in trees containing 

 standing water, and all such situations will accomplish a great deal. 

 The drainage of the salt marshes of the New Jersey coast and elsewhere 

 has resulted in a marked relief from the attacks of mosquitoes in those 

 localities. Where the water can not be drained off, covering it with a 

 film of kerosene will suffice to destroy the eggs on the surface, larvae and 



FIG. 328. Adult Yellow 

 Fever M o s q u i t o ( A cdes 

 ccyypti L.), considerably en- 

 larged. Note black and 

 white banding of the legs. 

 (After U. S. D. A. Farm. 

 Bull. 547.) 



