4 LEAFLET 18 6, U. S. DEPARTMENT OF AGRICULTURE 



worms of dogs. The yellow-fever mosquito is the principal carrier of 

 the dreaded disease of man from which it derives its name and also 

 of dengue, or breakbone, fever. Fortunately, as long as yellow fever 

 is kept out of the country by quarantine regulations there is no danger 

 of contracting it from the bite of this mosquito. However, when the 

 malady gets a start in a country where it is not native, the resulting 

 sickness, death, and economic losses are terrible. With the presence 

 of yellow fever in a number of South American and African countries 

 and with the use of airplanes and other rapid methods of transporta- 

 tion now employed, the danger of the introduction and spread of the 

 disease is apparent. 



Life History and Habits of Domestic Mosquitoes 

 Breeding Places 



The domestic mosquitoes, and in fact all other mosquitoes as well, 

 breed in water. Salt-marsh and floodwater mosquitoes and a few 

 others lay their eggs on the soil, and these hatch only after they are 

 covered by water. Many are of the opinion that mosquitoes breed 

 in weeds, tall grass, shrubbery, and vines. This is not the case; they 

 must have free water in which to develop. Heavy vegetation serves 

 as a harboring place for adult mosquitoes and may break the wind 

 so that the mosquitoes can bite more freely in enclosed yards. Grass 

 and weeds also hide water-filled tin cans and depressions in which the 

 pests may breed. The kind and amount of the water and the place 

 or container in which it occurs largely determine the particular kind 

 of mosquito that will breed in it. Thus the yellow-fever mosquito 

 breeds almost exclusively in what might be called man-made containers, 

 and these must be close to habitations of man; rain-pool mosquitoes, 

 on the other hand, breed largely in temporary pools formed by rains 

 or by streams overflowing their banks. 



The northern and southern house mosquitoes breed in water-filled 

 rain barrels, tubs, and the many different places about houses and 

 yards where water is retained for a sufficient length of time. They 

 also breed in pools and sluggish streams heavily contaminated with 

 manure, with water from barnyards, or with sewage. Cesspools and 

 septic tanks are often prolific breeding places for them if not properly 

 constructed or cared for, as are also barrels containing manure water 

 for use in watering plants. These mosquitoes also breed in water 

 retained in eaves troughs, on flat roofs, in street catch basins and 

 gutters, and in ornamental pools. 



The yellow-fever mosquito prefers relatively clear water and seldom, 

 if ever, breeds in natural ponds or pools. Its wigglers are found in 

 tanks or cisterns, and in cans, bottles, pots, jars, and other vessels 

 that will hold even very small quantities of water. They often occur 

 in unexpected places, such as discarded automobile casings, flower 

 vases, holy-water and baptismal fonts, urns in cemeteries, water 

 troughs, water pans for chickens, grindstone cans, dishes of water 

 placed under legs of refrigerators, and unused toilet bowls or tanks. 



Stages and Development 



The black, oval eggs (fig. 3) of the yellow-fever mosquito are laid on 

 the sides of water containers, usually above the water surface. If 

 placed on the water at once, they hatch in about 2 days. If not 



