444 



MOSQUITOES 



lyre-shaped design on the thorax. The female, which, of course, 

 is the only sex connected with the transmission of disease, since 

 the males do not suck blood, has very short palpi which are white 

 at the tip. The wings arc clear and somewhat iridescent. 



Habits of Aedes calopiis. — The yellow fever mosquito is the 

 most thoroughly " domesticated " species known. It is seldom 

 found except in the vicinity of houses and shows a decided pre- 

 ference for human blood. As a rule it 

 seldom leaves the rooms of houses ex- 

 cept to find a suitable place to lay its 

 eggs. Long familiarity with man has 

 made this mosquito one of the most 

 elusive and well-adapted pests of the 

 human race which nature has ever 

 evolved. Its stealthy attack from be- 

 hind; its habit of crawling up under the 

 clothing to bite in preference to attack- 

 FiG. 202. Head of Aedes ing the exposed ankles; the suppres- 

 calopus, male. (After Gold- g^Q^ of the characteristic mosquito 

 ^'^^^'^^■' "song," so that its bite comes silently 



and without warning; its habit of concealing itself in pockets, 

 folds, etc., of garments; its hiding behind pictures, under chairs, 

 etc.; the wariness of its larvae; — all these are the result of 

 lessons learned from long and close association with man. 



Aedes calopus is principally a diurnal mosquito, and becomes 

 particularly hungry in the early morning and during the after- 

 noon. It will bite in lighted rooms, but will never bite in the 

 dark. The French Yellow Fever Commission in Rio de Janeiro 

 stated that Aedes calopus is nocturnal. The evidence for this 

 conclusion, which is at variance with the observations of other 

 workers, has been shown by Howard, Dyar and Knab to be very 

 inadequate and faulty. The danger of sleeping in an infected 

 place, and the comparative freedom from danger enjoyed by 

 persons who visit infected places only in the daytime, is thought 

 to be due to the fact that most of the mosquitoes obtain a meal 

 very early in the morning, just after daybreak. 



Breeding. — Aedes calopus never lays eggs until it has had a 

 meal of l)lood and when water or moist surfaces are available. 

 According to recent experiments by Bacot a single male mosquito 

 may fertilize a number of females. Fertile eggs are usually 



