. Preventive medicine and hygiene. t and sun-light. I have watchedStegomyia mosqu i t o e sbite me by electric lightat eleven oclock at attack is often noise-less and its bite , as a rule, theyrest at night, which,therefore, diminishes therisk of exposure at thattime. The Stegomyiamosquito, however, can-not survive for long inthe direct rays of a tropi-cal sun. There is, therefore, little danger in visiting a community whereyellow fever is epidemic during the day time, provided the person keepsout of houses. The experiences during the last yellow fever epidemicat New
. Preventive medicine and hygiene. t and sun-light. I have watchedStegomyia mosqu i t o e sbite me by electric lightat eleven oclock at attack is often noise-less and its bite , as a rule, theyrest at night, which,therefore, diminishes therisk of exposure at thattime. The Stegomyiamosquito, however, can-not survive for long inthe direct rays of a tropi-cal sun. There is, therefore, little danger in visiting a community whereyellow fever is epidemic during the day time, provided the person keepsout of houses. The experiences during the last yellow fever epidemicat New Orleans, 1905, showed that the radius of activity of an infectedStegomyia is contracted. It may possibly at times fly across the street,but it is evident that it neither flies far nor is it ordinarily transportedto any great distance on railroad cars, although it may be carried overseas on ships. The yellow fever mosquito may pass a screen composed of 16 strandsor 15 meshes to the inch, but cannot pass one containing 20 strands or. Fig. 22.—Stegomyia Caloptjs (female). MOSQUITOES 239 19 meshes to the inch. Effective screens must, therefore, be at leastthis fine. Stegomyia is a grayish mosquito of average size with beauti-ful glistening silver-white iiiarkiugs. These markings are lyre-shapedon the back of the thorax; silver-white spots are seen on the side of thetliorax. White lines are apparent at each tarsal Joint and also on thej;alpi; the scutellum is white. In the female the palpi are much shorterthan the proboscis, which at once distinguishes it from Anopheles. Egg.—The female lays her eggs on the surface of the water or justabove the water line. The eggs do not adhere to one another, and hencedo not form the compact boat-shaped mass characteristic of the culex,but float on their sides more or less singly. At the moment of layingthe eggs are a cream color,but rapidly become jet are somewhat cigar-shaped, and measure on theaverage about mm. inle
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Keywords: ., bookauthorwh, bookcentury1900, bookdecade1910, booksubjecthygiene
