. Preventive medicine and hygiene. low fevermosquito. The winged insect may also survive a short winter. Underthe most favorable conditions as to temperature (30° C.) Stegomyiaeggs hatch out in about 36 hours after they are laid. Under 20° will not hatch at all. Larva.—The egg hatches the larva (wiggle-tail), which has ablack barrel-shaped respiratory siphon. This distinguishes it from Culexpipiens, its common mess mate, in which the air tube is brown, longer,and more slender. Although the larva lives in the water, it is strictlyan air-breather and must come to the surface for air. It t
. Preventive medicine and hygiene. low fevermosquito. The winged insect may also survive a short winter. Underthe most favorable conditions as to temperature (30° C.) Stegomyiaeggs hatch out in about 36 hours after they are laid. Under 20° will not hatch at all. Larva.—The egg hatches the larva (wiggle-tail), which has ablack barrel-shaped respiratory siphon. This distinguishes it from Culexpipiens, its common mess mate, in which the air tube is brown, longer,and more slender. Although the larva lives in the water, it is strictlyan air-breather and must come to the surface for air. It thrusts itsbreathing tube up into the surface film and remains suspended, headdown, at an angle of somewhat less than 45 degrees, which distinguishesit from Anopheles larvae, which lie horizontal. A film of oil on thesurface of the water is sufficient to obstruct the air tube and thus causethe death of the larva by suffocation. The larva is very timid, so thata slight jar or agitation or a sudden shadow will cause it to wriggle. Fig. 23.—Head of Stegomyia Calopus (male). 340 INSECT-BOENE DISEASES \ rapidly to the bottom, where, indeed, it may very commonly be observedto feed. The duration of the larval sta^e is never less than 6 to 7
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Keywords: ., bookauthorwh, bookcentury1900, bookdecade1910, booksubjecthygiene
