. Elementary textbook of economic zoology and entomology. Zoology; Insect pests. INSECTS AND DISEASE 369 ment, a rather long breathing tube, the tip of which is thrust just above the surface of the water when they come up to breathe. Other larvae do not have such a breathing tube, the spiracles which open into the trachea being situated on the surface of the eighth segment. The pupas of all species are active but take no food. The two trumpet-shaped breathing tubes of the pupae are situated on the thorax, and when the pupas come to rest these extend just above the surface of the water. When th
. Elementary textbook of economic zoology and entomology. Zoology; Insect pests. INSECTS AND DISEASE 369 ment, a rather long breathing tube, the tip of which is thrust just above the surface of the water when they come up to breathe. Other larvae do not have such a breathing tube, the spiracles which open into the trachea being situated on the surface of the eighth segment. The pupas of all species are active but take no food. The two trumpet-shaped breathing tubes of the pupae are situated on the thorax, and when the pupas come to rest these extend just above the surface of the water. When the adult is ready to issue the pupal skin splits along the back and the mosquito slowly comes forth, usually. FIG. 157.—Mosquito pupae, T. incident, resting at the surface of the water. (Enlarged.) resting for a short time on the cast-off pupal skin until the wings become dry and firm enough to use. Malaria-carrying Mosquitoes.—In the United States only mosquitoes belonging to the genus Anopheles carry malaria, so it is important to be able to distinguish the members of this genus in their various stages. The eggs of Anopheles are laid singly, but are often found together in groups of three or four floating on the surface of the water. Each egg is provided with characteristic membranous expansions on each side near the middle. These keep the eggs afloat. The larvae feed largely on minute plants or other organisms at the surface of the water, and when feeding lie nearly horizontally, with the body touch- ing the surface at several points. The absence of a breathing tube, and this habit of always lying with the body parallel to the 24. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Kellogg, Vernon L. (Vernon Lyman), 1867-1937; Doane, Rennie Wilbur, 1871-. New York, H. Holt and company
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