. A text-book of agricultural zoology. Zoology, Economic. DIPTEKA OK TRUE FLIES. 195 DIPTEKA, OR Teue Flibs. The Diptera form the last order of insects with a complete metamorphosis. They can easily be identified by the presence of a single pair of wings onlyâthe pos- terior or second pair being reduced to two !&â - -'^^^^ club-shaped processes called " balancers," -^^ ^^-if "halteres," or "poisers" (fig. 90). The two anterior wings are flat membranous Fig. 90.âHaltebe of Ply. expansions, never covered with scales, although they are sparsely present in gnats {
. A text-book of agricultural zoology. Zoology, Economic. DIPTEKA OK TRUE FLIES. 195 DIPTEKA, OR Teue Flibs. The Diptera form the last order of insects with a complete metamorphosis. They can easily be identified by the presence of a single pair of wings onlyâthe pos- terior or second pair being reduced to two !&â - -'^^^^ club-shaped processes called " balancers," -^^ ^^-if "halteres," or "poisers" (fig. 90). The two anterior wings are flat membranous Fig. 90.âHaltebe of Ply. expansions, never covered with scales, although they are sparsely present in gnats {Gulieidm) (fig. 91) and a few gall-flies [Oecidomyidm). Hairs are often present on. Fio. 91. A Ghat (Cidex antiulotus). Head or Gnat (Piercing mouth). A, Piercing lancet; U, lower lip ; Ul, upper lip; Md, mi^ndible; Mx, maxilUi; I^, labi^ palp. the wings, both upon and around them. S^me Diptera, such as the Fleas (Pidicidm), fig. 117, and the Sheep-ticks (Melophaga), fie. 116, are entirely apterous. In regard to the mouth parts of. 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 Theobald, Frederick Vincent, 1868-1930. Edinburgh and London, W. Blackwood and sons
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1899
