. Animal parasites and human disease. Medical parasitology; Insects as carriers of disease. Fig. 230. Hypo- pygium of male tsetse fly. Alcock.) (After mouthparts when the latter are not in use, and it is thus the palpi alone that are seen when the long blunt-tipped proboscis is ob- served. The characteristic form of the antennae is shown in Fig. 229. The thorax is relatively large and quadrangular, with a characteristic pattern which is, however, inconspicuous in some species. The abdomen may be nearly uniform dark brown, or pale brown banded with a dusky color. The male has a large oval swell
. Animal parasites and human disease. Medical parasitology; Insects as carriers of disease. Fig. 230. Hypo- pygium of male tsetse fly. Alcock.) (After mouthparts when the latter are not in use, and it is thus the palpi alone that are seen when the long blunt-tipped proboscis is ob- served. The characteristic form of the antennae is shown in Fig. 229. The thorax is relatively large and quadrangular, with a characteristic pattern which is, however, inconspicuous in some species. The abdomen may be nearly uniform dark brown, or pale brown banded with a dusky color. The male has a large oval swell- ing on the under side of the last segment of the abdomen, the " hypopygium " (Fig. 230), which forms a good distinguishing mark be- tween the sexes. Distribution, Habits, etc. — Tsetse flies, fortunately, are lim- ited in their distribution to the middle portion of the African continent from south of the Sahara Desert to the northern borders of British South Africa (Fig. 231, = ). One species occurs in the southwestern corner of Arabia. Tsetses are by no means evenly distributed over this great area, but are limited locally to "fly-belts," chiefly along rivers and at the edges of lakes. All the factors which cause the " patchy " distribution of tsetses are not known; there are cases where close limita- tion to certain areas cannot be explained by any known requirements of the flies. Different species vary in their choice of habitats; Glossina palpalis (Fig. 236), the carrier of Gambian and Nigerian sleeping sickness, is seldom found more than 30 yards from the edge of water where a sandy bottom and overhanging vegetation is abun- dant, though it follows animals and man for a few hundred yards from such positions. This species is found only in shady. Fig. 231. flies. \\\ /// Approximate ranges of tsetse (Compiled from Austen.) range of entire genus glossina range of g. morsitans range of g. palpalis. Please note that these images are extracted f
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmedical, bookyear1918
