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About Tsetse Flies

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General Morphology

Glossina species are tan or brown flies, ranging in length from 6 to 14 mm, excluding the proboscis (tubular mouthpart in invertebrates used for feeding). Members of the fusca group are the largest (9.5-14 mm). The palpalis and the morsitans group species are small to medium in size (6.5-11 mm). Tsetse adults are characterised by several distinctive morphological features. These include the shape of the proboscis, the position and branching of the fringe on the arista of their antenna, and the wing venation and folding pattern. When not feeding, the proboscis extends directly forward between the palps in front of the head. For further details on morphology see e.g., Krinsky (2002). Adults of both sexes feed exclusively on blood.

Once inseminated, the female remains fertile for life and rarely mates more often than once in nature. Inseminated females start ovulation of single eggs, which develop up to a third-instar larva within the uterus of the female. About 9 days after ovulation, the fully developed third-instar larva is deposited on the ground by the female (larviposition). Shortly thereafter, the female ovulates again, depositing a third-instar larva about every 7-11 days, when well-nourished and in ambient temperature. The average interval for all tsetse species is 9-12 days. Life span of females is about 20-40 days in general; males apparently survive 2-3 weeks in the wild (Glasgow, 1963; Potts, 1973). The developmental cycle includes these three larval stages, a pupa and the final adult. The low reproductive rate in tsetse is compensated by the extreme protection given to each larva by the female, but it also makes the impact of any loss of female flies greater than in species with a mass production of eggs (Krinsky, 2002).

Further information

  • Glasgow JP: The Distribution and Abundance of Tsetse. 1963, Macmillan, New York
  • Krinsky WL: Tsetse flies (Glossinidae). In: Mullen G, Durden L (eds.): Medical and Veterinary Entomology. 2002, Academic Press, London, pp 303-16
  • Potts WH: Glossinidae (tsetse flies). In: Smith KGV (ed.): Insects and other Arthropods of Medical Importance. 1973, British Museum (Natural History), London, pp 209-49

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