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202 mother; it is a yellowish ovoid body composed of twelve segments and presenting two small hooks at the anterior pole, and two protuberances at the posterior extremity, which is black. The perfect insect emerges from its pupa-case in about six weeks. In the case of G. palpalis the pupa has been found in Uganda buried in the loose earth about the roots of banana trees (Bagshawe) and similar situations.

Habits.—Tse-tse flies are voracious blood-suckers, exhibiting great persistency in their attacks on man and animals. They bite almost exclusively during the day, though some of the larger species bite at night, and one of them, G. brevipalpis, is stated to be definitely crepuscular in its habits. Contrary to what is the case among horse-flies (Tabanidæ) and mosquitoes (Culicidæ), of which the females alone suck blood, in the tse-tse both sexes are blood-sucking, and with some species the males are more voracious, or more pertinacious, than the females.