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Write an Account of the Distribution, Habits, and Life- History 

 of Glossina palpalis. 



The Dusky Tsetse-fly, Glossina palpalis, the chief carrier 

 of the deadly trypanosome of "sleeping sickness," is 

 common throughout West and Central Africa, in the forest 

 country of the Senegal, Congo and Niger Rivers. " Usually 

 it infests certain areas ; but its prevalence in these tracts 

 or " fly-belts " varies according to rainfall and the migratory 

 habits of the big game. It is most numerous about fords 

 where the human inhabitants frequently congregate." 

 It " bites " in the daytime, and is active only in sunny 

 weather. It has, like other tsetse flies, a characteristic 

 habit of resting with the wings folded flat over the back, 

 like a closed pair of scissors. As in all the blood-sucking 

 Muscidae, the blood-sucking habit is common to both 

 sexes. Unlike other Muscids, it is (as all tsetse-flies are) 

 larviparous ; and the larvae (8 to 10) are born (at intervals 

 of nine or ten days) ready to pupate. Before birth the 

 larva is nourished by specialised milk-glands which open 

 into a '* teat " on the inner wall of the uterus. The larva 

 remains within the uterus about ten days ; then it crawls 

 to some suitable spot, e.g., under soil or debris (an inch 

 under or thereabout) at the base of a tree near the edge 

 of a stream, and at once pupates within a puparium which 

 is barrel-shaped and has two small protuberances ai the 

 posterior end. The duration of the pupal state is from 

 thirty-two to thirty-five days. 



State what you know about the Life - History and Habits of 

 Lice t and their connection with Disease. 



The whitish oval eggs or "nits," truncated at the end 

 where the young louse emerges, are laid one at a time. 

 " A female louse lays four or five eggs a day for about a 

 month, and then dies." The eggs are '* glued " to hairs 

 or fibres of underclothing, and hatch out in from eight days 

 to five weeks. There are three growth-stages with accom- 

 panying moults. The young resemble the adults ; and the 

 adult stage is attained in about twelve days. 



Lice are permanent ectoparasites and, unlike fleas and 



