Carrier of Trypanosome Disease in Nyasaland. 24 



I. Habits of G. bkevipalpis. 



G. brevipalpis is found frequenting the roads in a small area of country 

 around Markho village on the west shore of Lake ISTyasa, at the mouth 

 of the Lingadzi river. This tract of country, which may be roughly 

 estimated at about 5 square miles in extent, is broken up by swampy hollows 

 and streams forming the delta of the Lingadzi. It is covered with palm 

 forest and a dense undergrowth of high grass and bush, and is traversed by 

 two main roads, one between Markho and Lingadzi estate running east and 

 west, and another running parallel to the Lake-shore and about 1 mile to 

 the west of it. The roads are hoed tracks about 3 yards broad, cut through 

 the palm forest and walled in by high grass and almost impenetrable bush. 



G. b?-evipalpis is crepuscular in its habits and quite unlike other Nyasa- 

 land tsetse flies. During the daytime, from dawn till about an hour before 

 dark, one may pass along the roads or wander in the surrounding jungle 

 without encountering a single fly of this species. But as evening approaches 

 odd flies suddenly appear sitting motionless in the middle of the hard-trodden 

 path all the way along the road between Markho and Kasache, a distance 

 of 2 miles, and for about 2 or 3 miles up the Lingadzi road. They do not 

 follow or settle upon passers-by like other tsetse flies, and they would pay 

 no attention to a dog which was repeatedly walked through their haunts 

 in the evening. In the dim light they are difficult to see, and resemble little 

 bits of earth on the path, but the searcher's attention is attracted by the 

 sound of them buzzing up as they are disturbed by his footsteps. They 

 immediately settle on the path again and are easily caught, for if missed 

 by the first stroke of the net they at once resettle near the same spot. 

 The hard-trodden surface of the path seems to have an irresistible attraction 

 for them. They do not move about in search of food or chase each other, 

 but remain motionless for several minutes, and when they move it is only 

 to fly up and immediately settle again in the middle of the path. They 

 were never seen on the roads at dawn, as the mornings at this time of the 

 year were invariably cold and misty. 



Out of the 500 flies caught and examined on the spot all were males. 

 Some of them were found on dissection to contain mammalian blood. Game, 

 such as buffalo and several species of antelope, is common in the district. 



Flies kept in captivity remain dormant on the sides of their cage during 

 the day. At night they are very active and buzz incessantly in their efforts 

 to escape. If the side of the cage be applied to the skin of a goat or a dog 

 they will feed with avidity at any time of the day or night. 



A few wild flies were dissected in order to ascertain their natural food. 



