316 C. F. M. SWYNNERTOK. 



28tli July, and proved quite invaluable during the remaining six weeks. They 

 revealed abundant fly in places in which the nature of the vegetation had previously 

 been the only indication of its possible presence, and led to the suggestion that one 

 i*eason why investigators have commonly met with so enormous a preponderance 

 of male flies is that insufficiently attractive bait has been offered to the sex that 

 comes only to feed. 



The part of my investigation already referred to, east of the Sitatonga Hills, 

 was carried out with the help of my own farm natives only, and was concerned 

 chiefly with the small flies, Glossina morsitans and G. pallidipes, which I there found 

 mixed. I also then made my discovery, and commenced my study, of the Mtsha- 

 nedzi-Buzi brevipalpis area, which at its other end affects Spungabera. 



The second month (I was now being assisted in the matter of labour by Snr. 

 Lanne) was occupied mainly with a fly survey of the northern part of th^ district. 

 It included also the completion of my work on the breeding habits of G. morsitans 

 and a week's study, south-west of Chibabava, of a typical piece of the surface-basalt 

 country that constitutes so very large a proportion of the low-lying parts of the 

 Mossurise district. At this period I sent a successful side-expedition round north 

 of the entire Lusitu River in the Moribane district in order to gain some idea of the 

 full extent and importance of the eastern fly-areas. 



The third section of the trip was occupied with the completion of the above work, 

 with experiments directed to ascertaining the effect and cost of particular forms of 

 clearing for fly, a study of the habits of G. brevipalpis and a special study of the 

 Spungabera problem. Spungabera being the official head- quarters of the district, 

 and the seat of a herd of cattle belonging to the Mozambique Company that had 

 lost heavily from trypanosomiasis, its protection from fly appeared to be of the 

 first importance. 



I returned home finally on 10th September, and afterwards I sent a small 

 expedition to the Chinyika Eiver, south of Spungabera, and completed my 

 breeding experiments. 



Four days had been spent near the British border examining the details of nagana 

 outbreaks in Portuguese territory, two in trying to ascertain the maximum 

 dry season elevation of G. brevipalpis, and two in all at Spungabera itself. Otherwise 

 all the work was more or less far within Portuguese territory. I had had four 

 working camps — one on the Umvuazi River east of the Sitatongas, one on the 

 Buzi in the Gunye-Umpombo country south-west of Chibabava, one near the east 

 end of the great southern brevipalpis area, and "one at its west end at a point on the 

 Buzi six miles from Spungabera. 



The Mossurise fly problem quickly proved to be of quite extraordinary interest. 

 Apart from the presence in the district of so many different tsetses, and the oppor- 

 tunity of studying them usefully that is offered by the very varied but well- 

 demarcated conditions of vegetation, elevation, rock-formation, etc. , that the district 

 affords, the area west of the Sitatonga HiUs was, under the Zulu domination, the 

 scene of a particularly fine experiment in the banishment of tsetse. It was not 

 difficult to obtain the details of this experiment, as most of the older natives had, 

 incidentally or by compulsion, taken part in it. I made particular efforts to 

 obtain information on this point, (a) because a study of any successful campaign. 



