334: C. F. M. SWYNNERTON. 



In Zinyumbo's hills and even just on the Mwangezi cattle succeeded, as they did 

 thence westward through the Mossurise valley and northward to Spungabera. 

 This tract was full of cattle. But few deaths took place, and these always along 

 its extreme eastern margin, on the borders of the " Oblong." 



In the Gogoyo-Makwiana tract cattle were kept right under the Sitatongas both 

 at and opposite the Rupisi and from the great bend of the Mtshanedzi to its source, 

 also in the hills behind the cleared guard-area between the Mtshanedzi and Puizisi 

 and up to and beyond the present British border. Many of the herds were large. 



On the Sabi (present British territory) the results were particularly interesting, 

 for this had previously constituted a separate fly-belt, which was eventually almost 

 completely wiped out by native cultivation. The rinderpest may have given the 

 cowp de grace to the surviving remnant or two (recent events render this doubtful), 

 but at any rate cattle were already being placed and kept successfully all over the 

 old fly area in the seven years between Oungunyana's departure (with all the cattle 

 he could take) and the advent of the rinderpest (W. M. Longden and others). 



When the country was closely settled, cattle were kept successfully in places 

 where they had always died before ; and when the settlement was well established, 

 they succeeded where in its earlier days they failed, though fluctuations still took 

 place with successive shifting of the population. It is true that herds actually 

 abutting on the fly still suffered small and occasional losses, as they are doing to-day 

 to a greater extent on the present fly boundary. 



What drove the Fly out ? 



From the failure throughout the 25 years or so of this experiment to keep cattle 

 near the Mafusi rubber forests, well settled and well cleared of large mammals 

 though they were, it is likely that it was not the mere destruction of its food supply 

 that cleared the Zinyumbo, Gwenzi and Puizisi-Mtshanedzi areas of fly. We may 

 compare also Mr. Pollard's statement with regard to the Munshi division of Northern 

 Nigeria (Bull. Ent. Res. iii, 1912, p. 221). "It is interesting," he writes, ''to note 

 that the Munshis are great hunters and that they have practically destroyed all the 

 wild game in their district, and yet, in spite of this, the trypanosomiasis of cattle 

 and horses is rampant." 



But the game does not merely feed the fly ; it also carries it, each year, from the 

 permanent fly-areas into the more deciduous areas adjoining them as soon as these 

 have sufficiently regained their leaves. The heavy settlement of the broad river 

 valleys and the base of the Sitatongas, by clearing the bush, not only rendered 

 those areas themselves inhospitable to the fly, but also opposed a barrier to the 

 passage of game, and so protected from the fly the large enclosed piece of chiefly 

 deciduous bush behind the guard-area. Previous to the establishment of the guard- 

 area it had been impossible to keep cattle in the area behind it, as it is now again 

 impossible, and the broad guard-area itself, to judge from the descriptions of 

 the bush cleared, had probably harboured even more permanent fly then than it 

 does to-day. That the fly-population itself was diminished by the Zulu system of 

 late burning is also by no means unlikely. 



The case is most instructive and points the way for future measures. It must 

 be remembered that the flies concerned — brevipalpis and fdllidijpes, especially the 



