126 RUPEKT W. JACK. 



and for a distance exceeding the radius explored around Sipane Vlei. It is obviously 

 possible that this may have occurred, but it appears very unhkely. Whatever 

 be the correct explanation, it is certain that Sipane Vlei had ceased for the time 

 being to serve the purpose it had served in the past, as a favourable breeding haunt 

 for the fly during the latter part of the dry season. During the season of dispersion 

 a considerable area of country would be affected by this fact. 



It is interesting to note that some years ago an experiment was planned in connec- 

 tion with Sipane Vlei with a view to determining whether the fly there was dependent 

 upon the visits of big game or otherwise. The plan was to surround the whole vlei 

 with a game-proof fence and thus keep the game away during the season of concen- 

 tration. It was not carried into effect on account of the doubtful practicability 

 of effective control at such a distance from communications. It would almost 

 seem, however, as if meteorological conditions, in reducing the pecuHar attraction 

 of the vlei to game, had effected a demonstration instead. Unfortunately further 

 observations bearing on this point will not be possible at this centre as the ever- 

 green trees on the margin of the vlei have now been cut down. 



Time was not available for a detailed inspection of other dry season haunts in the 

 same region, but fly was scarce at the crossing of the Gadzi River, known to the 

 natives as Matjagenya, on the way to Sipane, though formerly numerous. The 

 natives resident at this point also bore out this observation. Again, at Depota 

 Vlei some seven miles east of Matjagenya, no fly at aU were seen, and some natives 

 who had taken up their residence there the previous year had a number of apparently 

 healthy dogs. They stated that they never saw fly near the vlei, although a very 

 few were seen there by the writer in 1916. Winter shade is scarce at Depota, other- 

 wise it would be a typical first-grade focus, as it is attractive to game as a rule. 

 The writer has in the past seen eland, kudu, sable, impala, zebra, and sessaby in the 

 vlei, and the fresh tracks of buffalo and rhinoceros in addition. In August 1919 

 only one duilier was seen in the neighbouring forest, and the tracks of three kudu. 

 For the moment, therefore, the fly seems to be retrogressive rather than otherwise 

 in this region, and it is essentially a region of isolated dry season haunts. 



On the other hand, at the point where S^dvance has been recorded definitely, 

 namely up the Shangani River, the region is one of diffused dry season haunts 

 (second and third grade foci), and game w^as very plentiful in October 1919, though 

 their numbers had doubtless been augmented owing to the organised shooting 

 further down the river which commenced in June. Here then we have an iUustration 

 of " the fly following the game," only as the area of increase is some ninety miles, 

 as the crow flies, from Sipane Vlei the fly can hardly have migrated thither. The 

 presumption is that conditions the previous year favoured breeding in the one area, 

 and were unfavourable in the other. 



WTnilst conditions in the northern part of the Umniati fly area have no doubt 

 been affected to some extent by the efforts of hunters in shooting game for the 

 " Emerald " and " Copper Queen " Mines, and the portion to the east of the river 

 considerably affected on account of being in the open shooting area, the writer 

 has been, so far as is known, the only European visitor to Sipane Vlei for several 

 years past. 



