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acacia veld near Bulawayo and other open districts is far too deficient 

 in shade, and never has been or could be a fly country. The bush 

 generally is of two types, the mopani {Copaifera mopani), of which 

 great belts exist within the fly areas, and the other type of bush known 

 to the Matebele is " gusu," which term appears to indicate almost 

 any species of not too open forest, apart from mopani, with httle under- 

 growth except grass. The commonest trees in gusu bush are species 

 of Brachystegia. Mopani generally grows on a poor soil, yielding but 

 little grass even in summer, though, such as it is, this grass appears 

 to be palatable to grazing animals. The gusu type of bush is generally 

 found on more fertile soil, and the grass in it may grow to a considerable 

 height during the wet season. There are other types of forest in the 

 country, though none of them of any great extent. 



In the dry season, the trees in general lose their foUage, but many, 

 along the edges of water-courses and vleis, whether containing surface 

 water or not, retain their leaves. The result is that, from July to the 

 beginning of the rains, the fly is confined to the shade provided by such 

 trees. When the bush comes into leaf, which in many parts is not 

 before December, the fly scatters, and far from being found to be 

 especially associated with water-courses and vleis, is generally more 

 plentiful in the surrounding bush, whether gusu or mopani. Thorn 

 brake is not much affected by tsetse, but it rarely covers any great 

 extent of country. Large thorn trees {Acacia catechu, etc.) frequently 

 form the shade near a vlei or river, and this suits tsetse very well in 

 winter. 



The author's photographs are intended to show the relationship of 

 G. morsilans to vegetation, and he quotes an instance in which on one 

 day nearly 100 tsetse were collected with a net in about an hour on the 

 western side of a vlei, characterised by the presence of large shade 

 trees. Keturning by the eastern side, where the leafless bush came 

 down to the edge of the vlei and terminated abruptly with no fringe 

 of trees of evergreen habit, not a single fly was seen, although the dis- 

 tance from the termination of the forest on either side was not more 

 than a few hundred yards. 



He sums up his observations as follows : — Tsetse may be expected 

 to be found in fly-infested areas in the gusu or mopani bush during the 

 wet season, but not after the trees have lost their leaves in the dry 

 season ; during the latter period the shady banks of streams and water- 

 courses and the shady borders of vleis, constitute danger zones, that 

 is to say, the nature of the forest determines the suitability of a tract 

 of country for tsetse, provided always that the suitable food supply be 

 present. If there is no winter shade, no matter how suitable the 

 forest may be to tsetse-fly during the summer, the fly cannot estabhsh 

 itself in that locahty. The exact range to which the fly will spread 

 from its winter haunts during the wet season has not been ascertained, 

 but it is quite three miles, and may possibly be more. The fly will 

 follow a food supply for a considerable distance, upwards of seven 

 miles, but apparently returns regularly to its haunts. The author 

 says that there is no fear whatever of tsetse spreading over the whole 

 country ; that the area suited to and inhabited by it in the early days 

 is comparatively hmited ; that the pest retreats before civihsation ; 

 and that there is no danger whatever of the invasion of settled parts 

 by the tsetse. 



