303 



REPORT ON A JOURNEY TO THE LUANGWA VALLEY, NORTH- 

 EASTERN RHODESIA, FROM JULY TO SEPTEMBER, 1910. 



By S. A. NEAVE, MA., B.Sc. 



(Map.) 



Itinerary, 



Leaving Karong*a, at the northern end of Lake Nyasa, on July 15th, I 

 reached Katumbi on the Luwiimbu River, the chief tributary of the Upper 

 Luangwa, about a week later. I had made this river my objective, as I had 

 already examined, in 1908, a considerable portion of the Luangwa above its 

 junction with the Luwnmbu. After following the Luwumbu down to this 

 point, the Luangwa itself was followed for a considerable distance, chiefly on 

 the left bank. 



I crossed to the right bank a little above the mouth of the Mwailesi River, 

 and after following the Luangwa for some 30 miles further, I temporarily left 

 it and proceeded westward to the Nyamadzi River, in the valley of which three 

 cases of Sleeping Sickness w^ere discovered by Dr. Leach some months ago. 

 Unfortunately, I did not receive information as to the position of the villages 

 in which these cases were found, in time to do more than make a special 

 search in the vicinity of one of them. I examined, however, a portion of the 

 Nyamadzi River in the vicinity of Nawalia, as also the lower portion of the 

 Mpamadzi River further south. The evidence as to the existence of Glossina 

 pcdpalis or G. fusca on these rivers was negative. The locality seemed, how- 

 ever, a not unlikely one for the latter species and not altogether unsuitable 

 for the former. At the same time, the amount of cover and shade on the 

 banks of these rivers is considerably less than on a typical palpalis river of 

 the same size in the Congo basin. It would appear probable that the amount 

 of shade required for the well-being of the species varies with the climatic 

 conditions and the volume of water present ; so that heavier shade would be 

 required in a relatively drier country. 



It is possible that G. fusca occurs in this locality, but in such small numbers 

 at the time the visit was made — viz., at the height of the dry season — that it 

 was overlooked. At the same time. Dr. Leach, whose visit was made during 

 the rains, does not appear to have met with it either. 



It may be noted that these Western tributaries of the Luangwa differ con- 

 siderably from those of the Eastern side of the valley. They take their rise 

 on the lofty Mchinga escarpment, and the larger ones among them are 

 permanent running streams. Indeed, but for the Mwailesi, Nyamadzi, and 

 Mpamadzi, the Luangwa would itself be dry for many months of the year. 



On the other hand, on the eastern side of the valley the tributary streams 

 which rise on the comparatively low watershed between North-Eastern 



BULL. ENT, RES, VOL. I, PART 4, JANUARY I9II. 



