299 



N0TE8 ON GLUSSISA FUSCA, WALK., IN NORTH NYA^A. 



By Dh. MEREDITH SANDERSON, 



Medical Officer, Nya8ala>-d Protectobate. 



(Map.) 



The following notes are based on observations made during the months of 

 June and July, in and near the Songwe valley. 



Between Karonga and the River Songwe the country consists of a plain 

 about 10 miles in width, lying betw^een Lake Nyasa and an irregular line of 

 foot-hills, behind which the country becomes more and more hilly, gradually 

 rising to the Misuko Hills, some thousands of feet above sea-level. 



The plain (1) * is open^ i. e., it is covered with long grass and a few small 

 trees, and is crossed by numerous rivers and streams rising from the hills and 

 running into the lake. All these streams are marked throughout their course 

 by narrow lines of thick bush and large trees, usually including a few palms, 

 but not invariably (fig. 1^ p. 300). G. fusca was found in the bush on all 

 these streams, though many of them are dry or are represented by a few 

 stagnant pools only, at this time of the year. No fly was found on the plain, 

 though the natives state that it is very prevalent there also during the rains 

 {i. e. about January). 



For the first few miles up the Songwe the character of the country is very 

 similar, and G. fusca was found on the river and on all its tributaries. On 

 leaving the plain, however, and entering the Songwe valley, the wooded hills 

 gradually close in near the river, so that the open spaces of the plains are 

 soon altogether absent, and the bush is continuous between the streams 

 running into the Songwe (2). The trees, however, are smaller, and the brush- 

 wood almost absent, being replaced by coarse grass^ brambles, etc. Here in 

 the course of every stream, however small and however dry, this species of 

 Glossina was found, frequently in very large numbers, and the fly could be 

 observed in almost any sheltered spot. They were, in this locality, invariably 

 absent from places where the trees were thin, or where they were not 

 protected from sun and wind. They were also found in the rank bush 

 bordering the main river. 



Towards Nkana the trees on the hills become scarcer^ the hills are bigger 

 and the valleys between them deepei', and G. fusca became difficult to find (3) . 

 At the River Makeye there is a wide valley with long grass and few trees, and 



* These numbers will be found on the map, indicating the localities referred to. 

 BULL. ENT. RES. VOL. I. PART 4, JANUARY 1 91 1. 2 A 2 



