t5l> W. A. LAMBORN. 



Fly is undoubtedly more concentrated in this district in the dry season than in 

 the wet, coincident with the greater concentration of the game which then takes 

 place, as I have been informed by several professional hunters and others, the 

 reason for which is not far to seek. Over the greater part of the country in the dry 

 season rivers and water-holes dry up, all shady verdure disappears, and the grass 

 is burnt ofi, leaving a blackened wilderness which then compels the game to seek 

 certain localities, such as are included in the area under consideration, where they 

 can obtain shade and the necessities of life. This district, partly woodland and 

 partly plain and all lowlying ground, is situated between Lake Nyasa to the east 

 and tiers upon tiers of mountains to the west, and is in the wet season, as I am 

 informed, permeated by numerous rivers and streams, when large areas often remain 

 under water for weeks. Its soil is composed of rich black humus and, unlike that 

 in other parts, contains little sand, which with the constant presence of subsoil water 

 renders it extraordinarily fertile. Even in the dry season over the greater part of 

 the area water is only surface deep and is always obtainable in the extensive marshes 

 and elsewhere in hollows ; as a consequence grass is to be found here when no vestige 

 can be seen elsewhere, and large forest trees, such as are found nowhere else at the same 

 elevation, occur abundantly and always afford a certain amount of shade. In this 

 district in the late dry season the grass was ankle-high when not a single blade could 

 be seen in other parts, and as further evidence of the fertility of the soil it may be 

 added that the native farmer can grow as many as two or three crops of maize on 

 it in a favourable season, when elsewhere only one can be raised, though comparatively 

 very little is under cultivation. Certain districts are well populated, but the 

 habitations are all arranged along three definite narrow lines, so that the greater 

 part is rarely traversed by human beings. The reasons for the concentration of the 

 game are therefore obvious, and it seems a natural corollary that the fly, which, so 

 far as has been ascertained at present, is entirely dependent on the game, should 

 concentrate at the same time. 



Though the fly does occupy certain definite regions in the dry season from which, 

 as I quite agree, they radiate out farther afield when the grass springs up everywhere 

 and the game spreads abroad, the foci, in this district at all events, are in my opinion 

 far too extensive to make any experimental attempt at clearing and reducing their 

 number by systematic capture practicable. I have not been able to discover that 

 the " primary centres " form localised breeding grounds, so that this very attractive 

 hypothesis is up to the present unsupported by a shred of evidence. 



The whole question will be more fully studied in another district at a later date. 



Flight Experiments with Glossina morsitans. 



Preliminary experiments have been conducted with a view to determining the 

 range of flight of Glossina morsitans. 



Between 4th and 22nd December, 1,810 males and 312 females were captured 

 in the Lingadzi district, where the elevation is about 1,700 feet, and between 4th and 

 17th December 854 males and 66 females had been marked and released at two 

 different points — at Chunzi, at an elevation of 2,420 feet, 10 miles due south of the 

 Lingadzi fly area ; and at a spot which has an elevation of 1,950 feet and is situated 

 2 miles south of the Lipimbi River and 5 miles south of the same fly area. 



