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THIRD REPORT ON GLOSSINA INVESTIGATIONS IN NYASALAND. 



By W. A. Lamborn, M.R.C.S., L.R.C.P., 

 Imperial Bureau of Entomology. 



I remained in the proclaimed area till Gth August 1915, then returning to the 

 vicinity of Monkey Bay for the purpose of endeavouring to establish artificial 

 breeding places on a large scale. 



While in the proclaimed area I took the opportunity of completing my survey of 

 the distribution of Glossina morsitans, especially in the neighbourhood of Rifu and 

 Kuti described by Dr. Shircore (Bull. Ent. Res., v, p. 87) as " primary centres 1 and 

 2," which I had been unable to examine last season before the advent of the rains. 

 As in the case of " centres 3 and 4," at Nyansato and Lingadzi respectively, I have 

 not been able to find that the fly is sufficiently localised, even when the dry season 

 is far advanced, as to render feasible any attempt to control it by prophylactic clearing 

 of the bush. In the Rifu district there is a range of rocky hills and high ground 

 running more or less parallel to the lake, with corresponding modification of the soil, 

 so that a zone of scrub has sprung up, from half a mile to two miles in width, 

 consisting very largely of thorn bush> among which are a few big trees. Towards 

 the north this gradually dwindles, to be replaced by the borassus palms usually 

 growing in the sandy ground along the Lake shore, and towards the south it 

 gradually widens out and becomes continuous with the Kuti bush some five miles 

 distant. Throughout its whole extent the fly was plentiful. 



At first sight it was thought that on account of its narrowness this zone might be 

 suitable for attempting measures other than by clearing for the control of the fly, but 

 it was subsequently found that there was inter-communication between the flies in it 

 and in the main area distant from two to five miles across the dambo. Over this 

 intervening space isolated trees and thickets of dwarfed bushes are scattered thickly, 

 the latter usually from 50 to 200 yards apart, and from north to south runs in the dry 

 season a very rough path, in passing along which it has been my constant experience 

 to be assailed by the fly in small numbers. I have found them also at many other 

 points on the dambo, so that there can be no question as to communication between 

 those at Rifu and those in the main area. The lower branches of the bushes, which 

 on the dambo are stunted and low-growing, have been found to afford shelter for 

 small numbers of pupae. Rifu is not, in my opinion, therefore suitable for a control 

 experiment of the nature suggested by Dr. Shircore. 



At Kuti there was no greater concentration of the fly, and there was nothing 

 approaching to a break in its distribution right up to Nyansato. 



