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SECOND REPORT ON GLOSSINA INVESTIGATIONS IN NYASALAND. 



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



Imperial Bureau of Entomology. 



(Plates IV and V.) 



Until 13th March I remained in the Proclaimed Area, then, as the weather conditions 

 were very bad, and as moreover the grass had so overgrown all the paths, which are 

 little used, that my movements w^ere very much hampered, I removed to Fort 

 Johnston at the southern extremity of the Lake, and have since been working in 

 its neighbourhood. 



Some preliminary tramps were necessary for the purpose of finding out the locality 

 most suitable for the work, and accordingly in late March and early April, when 

 the rains were just over, I took the opportunity of studying the distribution of 

 Glossina morsitans on the east side of Lake Malombe ; then to the south of Chingaras, 

 a large village 25 miles south of the Fort on the main road to Zomba ; and finally, 

 along the west side of Lake Nyasa as far as Monkey Bay, 25 miles north of the Fort, 

 where, as the fly was more numerous than elsewhere, I decided to continue the work. 



The outcome of these expeditions was to revolutionise the ideas which I had 

 obtained by reading as to the distribution of the fly at this season, for though in 

 none of these localities were they as numerous as in the proclaimed area, isolated 

 flies were found over a very wide range. Thus, in the course of a six hours' trek 

 from Fort Johnston to Malombe, a distance of some 20 miles, I took five ; two 

 in the early morning when I first set out, many miles from where I subsequently 

 found them to be numerous. On the journey from Fort Johnston to Chingaras, 

 a distance of 25 miles, I took four in country hitherto considered free from them ; 

 and on the journey from Monkey Bay to Fort Johnston, which I have made several 

 times, I have always been able to take one or two flies many miles from the locality in 

 which I know them to be numerous. Such isolated flies are always very unobtrusive, 

 and as they do not necessarily bite, though persistently following one, it is probable 

 that they escape the untrained eye. In the proclaimed area the physical conditions 

 of the country — the Lake to the east and a range of hills, devoid of trees, to the 

 west — make the term " fly belt " applicable ; but in the Fort Johnston district there 

 was nowhere at that season anything approaching a hard and fast line marking 

 the distribution of the fly, which indeed seems to occur under widely differing 

 conditions. 



Its distribution in varied types of country was well exemplified in the " fly belt " 

 of the proclaimed area. Here on travelling due west from the Lake one passes first 

 of all over a dambo [open swampy land], where of course there are no fly ; then 

 through scattered Borassus palms, which at a distance of about 2| miles from the 

 Lake grow thickly, with low shrubs, and tufts of comparatively low wiry grass in 

 between (Plate iv, fig. 1). The soil is very sandy, such being favoured by these 

 palms ; and here the fly begins. Further on, at a distance of two or three miles 

 more, the sandy soil gradually gives place to a heavy black soil, very tenacious in 

 wet weather, and there is a marked change in the vegetation, the palms becoming 

 fewerand fewer till they give place entirely to large shade trees, baobabs and lower 



