64 W. A. LAMBORN. 



In mid-December, however, a Bemhex was actually seen to seize a tsetse-fly and 

 to carry it away. The particular species had been repeatedly observed buzzing round 

 as I walked, but little attention was paid to it at first, seeing that an inquisitive 

 disposition seems to characterise many Sphegid wasps. Then one of the insects was 

 seen to make a rush at a tsetse-fly on my leg, which it failed to secure. When a 

 goat was led through the district three more were seen in the course of half an hour,, 

 after flying round and round the animal and hovering a few feet away, to rush at 

 tsetses on it, two unsuccessfully, but the third was captured on the wing having 

 seized one of the flies. So far, all attempts to find out the other habits of the insect 

 have failed, though the matter is receiving attention. 



Flies of the family Bombyliidae, some small species of which exist in great numbers 

 in the Lingadzi district, have also been under consideration as potential enemies 

 of the fly, in view of Mr. Lloyd's discovery of one as a parasite of a tsetse pupa, but 

 little advance has been made, beyond the discovery that three of the species, after 

 careful selection of a site, oviposit in irregular fissures in the ground frequently 

 under trees, though what influence induces them to do so has not been determined. 



Tsetses and Caterpillars. 



An endeavour was made to ascertain whether the fly will ever feed on Invertebrates 

 by caging them with the caterpillars of a large Saturniid moth, such as were to be 

 found recently in enormous numbers in the Rifu district, where large trees had 

 been entirely defoliated by them. The results were negative. 



Spread of the Fly in Marimba District. 



When on my arrival in late October I had an interview with H.E. The Governor,. 

 he informed me that disquieting reports had been received from members of the 

 Livingstonia Mission to the effect that tsetse-fly had recently spread in from 

 North-Eastern Rhodesia and was within measurable distance of one of their principal 

 stations at Kasungu in the Marimba district, and he asked me if I could make it 

 convenient to look into the matter. I was unable to do so until late December, when 

 I travelled to the district and found Glossina morsitans existing over a wide area 

 in small numbers and more abundantly as one approached the border. 



The district is hilly and covered with stunted trees, which nowhere approach the 

 size of so many found in the sleeping sickness fly area, and the soil differs in being 

 mostly very sandy, producing small fine grass, growing in many places in tufts only, 

 instead of spreading uniformly. It is very arid also, stretches of 18 miles without 

 a trace of water being several times met with, and as a consequence the district is 

 very thinly populated. 



This new fly area is situated in the Marimba district of Nyasaland just north 

 of the Duangwa River, where it crosses into Rhodesia. 



I am informed by Dr. J. B. Davey, one of the Medical Officers, that he has also 

 found the fly extending well into Nyasaland south of the Duangwa River, also over 

 a wide area. 



General Observations. 



As has already been remarked, tsetses are especially attracted by moving objects, 

 and it has been my frequent experience that the faster one moves the more one is 



