THE TSETSE PROBLEM IN NORTH MOSSURISE. 369 



Craieropus kirki (Kirk's babbler) and the two guinea-fowls, Gnttera exlmmnU 

 (crested) and Numida mitrata (East African), were observed once or twice (out of 

 many times) scratching in positions like those in which tsetses deposit their larvae^ 

 as was also the bristle-necked bulbul {Phyllastrephus capensis)* A more interesting 

 observation was made on an elephant shrew (presumably Petrodromys tetradactylns) 

 in a dry but shady donga entering the Buzi at the south end of the Sitatongas. We 

 had searched for and found puparia (austeni) under a large fallen tree and, going 

 on to search under other logs and stones, found we had been anticipated by a small 

 animal. For a distance of 47 paces along the donga every hiding place that would 

 have been used by tsetse had had the surface soil scratched out and the spoor and the 

 droppings were, I should say (and the natives also were certain), distinctly those of 

 one of these elephant shrews. I have actually watched the above elephant shrew 

 in the wild state scratching thus for slightly buried insects and, having kept indi- 

 viduals in captivity, am tamiliar with their droppings, etc. 



The natives stated that ox-peckers {Buphaga) regularl}^ P^ey on tsetses that are 

 feeding on game animals, and that from the movements of the birds it is obvious 

 that the flies employ against them the sidelong movements I have referred to in 

 relation to attack by knife and assegai. The flies also no doubt continually come 

 within the ken of the birds that carefully search tree-trunks and twigs, and it is 

 no doubt in relation to these that their choice of protective resting surfaces is of 

 use. Such birds form a very large proportion indeed of our small bird population. 



Spiders of various bark-haunting species that hide in crannies and leap on their 

 prey accounted for a number of the flies I had under observation in the net, and it 

 is probable that these are the female tsetse's most, important enemy. One ts('tse 

 (morsitans) was seen caught in the net of a web-making spider. Dragonflies on 

 several occasions in fly country inspected the backs and necks of my companions. 

 A w^asp once did the same. On one occasion, travelling from the Buzi to the 

 Mtshanedzi, five brevipalpis were under the cattle, four being under the leading ox. 

 We ran into some dragonflies, which at once began passing to and fro immediately 

 under the belly of that ox. I saw no captures, but these four brevipalpis had dis- 

 appeared when the dragonflies left us. The one survivor travelled with us for over 

 one and a half hours and remained about our camp for long afterwards. Dragon- 

 flies were exceptionally and extraordinarily numerous in 1918, but the tsetse popula- 

 tion remained large. I do not remember seeing any Asilidae. They only become 

 abundant here in October. 



XVII. — Tsetse Concentrations. 



]My closer observations on this subject, which may be of high practical importance, 

 were limited to a single morsitans centre, but I searched and studied much country 

 in which there was no concentration, both before and after the commencement of 

 leaf-fall, and secured much native information also. I obtained, I believe, a fairly 

 clear idea of the conditions obtaining in this particular fly-area. I spent a fortnight 

 in all at the Kanyezi fly-centre. This was a large and very definite breeding 



* The existence of soft pockets of earth, breaking the harder crust under most ot the 

 logs examined, constitutes indirect evidence also of the scratching of some animal or 

 animals in these places. 



