IN THE ILORIN PROVINCE OF NORTHERN NIGERIA. 9 



it seemed reasonable to assume that the presence of tsetse-flies on any of the 

 streams on the Agugi road is determined by the suitability of the conditions, the 

 most important of which appears to be the presence of deep shade ; and I came 

 to the conclusion that, provided the crossings were properly cleared, the road 

 might safely be used for animal transport. Unfortunately, it was necessary to 

 send out the first drove before the clearing could be effected, and ten healthy 

 donkeys left Ilorin for Agugi on 4th August. On 14th September only three 

 survived, all suffering from trypanosomiasis ; and the last of these died on 

 1st November, within three months of the beginning of the experiment. 



The Eastern Division. 



In the eastern division of Ilorin province there are two great uninhabited 

 districts lying on either side of the Kampe River, and a third smaller uninhabited 

 tract just south of Zumbufu. Although it was not possible to examine this 

 division with the same thoroughness as the western, yet the 188 collections 

 obtained are representative of all the inhabited regions, and are probably typical 

 of the whole division. 



The tsetse-flies collected were of the following species : G. palpalis, G. taclri- 

 noides, G. submorsitans, and G. longipalpis. On referring to the map it will be seen 

 that the first three species are distributed over practically the whole district, the 

 only important exception being the country lying to the west of Oke Odde, 

 where only G. palpalis and G. tachinoides were found. G. longipalpis was taken 

 in only a few localities, and as they are widely separated, it is possible that this 

 species has been overlooked in the intervening areas. 



The vegetation of this division is generally closer than in the western division, 

 the country is less widely farmed, and in places there are actual belts of forest. 

 This, no doubt, accounts in part for the general distribution of G. submorsitans, 

 a species which is absent from the western division. Many of the collections 

 which contained specimens of G. submorsitans were, however, made actually on 

 the banks of streams, and there seems to be no doubt that, during the dry season 

 at any rate, this species of tsetse is to be found in considerable numbers along 

 the rivers. On the banks of the Noako River, for example, G. submorsitans was 

 abundant during the dry season ; but later in the year, in October, towards the 

 end of the rains, they were conspicuously less numerous. At several places 

 where tsetses of the palpalis group only were found during the dry season, 

 G. submorsitans was present in addition during the rainy season, a fact that 

 considered in conjunction with the preceding observation, suggests that this 

 species takes refuge in the dry season near the rivers. It would, therefore, be 

 interesting to ascertain whether, by clearing the banks of this stream so as to 

 deprive them of this refuge, the subsequent dissemination of G. submorsitans in 

 the neighbouring country might not be checked, as it was found to be in the 

 case of G. palpalis, by the clearing oi: the belt at Offa.* In the dry season, 

 moreover, the vicinity of the Noako River is the haunt of big game. As might 

 be expected from the nature of the country, tsetse-flies are much more common 



* See pp. 12-13. 



