188 JAS. J. SIMPSON — ENTOMOLOGICAL 



In my report on Southern Nigeria, I dealt at considerable length with the 

 factors influencing the distribution of G. palpalis, G. tachinoides, G. submorsitans, 

 G. longipalpis, and G. Jusca in Nigeria, and the conclusions arrived at for that 

 region are equally applicable to Sierra Leone. Briefly stated, it may be said 

 that Southern Nigeria and Sierra Leone are almost identical in the conditions 

 which tend to support the existence of the three species of Glossina to be 

 discussed here. 



In the report mentioned the following occurs : " This species {Glossina palpalis) 

 is ubiquitous along the coast region and follows the course of all the rivers. It 

 exists wherever the rainfall is great, where the dry season is not of long duration, 

 where the vegetation is dense, and always along the basins of rivers. Where any 

 or all of these factors are less accentuated, the number of individuals tends to 

 decrease." 



Reference to the chapters on Geography and Climate in this report will show 

 that these conditions are fulfilled throughout the whole of Sierra Leone, and a 

 glance at the map will be sufficient to indicate that this species is ubiquitous but 

 follows more closely the river courses. 



In the same report a comparison was made between the conditions most favour- 

 able to G. submorsitans and G. longipalpis, and it was pointed out that G. sub- 

 morsitans inhabited the drier regions where savannah forest was predominant, 

 while G. longipalpis was associated with a moister climate and a slightly denser 

 type of vegetation. In no part of Sierra Leone are the conditions favourable 

 for G. submorsitans, but in the Koinadugu district conditions similar to those in 

 which G. longipalpis occurs in Southern Nigeria are to be found, and there, as 

 the map will show, do we find this species widely distributed. 



Glossina fusca favours dense vegetation and a moderately moist climate, and 

 is to be found in Sierra Leone in the regions of densest forest growth ; in fact, as 

 the map will indicate, the delimitation of the forests {see page 155) is at the same 

 time a delimitation of the areas where Glossina fusca occurs. 



VIII. The Genus Stegomyia. 



This genus being instrumental in the transmission of yellow fever, which is 

 all too prevalent in West Africa, calls for some consideration. I have already 

 referred* to two papers on this subject, the first by the late Sir Rubert Boyce, 

 and the second by Dr. W. M. Graham, and I have also detailed the distribution 

 of the various species of this genus in Southern Nigeria and elsewhere in West 

 Africa. 



In Sierra Leone three species are met with, namely, S. fasciata, S. sugens and 

 S* ipicoargentea. Reference has been made in different parts of this report to 

 the breeding places of this genus, so that it is unnecessary to reiterate them here, 

 and I shall content myself for the present with recording the localities in which 

 each species has been found. 



S.fasciata :— Freetown; Cline Town; Batkanu ; Moyamba; Daru; Makump; 

 Gberea ; Tungea ; Kondundu ; near Kondita, at the River Lolo ; Benikoro ; 

 Firiwa ; Sandea ; Jowati and Bonthe. In several places this species was found 

 in the bush far from human habitations. 



* Bull. Ent. Res., iii, p. 191. 



