320 JAS. J. SIMPSON—ENTOMOLOGICAL 
this subject extending over a long period, informed me that of the horses brought 
into Lokoja over 60 per cent. developed trypanosomiasis within a year, and of 
these 50 per cent. died within the same period. The question naturally arises : 
What is the carrier? It must be remembered that these horses are very seldom 
taken out of the station, and consequently must be infected within that area. 
As has been mentioned, /Hippocentrum versicolor does oceur, though in small 
numbers, but the most prevalent horse-biting flies are Stomoxys nigra and S. 
calcitrans, whereas Glossina submorsitans has never been seen in Lokoja. 
These facts apparently point to Stomoxys as the carrier, and since we have no 
direct evidence, experiments should certainly be made to prove or disprove this 
possibility. But, apart from this, the fact remains that at present two out of 
every three horses brought into Lokoja are incapacitated for work within a year 
of their arrival, and it is almost superfluous to emphasise the necessity of trying, 
so far as possible, to reduce the chances of infection by instituting a segregation 
camp and making the stables mosquito-proof. To this subject, as well as to the 
question of launches as agents in the dissemination of mosquitos, I shall refer 
later on. 
(c.) Offa to Zungeru. 
The greater part of this journey was made by railway, and as by this means it 
is possible to examine only the chief towns “en route” I shall here content myself 
with giving a few general notes and the records of blood-sucking insects so far 
available. The town of Offa is situated on the boundary of Southern and 
Northern Nigeria and is connected with Lagos in the south and Jebba in the 
north by the Lagos Government Railway. The biting flies recorded from this 
station are :—Myzomyia jfunesta, M. costalis, Hippocentrum versicolor, Tabanus 
secedens, T. subangustus and Tabanus sp. nov. near kingsleyi. The only ticks 
recorded are Aponomma exornatum and Amblyomma nuttalli, of which Dr. R. C. 
Hiscock obtained specimens from a large monitor lizard (locally called an 
iguana) captured near the European quarters. 
Northwards the next important town is Ilorin, and here the following insects 
were obtained :—Myzomyia costalis, Myzorhynchus paludis, Trichorhynchus 
(Culiciomyia) nebulosus, Reedomyia annulata and Culex sp. indet. 
At Jebba the only blood-suckers seen were Myzomyia funesta, M. costalis, 
Glossina palpalis and Tabanus taeniola. The town of Jebba is now connected 
with Zungeru by what is known as the Northern Extension of the Lagos 
Railway, but at the time of my visit this line was under construction, Through 
the kindness of the Director I was, however, enabled to examine this area as far 
as Charati, the terminus at that time, and the following records were made during 
several excursions by trolley. 
At Gana, on the left bank of the Niger, from which the photograph shown in 
Plate VII, figure 2, was taken, G. palpalis was far from uncommon, and this 
species occurs at several places before reaching Mokwa. The railway skirts for 
a considerable distance a large expanse of water known as Lake Tatabu, which is 
not surrounded by much dense shade, but everywhere high grass is predominant. 
Throughout this whole region G. tachinoides is extremely abundant. 
