188 JAS. J. SIMPSON 
ENTOMOLOGICAL 
little has been done, and thus stimulate others to add their quota so as to bring 
the Gambia into line with other parts of the world. 
An appendix has been added emphasising the chief points to be observed in 
collecting and preserving insects for identification, and indicating the method by 
which such collections will be identified, acknowledged, and incorporated with 
previous work. 
I. INSECT-BORNE DISEASES. 
Before we proceed to the purely entomological part, it might be well to draw 
attention to some of the factors which necessitate such work being carried out, 
and, in this connection, the occurrence and prevalence of insect-borne diseases 
command primary consideration. 
(a.) Malaria, as in all the other West African Colonies, is almost universally 
distributed, and is by far the commonest insect-borne disease of the Gambia. 
(b.) Yellow Fever is far from infrequent, however, and in May of this year 
four Europeans in Bathurst succumbed to it. In 1904 the late Dr. Dutton 
pointed out that Stegomyia fasciata was the mosquito most frequently met with 
in Bathurst, but this is not now the case, though, even in the dry season, numbers 
of this species are always present. At the end of April, while stationed in the 
Military Barracks at Bathurst, I caught several S. fasciata in that building, and 
it is noteworthy in this connection that two of the four Europeans who died of 
yellow fever were quartered in an adjoining building within the same enclosure. 
(c.) Sleeping Sickness is endemic in the Gambia. In 1901-2, two Europeans 
and six natives were found to be suffering from this disease and since then one 
other European contracted it in the Colony. In the spring of this year, 
Drs. Todd and Wolbach made an investigation of the sleeping sickness in the 
Gambia, and, after an examination of a very large number of natives, concluded 
that about 0°8 per cent. are probably affected with Trypanosoma gambiense. 
This is a fairly high percentage, and although there never have been regular 
epidemics, and the natives may have acquired some sort of immunity or resisting 
power, still the question of transmission to Europeans is too serious a factor to 
be lightly passed over. 
(d.) Animal Trypanosomiasis is also very prevalent; a large percentage of 
the cattle are infected, and the rate of mortality amongst horses is high. 
With these facts kept well in view, the importance of a fuller knowledge of 
the various species of blood-sucking flies, their distribution, habits, and life- 
history must take a high place in any economic consideration of the Colony. 
II]. GEOGRAPHY AND VEGETATION. 
The Colony and Protectorate of the Gambia is the most westerly and, at the 
same time, the most northerly of our West African possessions, being 
approximately in the same latitude as the north of Northern Nigeria. Its 
extreme limits north and south are approximately 13° 48’ N., and 13°4' N,, 
while 13° 46’ W., and 16° 50’ W. may be taken as its eastern and western limits. 
It is a long narrow strip of country on the banks of the river from which it takes 
its name, and lies practically east and west. At no part is it more than 30 
miles wide, while in some places it is only 15. Its total area is roughly about 
5,000 square miles. 
