258 SCIENCE IN AFRICA 



means of naming insects. The importance of the British Museum 

 (Natural History), and similar museums in other countries, as 

 headquarters of taxonomic zoology has already been mentioned, 

 but the enormous variety of insects, of which some 7,500,000 species 

 are already known to science, creates difficulties peculiar to this 

 branch of the study. In Africa the insects of no single area are 

 well known, and indeed it is not known what insects are more or 

 less widely distributed. There is, moreover, except with regard to 

 a few groups of South African insects, such as the moths described 

 by Janse (1932-5), a serious lack of taxonomic monographs of a 

 type suitable for local use, so that research work is liable to con- 

 stant delays for reference to Europe. 



The Imperial Institute of Entomology, in collaboration with the 

 British Museum specialists, is performing an extremely important 

 function in the identification of insects and as a clearing-house 

 for information, but if reference works were available, it would be 

 relieved of much laborious work. 



Turning to the major insect pests, there are three principal 

 species of harmful locusts. These are commonly known as the 

 Desert locust, mainly in the north and east; the Migratory, mainly in 

 the west and east; and the Red, in the south-central and south. In 

 addition, some anxiety has been caused by another kind, the Brown 

 locust in South Africa. Locusts have probably caused more total 

 loss to Africa than any other factor, animal, vegetable, or mineral, 

 in their sudden and overwhelming incursions. The ravages of 

 locusts are, however, intermittent; when every green thing is eaten, 

 they have to move on, and even where breeding takes place, the 

 insects disappear after a time, persisting only in the few permanent 

 centres of dispersal in a different form and living quite a different 

 kind of life. The war against locusts consists, therefore, of a series 

 of intense but comparatively short battles, after which agricultural 

 activity again springs back into life. The intermittent character of 

 this pest may militate against the progress of research, since interest 

 in this work is naturally less when there is no immediate danger 

 from the insects. 



The war against tsetse ffies, of which twenty-one kinds are 

 known in Africa, eight being really important, is of an utterly 

 different nature. It is a gruelling continuous fight, during which 



