INTRODUCTION. 



Recent years have witnessed the publication of a large number of 

 works on the biology of various species of Glossina or Tsetse-flies, the 

 vectors of African typanosomiases. Indeed, in the domain of applied 

 entomology few subjects are attracting more attention, and many 

 specialists, especially in the British Colonies and Protectorates in 

 Africa, are concentrating their labours upon it. 



The literature dealing with Tsetse-flies is unfortunately scattered 

 through a large number of scientific technical journals, and anyone in 

 Tropical Africa who might wish to make investigations upon these 

 Diptera, would find it a very difficult matter to accumulate the necessary 

 papers. For this reason it seemed that it might perhaps be of some 

 service, particularly to government officials, to combine in one small 

 volume all the information that we have been able to collect with 

 regard to the species of the genus Glossina. A mass of memoirs 

 has been consulted with this end in view, and all facts elicited have 

 been condensed into a series of short chapters, while we have done 

 our best to render these as intelligible as possible. 



The chapter devoted to the distribution of Tsetse-flies in Belgian 

 Congo, although admittedly incomplete, will, it is hoped, be found to 

 contain sufficient information for the needs of English readers. 



We would ask those scientific men who have made a special study of 

 Tsetse-flies to be good enough to treat this little volume with indulgence, 

 in view of the fact that it has been compiled solely in order to popu- 

 larise the results of their labours, to point out the possible means 

 of conducting a campaign against Tsetse-flies, and to indicate the 

 investigations that need to be undertaken with this end in view. 



Our best thanks are due to Dr. G. A. K. Marshall, C.M.G., Director 

 of the Imperial Bureau of Entomology, for the skilled advice and 

 courteous assistance that he has given us. We likewise wish to express 

 our acknowledgments to the Trustees of the British Museum for 

 permitting us to reproduce a series of plates and figures with which 

 the following pages are illustrated. 



IMPORTANCE OF THE STUDY OF TSETSE-FLIES. 



At the present time the economic development of many parts of 

 Tropical Africa is impeded by two devastating diseases, human sleeping 

 sickness and the corresponding malady of domestic animals known as 

 Nagana. The first of these causes terrible ravages among native 

 populations, limiting the amount of labour available for agricultural 

 and commercial enterprises ; the second entirely prevents stock- 

 raising in important regions, and in some cases compels European 

 colonists to have recourse to mechanical assistance for transport 

 purposes and the operations of clearing and cultivation. 



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