PREFACE. 



A PRACTICAL and detailed knowledge of Tsetse-flies is essential 

 for the material progress of a large part of Africa. How large 

 a part is affected by these formidable insect-pests may be 

 estimated by a glance at the Map which appears in this 

 " Handbook." 



In order to settle the grave questions which are connected 

 with the transmission of certain insect-borne diseases, it is not 

 sufficient to know that a given insect belongs to the genus 

 Glossina — or, in other words, is a Tsetse-fly — but, as indicated 

 by the author in his Introduction, it may be of vital importance 

 to know with certainty the species to which it belongs. 



The study of the Tsetse-flies was greatly advanced by the 

 appearance of Mr. Austen's " Monograph of the Tsetse-Flies," 

 which was published by order of the Trustees of the British 

 Museum in 1903. That work has been out of print for some 

 time, and moreover our knowledge of the genus Glossina has 

 considerably increased during the interval. The present " Hand- 

 book," by the same author, is an attempt to bring the subject 

 up to date ; and it is hoped that it has been drawn up in such 

 a way that, in addition to being a reliable contribution to 

 systematic literature, it will prove useful to medical officers and 

 others engaged in the struggle with disease in Africa. 



SIDNEY F. HARMER, 



Keeper of Zoology. 



British Museum (Natural History), 

 London, S.W. 

 March ISth, 1911. 



