PREFACE. 



THE belief that Insects act as the carriers of certain diseases has only 

 of late years been scientifically established. There is, however, at 

 the present time no disposition to underrate the practical importance 

 of an accurate knowledge of the blood-sucking forms. It is hoped 

 that the " Illustrations " now published may be of service to some 

 of those who are engaged in the conflict with disease in Africa, as 

 well as to others who are interested in the study of the Diptera. 



A scheme for the preparation of a Monograph dealing with blood- 

 sucking Insects in general was made by Sir E. Ray Lankester, K.C.B., 

 when Director of the Natural History Departments of the British 

 Museum. To wait until the Monograph could have been completed 

 would have been to delay unduly the publication of the information 

 which can now be given. The Diptera, or Two-winged Flies, are 

 not only wanting in the attractiveness of form and colour so 

 noticeable in the Lepidoptera for instance, but they are even 

 regarded with dislike by the majority of people These considera- 

 tions will account for some of the deficiencies in the collections 

 contained in our Museums ; and the preparation of a satisfactory 

 Monograph must accordingly be preceded by the accumulation of a 

 large amount of material for study. 



The Trustees therefore decided, on the suggestion of Mr. Charles 

 O. Waterhouse, Assistant Keeper in charge of the Insect Section, 

 to issue a series of volumes, from time to time, dealing with the 

 blood-sucking Diptera in the way that is found possible and 

 desirable at the moment. Four volumes of a Monograph of 

 Mosquitoes, by Mr. F. V. Theobald, have been issued, from 1901 

 to 1907 ; and a fifth volume of the same Monograph is in course of 

 preparation. The Tsetse-flies were described by Mr. E. E. Austen 



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