NATURE 



241 



THURSDAY, DECEMBER 30, 1909. 



BLOOD-SUCKING FLIES. 

 Illustrations of African Blood-sucking Flics, other 

 than Mosquitoes and Tsetse-flies. By E. E. Austen. 

 With coloured figures by Grace Edwards. Pp. xv + 

 221; 13 plates; 3 text-figures. (London: British 

 Museum, Natural History, 1909.) Price i/. 7^. 6d. 



THE extraordinary progress that has been made of 

 recent years in the study of tropical medicine has 

 had the result of establishing clearly the general truth 

 that most of the diseases peculiar to the tropics, 

 whether of man or animals, are due to the effects of 

 parasites, microscopic or ultra-microscopic, introduced 

 into the system by the agency of blood-sucking inver- 

 tebrates. The intermediate host in such cases is 

 usually an arthropod, and most frequently a dipterous 

 insect. Not #nly has this mode of infection been 

 demonstrated beyond all possibility of reasonable 

 doubt, for such formidable scourges as malaria, yellow- 

 fever, sleeping sickness, and various diseases caused 

 by trypanosomes in animals, such as nagana- and 

 surra, but it is highly probable that many other 

 forms of disease, less thoroughly investigated at pre- 

 sent, originate in a similar manner. Moreover, as 

 in many other cases of parasitism throughout the 

 animal kingdom, a particular disease-producing para- 

 site may be transmitted from one vertebrate host to 

 another only by one restricted group, perhaps even 

 by a single species, of the blood-sucking invertebrates 

 concerned, while other forms may be incapable of 

 harbouring the parasite, or, to express the matter 

 more correctly, are capable of digesting the parasite 

 together with the blood, when taken up in the usual 

 course of feeding. 



For these reasons the study of the Diptera, or two- 

 winged flies, has assumed an importance which, 

 twenty years ago, could hardly have been foreseen 

 either by the scientific or the practical man, even in 

 the wildest flights of the imagination. At that epoch, 

 which seems very remote when considered from the 

 standpoint of present knowledge, none but professed 

 entomologists, and not many even of them, occupied 

 themselves with a group of insects unattractive or 

 even repulsive when compared with such popular 

 favourites as butterflies or beetles. Now, however, 

 the Diptera and other blood-sucking arthropods are 

 studied eagerly in all parts of the world, and not bv 

 specialists alone. The scientific knowledge of these 

 creatures, their habits and life-histories, has become 

 of immense importance from the economic and medi- 

 cal standpoint, and the distinction and recognition of 

 forms harmful or harmless, from the human point of 

 view, is a branch of study which has invaded even 

 the medical curriculum, at least in schools of tropical 

 medicine. The attention of the medical man is not 

 directed solely, however, to blood-sucking insects, 

 since it is becoming generally recognised that the 

 common flies which haunt our houses and crawl over 

 our food are also fruitful sources of disease. 



An Englishman may feel legitimate pride in the 

 NO. 2096, VOL. 82] 



lead taken by our national museum in this branch 

 of study. Under the auspices of the British Museum 

 of Natural History, and by the initiative and en- 

 couragement of its former director. Sir Ray Lankester, 

 a number of works on blood-sucking Diptera have 

 been published, works of the highest value both from 

 the scientific and the practical point of view. The 

 museum is especially fortunate in having the services 

 of the foremost authority on the Diptera, Mr. E. E. 

 Austen, whose monograph on the tsetse-flies is now 

 a classic, and recognised all over the world as the 

 standard work on these insects. 



In the present work Mr. Austen excludes the tsetse- 

 flies already dealt with by him, and the mosquitoes, 

 on which a monograph by Theobald is in progress, 

 and deals v^ith other African blood-sucking flies. He 

 aims at giving descriptions, figures, and general in- 

 formation such as will enable, not only experts, but 

 more especially travellers and medical men in Africa 

 to distinguish and identify the various forms already 

 known, and to collect more material for the study of 

 the Diptera, and so fill some of the many gaps in 

 our knowledge of this group. It is not possible to 

 praise the work more highly than by saying that it 

 comes up to the standard of former works by the 

 same author. Written with a view to the require- 

 ments of those who are not specialists, the book does 

 not contain cumbrous descriptions in technical 

 language, but relies chiefly on the excellent illustra- 

 tions. Every species of fly dealt with is figured in 

 colours at a scale of magnification indicated by 

 a line below the figure. The distinctive char- 

 acters of the families and genera are given 

 in plain language, together with brief accounts 

 of their habits, life-histories, and relations to disease, 

 so far as such facts are known at the present time. 

 The species are not described in detail, but where 

 necessary their distinctive features are pointed out, 

 and their distribution is given, with a list of the 

 localities whence the specimens in the museum have 

 been obtained. Finally, a list of the flies is given, 

 arranged under countries, so that anyone residing in 

 Africa or intending to travel there can see at once 

 what biting flies other than tsetses or mosquitoes are 

 known at present to occur in any particular region. 



This book fulfils admirably the purpose for which 

 it is intended, and will certainly be of the utmost 

 value to travellers and residents in Africa. It will 

 also stimulate the collection and study of these insect- 

 plagues, and will thereby contribute more than any 

 other cause to itself becoming out of date. It is to 

 be hoped that supplementary volumes will be pub- 

 lished as material accumulates and knowledge in- 

 creases. If so, the supplements will probably far 

 exceed in bulk the original work, in course of time. 

 The subject-matter of the work could only be criticised 

 by an expert, and is distinguished by erudition and 

 accuracy. The arrangement of the contents is clear 

 and time-saving, with a complete index. The illus- 

 trations are admirably executed and reproduced. If 

 we might offer a suggestion, it is that a national 

 achievement of such importance would have its value 



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