tliat spread Disease. 27 



Tabanid flies are large flies, sometimes termed horse-flies or 

 mangrove-flies, widely represented in tropical, subtropical and 

 temperate parts of the world. Only the females suck blood. The 

 larvae of the flies are carnivorous, and live in water, wet sand or 

 mud, earth or decaying vegetable matter. 



In the table-case that stands at the entrance to Bay I are 

 shown examples of Chrysops diniidiata v. d. Wulp and Chrysops 

 silacca Austen, both of which are known to be instrumental in 

 the spread of the disease. Both species occur in West Africa, the 

 former ranging from Portuguese West Africa to Ashanti, the latter 

 through Southern and Northern Nigeria and the Belgian Congo. 



For comparison with the two foregoing species are shown 

 some tabanid flies that do not, or, at all events, are not definitely 

 known to disseminate disease, although certain of them are 

 suspected of spreading forms of trypanosomiasis among domestic 

 animals. In many parts of tropical Africa tabanid flies are 

 abundant at certain seasons, when owing to the bloodthirstiness 

 and pertinacity of the females, the insects become an intolerable 

 pest, both to man and to stock. The exhibited specimens belong 

 mainly to the genera Chrysops, Silvias, Panyonia, Tabanus, 

 ILtonatopota and Hippoccntrum, and in each case the range of 

 the species and any features of interest in their natural history 

 are mentioned. 



HOUSE-FLIES AND INTESTINAL 

 DISEASES. 



Many of the diseases broadly termed filth diseases are spread 

 by house-flies; some of them are skin-diseases, others are 

 diseases of the alimentary canal, such as enteric or typhoid 

 fever, cholera, dysentery and infantile summer diarrhoea. 

 House-flies are something more than disagreeable com- 

 panions and pertinacious nuisances of the hot weather; they 

 are dangerous by reason of their habit of settling upon food 

 and contaminating it with such disease germs as they may 

 happen to be carrying. In America the common house-fly has 

 been termed the typhoid-fly, an unfortunate expression implying 

 that typhoid fever is the principal, if not the only, disease that 



