CHAPTER III. 



Family SIMULIID^]. 



PLATE I., FIGS. 5-8. 

 This family consists of the single genus Simulium. 



Genus SIMULIUM, Latreille. 



Histoire Naturelle, Generale et Particuliere, des Oustaces et des 

 Insectes, T. III., p. 426 (1802-03). 



(Sometimes called " Sand-flies.") 

 PLATE I., FIGS. 5-8. 



At the present time the genus Simulium, which is represented in 

 all parts of the world, includes some eighty recognised species, of 

 which not more than five or six are known to occur in Africa, 

 though no doubt a certain number of new species have still to be 

 discovered. In appearance these insects are small black or greyish* 

 flies, varying in length in the case of the African species at present 

 described from 1.5 to 2.5 mm., with a conspicuously humped thorax, 

 short, straight antennae, short, bent, four-jointed palpi, broad, 

 delicate, iridescent wings, and moderately stout legs. The proboscis 

 is short, projects vertically beneath the head, and is not visible 

 from above. In the male the eyes appear to occupy the whole of 

 the head, and meet in the middle line above ; in the female they 

 are smaller and separate. The thorax and abdomen are frequently 

 clothed with short, close-lying, greyish or shining silvery or golden 

 hair, which, as on the sides of the dorsum of the abdomen of 

 Simulium wellmanni, Roubaud (Plate I., fig. 7), sometimes forms 

 conspicuous patches. In the case of captured specimens, unless 



* In Simulium perflavum, Roubaud, which occurs in Brazil, the body is 

 ochraceous, but such a coloration is highly exceptional. 



