8l2 



THE DIPTERA 



mistakes have been made with regard to the blood-thirsty pro- 

 pensities of some species, and it is possible that the real culprit 

 was one of the Ceratopogoninse, and therefore it is necessary to be 

 quite certain that the insect in question is really a Simulium, and 

 this can only be done by careful examination. For purpose of 

 quick field examination, it is as well to inspect the antennse care- 

 fully, as they are fairly characteristic. 



Enemies.— The Simuliidce have many enemies, among which 

 may be mentioned the larvse of the May- and that of the Caddis-fly, 

 and many kinds of fish which prey upon the larvae, pupae, or flies. 



Fig. 405. — Simulium Larva. Fig. 406. — Simulium Pupa. 



(X8.) (X8.) 



Classification. — ^The genus has been divided into two subgenera 

 by Roubaud — i.e.,Prosintulium and Eusimulhm, but the differenti- 

 ation of the species is very difficult. In fact, the family urgently 

 requires revision. 



Pathogenicity. — ^Although sand-flies are very irritating, and cause 

 the death of cattle, it is not known whether they are the carriers of 

 any definite disease of cattle or man, though it seems ! possible 

 that they may be associated with the spread of pellagra, as Sambon 



