8i6 



THE DIPTERA 



with well-marked labial palps (labella). The wings have a large discoidal 

 cell and very elongate basal cells. When at rest the wings diverge at the 

 tips. They may be mottled. The legs are large and strong. The body is 

 brown, whitish, or yellowish in colour, but there may be markings on the 

 abdomen. 



Fig. 4o8.' — Antennae of the Tabanidje. 



a, a', a", Silvius; b, b', Chrysops; c, Rhinomyza; d, d' , Cadicera; e, Dorca- 

 loemus; /, Pangonia; g, Erephopsis; h, Lepidoselaga; i, i' , Tabanus; j, j' , 

 Haematopota; h, h', Hippocentrum. 



Life-History. — ^The eggs, which are spindle-shaped, and whitish 

 in colour, are laid in raft- or flask-shaped masses attached to 

 water-plants. The larvae live either in water or damp earth, and 

 feed upon small animal organisms. They are spindle-shaped and 

 segmented, with knobs or protuberances on the rings, either all 

 round or only ventrally. The pupa, which is free, is found in water 

 or damp rubbish. 



Fig. 409. — Larva of a Tabanus. (X2|^.) 



Pathogenicity.— It is possible that they may disseminate try- 

 panosomes. The diseases m'bori in dromedaries in Timbuktu and 

 souma in Segon are believed to be spread by Tabanus ditcBniatus, 

 while the dromedary disease of Algeria is spread by T. nemoralis 

 Meigen and T. nigritus Fabricius. T. glaucopis Meigen is infected 

 with Herpetomonas suhulata. According to Leiper, Chrysops is the 

 carrier of Loa loa Cobbold, 1864. 



