TahanidcB, or Horse-flies 



an active, carnivorous life, feeding mainly on insect larvas, and worms. 

 In the forms which have been best studied the larval life is a long 



one, lasting for months or even for more 



than a year. Until recently, little was 



known concerning the life-histories of this 



group, but the studies of Hart (1895), 



and Hine (1903 



+) have added 



greatly to the 



knowledge con- 

 cerning North 



American 



forms. 



Many of the 



species attack 



man with avid- 

 ity and are able 



to inflict painful 



bites, which 



may smart for 



hours. In some 



instances the 



wound is so 



considerable 



that blood will 



continue to flow 



after the fly has 



left. We have 



seen several 



cases of secondary infection following 



such bites. 



The horse-flies have been definitely 



convicted of transferring thetrypanosome 



of surra from diseased to healthy animals 

 and there is good evidence that they transfer anthrax. The possi- 

 bility of their being important agents in the conveyal of human 

 diseases shotild not be overlooked. Indeed, Leiper has recently 

 determined that a species of Chrysops transfers the blood parasite 

 Filaria diurna. 



80. (6) Larva of Tabanus. 

 Photograph by M. V. S. 



80. (o) Eggs of Tabanus. Photo 

 graph by J. T. Lloyd. 



