BIBIONID^. 



391 



wanting, while the posterior tibise, and first joint of the hind 

 tarsi are dilated. The body is short and thick. The labrum 

 is free, sharp as a dagger, and the proboscis is well 

 developed and draws blood profusely. The species 

 are numerous. The Black-fly, so well known as 

 the torment of travellers in the North, is black, 

 with a broad silvery ring on 

 the legs. We have received a 

 large species from Mr. E. T. 

 Cox, called in the West the 

 Buflalo fly. On the prairies 

 of Illinois it has been known 

 to plague horses to death by 

 its bite. The S. (Rhagio) 

 Columbaschense Fabr. in Hungary abounds in im- 

 mense numbers, often killing cattle. Other species 

 abound in the American tropics where they are a 

 great scourge. The cj'lindrical larva of the Euro- 

 pean species is furnished with short antennse and two flabelli- 

 form appendages. On the nnder side of the prothorax is a 

 thick conical and retractile tubercle, and there are several 

 curved filaments at the end of the body. The pupa has eight 

 very long lateral filaments on the front of the thorax, and the 

 posterior end of the body is enclosed in a semioval membra- 

 nous cocoon, open in front, and posteriorly attached to some 

 plant. The fly leaves the pupa beneath the water. 



Fig. 312, a. 



BiBiONiD^ Macquart. This group is characterized by hav- 

 ing three ocelli and the prothorax much developed ; the wings 

 have no discal cell. The coxse are not prolonged and the em- 

 podium (supplementary cushion) is proportionally long, while 

 the pulvilli are sometimes wanting. The typical genus, Bibio 

 of Geoffi'oy, has short, nine-jointed antennae, five-jointed palpi, 

 and the eyes of the male are large and contiguous, while those 

 of the females are small. The larvae are cylindrical, footless, 

 with ten spiracles, and furnished with transverse rows of short 

 hairs, being found in dung, but they mostly feed on the roots 

 of grass, whole patches of larvae appearing as if winter-killed. 

 Robins destroy immense numbers of them. Westwood has 



