DIPTEEA. 



Fin-. : 



however, that in its larval state the horse-fly is useful to man, 

 as it feeds on snails and probably the larva' of other root- 

 eating insects. The larva; of other species are aquatic, living 

 under submerged objects. Walsh describes 

 a greenish transparent larva which is cylin- 

 drical, twelve-jointed, the body being most 

 slender towards the head, which is small. 

 truncate, conical, the anterior part capable 

 of extension, with short, fleshy, exarticulate 

 antenna 1 and without ocelli. There are six 

 pairs of dorsal fleshy tubercles. On the un- 

 der side of the abdominal segments are six 

 retractile false legs, and a single anal retractile proleg. It 

 is, when disturbed, vigorous and restless, swimming quickly, 

 often elevating the anal slit, in which the stigmata are probably 

 placed, out of the water to take in the air. The pupa is cylin- 

 drical, obtuse at the head, tapering a little posteriorly, and is 



of a pale yellowish brown. There are six 

 tubercles at the mouth, above which are 

 the trigonate three or four-jointed antenna'. 

 The abdominal segments are furnished with 

 a ring of appressed bristles directed buck- 

 wards, and the anal spine is large, trun- 

 cated, and terminates in six small, stout spines. T. (itrnfii.-i 

 Fabr. is a common species ; it is black, covered with a whitish 

 bloom, and expands nearly two inches, while the Tabanus chtc/n.-i 

 Fabr., or Orange-belted horse-fly, is smaller and less abundant. 

 Of the smaller species the Talxnnix liiirultt Fabr. (Fig. 315) 

 is so named from the whitish line along the abdomen. This 

 fly is our most common species, thousands of them ap- 

 pearing during the hotter parts of the summer, when the sun 

 is shining on our marshes and Western prairies ; horses and 

 cattle are sometimes worried to death by their harassing bites. 

 In cloudy weather they do not fly and they perish on the cool 

 frosty nights of September. 



Fur. 



Meigen. This family is easily distinguished from 

 the preceding by the simple third joint of the antenna, which 

 are provided with a simple or thickened styliform bristle. 



