BIBIONIDJB. 39 



dilated in the male ; the last joint very small. Wings large 

 and broad, with distinct alulae, anterior veins thickened, the 

 others slender ; auxiliary vein terminating in the costa about 

 the middle of the wing; humeral cross- vein present; second 

 longitudinal vein wanting, the first and third lying close by 

 each other; the third arising from the first rectangularly be- 

 fore the end of the auxiliary vein ; anterior cross-vein very 

 short ; fourth vein curved, forked nearly opposite the anterior 

 cross-vein ; the forks terminating near the tip of the wing. 



The family Simuliidae, comprising about seventy-five known 

 species, is one of the best known popularly among diptera, on 

 account of the troublesome character of the flies, which are 

 scarcely less annoying than the true mosquito; they rarely 

 exceed five or six mm. in length, usually not more than three 

 or four, and will be immediately distinguished from the mos- 

 quito by their thick-set appearance, their shorter legs, their 

 shorter proboscis, and less slender antennae. In the southern 

 States they are known as "buffalo gnats" and '-'turkey gnats", 

 and sometimes occur in almost incredible numbers ; cattle 

 when attacked by large numbers are driven almost frantic, 

 and will seek to evade them by rolling in the dust, rushing 

 about, or going into the water. When the flies are numerous 

 they will almost literally cover the cattle, especially seeking 

 the openings of the body, entering the nostrils and the ears, 

 the margins of the eyes, where they will actually lie piled 

 upon each other. When very numerous they will produce an 

 inflammatory fever, frequently terminating in death. The 

 Avell known European species is S. columbaczense, which during 

 some seasons in the regions of the Danube costs the death of 

 many cattle. 



The larvae are very interesting creatures ; they are aquatic, 

 living most frequently in mountain streams, on stems of 

 plants, or stones, where they form for themselves elongated 

 cocoons, opened above. In the open end of these cocoons the 

 pupae ensconce themselves with the anterior part of the body 



