DIPTERA 



821 



The larvae vary in habits; some species feed on decaying matter, 

 while others attack the roots of growing plants, especially of grass. 



MiJr'i 



Fig. 1041. — Wing of Bibio. 



They have ten pairs of spiracles, which is a rather large niimber, al- 

 though there are other insects with as many. The pupae are usually 

 free. 



For descriptions of our species of bibionid flies see McAfee ('21). 



Family SCATOPSID^E 



This family includes minute black flies ; our known species measure 

 in length from less than one miUimeter to three millimeters. Formerly 

 these flies were included in the Bibionidee; but they differ markedly 

 in the venation of their wings from members of that family. In the 

 Scatopsidce vein Cu forks 

 at or very near the base J?i 



of the wing (Fig. 1042) 

 and the cross-vein m-cu 

 is wanting. In some 

 species there is a vestige 

 of an anal vein but 

 usually there is none. 



This is a small family, 

 only about a score of 

 species are known from 

 our fauna; these are de- 

 scribed by Melander (' 16) . 



Most of the known larvae live in excrement. One species, Cobol- 

 dia formicdrium, is believed to be myrmecophilous, for the adult was 

 taken as it crawled from a populous nest of the carpenter ant. In 

 this species the wings are vestigial. 



Family SIMULIIDAE 

 The Black-Flies 



The common name, black-flies given to the members of this family 

 is not distinctive, for there are many species of other families that are 

 of this color; but like many other names that are descriptive in form, 



Fig. 1042. — Wing of Reichertella collaris. 

 Melander.) 



(After 



