DIPTERA 



845 



This is a ven,- large family ; and representatives of it are common 

 everywhere in the United States and Canada. 



Family EMPIDID^ 

 The Dance-Flies 



The dance-flies are of medium or small size; they are often seen 

 in swarms flying with an up and down movement under trees or near 

 shrubs and over the surface of water. These flies are predacious, like 

 the robber-flies, but they also frequent flowers. The family is a 

 rather difficult one to characterize owing to great variations in the 

 form of the antennse and in the venation of the wings. 



The branches of vein Cu coalesce with the adjacent veins (vein 

 Cui with vein M3 and vein Cu2 with vein 2d A) from the margin of 

 the wing towards the base for a considerable distance (Fig. 1096). 

 In most genera this coalescence is carried so far that the free parts of 

 the branches of vein Cu appear like cross-veins. The only other 



Fig. 1096. — Wing of Rhamphomyia. 



families of the suborder Orthorrhapha in which this occurs are the 

 Dolichopodidce and the Lonchopteridce, and the venation of the 

 wings in each of these is very different from that of the Empididas. 



The antennas are three-jointed, the flrst and second segments are 

 often very small, and then appear like a single segment, the third 

 segment may or may not bear a style or an arista. The mouth -parts 

 are in many cases long, and extend at right angles to the body or are 

 bent back upon the breast. 



The larvce live in various situations, some in the ground or in 

 decaying wood, and some species are aquatic; they are believed to be 

 either predacious or scavengers. The pupaj are free. 



This family is a large one. It was monographed by Coquillett 

 ('96) and by Melander ('02). 



