i6o 



NORTH AMERICAN DIPTERA. 



The eggs of Atherix are depOvSited in dense masses at- 

 tached to dry branches overhanging water. Not only do 

 numerous females contribute to the formation of these 

 masses, but they remain there themselves and die. The 

 larvae hatching, escape into the water. The flies of spe- 

 cies of Vermileo deposit their eggs in sand, and the larvse 

 form conical pitfalls in which to ensnare small insects. 

 The tenth segment of these larvse bears above at its tip a 

 transverse row of long booklets directed backward, but 

 with the hooks bent forward; the eleventh segment has 

 a similar row directed for\vard, the hooks of which are 



Fig. 53. Leptidae. i, Ilihiriinorpha, wing; 2, Hilarimorpha, an- 

 tenna; 3, Coenomyia. wing; 4, Coenomyia, antenna; 5, Phenens, 

 antenna; 6, Chrysopila, wing; 7, Chrysopila, antenna; 8, Symphoro- 

 ntyia. head; 9, Atheri.v, antenna; 10, Ptiolina, antenna (Becker); 

 n, Spania, antenna (Becker); 12, Xylophagus, wing; 13, Xylofihagiis, 

 antenna; 14, Dialysis, tarsus; 15, Dialysis, antenna; 16, Glutops (type) 

 antenna (Burgess); 17, Xy/oinyia, antenna. 



