DIPTERA OF MINNESOTA. 



85 



other animal organisms. One form, according to Williston, lays its 

 eggs on the sand, and the larvae form conical pits therein for the pur- 

 pose of capturing other insects. Aldrich (1905) gives about 120 

 species as occurring in North America. The females of an exotic 

 species, Atherix ibis, lay their eggs in a common mass on a twig over 

 water, die as they do so, until, according to Sharp, the mass may in- 

 clude thousands of individuals ; ultimately it falls into the water. 



Minnesota species as far as collected by this department are : 

 Chrysopila quadrata, Say; C. fasciata, Say; C. oriiata, Say; C. 

 proxima, Walk. ; C. thoracica, Fab., shown in color as Fig. 4, Plate I, 

 and also in text ; Xylophagtis mHpes, Loew ; Atherix rariegata, Walk. ; 

 Coenomyia ferruginea, Scop., Colored Plate II, Fig. 2; Xylomyia 

 farciis, Will.; Leptis ochracea, Loew; L. pnnctipcnnis. Say; Leptis 

 mystacea, Macq., Fig. 17, Plate I, also shown in text. There are doubt- 

 less others not yet met with. 



ACROCERIDAE=CYRTIDAE, 



Small-headed Plies. 



The writer has not met with these flies in this state. They have 

 a strikingly small head, a prominent humped thorax, and a large 



Fig. 76 and 77. Ofsebius ptcrodonlinus, dorsal and side view. Lugger. 



abdomen. Some have very large proboscids, sometimes longer than 

 the body. These feed upon flowers, others take no food in the adult 



