68 Key to Families of North American Insects. 



fly], Lucflia [Green-bottle fly] Cynom.'ia [Blue-bottle fly], Pollenia, Chry- 

 somyk [C. macellaria, Screw-worm]) (PL 13, figs. 302, 303, 304, 305). 



CALLIPHORIIXE 



Last posthumeral bristle placed in front or inside of the presutural bristle; 

 arista bare or hairy at the base .................................... 48 



48. Fifth ventral segment of the male with a straight hind margin, or entirely 



absent. (Sarcophaga, Pachyophthalmus, MetSpia.) . . . SARCOPHAGUS 

 Fifth ventral segment of the male split to the middle. (Phyto, Melanophora.) 



RHINOPHORIIXE 



49. No presutural intraalar bristle (PI. 12, fig. 303); second to fifth ventral seg- 



ments hidden; antennae usually at or below the middle of the eye, arista 

 usually hairy; legs often lengthened. (Ptilodexia, Theresia, Thelaira. 



Intraalars usually extending in front of the suture, if not the ventral segments 

 broadly visible or the fifth ventral of the male vestigial; antennae above the 

 middle of the eye, with a bare arista; at least two posthumeral and three 

 posterior intraalar bristles. (Tachina, Ocyptera, Exorista, Archytas, G&nia) 

 (PI. 11, fig. 253; PL 12, fig. 297) (Including EXORISTID^, MASICERID*:, 

 OCYPTERID^E, HiSTRiciiDiE and two score of other so-called families) (LAR- 

 VMVQRIDM) ........................................ TACHINnXE 



50. Either the hypopleural or pteropleural hairs or bristles present (PL 13, fig. 



303); basal bristles of the abdomen reduced; fourth vein bending or curving 

 forward; arista feathered to the tip. Musca [Af. domestica, Housefly], 

 Morellia, Graphomyia, Stomoxys [S. calcitrans, Stable-fly], Haematobia 

 [H. (Lyperosia) serrata, Horn-fly]) (PL 12, figs. 259, 296) ...... MtJSCIDJE 



Neither the hypopleural nor pteropleural hairs or bristles present; abdomen 

 usually bristly; fourth vein usually curving backward; arista sometimes bare. 

 (Ccen&sia, Aricia, Fannia (= Homalomyia), Muscina, Myiospila, Ph6rbia 

 [P. brassicce, Cabbage and Radish maggot; P. cepetorum, Onion maggot].) 



ANTHOMYIIDvE 



51. Auxiliary vein distinctly separate from the first vein and ending in the costa, 



the first vein usually ending near the middle of the wing; anal cell present, 52 



Auxiliary vein less distinct, sometimes partly touching the first vein or vestig- 



ial, the first vein usually ending much before the middle of the wing ..... 66 



52. Oral vibrissse present (PL 13, fig. 305); abdomen with more than four visible 



segments; eyes bare; wings rarely pictured .......................... 53 



Oral vibrissse absent ................................................. 57 



53. Costa beset with numerous spines; post vertical bristles convergent; tibiae with 



spurs and with preapical bristles. (Leria, Helomyza, Tephrochlamys.) 



HELOMYZID^ 



Costa not spinose, even at the auxiliary vein; postvertical bristles divergent 

 or (Phycodromia) subparallel ...................................... 54 



54. Front bristly on the sides and on the vertex ............................ 55 



Front never bristly near the antennae; abdomen somewhat elongate and usually 



narrower at the base; small, black scavenger flies. (Sepsis, Nem6poda.) 



SEPSHXfE 



