68 Key to Families of North American Insects. 



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

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



CALLIPHORID^ 



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 r/ 



absent. (Sarcophaga, Pachyophthalmus, Metopia.). • . SARCOPHAGID^ ^ 

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



RfflNOPHORID^ 



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. / 



DEXIID^ 

 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 bri.stles. (Tachina, Ocyptera, Exorista, Archytas, Gonia) 

 (PI. 11, fig. 253; PI. 12, fig. 297) (Including Exoristid.e, Masicerid^, 

 OcYPTERiD.E, H1STRICIID.E and two score of other so-called families) (LAR- 

 V^VORlDiE) TACHINm^ 



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



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

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

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



[H. {Lyperosia) serrata, Horn-fly]) (PI. 12, figs. 259, 296) MUSCID^ / 



Neither the hypopleural nor pteropleural hairs or bristles present; abdomen 

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

 (Ccenosia, Aricia, Fannia (= Homalomyia), Muscina, Myiospila, Phorbia 

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



ANTHOMYIID^ -'' 



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 (PI. 13, fig. 305); abdomen with more than four visible 



segments; eyes bare; wings rarely pictured 53 



Oral vibrissas absent 57 



53. Costa beset with numerous spines; postvertical bristles convergent; tibiae with 



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



HELOMYZIDiE ij 

 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, Nemopoda.) , / 



SEPSID^ '' 



