52 Everett E. Wehr 



Xylota Meigen 



KEY TO THE SPECIES 



1. Legs wholly black; hind femora much thickened 2 



Legs not wholly black 3 



2. Wholly black; wings black chalybea 



Abdomen chiefly red ; the second segment with a basal black 

 triangle; wings nearly hyaline jngra 



3. Second and third abdominal segments (at least) red 4 



Second and third segments wholly black, or with yellow spots.... 5 



4. Abdomen wholly red except the first segment; hind coxae of the 

 male without a tooth below bicolor 



Abdomen except the first segment not wholly red ; hind coxae 



of male with a spur below flavitibia 



5. Abdomen long and slender, with two yellow spots on the second 

 segment angustiventris 



Abdomen not unusually slender 6 



6. Abdomen with two pairs of yellow spots 8 



Abdomen wholly black 7 



7. Arista luteous at base anthreas 



Arista wholly black obscura 



8. Hind femora much thickened, small species; arista yellow at the 

 base fraudulosa 



Hind femora moderately thickened 9 



9. Fourth abdominal segment brilliant bronze; third longitudinal 

 vein gently curved analis 



Fourth abdominal segment black; third vein quite straight ejuncida 



Xylota chalybea Wiedemann. Auss. Zweifl. Ins., ii, 98 (1828); Will- 

 iston, Synop. N. A. Syrph., 233 (1886); Townsend, Trans. Amer. 

 Ent. Soc, xxii, 53 (1895). 



A s taken at Omaha, Douglas County, June 11, 1913 (L. 

 L. Williams). 



158 



