Syrphidae of Nebraska 41 



by dense, straight {H. similis, latifrons) or branched (H. conosto- 

 mus, laetus, chrysostonms, integer) cilia Helophiliis 



Stigmatical cross-vein present 3 



3. Less pilose; eyes of male broadly separated; in the male hind 

 coxae, hind femora, and tip of hind tibiae provided with spurs or 

 protuberances; abdomen of male narrowed posteriorly (Tri- 

 odontia) Polydontomyia 



More pilose; eyes of male contiguous; in the male hind coxae, 

 hind femora, and tip of hind tibiae not provided with spurs or 

 protuberances; abdomen of male not narrowed posteriorly. ...Ma//ofrt 



Eristalis Latreille 



KEY TO THE SPECIES 



1. Eyes bare with small round dark spots; dorsum of thorax in fe- 

 male distinctly vittate; abdomen without light markings aeneus 



Eyes pilose 2 



2. Thorax with transverse bands; front in female narrowed above 

 transversus 



Thorax without such bands 3 



3. Mesonotum with four opaque black stripes, the median pair in 



the shape of a tuning fork furcatiis 



Mesonotum not so marked 4 



4. Third segement of abdomen wholly shining, without opaque spots 

 or bands (opaque spots in $ latifrons, opaque bands in $ 

 nitidus) 5 



Third abdominal segment with opaque markings 7 



5. Pile of eyes not confined to a vertical stripe; the black of second 

 abdominal segment, at least in part, opaque (except 5 lati- 

 frons) 11 



Pile of eyes mostly confined to a vertical stripe; the abdomen 

 wholly shining; large species 6 



6. Honey-bee like in appearance; moderately pilose; base of tibiae 

 yellowish, posterior tarsi blackish; arista nearly bare tenax 



147 



