Syrphidae of Nebraska 29 



Syrphus Fabricus. 



KEY TO THE SPECIES 



1. The three principal bands entire; the second and third ones not 

 reaching the lateral margin, face with a brown stripe amerxcanus 



The three principal bands interrupted 2 



First cross band interrupted; the others entire 5 



2. Abdominal spots of the third and fourth segments distinctly 

 arcuated 3 



Abdominal spots straight and transverse 4 



3. Abdominal spots of second and third segments truncate near an- 

 terior margin ; eyes pilose creper 



Abdominal spots of second and third segments rounded near 

 anterior margin ; eyes bare urcuatiis 



4. Fifth abdominal segment, at least, entirely red snoivi 



Fifth abdominal segment not red mentali^ 



5. Eyes pilose, not pubescent creper 



Eyes bare 6 



6. Abdominal spots of the second segment reaching the lateral 

 margin 7 



Abdominal spots of the second segment not reaching the lateral 

 margin 10 



7. Eyes pubescent torvus 



Eyes bare 8 



8. The cross-bands of the third and fourth segments reach the lat- 

 eral margin ribesii 



The cross-bands of the third and fourth segments do not reach 

 the lateral margin ^ 



9. Fifth abdominal segment, at least, red snowi 



Fifth abdominal segment not red opinator 



10. Face with a bi-own stripe americanus 



Face without brown stripe snowi 



135 



