SYNOPSIS OF NORTH AMERICAN SYRPHID^. 16& 



longitudinal vein strongly bent into the first posterior cell; anterior 

 cross-vein near the middle of discal cell, oblique. 



1. — Scutelluui of tbo same color as the thorax, abdomen without light markings, 

 wholly shining ; eyes bare (except on uppermost part) with small round 

 dark spots; dorsum of thorax in female distinctly vittate; arista bare, 



aeneus 

 Scutellum more or less yellowish or reddish ; eyes distinctly pilose, not so 



spotted ; 2 



2. Third segment of abdomen wholly shining, without opaque spots or bands . 3 



Third abdominal segment with opaque markings 6 



3._Third joint of antennie large, red; arista bare. Thinly pilose species; second 

 segment of abdomen with reddish side spots and a shining cross-band ; 



wings on the basal two-thirds in front brown compactus 



Third joint of antenna} of usual size; wings with or without brown ... 4 

 4. — Pile of eyes not confined to a vertical stripe ; the black of second abdominal seg- 

 ment, at least, in part opaque 17 



Pile of eyes mostly couiined to a vertical stripe ; abdomen wholly shining; large 



species ^ 



5._Honey-bee like in appearance ; moderately pilose ; base of tibiae yellowish, pos- 

 terior tarsi blackish ; arista nearly bare . . • tenax 



Humble-bee like in appearance ; thorax and abdomen with thick long pile (on 

 the dorsum of thorax sometimes blackish pilose, var. melanostornus) ; arista 



plumose, hind tarsi red flavipes 



6._Thorax with one or more distinct light dusted bands; front in female narrow 



above ' 



Thorax without such transverse bands H 



7,— Hind femora slender ; frontal triangle, and front below ( $ ), with black pile . 8 



Hind femora dilated or thickened 9 



8.— Arista bare ; yellow spots of second segment touching the front border in their 



whole extent atrimanus 



Arista briefly pilose; the opaque black extends nearly the whole width of the 



front border transversus 



9.— Third segment of abdomen with a shining cross-band ; dorsum of thorax, besides 



the front border, with two complete light cross-bands ; arista bare . lO 



The black of the third abdominal segment wholly opaque ; dorsum of thorax with 



one complete cross-band along the suture; frontal triangle thickly white 



pilose albiceps,? 



10.— Second abdominal segment broadly opaque black in the middle ; lower part of 



front not wholly white pilose albiceps 9 



Second abdominal segment narrowly black in the middle; pile of lower part of 



the front, or the frontal triangle, wholly white vinetorum 



11. — Thickly pilose species 1^ 



Moderately pilose species 12 



12.— Third abdominal segment with a posterior velvety black cross-band not inter- 

 rupted in the middle 13 



Third abdominal segment with an interrupted band, or none ..... 16 

 13. — Third segment of abdomen broadly and conspicuously yellow on the sides, join- 

 ing the yellow of the second segment, the black of the second segment 

 wholly opaque, not extending outwards on the sides behind ; the third seg- 

 ment with an opaque spot in front, and an abbreviated cross-band behind ; 

 fourth segment metallic; eyes briefly contiguous in male. . . . Brousi 

 Third segment not conspicuously yellow, the posterior opaque fascia of second 

 segment behind reaching toward the lateral margin ; eyes broadly contigu- 

 ous in male 1* 



