72 
BULLETIN 94. 
23. Labrum entirely light red; light markings primrose-yellow; 
wings clear, strongly clouded at apex. (Colo.).uhleri Ckll. 
Labrum yellowish-white. (Colo.).snowi Cress. 
Labrum blackish, or with a large black spot.24 
24. Light markings white; flies in spring. (N. M.).vierecki Ckll. 
Light markings yellow; fly in middle and late summer .25 
25. Ventral surface of abdomen with two light bands. (N. M.) crucis Ckll. 
Ventral surface of abdomen dark with only minute light 
marks (N. M.).neomexicana Ckll. 
26. Abdomen red, without light bands.27. 
Abdomen with light bands. .28. 
27. Flagellum clear red. (N. M., Colo.).mariinelia Ckll. 
Flagellum strongly dusky. (Colo., Mont.)-americana dacotana Ckll. 
28. Mesothorax reddish (here expect the unknown 9 of lamaranais Ckll.) 
Mesothorax black, with little if any red.29. 
29. Abdomen red with white bands .30. 
Not so, ground-color of abdomen mainly or wholly black.31. 
30. Mesothorax densely punctured. (Colo.). ..ridingsii Cress. 
Mesothorax with well-separated punctures on a shining 
ground. (N. M.).vierecki Ckll. var. 
31. Lateral face-markings white or yellowish white.32. 
Lateral face-markings yellow. 33. 
32. Mesothorax densely punctured (Colo.).snowi Cress. 
Mesothorax sparcely punctured on a shining ground (N. 
M.) .vierecki Ckll. 
33. Mesothorax with well separated punctures on a shining 
ground; ground color of first abdominal segment red 
(Colo.).vegana nitescens Ckll. 
Mesothorax densely punctured.34. 
34. Metathorax with yellow spots (Colo., N. M.).vegana Ckll. 
Metathorax without yellow spots (N. M.) .neomexioana Ckll. 
35. Abdomen with numerous entire (or some slightly interrupted) 
light bands.36. 
Abdomen with light bands, more or less widely interrupted, 
at least on some of the segments.59. 
Abdomen red, with small yellow spots (sometimes bands on 
apical segments) or no light markings. 66. 
36. Abdominal bands white or yellowish-white; no light mark¬ 
ings on head or thorax; venter of abdomen ferruginous, 
immaculate.37. 
Abdominal bands yellow.38. 
37. Scutellum strongly bilobate; wings paler (Colo.).paraia Cress. 
Scutellum not strongly bilobate; wings darker (Colo.), .tminda Cress. 
38. Legs yellow and black, without very much red.39. 
Legs wholly or mainly red, or red and yellow. 40. 
39. Smaller; third antennal joint shorter than fourth on the un¬ 
der (light) side (Colo.).civilis Cress. 
Larger; third antennal joint longer than fourth on the under 
side (N. M.).peccsensis (Ckll.) 
40. First abdominal segment without yellow; rfs .41. 
First abdominal segment with yellow.43. 
41. First abdominal segment black;scutellum black(N.M.)ruidosensis Ckll. 
First abdominal segment red and black. 42. 
42. Size larger, scutellum red (Colo.).eoloradensis Ckll. 
Size small, scutellum black with small light spots (Colo.) 
.coloradella Ckll. 
43. First abdominal segment black and red, with a yellow spot 
on each extreme lateral margin; flagellum stout, third an¬ 
tennal joint shorter than fourth; basal nervure basad of 
transverse-medial.44. 
First abdominal segment with a yellow band, entire or inter¬ 
rupted .45. 
