248 UNIVERSITY OF COLORADO STUDIES 



1. Hind margins pf abdominal segments black or blackish 2. 



Hind margins of abdominal segments not darkened 3. 



2. Hind margins very black; segments 4 and 5 each with two yellow spots (Bovdder, 



June, W. P. Ckll.) packardiella Ckll. 



Hind margins not very black; no yellow spots (Bovilder, April, fls. Pulsatilla) 



pulsatillae Ckll. 



3. Basal nervure arising far basad of transverso-medial; mandibles bidentate 



(Boulder, fls. Drymocallis) lepida Cresson9. 



Basal nervure arising little basad of transverso-medial; mandibles simple; abdo- 

 men distinctly punctate (Boulder) martinella Ckll.$ 



4. Scutellum black; tegulae yellow, hair of thorax above fox-red (Boulder, fls. 



Ribes) collinsiana Ckll.,J 



Scutellum red 5. 



Scutellum yellow; tegulae yellow; pleura with a large yellow mark; bands of 

 abdomen bright yellow; scape bright yellow (Boulder, June, W. P. Ckll.) 



omithica Ckll. 



Scutellum spotted 6. 



$. Face and antennae red; hair of thorax above red .... collinsiana Ckll.$ 

 Clypeus and sides of face yellow; antennae yellow beneath, flagellum above partly 

 black and partly reddish (Boulder, fls. Senecio, June, W. P. Ckll.) 



articulata dacotana Ckll. 



6. Tegulae bright red; antennae long, the flagellum black above and red beneath; 



male (Cheyenne Canyon, May, W. P. Ckll.) fragilis Cresson* 



Tegvdae yellow, with a pale or reddish spot 7. 



7. Abdominal bands cream-color; antennae yellow beneath . . martinella Ckll.<5 

 Abdominal bands bright yellow 8. 



8. Mandibles strongly bidentate lepida Cresson^ 



Mandibles simple; flagellum red beneath (Boulder, fls. Pulsatilla, May i, Marie 



Gill) subrutila Lovell & Ckll. 



Other species will doubtless be found. A^. uhleri, Ckll., N. coloradella Ckll., 

 and A'', alpha Ckll., were described from Fort Colhns; N. gillettei Ckll. and N. 

 agynia Ckll. from Golden. 'j^i 



EPEOLUS Latreille 



Anterior middle of mesothorax with two clean-cut club-shaped ochraceous stripes; 

 scutellum red (Boulder, fls. Townsendia grandiflora, July, W. P. Ckll.) 



intemiptus Robertson 

 Anterior middle of mesothorax washed with ochraceous, and with no clean-cut 

 stripes; scutellum black (near Florissant) beulahensis Ckll.* 



TREEPEOLUS Robertson 



Large, length over 13 mm.; legs black; upward extension of light band at sides of 

 second abdominal segment forming an angle with the band (within) of about 45° 



(Boulder, Aug. 26, 1906, Rohwer) martini (Ckll.) 



Much smaller; legs red i. 



