BEES OF BOULDER COUNTY, COLORADO 245 



Flagellum dark (Boulder, fls. Drymocallis, May 24) . fragariana, Grsenicher 



14. Hair-bands of abdomen very conspicuous 15. 



Hair-bands feeble or wanting 17. 



15. Larger, about II J mm. long; hair of thorax very yellow (Ft.CoUins) . 



mentzelise Ckll.* 

 Smaller, hair of thorax not thus yellow i6. 



16. Punctures of abdomen stronger and closer; flagellum dark (Boulder, fls. Pul- 

 satilla, April, Marie Gill) bridwelli Ckll. 



Punctures of abdomen weaker and less close; flagellum largely bright red beneath 

 (Boulder, June, W. P. Ckll.) gardineri CkU. 



17. Mesothorax with few, widely scattered, strong punctures (Boulder, May 21, G. 



Hite) nuda Robertson 



Mesothorax not so 18. 



18. Stigma very small; large species visiting sunflowers in August (Boulder, W. P. 



Ckll.) helianthi Robertson 



Stigma normal 19. 



19. Abdomen with long erect grayish-white hair, not hiding the surface; hair of pleura 



white (Boulder, fls. Salix, H. House) cockerelli Grsenicher 



Abdomen without such hair 20. 



20. Hair of pleura black; abdomen beyond second segment with coarse black hair; 

 first two segments and thorax above with whitish hair (Ward, July, fis. Edwinid) 



edwiniae Ckll. 

 Hair of pleura black; abdomen beyond second segment vnXh black hair; first 

 two segments with very scanty dark hair; thorax above with bright fox-red hair. 



(Boulder, June, fls. Lupinus) lupinorum Ckll. 



Hair of pleura at least mostly black; abdomen shining black, with scanty black 

 hair; thorax above with pale ochraceous hair (Boulder, fls. Pulsalilla hirsutissima, 



April, E. Bethel) carlini Ckll. 



Hair of pleura light 21. 



2 1 . Area of metathorax coarsely sculptured; abdomen strongly though finely punctured; 

 hair at apex of abdomen red (Boulder, S. A. Rohwer) . . crataegi Robertson 

 Area of metathorax granular, or feebly plicatulate toward base . . 22. 



22. Hair at apex of abdomen black or sooty, of thorax above whitish or ochraceous. 



23- 

 Hair at apex of abdomen red 24. 



23. Much larger, anterior wing about 10 mm., abdomen black without con- 

 spicuous hair (Castle Rock, Boulder Canyon, May, S. A. Rohwer) . . vicina Smith 

 Much smaller; first abdominal segment with some conspicuous hght hair; vertex 

 with black hair (Ward, fls. Cilia and Drymocallis) birtwelli Ckll. 



24. Hair of thorax above orange-fulvous, bright on scutellum (Boulder, fls. Rubus 



deliciosus, May 22, Ckll.) vibumella Grasnicher 



Smaller; hair of thorax above gray, of apex of abdomen very bright red (Boulder, 

 W. P. Ckll.) pyrura Ckll. 



25. Tegument of abdomen partly red; clypeus yellow with two black dots 



prunorum gillettei Ckll. 

 Tegument of abdomen not red 26. 



