BEES OF BOULDER COUNTY, COLORADO 257 



BOMBUS LatreiUe 



Abdomen with a very conspicuous red band i. 



Abdomen without such a band 6. 



1. The red band subapical, with a broad black band before it, and the base of the 

 abdomen broadly pale (Arapahoe Peak, above timber-line, Aug. 31, 1906, W. P. 

 Ckll.; Eldora, fls. Delphinium, Sept. i, 1906, S. A. Rohwer) . frigidus Smith 

 (Titus records frigidus from Ward as oregonensis. He also reports B. couperi 

 Cresson, and B. piUnami Cresson, from Ward. These are similar in most respects 

 to frigidus. I examined the types in the Cresson collection, and noted as follows: 

 "B. putnami and couperi are very similar, with fulvous pubescence, broad black 

 thoracic band, and very broad black abdominal band, occupying the third and 

 fourth segments. B. putnami is the larger.") 



The red band occupying the third and fourth segments, with no black band before 



it 2. 



The red band occupying the second and third segments, with a yellow or yellowish 

 band following it 4. 



2. Abdomen beyond the red band with yellow hair; only a little black, on apex of 

 sixth segment (Eldora, fls. Gaillardia, Aug. 31, Rohwer) . rufocinctus Cresson^ 

 Abdomen beyond the red with black hair 3. 



3. Yellow hair of thorax above without black intermixed (Boulder) juxtus Cresson 

 Yellow hair of thorax above with much black intermixed (Ward, cf . Titus ; Eldora, 

 fls. Gaillardia, Aug. 31, Rohwer, Arapahoe Peak, above timber-line, Aug. 31, 

 W. P. Ckll.) flavifrons Cresson 



4. Yellow of scutellum and first abdominal segment divided into two spots; form 

 compact (Ward, cf. Titus; Boxilder, April and May, Rohwer) . bifarius Cresson 

 Yellow of scutellum not divided 5- 



5. Abdomen more elongate, face with ftilvous hair (Ward, cf. Titus; Boulder, August 



etc. W. P. Ckll, Rohwer) huntii Greene 



Abdomen heart-shaped, face with black hair, a little pale intermixed (Ward, fls. 



Phacelia) rufocinctus phaceliae (Ckll.) 



(In recent years, the validity of B. bifarius has been questioned, but it is evidently 

 a perfectly good species. I follow Mr. Franklin in treating iridis, phacfilice and 

 astragali as varieties of rufocinctus. He has accumulated a large amount of infor- 

 mation on this group, which he will shortly pubhsh. Mr. Titus has recorded B. 

 sylvicola Kirby, and B. mixtus Cresson, from Ward; I have not met with them 

 in Boulder County. B. sylvicola was originally described from Lat. 65° N.; the 

 abdomen is yellow with a broad median red band; the apex is, I beUeve, not black, 

 in which case there must be some doubt about the sylvicola of Mr. Titus' table 

 (Canad. Ent., 1902, p. 39). B. mixtus was described from Colorado; it has the 

 black band between the vdngs ill-defined.) 



6. Thorax black, with the anterior part broadly fulvous-haired; abdomen fulvous with 

 the apex broadly black; large species (Boulder, G. Weston, at sunflower, Aug. 7, 

 W. P. Ckll.; at Melilotus alba, Sept. 27, Rohwer) . . americanortim Fabricius 

 (B. americanorum is said by Mr. Franklin to be the same as pennsylvanicus, but 

 there is much confusion about the latter; Robertson holds it to be fervidus, while 

 Pierce has given auricomus as pennsylvanicus.) 



