382 AMERICAN HYMENOPTERA. 



Types. — Queen and worker from Colorado, in the collection 

 of the American Entomological Society; male (described 

 as B. frigidus by Cresson) in the same collection. 



Pile of medium length . Face bearing yellow pile ; occiput and dor- 

 sum, of thorax back to scutellum bearing a mixture of yellow and black 

 pile ; outlines of black interalar band somewhat indefinite ; scutellum. 

 yellow ; pleura yellow to bases of legs ; dorsum, of abdomen yellow at 

 base, black in m.iddle and yellowish-ferruginous at apex; corbicular 

 fringes more or less ferruginous ; m.alar space short. 



Queen. Head. — Triangular in outline; face and occiput bearing a 

 mixture of yellow and black pile ; sides behind eyes usually entirely 

 black. Labrum with very large tubercle-like areas, their slightly con- 

 caved summits smooth and the shelf-like projection between them very 

 small. Malar space shorter than its width at the apex, not more than 

 one-fifth as long as the eye. Clypeus almost entirely smooth, except at 

 the coarsely punctate corners. Flagellum of antennae scarcely twice as 

 long as scape ; third antennal segment distinctly longer than fifth, 

 fourth and fifth subequal. 



Thorax. — Anterior part of dorsum covered with yellow and black 

 pile mixed in varying proportions ; black interalar band wide, but 

 rather indefinite, there being considerable yellow mixed with the black 

 on the sides ; scutellum usually pure yellow, but often with a slight 

 admixture of black hairs ; the very center of the disc bare, smooth and 

 shining, and often surrounded by a small but noticeable amount of 

 ferruginous pile ; pleura covered with yellow to bases of legs ; sides of 

 median segment sometimes covered with yellow, sometimes with black 

 pile. 



Abdomen. — Dorsum : first segment covered with yellow pile ; second 

 segment with only the basal middle bearing yellow hair, the remainder 

 being black, or all degrees of variation from this to having this seg- 

 ment entirely covered with yellow ; third segment entirely black or 

 apical portion covered with deep ferruginous, or yellow-ferruginous 

 pile ; fourth segment sometimes black on anterior corners, but usually 

 entirely ferruginous ; fifth and sixth segments entirely yellow or yellow- 

 ish-ferruginous. Venter sparsely clothed with light pile. Hypopygium 

 without median carina. 



Wings. — Subhyaline, only slightly stained with brown ; fore wings 

 darkest on median and submedian cells, on anterior portion of radial 

 cell and in region beyond the veins. 



Legs. — Apices of coxae and trochanters bearing considerable light 

 pile ; femora sometimes entirely black, but usually bearing more or less 

 light pile, often nearly to their apices ; fore and middle tibiae black 

 on their inner sides, but usually with considerable ferruginous hair on 

 their outer sides ; fringes of corbiculae usually more or less strongly 

 ferruginous, rarely entirely black ; tarsi usually more reddish than 



