408 AMERICAN HYMENOPTERA. 



width at the apex, about one-fourth as long as the eye. Clypeus 

 rather coarsely punctate, but somewhat smooth on the very middle 

 portion. Flagellum of antenna about twice as long as the scape ; 

 third antennal segment much longer than fifth, the fifth longer than 

 the fourth. 



Thorax. — Dorsum covered with yellow pile, except for a broad black 

 interalar band, the yellow on the front part extending down on the 

 sides to slightly below the level of the bases of the wings ; the very center 

 of the disc bare of pile as usual. Pleura black. Sides of the median 

 segment black. The extreme sides of the metanotum very often with 

 yellow pile (just behind the bases of the hind wings). 



Abdomen. — First three segments of the dorsum yellow, the rest black. 

 Venter black. 



Wings. — Very dark, with slight violaceous reflections ; the fore pair 

 darkest on their basal portion and about the apex of the radial cell 

 and usually lightest in the region beyond the veins. 



Legs. — Black and with black corbicular fringes. 



Worker. — Much like the queen, but usually with somewhat lighter 

 wings ; the fore pair often lightest across their middle portions. 



Male. Head. — Mostly dark, but usually with an admixture of whit- 

 ish hairs (noticeable under a lens) above and below the bases of the 

 antennae and over the clypeus and occasionally on the occiput and on 

 the cheeks. Malar space somewhat longer than its width at apex, 

 about one-fourth as long as the eye. Clypeus mostly covered up with 

 pile. Flagellum of antenna about four times as long as the scape, 

 its segments, except the basal ones, usually appearing somewhat arcu- 

 ate when viewed laterally, much as \xi B . pennsylvanicus (fig. 17); fifth 

 antennal segment much longer than the third, the third and fourth 

 segments subequal in length. 



Thorax. — Coloration of pile much like that of females. 



Abdotnen. — Dorsum with the first four segments covered with yellow 

 pile and the last three entirely black. Venter black. 



Gejiitalia. — Outer spatha (fig. 32) with anterior margin broadly and 

 evenly incurved ; the posterior and lateral margins broadly and evenly 

 outcurved, sometimes nearly straight ; the sides of the ventral surface, 

 somewhat behind the middle, bearing rather long scattered hairs. 

 Inner spatha (fig. 32) with the sides of the anterior margin slightly 

 incurved and bent backward slightly ; the side margins straight and 

 converging rapidly to the anterior end of the quadrate apical por- 

 tion ; the hind margin of the apical portion sharply indented so as 

 to form an acute lobe on each side ; a very long narrow fenestra 

 present, often running from somewhat behind the center of the spatha 

 nearly to its apical margin ; ventral surface with considerable rather 

 long hair on the apical lobes and along the apical margin between 

 them. Claspers and sagittse not separable by any noticeable character 

 from those of B. pennsylvanicus (figs. 66 and 70). 



