66 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.52. 



a pair of discal marks on same, spot on tegulae, another on base of 

 anterior wing, pair of lateral spots on scutellum, pair of spots on 

 metanotum, occasionally a curved line on dorsal surface of median 

 segment, lateral angles of same, one or two spots on mesopleura, 

 fasciae on tergites 1-4 interrupted and narrowed medially, lateral 

 spots on sternites 2-3, spot on anterior coxae below, stripe on lower 

 surface of femora less extensive on posterior pair, tibiae, and tarsi, 

 yellow; wings as in the male; apical tergite densely punctured later- 

 ally, more sparingly along the midline, lateral ridges short and feebly 

 developed, pygidial area lacking; apical sternite with faint longitu- 

 dinal median carina. 



Length. — 12-14 mm. 



This is one of our largest and most easily recognized species. The 

 ground color is decidedly black and shows a marked bluish irides- 

 cence. The color of the markings is pale or creamy yellow, sometimes 

 tinged with orange, more rarely faintly greenish. The yellow of head, 

 thorax, and legs is usually deeper than that of the abdomen. The 

 scape of the antenna is always yellow below and the flagellum is 

 always black, save that the apical joint in some females shows a trace 

 of reddish. The flagellar segments of the male are not rounded out 

 or prominent below, but joints 6-10 have flattened specialized areas 

 beneath, most conspicuous on 6 and 7. The marking of the labrum 

 varies greatly; on the female it is usually yellow with the lateral 

 margins piceous, but in a few specimens it is entirely yellow and in 

 about as many it is wholly black. In the male the labrum is usually 

 black, but in some individuals only the lateral borders are black, and 

 in a few it is entirely yellow. The clypeus is marked basally with 

 a black spot that varies in size in both sexes and is usually more 

 extensive in the male than in the female, but in all cases there is 

 always more or less yellow on the apical border. 



The line on the posterior border of the pronotum may be wanting, 

 may be represented by two or more spots, or may be broad and con- 

 spicuous. The scutum may be immaculate, may have a small spot 

 on each lateral margin, which in some cases takes the form of a rather 

 broad lateral stripe, and in some specimens may bear a pair of short 

 discal lines or spots. In specimens on which the markings are best 

 developed a pair of lateral spots occurs on both scutellum and meta- 

 notum, and in extreme cases there is a more or less well developed 

 curved line on the dorsal surface of the median segment. In such 

 specimens the small spots on the mesopleura form one large conflu- 

 ent area, and a smaller spot may be present on the metapleura. All 

 coxae may be more or less spotted with yellow. The color of the 

 fasciae and spots on the tergites, together with their arrangement 

 are the characters that best distinguish this species. The fasciae are 

 broad at the sides and narrowed toward the median line, where they 



