418 U. S. NATIONAL MUSEUM BULLETIN 216 



about 0.2 the length of the tergite; apicolateral angles of tergites 3-5 

 about 75° to 90°. 



Head black or blackish brown, the lateral 0.3 of face, side of frons, 

 and temple yellow; thorax black or blackish brown, often light brown 

 above, a spot on side of pronotum, subtegular ridge, scutellum, 

 postscutellum, subapical spot on mesopleurum, and lateral subapical 

 spot on propodeum, yellow; coxae blackish or the front coxa brown; 

 trochanters yellow or the first trochanter of middle and hind legs 

 more or less brown or blackish; front and middle legs beyond tro- 

 chanters yellow, the basal half of middle femur mostly brown or black- 

 ish; hind femur blackish, its base and apex yellow; hind tibia yellowish 

 brown, yellow basally and apically; hind tarsus yellow; abdomen 

 brown, the tergites usually darker medially, the first two tergites 

 with a median subapical yellow spot; wings uniformly tinged with 

 fulvous brown. 



Female: Front wing 13 to 29 mm. long; cheek about 1.3 as long as 

 apical width of mandible; median part of apical edge of first sternite 

 just in front of spiracle of first tergite; apicolateral angles of tergites 

 3-5 about 110°; fourth tergite mostly polished, with fine, moderately 

 dense punctures basally and near the ventral edge, the rest almost 

 impunctate; ovipositor sheath about 2.7 as long as front wing. 



Light reddish brown to blackish brown, the abdomen usually a 

 little paler than the thorax. Head, thorax, legs, and wings colored 

 as in the male except that dark markings on legs are a little more 

 extensive. Subtriangular median subapical spot on first and second 

 tergites, large round yellow spot on side of tergites 3-5, and vertical 

 yellow blotch on side of sixth and seventh tergites, yellow. 



This species is closely related to the European Megarhyssa superba 

 (Schrank). It has weakly differentiated eastern and western sub- 

 species, as keyed and described below: 



1. Mesoscutum usually entirely black, sometimes partly or entirely reddish 

 brown; general color of abdomen medium reddish brown to blackish brown; 

 range: western half of North America, in Canadian and colder part of 

 Transition zones, rarely in the East . . . la. nortoni nortoni (Cresson) 

 Mesoscutum reddish brown; general color of abdomen light to medium reddish 

 brown; range: eastern half of North America, in Canadian and colder part 

 of Transition zones lb. nortoni quebecensis (Provancher) 



la. Megarhyssa nortoni nortoni (Cresson) 



Figure 318,c 



Rhyssa nortoni Cresson, 1864, Proc. Ent. Soc. Philadelphia, vol. 3, p. 117; ? . 



Type: 9 , Colorado (Philadelphia). 

 Biology: Essig, 1926, Insects of western North America, pp. 795, 796. 



This is the western subspecies. It has the ground color generally 

 dark reddish brown or blackish, as noted in the key. 



