AMERICAN HYMENOPTERA. 177 



Males. 



Ocelli in narrowest part of front, lateral one about one-half its diameter from 

 eye; malar space about one-third as long as wide; joint 3 = 5; seg- 

 ment 1 yellow, this color extending upon 2, usually on basal middle, 

 and inclining to reddish; mesonoturu yellow, disc often with black 

 hairs separatus. 



Ocelli below narrowest part of front, lateral one less than one-half its diameter 

 from eye; mesonotum yellow, with a transverse or rounded patch of 

 black hair 1. 



1. Joint 3 = 4 -\- 5 ; lateral ocellus almost touching eye; front above narrower 

 than space occupied by ocelli ; malar space about one-half as long as 

 wide; segments 1-3 yellow, rarely 4 also, 1 usually more or less black 



in the middle and in front auricomus. 



Joint 3 = 5; front above about equals space occupied by ocelli; malar space 

 transverse linear; segments 1-2 yellow scutellaris. 



IJOUISIS Latreille. 



Females. 



Vertex yellow ; mesonotum yellow 2. 



Vertex black; mesonotum with a yellow band in front; base of labrum with two 

 tubercles 1. 



1. Seutel and segments 1-4 yellow ; malar space a little longer than wide. 



pennsylvanicus (= fervidusi. 

 Scutel black, often mixed with yellow ; segments 2-3 yellow ; 1 yellow, mixed 

 with black on the lateral basal angles, or the entire basal portion 

 black, the apical margin always yellow, the yellow hairs more abund- 

 ant in the middle ; malar space about as long as wide. 



americanorum . 



2. Segment 1 yellow ; disc of mesonotum without black ; labrum with basal ridge 



forming a subquadrate sinus nearly reaching apical margin ; malar 



space shorter than wide virginicus. 



Segments 1-2 more or less yellow ; mesonotum with black hairs; base of lab- 

 rum with two tubercles ; malar space longer than wide 3. 



3. Segment 2 yellow on basal middle riding-sii. 



Segment 2 yellow, sometimes more or less black apically consimilis. 



Ma les. 



Hind tibia rather evenly clothed with short hair; antenna long, joint 5 nearly so 

 long as 3 -\- 4; vertex and band between the wings black ; segments 

 1-4 yellow ; 5-7 yellow, black or fulvous, or yellow with fulvous tip, 

 yellow with black tip, or black, with fulvous tip. • • -americanorum. 



Hind tibia with short sparse hair on outer face, posterior border with hair as lon^; 

 as diameter of the joint ; vertex, segment 1 and mesonotum yellow, 

 the latter usually with black hairs on the disc 1 



TRANS. AM. ENT. SOC. XXIX. (23) APKIL. 1903. 



