﻿120 PROCEEDINGS OF THE NATIONAL MUSEUM vol. lOo 



16, 1926, F. p. Ide (Ottawa). 9, reared from Xiphydria maculata 

 in Acer, Lemoyne, Pa., May 21, A. B. Champlain (Washington). 

 2 9, Hemmingford, Quebec, August 6, 1925, T. Armstrong (Ottawa). 

 cT, Montreal, Quebec, July 16, 1925, L. Daviault (Ottawa). 9, 

 locality illegible, July 5, 1910, M. C. Van Duzee (San Francisco). 

 This species occurs from Quebec south to Pennsylvania and west 

 to Michigan. It parasitizes Xiphydria in Acer. 



Subfamily Gasteruptiinae 



The gasteruptiines are usually collected on flowers, especially those 

 of Umbelliferae, or while in exploring flights around stumps, logs, and 

 posts in which hosts may nest. All are parasites in the nests of 

 Apoidea and Sphecoidea nesting in wood or in twigs. There are no 

 reports on biological observations in North America. 



The Nearctic species of the subfamily may be divided into two 

 groups that may as well be considered genera. One of these (Gas- 

 terwption) is rather small, compact, and mostly Holarctic in distri- 

 bution. The other {Rhydinojoenus) is a large genus of world-wide 

 distribution. In spite of its size and a considerable diversity in its 

 species, it is difficult to subdivide along natural lines. 



The descriptions and keys are based primarily on females, in which 

 the specific characters are usually more pronounced. But males too 

 are considered and take only a little more experience for accurate 

 determinations. Males have shorter and more sloping temples, 

 usually stronger mesoscutal sculpture, and usually the pale markings 

 more restricted than in females. In some species there is a tendency 

 for the mesoscutum of the males to be more polished than in females. 



The lengths of the propleura of various species offer good characters, 

 which are expressed in this paper as the length of the propleurum 

 divided by the width of the mesoscutum. The length of the pro- 

 pleurum is measured from the truncation at the articulation of the 

 front coxa to the apical flange just behind the head. These are the 

 most practical extremes for measurement, though they are not at 

 the true base and apex, and the resulting measurement does not give 

 the true total length. 



KEY TO THE NEARCTIC GENERA OF GASTERUPTIINAE 



1. Ovipositor sheath 0.35 to 0.5 as long as forewing; female subgenital plate with 

 a median, apical, broadly V-shaped notch; upper anterior margin of pronotum 

 with a forward-projecting tooth that is blunt, weak, or sometimes obsolete; 

 propleurum of Nearctic species (measured from coxal articulation to apical 



flange) about 0.77 to 0.90 as long as mesoscutum is wide Gasteruption 



Ovipositor sheath 0.8 to 2.5 as long as forewing ; female subgenital plate with a 

 median, apical, narrow slit-shaped notch; upper anterior margin of pronotum 

 with a forward-projecting tooth that is usually acute; propleurum of Nearctic 

 species (measured from coxal articulation to apical flange) about 0.9 to 1.8 

 as long as the mesoscutum is wide Rhydinofoenus 



