HYMENOPTERA 963 



^i KEY TO THE TRIBES OF SPHECID^ OCCURRING 

 IN THE UNITED STATES 



A. Postscutellum with squamae which project backward, and base of propodeum 



with a median spine, p. 972 Oxybelini 



AA. Postscutellum and propodeum simple. 



B. Only I submarginal cell. Inner margins of eyes emarginate or strongly 

 converging toward the clypeus (except in Anacrabro, which may be recog- 

 nized by its flat venter). 



C. Inner margins of eyes entire, p. 971 Crabronini 



CC. Inner margins of eyes deeply emarginate. p. 965 Trypoxylonini 



BB. Usually 3 submarginal cells, sometimes two, rarely only one, in which case 

 the inner margins of the eyes are neither emarginate nor strongly convergent 

 toward the clypeus. 



C. Anal lobe large, reaching to opposite or beyond the apex of the cell 

 Mi + Cui + Cu. 

 D. The marginal cell not appendiculate. Abdomen with a cylindrical 



petiole. Middle tibias with two apical spurs, p. 966 Sphecini 



DD. The marginal cell appendiculate. Abdomen not petiolate. 



E. Ocelli normal. Middle tibias with two apical spurs, p. 964.. . . 



ASTATINI 



EE. Ocelli distorted. Middle tibiae with one apical sptir. p. 964. 



Larrini 



CC. Anal lobe small, not reaching to opposite the apex of the cell Mj + 

 Cui + Cu. 

 D. Ocelli normal, circular and convex. 



E. Antennae inserted low on the face, near the base of the eyes. 

 F. No epicnemium. 



G. First abdominal segment sessile or with a cylindrical petiole 

 which is composed only of the sternite. Middle tibiae with a 

 single apical spur. 

 H. An appendiculate cell present, or the mandibles with an 



external notch, usually both. p. 965 Dinetini 



HH. No appendiculate cell. Mandibles without an external 



notch, p. 968 Pemphredonini 



GG. First abdominal segment, petioliform, the petiole consisting 

 however of both sternite and tergite, nodose at apex. Middle 



tibiae with two apical spurs, p. 969 Melliniis in Nyssonini 



FF. An epicnemium present. Middle tibiae with two apical spurs. 



p. 969 Nyssonini 



EE. Antennas inserted near the middle of the face above the bases of 

 the eyes. 

 • F. Abdomen without a cylindrical petiole which is composed only of 

 the sternite. 



G. Transverse part of vein M distant from the stigma by less, 

 usually much less, than twice the distance between the apex 

 of the cell 2d Ri + R2 and the apex of the wing. Labrum rarely 

 exserted. 



H. Hind femora without a transversely expanded reniform 

 apical plate. 



I . Upper margin of clypeus extending across in a straight line 

 or arch, without a median lobe. Cell Rj usually small and 

 triangular, or if not, the middle tibiae have two apical spurs. 

 p. 969 Nyssonini 



II. Upper margin of clypeus with a median lobe extending up- 

 ward toward the antennae. Cell Rs four-sided. Middle 

 tibiae with one apical spur. p. 969 Philanthini 



HH. Hind femora broadened at apex, there forming a transverse 

 reniform plate, p. 969 Cercerini 



