980 AN INTRODUCTION TO ENTOMOLOGY 



A KEY TO THE TRIBES OF SPHECID^ OCCURRING 

 IN THE UNITED STATES 



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



with a median spine, p. 989 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. 989 Crabronini 



CC. Inner margins of eyes deeply emarginate. p. 982 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 

 M3 + Cu, + Cu. 

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



petiole. Middle tibiae with two apical spurs, p. 983 Sphecini 



DD. The marginal cell appendiculate. Abdomen not petiolate. 



E. Ocelli normal. Middle tibiae with two apical spurs, p. 981 



ASTATINI 



EE. Ocelli distorted. Middle tibiae with one apical spur. p. 981 



Larrini 



CC. Anal lobe small, not reaching to opposite the apex of the cell M3 + 

 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 stemite. Middle tibiae with a 

 single apical spur. 

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



external notch, usually both. p. 982 Dinetini 



HH. No appendiculate cell. Mandibles without an external 



notch, p. 985 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. 986 Melliniis in Nyssonini 



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



p. 986 Nyssonini 



EE. Antennae 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 R5 usually small and 

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

 p. 986 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. 986 Philanthini 



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

 reniform plate, p. 986 Cercerini 



