No. 22.] HYMENOPTERA OF CONNECTICUT. 669 



S. (H.) decemmaculatus Say. 



This species is known to prey on horse-flies. It has been 

 taken at New Haven, 26 July, 1902 (E. J. S. M.). 



S. (H.) chrysargynus LePeletier. Howard, Insect Book. 

 PI. iv, Fig. 19. 



Short Beach, 14 July, 1904 (P. L. B.). 



Crabro Fabricius. 

 In 1810 Latreille fixed, as the type of the genus Crabro, Sphex 

 cribraria Linnaeus. Ashmead in 1898, while tabulating the genera 

 of Crabroninae, overlooked this fixation by Latreille, and chose the 

 same species as the type of Thyreopus. This causes the group 

 which Ashmead called Thyreopinae to become Crabroninae, and 

 the genus Thyreopus must fall as a synonym of Crabro. 



Key to Subgenera. 



1. Ocelli arranged in an obtuse triangle; abdome marked with 



yellow '. 2 



Ocelli arranged in or nearly in an equilateral triangle; ab- 

 domen black 3 



2. Anterior margin of clypeus with a large quadrate projection; 



first recurrent vein received before apical third of first 

 cubital cell; antennae of male simple, not dilated; fore 



tarsi of male without appendages Synothyreopus p. 669 



Anterior margin of clypeus without a projection; first re- 

 current vein received at or beyond apical third of first 

 cubital cell; antennae of male dilated; fore tarsi of male 

 with an appendage Crabro p. 670 



3. Supraorbital foveae sharply defined; propodeum without a 



well defined circular area; pygidium narrow, foveated 



Blepharipus p. 671 

 Supraorbital foveae obsolete; propodeum with a well defined 

 circular area; pygidium broad, flat Crossocerus p. 671 



Subgenus Synothyreopus Ashmead. 

 The males belonging to this group are easily recognized by the 

 characters given in the subgeneric table. The females offer some 

 difficulty but by close study can be placed. Two species belong- 

 ing to this group have been taken within the State. 



Key to Species. 



Flagellum scarcely twice the length of scape tumidus 



Flagellum much more than twice the length of scape advena 



