158 KANSAS UNIVERSITY SCIENCE BULLETIN. 



Tachysphex Kohl. 



Kohl; Berl. Ent. Zeitschrift, XXVII, 166, 1883. 

 Fox; Proc. Acad. Nat. Sci. Phil., 504-5; 1893. 

 Syn. Larrada Sm. 

 Larra Patton. 



Form slender to stout, pubescence short and usually sparse. Head 

 usually distinctly wider than the thorax, face bituberculate behind the 

 antenna, the latter moderate, usually more slender in the o than in 

 Tachytes; ocelli bordering on a longitudinally furrowed swelling, the 

 anterior ocellus round, the posterior pair more or less reniform, flattened 

 and quite obliquely placed; mandibles more strongly emarginate than in 

 Tachytes; thorax rather short; propodeum rounded posteriorly; marginal 

 cell of fore wings more or less distinctly truncate; legs rather slender, 

 spinose. 



2 ■ Comb of fore tarsi of long, flexible spines; pygidial area naked 

 and shining, usually with delicate carinate borders. 



J' . Fore femora emarginate beneath at base; pygidial area not well 

 defined, with sparse pile; eighth ventral segment well emarginate; some- 

 times with a median tooth. 



This genus is represented in Kansas by twenty-two species. From a 

 systematic standpoint, it is the most diflicult group of the family, a:- 

 many of the species resemble one another very closely. By paying strict 

 attention to the clypeus, pygidium, venation, antenn* and sculpture, the 

 tables should prove helpful. 



The length of the pygidial area in the seems to have been over- 

 estimated by some writers. The author compares the basal width with 

 the length, which is taken to extend from where the lateral carinas end 

 (toward and not at the base of the segment) to the narrowed tip of the 

 disc. His figures here given will be found to differ, therefore, materially 

 from those of Fox in his monograph of the Larridse. 



Key to the Species of Tachysphex. 

 (Use a compound microscope here.) 

 Females. 

 1. Interocular space at vertex always distinctly more than one-half 

 the interocular space at the lower edge of the eyes; face with 

 long pile; vertex with long, erect pile, which is at least as long 

 as the diameter of an antennal joint; vertex and thorax always 

 with well-separated punctures, polished. Immediately behind 

 each posterior ocellus is a convexity which resembles a second 

 ocellus, then follows the transverse postocellar impression. . . .- 

 Interocular space at vertex never distinctly as much as one-half 

 the same space at the lower edge of the eyes; vertex glabrous 

 or with very short pile; vertex and thorax often with very fine 

 and close punctures, often subopaque. Immediately behind each 

 posterior ocellus the slope is scarce or not interrupted to the 

 ti-ansverse postocellar impression 4 



