222 U. S. NATIONAL MUSEUM BULLETIN 216 



26. Exochus albifrons Cresson 



Figures 188,j; 189,m; 193,g 



Exochus albifrons Cresson, 1868, Trans. Amer. Ent. Soc, vol. 2, p. 114; 9 • Type: 

 9 , Illinois (Philadelphia) . 



Front wing 3.8 to 7.9 mm. long; combined face and clypeus about 

 0.98 as high as wide in male, about 1.11 as high as wide in female, 

 their vertical convexity uniform, rather weak, their transverse con- 

 vexity a little stronger, their punctures coarse, separated by about 

 0.3 their diameter on face and by about 1.0 their diameter on clypeus; 

 interantennal process with an apical angle of about 85 to 100 degrees; 

 median swelling of frons weak, unusually narrow; median half of 

 clypeal margin truncate or weakly concave; mandible broad basally, 

 with sparse coarse punctures, evenly tapered to a moderately broad 

 apex, its lower tooth small; hind ocellus separated from eye by about 

 0.95 its long diameter in male, by about 0.77 its long diameter in 

 female; costula strong, complete, sometimes weak medially; second 

 lateral area of propodeum with hairs laterally and apicolaterally, 

 the rest bare; hind femur about 2.40 as long as deep; front spur of 

 hind tibia about 3.2 as long as wide in male, about 3.3 as long as 

 wide in female; punctures on second tergite moderately coarse and 

 deep, practically absent medially, sublaterally separated by about 

 1.3 their diameter; male clasper tapered apically to a narrow rounded 

 apex. 



Black. Face, sometimes part or all of side of frons, triangular spot 

 at top of eye, clypeus, cheek, temple next to mandible, mouth parts, 

 often spot on scape beneath, upper margin of pronotum from apex 

 usually to epomia (broadest near hind corner), much of subtegular 

 ridge, often postscutellum and apex of scutellum, and tegula except 

 for a postmedian light fulvous area, yellowish white. Face usually 

 with a median subdorsal elongate fuscous mark, clypeus with the 

 median part of apical margin usually blackish, and face sometimes 

 with a blackish spot above each clypeal fovea. Often these dark 

 marks are enlarged and more or less fused, often leaving the face 

 entirely black except for a broad dorsal whitish margin. Antenna 

 blackish brown, paler beneath. Frequently there is an ivory area on 

 upper part of prepectus and at base of middle coxa, and the thoracic 

 pleura are often more or less fulvous. Karely the entire propodeum 

 and some of the base of the abdomen may be pale and the scutellum 

 entirely whitish. Legs fulvous, the trochanters, and front and 

 middle coxae, tibiae and tarsi, pale fulvous, the apex of the tarsal 

 segments faintly darker. Hind tibia whitish on basal 0.15 ±, fulvous 

 from thence to near the apical 0.2 ±, the apical 0.2 ± fuscous; hind 

 tarsus stramineous, the apex of its first four segments brown, the last 

 segment brown with a pale base. 



