444 



U. S. NATIONAL MUSEUM BULLETIN 216 



PART 3 



Figure 247. — Localities for 

 Mesostenus gracilis. 



Male: Head black, the orbits except for an interruption on upper 

 part of temple, clypeus, and center of face, white, the white facial 

 orbit and central white spot on face often enlarged and fused, the 

 entire face thus sometimes white; mouth parts white; antenna black, 

 the scape often white in front and rarely the flagellum with a median 

 white stripe above that covers 2-4 segments; thorax mostly black ante- 

 riorly, mostly fulvous posteriorly, usually the pronotum, mesonotum, 

 and metanotum black marked with white and the rest of thorax mostly 

 fulvous. Sometimes the thorax is almost entirely black and rarely 

 it is all black except for restricted white markings. Sometimes the 

 mesoscutum is fulvous with the margins and notauli fuscous. White 

 thoracic markings include the upper and lower margins of pronotum, 

 tegula, subtegular ridge, basal carinae of scutellum, sides and apex of 

 scutellum, often more or less of mesosternum, usually a median spot 

 on mesoscutum, lower part of mesopleurum, dorsal part of prepectus, 

 and rarely the postscutellum. Coxae and trochanters fulvous, the 

 front and middle trochanters usually marked with white and all 

 coxae and trochanters often with fuscous areas of varying size; front 

 and middle legs bej^ond trochanters fulvous, their tarsi brown api- 

 cally; hind femur fulvous; hind tibia fulvous, its base and its dorsal half 

 more or less infuscate; hind tarsus fuscous, paler at the joints, some- 

 times its median segments and as much as the apical 0.2 of its first 

 segments partly or entirely white; wings hyahne or subhyaline. 

 Abdomen fulvous. 



Female: Colored about like the female of M. thoracicus except that 

 the scutellum is usually black rather than white. Very often the 

 face is black v/ith the orbits and a large median quadrate spot white. 

 Often these white areas are more or less enlarged and fused, the face 

 being sometimes entirely white. The ground color of the mesonotum 

 is sometimes fulvous with infuscate margins and sutures rather than 



