32 PEOCEEDINGS OF THE NATIONAL MUSEUM vol.79 



on narrow base, covered with thin gray pollen; calypters opaque, 

 white with a faint yellow tinge. 



Abdomen broadly red on sides with a wide black median stripe 

 expanding on first segment and including all but the posterior half 

 at sides, anal segment often blackish near base but sometimes wholly 

 reddish yellow ; intermediate segments gray pollinose or subpoll'inose 

 to the hind margins; fourth with denser gray pollen on basal half 

 showing three elongated changeable spots as the angle varies, the 

 median one extending forward interruptedly on segments 3 and 2; 

 basal segments ordinarily without any median marginal bristles 

 though sometimes a pair present on the second; third segment 

 bearing a marginal row of 8 to 12 strong bristles; fourth covered 

 with shorter ones on apical half; venter without defined patches of 

 hairs; genital segments small and retracted; inner forceps united 

 except at tip with a rather prominent sharp keel behind, in profile 

 thick to middle thence sloping forward to the abruptly curved 

 pointed and divided apex, bearing long black hairs directed upward 

 and outward; outer forceps yellow, with numerous long brownish 

 hairs on outer side, about three-fourths as long as inner ones, tips 

 rounded or blunt ; fifth sternite with a broad deep incision, the lobes 

 bearing long black hairs along the inner margins. 



Legs slender, black; mid tibiae with one large median anterior 

 bristle; hind tibiae thickly ciliate rarely with one longer bristle in 

 the row; claws and pulvilli elongate. 



Wings grayish hyaline ; fourth vein arcuate beyond bend reaching 

 costa well before wing tip; no costal spine; third vein with one or 

 two hairs at base. 



Female. — Front at vertex 0.26 to 0.29 of the head width, not much 

 wider at base of antennae; parafrontals gray pollinose to vertex, 

 bearing only a few short scattered hairs; the usual orbitals present; 

 inner and outer verticals developed; uppermost frontals stout, re- 

 clinate, but not very long; antennae red, third joint more or less 

 infuscated, wider than parafacial at narrowest; the latter usually 

 very inconspicuously haired; thorax densely gray pollinose, the dor- 

 sal stripes distinct; second abdominal segment bearing a pair of 

 median marginal bristles; claws and pulvilli short; hind tibiae less 

 thickly ciliated than in male with one larger bristle near the middle. 



Length, 5 to 11 mm. 



Type. — In the collection of J. E. Collin, Newmarket, England. 



Eedescribed from more than 200 specimens (both sexes), March to 

 October, College Station, Tex. (H. J. Eeinhard). Distribution rec- 

 ords: Mississippi (F. M. Hull); Iowa, reared from Papaipemn 

 nehris, July 26 and 27, 1929 (G. C. Decker) ; Michigan (L. G. 



