16 Bulletin of the Brooklyn Entomological Society Vol. XI 



black ; proboscis brown ; palpi yellowish, darkened apically. Mesonotum 

 with faint indications of a narrow brown vitta along the line of dorso- 

 centrals. Legs not so densely pruinescent as the thorax, knees very nar- 

 rowly reddish. Wings clear or slightly grayish, the veins black. Halteres 

 testaceous, the knobs brownish yellow. 



Orbits not clearly differentiated, the whole frons opaque, lower orbital 

 bristle slightly weaker than upper, both directed out over eye; surface of 

 frons with numerous short black setulse on anterior half; third antennal 

 joint rounded apically; arista barely longer than width of frons, sub- 

 pubescent, swollen at base. Acrostichal bristles irregular, about 3 rows 

 between the dorso-centrals ; disc of mesonotum with a few rather widely 

 separated setulose hairs ; mesopleura bare ; pteropleura bare ; scutellum 

 bare on disc, with 6 marginal bristles. Abdomen slender; hypopygium of 

 moderate size, recurved on venter. Legs rather strong, fore femora 

 much incrassated, twice as thick as mid pair, their ventral surface covered 

 with short, closely placed hairs and very short bristles; basal joint of fore 

 tarsus much shorter than second, armed at its apex with a claw-like spur ; 

 mid and hind femora without bristles ; fore and hind tibiae each with a 

 single weak preapical dorsal bristle; mid pair with about 6 apical bristles. 

 Costa with numerous soft, short hairs and a series of distinct short bris- 

 tles, an indistinct break in costa just proximad of the auxiliary vein, the 

 latter joining costa in line with inner cross-vein; first vein joining costa 

 but little proximad of a point midway between the cross veins ; anal vein 

 complete; outer cross vein about half its own length from wing margin. 



Female. — Differs from the male in having the fore femora normal in 

 form and with a number of long, curved, slender bristles on ventral sur- 

 face; the basal joint of fore tarsus much longer than the second and 

 unarmed apically; the mid femora with a number of short bristles on the 

 anterior surface, and the preapical tibial bristles slightly stronger. 



Length : male, 6 mm., wing, 6 mm. ; female, 5 mm., wing, 5.5 mm. 



Type locality, Urbana, 111.; male, November 13, 1915 (J. R. 

 Malloch) ; female, November 11, 191 5 (A. Peterson), — both 

 specimens taken in or near the Forestry of the University of 

 Illinois. No data was obtained as to the habits of the species, 

 but the male which I captured was taken close to the plot devoted 

 to the culture of vegetables, and may have been associated with 

 the decaying vegetable matter. 



The species is dedicated to Mr. Alvah Peterson, who captured 

 the first specimen. 



