392 



shining yellow ; mesonotum with the vittae blackish brown, very broad, 

 almost obscuring the pale ground-color; only the upper central por- 

 tion of pleurae yellow ; scutellum and postnotum blackish brown ; hairs 

 on thorax pale brown. Abdomen blackish brown, yellowish at the 

 incisions. Legs yellow; apices of femora and bases of tibise slightly 

 brownish; apices of all tibise dark brown; apices of basal and whole 

 of remaining joints of fore tarsi, apices of first two and all of the last 

 three joints of mid and hind tarsi dark brown. Wings clear, cross 

 vein brown, the other veins yellow. Halteres yellow. 



Antennae barely longer than head and thorax together, densely 

 plumose, basal joint much swollen. Mesonotum with the surface 

 hairs very short, those on scutellum barely longer than the discal 

 hairs. Abdomen slender, slightly spatulate at apex; hypopygium as 

 in Figure 9, Plate XXVIII ; surface hairs short and numerous. Legs 

 slender; basal joint of fore tarsus barely over half as long as fore 

 tibia, and subequal in length to the next three taken together ; no long 

 hairs on fore tarsus ; fourth tarsal joint on all legs obcordate. Radius 

 reaching slightly beyond the beginning of apical curve of wing; petiole 

 of cubitus half as long as posterior branch of cubitus. 



Female. — Similar in general color and markings to the male, but 

 considerably more of the reddish yellow ground-color of head is vis- 

 ible, as the brown color is absent except on the apical half of antennae; 

 the thorax is also much paler, the vittae being reddish except centrally, 

 where they become brown, being sometimes entirely brown, when the 

 resemblance to the male becomes more apparent ; scutellum yellow ; 

 postnotum brown apically. Abdomen shining dark brown. Legs as 

 in male. Wing veins more distinct than in male. 



Antenna distinctly shorter than thorax, third joint as long as 

 4+5, apical joint slightly longer than third, slightly swollen, surface 

 hairs about twice as long as diameter of the joints ; eyes much more 

 widely separated than in male. Thorax with hairs as in male. Hairs 

 on abdomen very short. Leg proportions as in male, as also wing 

 venation. 



Length, 4.5-5 mm. 



Localities: Algonquin, 111., June and August; and Havana, on the 

 Illinois River, during the months April to July and as late as Septem- 

 ber 21. The species probably occurs throughout the warm months of 

 the year. 



Originally described from Washington, D. C, and recorded from 

 New Jersey by Smith. 



The early stages are unknown to me. 



