468 Annals Entomological Society of America [Vol, VI, 



51. Dark cinereous; abdomen sordid testaceous, indistinctly trivdttate, last 



two segments blackish, lateral margins of segments whitish. Hypopy- 

 gium small, ninth tergite reniform. Wings grayish-fuscous, a small 

 white spot at the posterior margin of the second basal cell, discal cell 

 and base of fourth posterior cell indistinctly whitish. Length 14 mm. 



centralis Loew 

 Yellowish; thorax reddish; abdomen trivittate. Hypopygium moder- 

 ately large, ninth tergite membranous posteriorly, deeply emarginate 

 in the middle, sides deflected in the form of rounded lobes; ninth 

 sternite entire, a somewhat ellipsoidal shaped process arises from its 

 posterior margin. Wings strongly tinged with yellow. Length 

 10-24 mm flavescens Fabr 



52. Joints of flagellum unicolorous 53 



Joints of flagellum bicolorous .- 60 



53. Color grayish 54 



Color not grayish 57 



54. Three white spots along the posterior wing-margin; middle thoracic 



vitta obsolete anteriorly. Abdomen testaceous, lateral margins and 

 ' last segments fuscous; hypopygium subcarinate below; wings grayish. 



Length 9-13 mm fragilis d" Loew 



suspecta 9 Loew 

 Posterior wing margin without three spots 55 



55. Scutellum and metathorax shining; former yellow with a brown line in 



the middle. Abdomen brownish yellow, hind margin of segments 

 and interrupted dorsal stripe brown; hypopygium rather large, ninth 

 tergite broader than long, posterior margin with a crescent shaped 

 emargination; ninth sternite nearly completely divided; pleural suture 

 almost extending to the anterior margin. Wings pale gray, veins of 



apical portion white margined. Length 7-16 mm. beatula O. S. 



Scutellum and metathorax not shining 56 



56. Abdomen shining, sutures brown, wings with three clearly defined 



fuscous spots along the costal margin. Length 18 mm frigida Walker 



Abdomen trivittate; wings with three fuscous spots along the costal 

 margin near the apex. Length 12 mm resurgens Walker 



57. Pubescens of body very conspicuous. Testaceous; thoracic stripes not 



very distinct. Hypopygium very large; ninth sternite large, barbed 

 at the posterior margin with golden yellow hair. Wings grayish 

 fuscous, anterior branch of second longitudinal vein abbreviated; 

 most of the veins margined with fuscous; all posterior cells white 



margined. Length 18 mm . . . pubera *Loew 



Pubescens of body not conspicuous 58 



58. A whitish spot before and behind the stigma 59 



Wings not so marked. Brown; mesonotum with four brown stripes; 



abdomen with lateral stripes, latero-posterior margins of segments 

 yellowish; eight and ninth segments separated above by a deep furrow; 

 lateral margins of ninth tergite drawn out into a blunt point posterior- 

 ly, ninth sternite divided by a deep quadrate incision. Veins in apical 

 part of wing white margined, and tipped with fuscous; similar to 

 commiscibilis (contaminata). Length 22 mm. (9) abluta- fDoane 



59. The white spot before the stigma extends to base of fourth posterior cell; 



abdomen trivittate 60 



The white spot before the stigma does not extend to the posterior cells. 

 Brownish yellow. Mesonotum with four broad, brown stripes; 

 abdomen with broken, brown lateral stripe; ninth tergite with deep, 

 median furrow and rather deep V-shaped incision, the apex of which 

 bears a short triangular black tipped tooth; ninth sternite with broad, 

 deep U-shaped incision which contains a pair of large, tumid yellow 

 haired appendages. Veins with indistinct whitish border. Length 

 16 mm calif ornica Doane 



* Should have been placed under 37. 

 f Should have been placed under 37. 



