PROC. ENT. SOC. WASH., VOL. 20, NO. 9, DEC., 1918 201 



X. Cross-veins at middle of wing, apex of discal cell, 

 and furcation of 3rd vein distinctly dark clouded. 

 Y. Abdomen blackish-brown with small faint median 

 triangles and yellowish lateral spots, especially 



large on segments 1 to 3 lasiophthalmus 



YY. Abdomen otherwise. 



Z. Front broad, lower part of callosity squarish; 

 triangles on abdomen not connected along 

 posterior border of segments, not con- 

 spicuous reinwardtii 



ZZ. Front narrow, lower part of callosity ellip- 

 tical; triangles on abdomen very large, 

 bright white, their bases touching across 



posterior borders of segments cymatophorus 



XX. These wing veins not dark clouded. 



a. Face immediately above insertion of antennae 



denuded and shining carolinensis 



aa. Face immedately above insertion of antennae 



pollinose 



b. Central light markings of abdomen are large 

 triangles, almost or quite reaching anterior 

 margins of segments. 



c. Third joint of antenna long slender, basal an- 



gulation prominent, acute and slightly falcate, 



brown except at tip; general color brownish. .longus 



cc. Third joint of antenna short, stout, basal an- 



gulation neither prominent, acute nor falcate. 



d. Antennae black: tibiae gray; length about 



16 mm vivax 



dd. Antennae largely orange yellow; tibiae 



black; length about 12 mm astulus 



bb. Central light markings of abdomen are merely 

 shallow expansions of the narrow pale hind 

 margins of segments, 

 e. Length, 12 mm. or more; eyes unmarked, 



sparus 

 ee. Length usually 10 mm. or less; eyes 



banded pumilus 



T. acteon Osten Sacken. Washington, D. C., August 14, 1917, 

 at light, H. F. Wickham; Plummers Island, Md., August 31, 1907, 

 McAtee; Beltsville, Md., September 10, 1916, both sexes, F. R. 

 Cole, McAtee; August 22, 1917, C. T. Greene. The specimen col- 

 lected on Plummers Island was one of a number taking part in a 

 peculiar and very interesting performance. The flies poised about 

 20 feet above the ground in an opening that had been cut through 



