6 PROCEEDINGS OF THE NATIONAL MUSEUM. voi.. CO. 



Allied to T. simulatus Greene, but easily separated from that spe- 

 cies by the very broad wing, the shape of the spots at the apex of 

 the wing and the color of the orbital cilia. 



3. TACHYTRECHUS VORAX Loew. 



Fig. 1. 



Tachytrechus vora^ Loew, Neue Beitraege, 1857, vol. 8, p. 41. 



Male. — Face reaching lower edge of eyes, upper portion about 

 three-fourths as wide as the lower, covered with a dull, yellowish 

 dust; front a velvety brown. Antennae entirely black; first joint 

 nearly equal in length to the other two, enlarged towards the apex, 

 having a thumblike projection on the inside at the apex; second joint 

 not quite so long; third joint rounded on outer edges. Arista black, 

 bare and thickened on the basal third. Orbital cilia black above, white 

 below. Thorax on upper side with a gray-yellowish or brownish-yel- 

 low dust upon a metallic-green or partially copper-colored and lustrous 

 ground, very dull. Abdomen green and coppery, dull, with a gray- 

 whitish dust, Hypopygium black, upon the inferior side more 

 greenish-black, but gray from a pale dust; lamellae black, moderate 

 size, slightly rounded, covered with black hairs. Femora dark metal- 

 lic-green, thinly pruinose with whitish dust, tip brownish-yellow; 

 tip of the fore and hind tibiae blackened, tip of middle tibiae usually 

 only brown. Tarsi black, plain, fore tarsi usually brownish-^^ellow 

 only at the extreme root, middle tarsi brownish- jellow upon the first 

 half of the first joint. Wings narrow, large black spot nearly bi- 

 sected by the fourth vein, behind this spot is one of snow white 

 covering the extreme apex of the wing, and nearly equal size; 

 haiteres infuscated with brown, tegulae pale yellow with long black 

 cilia. 



Female. — Face and front pale silvery j^ellow, dull, face slightly 

 broader than in the male. Abdomen more greenish. Yellow of the 

 legs more reddish. Wing without spot, slightly tinged with brown 

 and more rounded at the apex. 



Length 5-6 mm. 



Type locality. — District of Columbia. 



Type. — In Museum of Comparative Zoology, Cambridge, Massa 

 chusetts. 



Distribution. — ^Lafayette, Indiana, May 27, 1915, to July 27, J. M, 

 Aldrich; Boulder, Colorado; Franconia, New Hampshire; Battle 

 Creek, Michigan; Chesterton, Indiana, June 2, 1916, J. M. Aldrich 

 Michigan City, Indiana ; Sa^nta Monica, California, July 31, 1911 

 Brookings, South Dakota, Westville, New Jersey, August 18, C. W 

 Johnson; Barcroft, Virginia, and Avalon, New Jersey, August 8 

 1909, C. T. Greene; Trenton, New Jersey, August 7, 1910, H. S 

 Harbeck. 



