AET. 17. FLIES OF THE GENUS TACHYTRECHUS — GREENE. 13 



10. TACHYTRECHUS OLYMPIAE Aldrich. 



Figs. 7, 9, 19. 



Macelloceius olympiae Aldrich, Trans. Amer. Ent. Soc, 1896, vol. 23, p. 83. 



Male. — Face not quite as long as eye height, dull yellow, just below 

 antennae, about half as wide as at lower end. Front deep, bronze 

 green, dull. Antennae mostly reddish-yellow, first joint swollen 

 towards tip and about two and one-half times the length of the second 

 and third joints together, black bristly hairs above; second joint 

 quite rudimentary; third joint blackened except at the base. Arista 

 about one and one-third times the height of head, white, base thick- 

 ened and blackish, lamella black, rounded at apex and the lower 

 point white- Orbital cilia black above, whitish below, an evenly 

 arranged lot of white bristles in the middle of the orbital cilia. Thorax 

 bronze-green, with two small velvety black spots in front of the wing 

 base. Abdomen bronze-green with a whitish dust. Hypopygium 

 large, basal part shining black, central segment bronze-green behind, 

 lamellae whitish, covered with black hairs, those of the margin hardly 

 coarser. Legs mostly yellow, tarsi brownish-black, in certain lights 

 silvery dusted. Front coxae yellow blackish at base ; middle and hind 

 coxae with golden dust, hind pair with silvery. Front femur very 

 broad on basal two-thirds, with a large blackish-brown spot on the 

 outside. Wings narrow and slightly brownish. Halteres yellow. 

 Tegulae pale yellow, fringe black. 



Female. — All the body colors darker. Face wider, greenish-j'ellow. 

 Antennae shorter, third joint black, faintly reddish at base. All 

 coxae black; femora more or less dark on the basal part, front 

 femora not swollen but with a gray, silvery area on outside near the 

 base, the hind ones black-green except the apical half or third ; tibiae 

 black on the apical third or fourth. Wings longer and much wider 

 than in the male. 



Lenth 6 mm. 



Type locality. — Olympia, Washington (Trevor Kincaid), June 3 

 and July 1, 1894. 



Disti^hution. — Corvalis, Oregon, August 15, 1902; Longmire 

 Springs, Mount Rainier, Washington, August 2, 1905; Algonquin, 

 Illinois, May 24, 1895 ; Keyport, Washington, August 7, 1905 ; Pot- 

 latch, Idaho, June 20, 1907; Mono Lake, California, July 22, 1911; 

 Owen's Lake, California, July 27, 1911; Pacific Grove, California, 

 May, 1906. 



Two cotypes (Cat. No. 24783, U.S.N.M.) and six specimens de- 

 posited in United States National Museum Collection by J. M. 

 Aldrich. Originally described from two males and two females 

 (cotypes). 



