142 INSECUTOR INSClTlzU MENSTRUUS 



brown dots surrounding the bases of the numerous long pale 

 hairs ; scutum blue-gray ; scutellum and postnotum gray with 

 a narrow dark brown median line. Pleura dark blue-gray, the 

 dorso-pleural membranes dark brown; sternites a little more 

 brownish. Halteres pale at the base, the stem brown, the 

 knob darker. Legs with the coxje dark, blue-gray pruinose; 

 trochanters dark colored with a sparse blue-gray bloom ; femora 

 deep brownish yellow passing into dark brown on the apical 

 third ; tibi^ and tarsi dark brownish black. Wings light gray, 

 the costal area brownish yellow, the membrane of the disk 

 with dark brown and subhyaline blotches, arranged as follows : 

 dark brown at the stigma, along the cord, along vein Cu and 

 at the base of Rs; subhyaline blotches near the base of cells 

 M, Cu and ist A ; near the tip of cell M, most of cell R, a 

 large blotch in the middle of cell ist R^ ; beyond the cord in 

 cell, 2nd i?i, base of R^, R^, i?,, and in ist M^. 



Abdominal tergites dull orange-yellow, trivittate with slate- 

 gray to dark brown, the orange colors brightest on segments 

 2 to 4 and the base of 5 ; extreme lateral margins of the seg- 

 ments paler; caudal margins of segments 3 and 4 pale yellow 

 except along the median area; segments 6 to 8 dark brown; 

 sternites with segments 2 to 4 dull orange, on the terminal seg- 

 ments passing into dark brown. Hypopygium with the ninth 

 tergite reduced to a narrow, transverse, chitinized band whose 

 caudal margin is heavily chitinized, smooth, black, and very 

 shallowly concave; eighth sternite subcarinate, unarmed. 



Holotype, male, Baldy Mountain, Boulder County, Colorado, 

 July 24, 1915 (T. D. A. Cockerell) ; above timber line. 



Paratype, male, Manitou Pass, Colorado (F. H. Snow) ; 

 from the S. W. Williston collection. 



The type is in the collection of the United States National 

 Museum, Cat. No. 19989 ; the paratype is in the collection of 

 the American Museum of Natural History. 



