240 Orthorrhapha brachycera. 



Dipt. Scand. I, 324, 1 (Ardoptera). — 1862 Schin. F. A. I, 85. (Ardoptera). 

 — 1903. Kat. palåarkt. Dipt. II, 270. 



Male. Frons grey with two darker impressions ; vertex grey, the 

 ocellar triangle brown, and this colour prolonged triangularly back- 

 wards. Epistoma light grey; palpi black. Occiput grey with black 

 bristles above, short, whitish hairs below. Antennæ black. Thorax 

 æneous brown, somewhat shining, with a whitish grey middle line, 

 which is narrowest in the middle and here sometimes interrupted; 

 also the lateral margin is somewhat whitish grey. Dorsocentral 

 bristles long, black. Further a humeral bristle, a posthumeral, a noto- 

 pleural and a postalar bristle, all black. Scutellum with two black 

 marginal bristles. Pleura grey pruinose. Abdomen black, shining, 

 slightly æneous, with short, pale hairs. Venter black. Legs reddish 

 brown, posterior coxæ grey pruinose, the extreme apex of the tibiæ 

 and the tarsi towards the end dark brown or blackish. The legs 

 short-haired with brownish hairs. Wings brown with a number 



Fig. 105. Wing of D. irrorata. 



(about twenty) of hyaline spots, and with the base yellowish; some 

 of the spots may be indistinct or confluent, and the number is 

 therefore not quite constant, but there are six along the anterior 

 margin. Veins black or blackish brown, the radial and cubital 

 veins somewhat undulated. No stigma. Halteres yellow or reddish 

 yellow. 



Female. Quite similar to the male with exception of the differen- 

 ces in the exterior genitalia. 



Length 2 — 3 mm. 



D. irrorata is somewhat common in Denmark; Lersøen at Co- 

 penhagen, Damhussøen, Ruderhegn, Frerslev Hegn; on Langeland at 

 Lohals, and in Jutland at Hald near Viborg. My dates are "^^/e — ^Vo. 

 It occurs on shaded, humid piaces in woods, in fens and at the hor- 

 ders of water. 



Geographical distribution: — Northern and middle Europe down 

 into France; towards the north to northern Sweden, and in Finland. 

 It occurs also in North America. 



