Dolichopodidae. 331 



I, 238. — 1877. Kow. Verhandl. zool. bot. Gesell. Wien, XXVII, 67, 23, 

 Taf. II, Fig. 1 — 11. — 1903. Kat. palåarkt. Dipt. II, 338. — Medeterus 

 nigricans Meig. 1824. Syst. Beschr. IV, 67, 16. — Hijdrophorus truncorum 

 1838. Zett. Ins. Lapp. 702, 8, p.p. 



Male. Vertex and frons grey pruinose. Epistoma grey or whitish 

 grey pruinose, but not densely and generally the metallic green or 

 blue ground colour slightly visible. Palpi black. Occiput grey; the 

 postocular bristles whitish, the uppermost blackish. Antennæ black, 

 third joint about as long as broad; arista subapical, long. Thorax 

 slightly metallic green, especially in the middle, grey pruinose with a 

 brown stripe at each side; sometimes also the stripe in the middle is 

 more brown than green; the acrostichal bristles short; the dorsocentral 

 rows consist of four long bristles and in front of them generally one 

 or two shorter. Scutellum with four bristles. Pleura greenish or 

 æneous, grey pruinose; propleura with three or four white prothor- 

 acic bristles. Abdomen green or bluish green, grey pruinose, clothed 

 with short, pale yellow or whitish hairs, very slightly longer at the 

 hind margins, and with longer hindmarginal bristles on the first seg- 

 ment. Venter somewhat greenish, slightly pale-haired. Hypopygium 

 large, black; the eighth segment grey pruinose, with pale hairs; the 

 ventral lobes long, somewhat curved, cleft or incised at the apex, and 

 with a pair of bristles; the outer lamellæ shorter, somewhat narrow, 

 especially towards the apex, hairy; both pairs yellowish or brownish. 

 Legs black, coxæ and also the femora somewhat greyish pruinose; 

 the knees distinctly yellow; hind metatarsus not half as long as the 

 second joint, very slightly excised at the base. The legs have short, 

 pale hairs; the bristly hairs on the anterior coxæ and the bristle on 

 the hind coxæ whitish; the hairs below the femora distinct, on the 

 hind femora long, and the hind femora have also long hairs above 

 on the basal half; middle tibiæ with one or generally a pair of bristles 

 near the base, hind tibiæ here with a small bristle, and the bristle 

 above the apex also somewhat distinct. Wings hyaline or almost so; 

 veins brownish black, the last part of the discai vein a little curved, 

 especially near the base, and a little converging towards the cubital 

 vein; the last part of the postical vein about half as long as the 

 cross-vein, this latter perpendicular, the inner angle between it and 

 the postical vein acute. Squamulæ pale yellow, the margin slightly 

 darkened, the fringe whitish. Halteres whitish or yellowish. 



Female. Quite similar to the male. 



Length 3,3 to about 4 mm. 



M.jacidus is very common in Denmark, and it has been taken 

 in almost every part of our country including Bornholm. My dates 



