464 Syrphidae. 



margin triangularly produced in the middle. The spots are pruinose 

 and may be quite whitish grey, or more yellowish at the sides. Ab- 

 domen is yellow-haired, more or less black-haired at the hind margins 

 of the segments. Genitalia relatively large, pale pruinose and pale- 

 haired. Venter greyish black, dull, with pale incisures and sides; it 

 is shining just along the middle; the first segment has pale hairs, for 

 the rest it is nearly bare, only sparingly haired at the sides. Legs 

 somewhat as in lunulatus but more reddish, anterior femora a little 

 pale at the extreme base, then black on the basal part but generally 

 only above and below, and below often to near the apex ; front tibiæ 

 with a dark ring before the apex, and middle tibiæ with traces of a 

 similar ring, both pairs sometimes with traces of an upper ring near 

 the base; tarsi dark towards the apex, front tarsi also more or less 

 on the rest; hind legs coloured as in lunulatus; hind femora with a 

 wart or protuberance below near the base and hind tibiæ at the apex 

 prolonged below into a triangular spur. Legs haired as usual, the 

 hairs mainly yellow but behind the front femora more or fewer black 

 hairs, and middle femora with some black hairs on the anterior side 

 in the apical half; front tibiæ more or less black-haired above and 

 middle tibiæ above and on the anterior side ; hind femora densely and 

 somewhat strongly black setulose below, the wart very densely. Wings 

 a little brownish tinged. Stigma consisting only of the cross-vein. 

 Squamulæ whitish with a yellow fringe. Halteres yellow. 



Female. Vertex and frons broad, a little widening downwards, 

 brownish yellow pruinose, blackish about the ocelli; the hairs black. 

 Occiput with or without dark spots at the upper eye-margin. Abdomen 

 with the spots as in the male, the grey triangles at the hind margins 

 of second and third segments larger and more distinct; fifth segment 

 quite grey with a small, black middle stripe at the front margin. 

 Venter without shining middle stripe, and with long, pale hairs. Legs 

 paler, anterior femora often with only small black spots; hind femora 

 simple, hind tibiæ with the apical spur present but short. 



Length 8,5 — 9,5 mm. 



H. transfugiis is somewhat rare in Denmark ; Utterslev Mose, 

 Ordrup Mose, Ermelund, Fure Sø, Hillerød, Hellebæk, Rørvig; on 

 Lolland at Maribo ; on Langeland at Lohals, and in Jutland at Randers. 

 My dates are ^^k — ^s/s. It occurs in fens and at horders of water. 

 The pupa has been taken in Utterslev Mose in April and May and 

 at Randers in May, in flood refuse (Schlick). 



Geographical distribution:— Northern and middle Europe down 

 inlo France; towards the north to middle Sweden, and in Finland. 



