Eristalis. 



443 



Fig. 156. E. alpinus d, hind leg 

 from the anterior side. X 12. 



the basal part and the middle tibiæ the basal half or two thirds 

 whitish yellow ; the front tarsi have the basal joints more or less pale 

 and the posterior tarsi have the two basal joints and generally also 

 the base of the third joint yellow ; the 

 hind femora are considerably thickened, 

 hind tibiæ a little compressed and 

 distinctly curved and hind metatarsi 

 a little thickened. The legs haired as 

 usual, but the hairs somewhat varying 

 in colour, sometimes the hairs behind 

 front femora more or less black and 

 also some black hairs present behind 

 the apex of middle femora, but some- 

 times they are black only behind the 

 apex of front femora and sometimes 

 all pale; hind femora with the hairs 

 all round the apical part black, some- 

 times only on a small part, but the 

 bristly hairs below the apical part al- 

 ways black; on the tibiæ the hairs all 



pale except below the black part of hind tibiæ, and there may be a 

 few black hairs behind the anterior tibiæ. Wings hyaline with a 

 narrow, brown fascia down over the base of the cubital vein and the 

 basal vein of the discai cell, sometimes it is rather indistinct. Stigma 

 small, almost not longer than broad, black. Squamulæ and fringes 

 whitish yellow, Halteres yellow. 



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

 the vertical space black and shining, the frontal half greyish pruinose, 

 darker posteriorly, broadly shining above the antennæ ; the hairs black 

 behind, dark yellow in front, but varying in the extent of the colours, 

 sometimes all black. Thorax still more pruinose on the front half 

 than in the male and with some greyish stripes prolonged backwards. 

 Abdomen with small spots, or only a little yellowish just at the basal 

 corners or quite black, shining, the hind margins of the segments dull 

 but generally indistinctly on third and fourth segments or these seg- 

 ments almost quite shining. The legs often more pale than in the 

 male, the anterior femora more or less yellow on the basal part, hind 

 femora to beyond the middle, and the tibiæ sometimes quite yellow 

 with only the apex dark; hind femora less thickened than in the male 

 but, however, distinctly thickened. Wings with a large, broad blotch 

 as in the female of rupium or still larger. 



Length 11 — 13 mm. 



