514 Tachinidae. 



from in front whitish pruinose. Orbits with very few fine hairs; 

 jowls black-haired. Occiput grey, with black hairs and some brownish 

 hairs below. Eyes brownish-hairy. Antennæ black, third joint rather 

 dilated; arista short, thickened in about basal half. Palpi black. 

 Thorax grey pruinose, with four darker grey stripes, the median 

 narrow, diverging and abbreviated behind, the lateral interrupted 

 at the suture. Thorax black-haired; scutellum with a pair of discai 

 bristles. Abdomen all greyish, somewhat shifting to brownish grey 

 according to view; it is black-haired, with discai and marginal bristles; 

 on second segment a pair of discai and marginal, on third a pair of 

 discai and a row of marginal and on fourth a row of both discai and 

 marginal; fifth segment quite covered with bristles. Legs black, 

 with long bristles; front tibiæ with an anterodorsal row of long bristles. 

 Wings a little tinged, yellow at base; veins brown. Squamulæ whitish 

 or slightly yellowish, the margin darker. Halteres yellow. 



Female. Similar; colour more yellowish grey and head whitish 

 yellow; frons broader than the eye, less protruding than in male; 

 third antennal joint not dilated. 



Length 6 — 7 mm. 



S. callida does not seem just rare in Denmark; near Copenhagen, 

 Tisvilde, Vemmetofte and in Jutland at Hald; the dates are in June. 

 The imago, however, is rarely seen, but the species has been bred. 

 It is parasitic on the larvæ of Melasoma populi and tremulae. Nielsen 

 has (Entom. Medd. 2, IV, 1909, 52) treated its biology; he bred it 

 from M. populi; the larvæ of this were taken in June; the parasite 

 larva was found only in fullgrown host larvæ and in pupæ ; the parasite 

 bored out of the host pupa and hibernated as pupa in the ground, 

 and the imagines came next year on ^/^ — ^/g. Sometimes the parasite 

 pupated in the host pupa. The species seems to belong to Pantel's 

 group 5. 



Geographical distribution: — Europe; towards the north to 

 northern Sweden, and in Finland. 



121. Pelatacliina Meade. 



Species of medium size, black with grey pruinosity. Head as 

 broad as thorax, strongly convex behind and puffed out below, as 

 long as high. Frons in male somewhat narrow, in female broader, 

 rather protruding; cheeks broad; jowls not half as broad as the height 

 of the eye. In both sexes fme, Outwards directed ocellar and inner and 



