282 Tachinidae. 



greyish silvery, jowls grey; frontal stripe velvet black. Orbits and 

 jowls black-haired. Occiput dark grey, with yellowish hairs, some- 

 what sparse above, and with rows of black hairs behind postocular 

 bristles, Antennæ black, tliird joint twice to nearly thrice as long as 

 second, not reaching to the large vibrissa; arista thickened in basal 

 third. Palpi black. Thorax black, with a bluish or brownish grey 

 pruinosity, leaving three broad black stripes, so that it may also 

 be termed black with two narrow grey stripes; the median stripe 

 may be more or less grey on the middle, and thus divided into two 

 narrow black stripes; scutellum black, grey pruinose along the 

 margin, Thorax sparingly black-haired, Apical scutellar bristles 

 parallel or slightly diverging and somewhat erect, Abdomen black, 

 often reddish translucent at the sides, the three last segments brownish 

 or greyish pruinose, on third and fourth segment or only on third 

 there is a roundish or triangular blackish brown spot on each side, 

 produced from the margin forwards, and in the middle there is a 

 narrow or sometimes broader black line, broadest on third segment, 

 Abdomen with black hairs, second segment with a pair of marginal 

 bristles, third and fourth with discai and marginal bristles which 

 may be one pair of each, except the marginal row on fourth segment, 

 but often the discai bristles may be more numerous, and on fourth 

 segment they may form transverse rows. Hypopygium small; upper 

 forceps divided into two close lying styles; arms of lower forceps more 

 elongated triangular, of the same lengtli as upper forceps. Legs black. 

 Wings brownish tinged, rather strongly towards the base; first post- 

 erior cell narrowly open quite near apex of wing. Squamulæ more 

 or less yellowish to yellowish brown. Halteres yellow. 



Female. Differing somewhat in colour. Frons about as broad 

 as the eye or somewhat broader, Thorax light grey pruinose, with 

 four narrow black stripes. Abdomen grey, with the markings present 

 only at the hind margins of the segments, where they form an incised 

 or undulated band, sometimes quite wanting. 



Length. Very variable in size, the length from 4 to 7,5 mm 

 (recorded from 3 to 8,5 mm). 



M. mutabilis is common in Denmark; at Copenhagen, Lersø, 

 Ordrup Mose, Ermelund, Dyrehaven, Frederiksdal, Ørholm, Holte, 

 Donse, Egebæks Vang, Humlebæk, Tisvilde, Gilleleje, Lave Skov 

 at Helsingør, Ringsted; on Bogø south of Sealand; on Funen at 

 Odense and Veflinge; in Jutland at Sønderborg, Kliplev, Kolding, 

 Horsens, Laven and Silkeborg, and on Bornholm at Hammeren; 



