Therevidae. 147 



T. piebeja is not common in Denmark; Ordup Mose, Dyrehaven, 

 Hillerød, Søllerød; in Jutland at Frijsenborg, at Mausing near Silke- 

 borg and at Støvring near Randers, It is this species of Thereva 

 which occurs earliest; my dates are 2*/5 — ^'"k. It occurs at the same 

 plaees as nohilitata, but it is much less common, Scholtz (Zeitschr. 

 flir Entom Bresl, Jahrg, V, 1851,40) mentions that it {lugens) frequents 

 Euphorbia especially, 



Geographical distribution: — Europa down into France; tovvards 

 the north to northern Scandinavia, 



5, T. circumscripta Loew, 



1847. Loew, Dipt. Beitr. II, 19, II. — 1862. Schin, F. A. I, 166, - 

 1903. Kat, palåarkt, Dipt. II, 208. 



Male. Frons and face yellow pruinose; frons with black hairs, 

 above the antennæ a few yellow hairs; the black hårs stretching 

 down the outer margin of the cheeks; towards the mouth-aperture 

 the hairs are yellow. Occiput yellowish with dark yellow hairs; 

 occipito-orbital bristles black; the hairs on the vertex black. Antennæ 

 black, the first joint somewhat greyish ; the first two joints with black 

 and a few yellow hairs. Thorax black or brownish black, two rather 

 broad, dark yellowish stripes more or less visible, and in the middle 

 a narrow line of a deep black colour. The disc densely clothed with 

 erect, black hairs and sparingly with somewhat decumbent, yellow 

 hairs. According to the small material I have examined the number 

 of dorsocentral bristles seems to vary between two and four. Pleura 

 and sterna grev with yellow to greyish yellow hairs, Abdomen black, 

 the segments somewhat brownish yellow towards the hind margin, 

 but the black and brownish colours confluent without any distinct 

 boundary; the hind margin of the segments bright yellow, The dorsal 

 side clothed with black hairs, only towards the sides sometimes red- 

 dish yellow. Venter grey with the hind margins of the segments 

 yellow; it is somewhat sparingly clothed with long, pale or more 

 reddish yellow hairs. Genitalia black with ferrugineous hairs at the 

 apex. Legs with the femora black, tibiæ yellow, somewhat broadly 

 black at the apex, especially the front tibiæ; tarsi black, the posterior 

 yellow at the base. Coxæ with yellowish hairs; anterior femora and 

 the hind femora at the base with long hairs which are yellowish inter- 

 mingled with black, sometimes nearly quite black, especially on the 

 front femora. Wings somewhat greyish yellow tinged; veins yellowish 

 to dark brown; the fourth posterior cell closed; stigma brown. Bal- 

 teres brown, the base of the peduncle paler, 



Female, Vertex and frons yellowish pruinose, cheeks more whitish 



10* 



