Therevidae. 143 



This species may in tlie male vary greatly in the extent of tlie 

 black hairs, these sometimes occupying nearly the whole dorsal side 

 of the abdomen, and the hairs on the anterior femora may also be 

 black to a great extent and in this case the species has a dark 

 appearance; in the female the colour of the hairs may vary from 

 pale brassy yellow to deeper, nearly reddisli yellow; the somewhat 

 dark form of the male and the paler form of the female are by far 

 the commonest with us. 



Length 9—13 mm. 



The full grown larva has a length of about 30 mm., the pupa of 

 13—14 mm. 



Remarks: In this species I have sometimes found the fourth 

 posterior cell somev^hat open in the female ; Loew 1. c. also mentions 

 a female with the cell open. 



This species is recognized by the distinct, triangular or more 

 semicircular spots on abdomen. In its brighter forms it is a very 

 beautiful species. 



T. nohilitata is common in Denmark ; vicinity of Copenhagen, 

 Vester Fælled, Damhusmosen, Ordrup Mose, Dyrehaven, Bøllemosen, 

 Ørhoim, Hillerød, Tisvilde; on Funen at Svendborg, Odense, Hofmans- 

 gave, Veflinge, Langensø and Middelfart; in Jutland at Ribe, Frijsen- 

 borg, Silkeborg and Støvring near Randers, and finally on Bornholm 

 at Hasle. My dates are ^^/6 — ^^/s. The larva was found in mole-casts 

 in Dyrehaven on ^/s, the imago came from ^^-^^/e. The pupa was 

 found in sand at Furesø on ^'-/s, it developed on Ve, finally it was 

 found at Ghristianssæde on Lolland in a decaying oak. The species 

 occurs on the outskirts of woods, in fens and on similar localities, 

 especially on Urtica. 



Geographical distribution: — Europe down into France; towards 

 the north to northernmost Scandinavia. 



3. T. arcuata Loew. 



1847. Loew, Dipt. Beitr. II, 9, 5. - 1862. Schin. F. A. I, 167. - 1903. 

 Kat. palaarkt. Dipt. II, 208. 



Male. Face and frons dark yellowish pruinose; the hairs on the 

 frons chiefly black with some yellow; on the face yellow and black 

 intermingled, the black especially at the outer margin. Occiput with 

 black and yellow hairs, the occipito-orbital bristles black; the hairs 

 on vertex black. Antennæ black, the first joint somewhat pruinose, 

 the first two joints with black hairs. Thorax greyish or brownish 

 black, with two, somewhat faint, yellowish stripes. The disc sparingly 

 clothed with erect, black and more densely with somewhat decumbent, 



