134 Orthorrhapha brachycera. 



Insectol. Sjælland. 1761) has the same, and it is again recorded in 

 1763 (Pontopp. Danske Atl). Muller (Flor. Fridrichsd. App. 1767) again 

 has only the same. About this species can only be said that it is 

 a Thereva, and probably our most common species, T. nohilitata. 

 Fabricius in 1775 (Syst. Entom.) has the new species Bihio nobilitata; 

 in his following works he has only the same, but in 1805 in his last 

 work (Syst, Antl.) he has further Bibio annnlata, also a new species. 

 These two common species were thus originally founded on Danish 

 specimens. Zetterstedt in 1842 (Dipt. Scand. I) records one species, 

 nobilitata, from Denmark and no more in the following volumes. 

 Finally Loew in 1847 (Dipt. Beitr. II) records bipimctata from Den- 

 mark. Thus in all three species were known. In the present work 

 10 species are enumerated. 



Only one genus, Thereva, occurs in Denmark. 



1. Tliereva Latr. 



Species of medium size, more or less hairy, generally the males 

 somewhat long haired, the females shorter and more sparingly haired. 

 The colours greyish or yellowish to blackish, sometimes silverwhite. 

 Head as broad as thorax, broader than high; it is somewhat arched 

 in front, but the face which looks forwards and downwards is some- 

 what flattened; the head is slightly arched behind; the frons is some- 

 times more or less protruding. Eyes in the male somewhat reniform, 

 touching, in the female well separated, the vertex being more or less 



Fig. 45. Antenna of T. nobilitata. X 35. 

 broad ; in the female the frons very often has a black, shining cailus, 

 sometimes divided into two. The eye-facets are in the male larger 

 in the upper part than below. The colour of the eyes is more or 

 less dark greenish, slightly metallic, in some species as anilis and 

 annulata bright green; along the posterior eye-margin there is a row 

 of weaker or stronger occipito-orbital bristles, they are generally 

 stronger in the females than in the males; also farther down on the 

 occiput there are some bristles. Antennæ inserted near to each other, 

 in or a little below the middle. Jowls small, slightly descending below 

 the eyes. Antennæ consisting of five joints, the first somewhat long, 



