Empldidae. 163 



and with bristles on the anterior side ; hind femora with longish hairs 

 above and shorter hairs below; front tibiæ with a row of bristles on 

 the dorsal side; middle tibiæ with a few short bristles on the antero- 

 and postero-ventral side and with two bristles basally on the antero- 

 dorsal side; hind tibiæ short ciliated and with a dorsal and anterior 

 row of bristles. Front metatarsi not much thickened, cylindrical, a 

 little more than three fourths of the tibiæ in length, and as long as 

 the other four joints together; they are short-haired ; all tarsal joints 

 longer than broad, The hairs and bristles are black, only a short 

 pubescence on the antero-ventral side of the front tibiæ yellow. Wings 

 yellowish hyaline. Veins black; the iipper branch of the cubital vein 

 issuing almost rectangularly, slightly diverging; anal vein visible near 

 to the margin. Stigma long, blackish. Halteres dark yellow, the base 

 of the knob darker. 



Female. I do not know the female, but according to the descrip- 

 tions cited it is similar to the male; frons somewhat broader ; the dorso- 

 central bristles irregularly biserial; the acrostichal bristles shorter, and 

 likewise the hairs on abdomen, and the marginal bristles not long. 

 The legs shorter haired, the hind tibiæ simple. 



Length 6 — 6,5 mm ; the female is recorded to be smaller, 5,5 — 6 mm. 



This species, which is our largest Hilara and one of the largest 

 species in the genus, is easily known by the size, the colouration of 

 thorax and by several other characters, especially the narrow frons. 

 — In the analytical table I have placed it in the group with yellow 

 halteres, according to Mik and Strobl it "may sometimes have dark 

 halteres, 



H. aeronetha is very rare in Denmark, only two specimens, both 

 males, have been taken; at Hald near Viborg in Jutland on ^^/g and 

 ■^•"»/e 1910 (the author); the specimens swarmed high in the air near 

 Flald Sø at tree-tops. Mik took it flying over a brook in the moun- 

 tains, and it was observed to envelop its prey in a web ; the prey 

 was Phryganids and a large Psocus. 



Geographical distribution: — The species is hitherto only known 

 from Styria, Hungaria and Denmark. 



Remarks: My species quite agrees with the description by Strobl 

 1. c, but two points in Mik's description are not in accordance; he 

 says about the acrostichal bristles, that they are present „bis zur 

 6 (nicht dentlich geordnete) Reihen" ; in my specimens they are regu- 

 larly quadriserial as also described by Strobl; further Mik says: „Die 

 vordere Gabelast ist spitzwinklig aufgesetzt und schwingt sich am Ende 

 nach vorwårts, so dass seine Miindung noch einmal so nahe gagen die 

 Miindung der 2. Långsader geriickt ist, als gegen jene des hinteren 



11* 



