Asilidae. 



33 



Fig. 14. L. brevirostris 

 front leg. X 15. 



pointed, tlie last three segments are narrow and form, together witli 



a small apical appendage, an ovipositor. Legs somewhat strong; the 



front tibiæ have at the base on the ventral side a small spine which 



is curved strongly outwards; the femora are 



clothed with long hairs on the ventral side, 



the front and especially the middle tibiæ have 



many long, thin bristles; the tibiæ have on 



the dorsal side some stronger bristles; the 



front tibiæ have long, the posterior tibiæ short 



apical spurs which on the middle tibiæ are 



very thick, resembling a pair of spines; the 

 tarsi have moderately 

 long bristles; the front 

 and hind tibiæ have a 

 dense pubescence on 

 the ventral side, it is 

 longest on the hind 



tibiæ; the tarsi are densely pubescent on the 

 lower surface. The hind metatarsus is in most 

 species somewhat thickened, in one species (brevi- 

 rostris) it is in the male very long and sharply com- 

 pressed. There are two pulvilli and a small, bristle- 

 shaped empodium. Wings with the 

 subcostal cell open, the cubital vein 

 forked ; between the discai cell and 

 the upper branch of the postical 

 L brevirostris ^^^^ ^ postical cross-vein; there are 

 five posterior cells, the fourth is 



somewhat narrowed at the margin; the anal cell is closed 



a little before the margin. Alula is small. The alar 



squamula small, distinctly hairy at the margin. 



The larval and pupal stages of this genus are, so 



far as I am aware, not known. 



The species of Leptarthrus seem to some degree to be 



mountain forms. Poulton 1. c. records from England the cap- 



ture of L. brevirostris with Meteorus obfuscatusl^ees as prey. 

 Of the genus 3 species occur in the palæarctic 



region; only one has hitherto been found in Denmark. 



Fig. 15. 



middle leg. X 15. 



1. L. brevirostris Meig. 



1804. Meig. Klass. eur. Zwelfl. 1,255, Tab. XIII, Fig. 16, L. brevirostris, 

 17 (Dioctria) et 1820. Syst. Beschr. Il, 273,24 {Dasypogon) hind leg. x 15. 



Dipteia Danica. II. 



