41 



Wings rather broad, hyaline, very irridiscent; petiole of second marginal cell 

 and second posterior cell both a little shorter than their cells; vestiture of black 

 and white scales; in some individuals almost all scales are white, in others the 

 black preponderate; outstanding scales narrowly lanceolate, both black and white; 

 fringe commonly grey, with white reflexions which give a mottled appearance. 

 Halteres yellowish with white-scaled knobs. 



Legs rather slender; femora clothed with whitish scales, mixed with a few 

 black ones dorsally, these predominating at apex; extreme tip narrowly white; tibiae 

 with whitish scales with black ones intermixed and a small annulus before tip of 

 hind ones; tarsi black scaled, with a white ring at base and apex of each joint; 

 hind tarsi with the first joint also largely white scaled in the middle, the last joint 

 almost quite white; fore tarsi with apex of second and all of last three joints black; 

 mid tarsi with apex of third and all of last two joints black. Claw formula: 1.11.11.1. 



Length: Body about 5 mm, wing 4 mm. 



Male: Palpi exceeding the proboscis by nearly the length of the last joint, 

 which is somewhat swollen; vestiture blackish with white scales intermixed; end 

 of long joint and last two joints with long blackish or greyish hairs: Antennae 

 plumose; the last two joints long and pilose, the rest short, blackish at insertions 

 of hair- whorls; hairs long and dense, grey and black. Coloration similar to the 

 female, but the variation not so- great. Wings narrower than in the female, the 

 stems of the fork-cells a little longer, vestiture less abundant. Abdomen long de- 

 pressed with dense, pale, lateral cilia tion. Claw formula 2.1 1.1 1.1. 



Length: Body about 6.5 mm. 



Genitalia : Side-pieces more than twice as long as wide, apical lobe well devel- 

 oped, rounding, running uniformly down to base; basal lobe quadrate, protuberant, 

 clothed with short, coarse setae from tubercular bases, from its lower angle a stout 

 thick spine and a shorter one. Clasp-filament slender, long, slightly swollen medianly, 

 distally serrate and bearing several short setae, a long slender, articulated terminal 

 spine. Harpes rather narrow, concave, slightly curved, margins revolute, inner one 

 thickened, curved over at tip in a short point. Harpagones slender, columnar, uni- 

 form, with an articulated filament at apex, which is ligulate, a little expanded beyond 

 the middle and tapered to a point at tip, shaft with a few setae. Unci approximate 

 with revolute margins, forming a short stout cone. Basal appendages narrow, with 

 short stout spines at the tip. 



Larva: Head rounded, rather small, wider than long; a notch at insertion of 

 antennae; front margin arcuate. Antennae short, slightly tapering at apex, spinose; 

 tuft inserrated only a little below the middle, small, consisting of about ten hairs. 

 At apex three hairs and two digits; two of the hairs a little below apex. Ante-an- 

 tennal tuft short, multiple; lower and upper frontal tuft with only one single hair; 

 the lower always, the upper rarely with two hairs. Eyes large. 



Thorax wider than long, angled at hair-tufts; hair formula at frontal border 

 3121551213. Lateral hairs in multiple tufts and some single strong hairs. Tuft 5 



D. K. D. Vidensk. Selsk. Skr., naturvidensk. og mathem. Afd. 8. R.-ekke, VII, 1. 6 



