Bibio brunnipes

Bibio brunnipes (Fabricius, 1794) (®gures 54±60)

Larva not previously described. Whitish yellow, dull. Total length full grown 13± 16 mm (n = 15).

Head. Head capsule width, seventh instar 1.12±1.32 mm (n =15). Labrum (®gure 54) with one pair of rather long setae on transverse carina, two pairs of strong conical sensillae on anterior edge. Mandible (®gure 55) with ®ve teeth. Maxilla (®gure 56) with two strong mesal teeth plus two smaller teeth on the inner edge, maxillary comb indistinct but with a very wide prominence situated on the inner side of front edge, two small but distinct teeth on the outer edge. Prementum (®gure 56) with prominent anterior corners, broad mesal process and eight sensillae. Stemmata absent in most of the specimens examined but one or two present on each side in some. Even when stemmata are absent there is a distinctive, unpigmente d spot where the stemmata would have been. Antenna diameter 50±60 m m with three or four sensillae.

Body. Dorsal processes situated on a straight line, arranged in three pairs, mesal pair somewhat shorter than the two lateral pairs. Processes covered by hairlike spines arising from small scales, three to ®ve spines from each scale on the ®rst segment but only one spine from each scale on the posterior segments. Processes on ninth abdominal segment situated close to hind border of segment, length approximately one-half of length of the ninth segment. Cuticle: prothorax (®gure 57) just behind head scales oval, rather regular in outline, approximately 20 m m wide by 15 m m long, each scale with three to seven spines which are approximately as long as scale. Area in front of dorsal process row: larger scales with up to 12 spines, some smaller, spineless scales between them. Bands of unarmed scales between processes rather wide. Larger scales in front of second prothoracic process row with 3±15 spines. Metathorax (®gure 58) larger scales 20±50 m m wide, with two to eight blunt spines, smaller scales ca 10 m m wide, unarmed or with a blunt peg. Spines on larger scales progressively fewer, stronger and blunter towards rear end, on ®rst abdominal segment two to ®ve spines on each larger scale, third abdominal segment and further back almost all larger scales with one spine (®gure 59). Outline of scales rather diVuse, at low magni®cation the spines appear to be situated directly on the cuticle. The single spines are 20±30 m m long. Ninth abdominal segment (®gure 60) spines shorter, on most segments reduced to blunt pegs, scales regularly oval and clearly delimited, 15 ±20 m m wide. Ventral surface of ninth abdominal segment densely covered by ca 15 m m long, pointed spines arising from small scales. Spiracles protruding one-third to one half spiracle diameter from body surface.

Distribution. Holarctic, boreoalpine species. Occurs in most mountain areas in Europe, and in North America as far south as Colorado, in subarctic areas also in the lowlands (Fitzgerald and Skartveit, 1997).

Ecology. Subalpine forest, alpine meadows, alpine willow shrublands, tundra. Rather eurytopical. Larvae frequently in grass tussocks. Probably 2-year life cycle.

Material. Norway, STI: Oppdal, Kongsvoll 950 m a.s.l., 7 July 1994 1 larva, Kongsvoll near Sprñnbekken, 1370 m a.s.l., under grass tussock, 17 June 1995 7 larvae, 17 July 1995, 88 larvae, J. Skartveit leg. (ZMUB).