Bibio varipes Meigen, 1830

Skartveit, John, 2010, The larvae of European Bibioninae (Diptera, Bibionidae), Journal of Natural History 36 (4), pp. 449-485 : 465-467

Bibio varipes Meigen, 1830 (®gures 1, 40 ±46)

Larva not previously described although aspects of its biology has been treated by Beling (1872), Schremmer (1958) and Hellrigl (1995). Yellowish brown, dull.

Head. Head capsule width ®rst instar 0.19 mm (n = 3), fourth instar 0.39±0.42 mm (n =27), ®fth instar 0.48±0.55 mm (n = 9), sixth instar 0.68±0.80 mm (n =33), seventh instar 0.93±1.06 mm (n =10). Labrum (®gure 40) with one pair of rather short, pointed setae on transverse carina. Mandible (®gure 41) with four teeth. Maxilla (®gure 42) mesally with two very strong teeth plus two small teeth on the inner edge, maxillary comb indistinct, with ®ve weak prominences. Seta on outer front edge rather long. Inside of maxilla with 6±11 round`holes’, spines on inner surface all pointed. Maxillary palp with a series of four to ®ve spines on membraneous area. Prementum (®gure 42) with anterior corners not prominent, 8±11 sensillae. Stemmata present in most individuals. Antenna diameter 45±55 m m.

Body. Dorsal processes arranged in three pairs, rather stout, the median pair slightly shorter than the other processes. Post-spiracular processes three to four times as long as diameter of spiracle, placed approximatel y 2.5 times spiracle diameter posterior to the spiracle. Processes on ninth abdominal segment approximately as long as the segment. Cuticle: prothorax (®gure 43) scales in front of ®rst process row closely packed, irregularly oval, 13±30 m m wide, most bearing 10±25 slender spines which are approximately as long as the scales. Prothorax behind ®rst process row with smaller scales, the spine-bearing ones each bear 2±10 spines. Outline of scales progressively more irregular and indistinct towards the rear end, with fewer and blunter spines. Metathorax (®gure 44) scales ca 13± 25 m m wide with two to eight spines. Fourth abdominal segment (®gure 45) scales 15±30 m m wide with three to six spines. Eighth abdominal segment scales mostly with two to four spines, ninth abdominal segment (®gure 46) scales on dorsal side ca 15±25 m m wide without spines but many with one or two blunt tubercles, outline very indistinct and irregular but apparently closely packed. On the ventral surface of the ninth abdominal segment some of the scales bear one to four blunt spines. Spiracles protruding approximatel y as far as spiracle diameter from the body surface.

Distribution. Western Europe, north to approximately 63ssN.

Ecology. Most common in deciduous forest, where the larvae feed on leaf litter, but also occurs in coniferous forest ( Schremmer, 1958). Full-grown larvae in February to April.

Material. Norway, RY: Finnùy , Sevheim, birch forest , 25 October 1993 7 larvae, 3 December 1993 4 larvae, 25 March 1994 6 larvae, 3 April 1994 4 larvae, 26 April 1994 1 larva, 23 October 1994 64 larvae, 31 December 1994 47 larvae, 16 February 1995 96 larvae, J. Skartveit leg. ( ZMUB) .