Bibio marci (Linnaeus, 1758)

Skartveit, John, 2010, The larvae of European Bibioninae (Diptera, Bibionidae), Journal of Natural History 36 (4), pp. 449-485 : 460-462

Bibio marci (Linnaeus, 1758) (®gures 19±25)

Larva described by Morris (1921).

Large, greyish, dull, head capsule black, larger cuticular spines black.

Total length 20.5±23.5 mm (n = 5, collected in January).

Head. Head capsule black, width in last instar 1.36±1.42 mm (n = 5). Labrum (®gure 19) with three pairs of large sensillae and one pair of short setae on the transverse carina. Mandible (®gure 20) with four teeth. Maxilla (®gure 21) without a comb of teeth, lateral part of fore margin evenly rounded, mesally with one distinct tooth. Inner surface with long, slender spines and 10±12 round`holes’. Maxillary palp with a row of approximately eight spines on membraneous area. Prementum (®gure 21) rather wide with prominent anterior corners and indistinct mesal projection, 8±10 sensillae. Stemmata absent. Antenna diameter ca 70 m m with one or two large and three to four smaller conical sensillae.

Body. Processes slender. Post-spiracular process absent on prothorax, situated above spiracle on metathorax. Otherwise post-spiracular processes approximately ®ve spiracle diameters long, situated 2.5 spiracle diameters posterior to spiracle. Dorsal process row with lateral processes approximately twice as long as the two mesal processes, submesal processes slightly longer than mesal ones. Processes on ninth abdominal segment situated near hind border of segment. Spiracles rather small, protruding approximately one-half spiracle diameter from body surface. Cuticle: cuticular scales with black spines, contrasting against scales. Prothorax (®gure 22) scales on anterior part rounded, well separated, regular in outline, 25± 40 m m wide with one to four spines, in the extreme anterior area with one size of scales only, smaller unarmed scales, 6±20 m m wide between the larger, spinebearing ones from just anterior to ®rst process row caudad. A few multispine scales, 30±45 m m wide with 5±10 spines, present between processes in ®rst process row. Most posterior part covered by large multispine and smaller unarmed scales. Metathorax (®gure 23) with rounded scales in three size categories: largest scales 30±45 m m wide, each with several spines, intermediate scales 6±15 m m wide with a single spine and small unarmed scales. First abdominal segment with large, nearly circular scales with fewer spines, many single-spine scales. Fourth abdominal segment (®gure 24), larger scales 30±45 m m wide mostly with one but some with up to three spines, smaller scales 8±13 m m wide, unarmed or with a short spine. Ninth abdominal segment (®gure 25) covered by single-spine scales, 40±55 m m wide. Venter of ninth abdominal segment with scales smaller than dorsum, but otherwise rather similar.

Distribution. Europe north to Southern Scandinavia.

Ecology. Mainly on seashore meadows at the northern border of its distribution, but rather eurytopical further south. Allen (1974) bred the species from welldecayed wood.

Material. Sweden, Sk: Revingehed ex coll. Christine Dahl, 6 larvae .