Bibio johanni

Skartveit, John, 2010, The larvae of European Bibioninae (Diptera, Bibionidae), Journal of Natural History 36 (4), pp. 449-485 : 462-465

Bibio johanni s ( Linnaeus, 1767) (®gures 3, 4, 33±39)

Larva described in great detail by Morris (1917).

Greyish brown (earth-coloured), dull. Cuticular scales conspicuously large, with several spines all over the body. Total length full grown 10.5±12.5 mm (n = 14).

Head (®gures 3, 4). Head capsule width ®rst instar 0.18±0.20 mm (n = 16), second instar 0.24 ±0.25 mm (n = 2), fourth instar 0.37±0.38 mm (n = 3), ®fth instar 0.46±0.50 mm (n = 5), sixth instar 0.61±0.70 mm (n =5), seventh instar 0.78±0.94 mm (n =18). Labrum (®gure 33) with one pair of rather short setae on transverse carina. Mandible (®gure 34) with three blunt teeth. Maxilla (®gure 35) mesally with two prominent teeth, maxillary comb without distinct teeth, on the inside with 11±17 round`holes’. Spines in the middle of inside of maxilla rather short, blunt, those on the sides longer and pointed. Maxillary palp with a series of three to ®ve spines on membraneous area. Prementum (®gure 35) anterior corners rather weakly produced, with eight conical sensillae. Stemmata present. Antenna diameter 40±50 m m with one large and four to ®ve slightly smaller conical sensillae.

Body. Dorsal processes row with processes arranged in three pairs, the six processes rather short, approximately equally long. Processes on ninth abdominal segment as long as two-thirds to four-®fths of segment length, situated near hind edge of segment. Cuticle: prothorax (®gure 36) scales 23±33 m m wide, irregularly oval with three to eight pointed spines, closely packed anterior to ®rst process row. Bands of unarmed scales narrow. Some large, unarmed scales just behind processes. A few`giant scales’ 50 ±90 m m wide with up to 40 spines present. Metathorax (®gure 37) and ®rst abdominal segment large scales 30±40 m m wide, irregular in outline, with three to eight spines, smaller scales 10±13 m m wide. Transverse band anterior to processes with tiny scales mostly carrying a short spine, posterior to processes with large unarmed scales. Smaller scales with one to three spines. Fourth abdominal segment (®gure 38) larger scales (width 30±45 m m) irregular in outline, with three to eight strong, pointed spines as long as scales. Smaller scales 13±20 m m wide mostly with one to three short spines. No large, unarmed scales posterior to processes. Eighth abdominal segment: large scales mostly with one to three short spines. Ninth abdominal segment (®gure 39): scales 40 ±70 m m wide, close-packed, very irregular in outline, with one or two short, blunt spines, laterally smaller. Venter of ninth abdominal segment densely covered by small scales each carrying a single, slender spine. Spiracles: protruding approximately one-half spiracle diameter from body surface. Post-spiracular process approximately two spiracle diameters long situated approximately 1.3 spiracle diameters posterior to spiracle. Dorsal process row: processes evenly spaced, the lateral two processes longer than the mesal four.

Distribution. All over Europe north to southern Scandinavia. Not at high altitudes.

Ecology. Seems to be most common on cultivated land but can also be found in gardens (lawns) and pastures. May occasionally damage crops ( Port and French, 1984). Full-grown larvae found in February to April.

Material. Norway, RY: Finnùy ( EIS 14 ): Sevheim, on cultivated meadow 18 October 1992 3 larvae, 31 December 1994 12 larvae, 19 February 1995 14 larvae, J. Skartveit leg. ( ZMUB) .