Dilophus febrilis (Linnaeus, 1758)

Skartveit, John, 2010, The larvae of European Bibioninae (Diptera, Bibionidae), Journal of Natural History 36 (4), pp. 449-485 : 474-479

Dilophus febrilis (Linnaeus, 1758) (®gures 84±90)

Larva described by Morris (1922).

Brownish white, dull. Full-grown body length 8.5±11.5 mm (n = 20). With short, conical dorsolateral processes on all segments.

Head. Head capsule width of ®rst instar 0.19±0.20 mm (n =10), ®fth instar 0.48±0.50 mm (n =5), sixth instar 0.55±0.69 mm (n = 8), seventh instar 0.87± 1.01 mm (n = 20) Labrum as in ®gure 84, with two pairs of short conical sensillae and a row of six or seven pointed sensillae on each side of inner surface. Mandible (®gure 85) with ®ve teeth. Maxilla (®gure 86), with two strong mesal teeth, lateral part evenly rounded without distinct teeth. Inner side of maxilla with hair-like spines. Prementum (®gure 87) front egdes and mesal projection strongly produced. Stemmata absent. Antenna diameter ca 30 m m with four sensillae.

Body. One pair of short, dorsolateral processes on each segment except ninth abdominal. Post-spiracular processes located approximately 3.5 spiracle diameters posterior to spiracle, as long as twice spiracle diameter. Eighth abdominal segment with a transverse row of six processes (including the dorsolaterals). Ninth abdominal segment with two pairs of relatively short processes which are placed nearly one process length anterior to segment hind edge. Cuticular scales roundish oval, in lateral view conical, strongly projecting. On prothoracic segment (®gure 87) scales rather close-packed, 20±25 m m wide, unarmed or with four to eight slender, pointed spines. Transverse bands with smaller scales. Metathoracic segment scales (®gure 88) approximately circular, diameter 13±17 m m with two to ®ve spines which are as long as scales. First abdominal and more posterior segments (®gure 89): scales with one to ®ve spines, some larger, oval scales (width approximately 25 m m) among the smaller, circular scales. Ninth abdominal segment, area anterior to processes covered by widely separated, tiny scales (®gure 90) each with one to three small spines, area posterior to processes with a few larger scales with four to six spines. Ventral surface of ninth abdominal segment covered by rounded scales (diameter 10±15 m m) carrying one to three spines. A few short, erect setae between the scales. Spiracles rather small and ¯at, extending one-third to one-half spiracle diameter from cuticle.

Distribution. Europe, north to Southern Scandinavia, North Africa. Common to very common in most lowland areas.

Ecology. Rather eurytopical but found in highest density in agricultural landscapes and gardens. Also common in deciduous forest and sand dunes. A lowland species, at least in Northern Europe. May occasionally damage crops and lawns ( Edwards, 1941). Full-grown larvae found in March to May and in August.

Material. Norway, RY: Finnùy , Sevheim, on cultivated meadow, 21 April 1994 3 larvae, 26 April 1994 13 larvae, 15 April 1995 2 larvae, 17 April 1995 510 larvae, 28 April 1995 93 larvae, J. Skartveit leg. (all ZMUB) .