Dilophus femoratus Meigen, 1804

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

Dilophus femoratus Meigen, 1804 (®gures 2, 91±97)

Larva described by Morris (1922, as D. albipennis ) and Nielsen et al. (1954).

White, dull, head capsule dark brown. Total length full-grown 8.4±10.0 mm (n = 25, slightly shrunk). Dorsolateral processes only on three last segments. Cuticle with coarse, dark spines. Habitus as in ®gure 2.

Head. Head capsule width last instar 0.83±0.92 mm (n = 10). Labrum (®gure 91) with the smaller setae blunt. Mandible (®gure 92) with three teeth. Maxilla (®gure 93) without a distinct comb, lateral part of anterior edge even, mesally with two teeth. Prementum (®gure 93) rather wide, without mesal projection, anterior corners weakly produced, carrying eight sensillae. Stemmata absent. Antenna diameter ca 30 m m with one large and four or ®ve smaller conical sensillae.

Body. The only processes present are one pair of short dorsolateral processes on seventh abdominal segment, three pairs of dorsal processes on eighth abdominal segment, and two pairs of terminal processes on the ninth abdominal segment. Postspiracular processes absent. One specimen out of 29 in the series examined also had a pair of minute dorsolateral processes on sixth abdominal segment. Cuticular scales: prothorax (®gure 94): scales on most anterior part transversely oval, with well- de®ned outline, each carrying two to four short spines. In the middle of segment scales transverse, width 23±36 m m, without spines, on posterior part of segment scales slightly transverse, oval with two to four spines. Metathorax (®gure 95): scales closely packed, outline indistinct, with one to four strong spines. Fourth abdominal segment (®gure 96): scale outline very indistinct, most scales with one spine but some with up to four spines. Ninth abdominal segment, dorsum: (®gure 97) scales closely packed, outlines strongly undulating, each carrying one or two short spines. On dorsum of prothorax four short, erect setae arranged in a transverse band in the anterior half. On each of the more posterior segments except the two terminal ones four short setae on each side behind and below the spiracle. Spiracles protruding approximately one-half spiracle diameter from body surface.

Distribution. Occurs all over Europe up to the timberline. Also recorded from tropical Africa ( Hardy, 1951) but these records are likely misidenti®cations.

Ecology. Eurytopical species, most common on ¯ower-rich meadows. Common up to the subalpine zone. Full-grown larvae found in March to June. When breeding larvae of D. febrilis , occasionally a few imagines of D. femoratus have emerged together with D. febrilis specimens. The sample in which the D. femoratus larvae were found consisted of 29 D. femoratus larvae and 2 D. febrilis larvae. These larvae were all collected from what appeared to be one single cluster of larvae. This indicates that the larvae of the two species occur together, perhaps even forming mixed aggregations.

Material. Norway, RY, Finnùy : Sevheim, under grass on cultivated meadow, 15 April 1995, J. Skartveit leg., 29 larvae ( ZMUB) .