Leptopa filiformis
A smallish pale yellow fly with a superficial resemblance to an acalyptrate, such as Lyciella spp., sometimes with brownish patches but without dusting. Unlike all other British members of the family, it lacks long fine hairs on the ventral part of the occiput. Palps short and yellow with a long terminal bristle. Legs entirely pale yellow, tarsi somewhat brownish. Abdomen frequently darkened (after death?) in dry preserved specimens. All strong bristles black. Wing length: ♂ 3.5 - 4.0 - 4.4 mm (13); ♀ 4.0 - 4.7 - 5.2 mm (11).
The larvae are unknown, but it is assumed to be a leaf miner like other members of the subfamily Delininae. Adults are usually found in damp woodland and carr. For example, it was abundant in captures from Malaise traps paced in carr woodland in Oxfordshire Fens.
Widespread, local, but probably overlooked and most often found by Dipterists searching for crane-flies.
World distribution: Palaearctic: Belgium, Czech Republic, Denmark, Estonia, Finland, France, Germany, Hungary, Ireland, Netherlands, Norway, Poland, Slovakia, Sweden, Switzerland; Russia: European regions.