Megamerina dolium (Fabricius, 1805)

Identification: Elongate black shining fly with orange legs. The swollen hind femur has a row of spines beneath. Distinctive patch of white hairs on the occiput behind the eyes.

Roháček, 2012: It is a distinctive, medium-sized (6.0-9.0 mm), elongate, shining black fly with reddish femora and hind femur strikingly swollen and ventrally spinose.

I have observed this species on a couple of occasions. At first glance it appears and moves like a dark ichneumon, weaving through brambles and not resting long. Locating likely ovipositing sites and staking those out might prove a good tactic.

Distribution

Europe: Countries (published), online at Fauna Europaea, Occurrences at GBIF
UK: Recording Scheme map of occurrences 2016 (verified.) Online (NBN Atlas) via Easy maps or Interactive Atlas