This is a pretty nice find. Given the (relatively) large size and the conspicuous colour, this species should be easy to record if present. But I've seen it only three times in the hundreds or sweepnet and Malaise trap samples I've examined, and always only single specimens.

This indeed is a great species.

It a very nice specimen; however, the name is wrong. It is correctly known as D. florea (Fabricius). The abdomen varies in color, as some females are almost completely brown. See Disney's 1982 paper in Ent. Mon Mag (118: 113-115).

Enlighten us, Brian. The catalogues I have seen list florescens (and, for example also Fauna Europaea), usually with florea Fabricius, 1794 as pre-occupied name. Does the 'other Bibio florea' not exist or was it a secondary homonym that has since been resolved?

Hmm, I might be wrong. I will look into this some more and get back to the list. I appreciate your pointing this out to me.

Yes, now I see it. The synonymy is in Thompson & Pont's book on Musca names. My apologies- Diplonevra florescens it is!