Aphrosylus

Not a species I've ever seen in my part of inland Britain, and as you may already know the few records available on NBN Atlas and on iRecord are all coastal. However, we should ask Martin Drake to check the scheme records (the Dolichopodidae recording scheme data is not yet available via NBN Atlas).

It's an Aphrosylus alright - the massive hooked proboscis ('beak') is a give-away.  The raptor/celtiber pair are easily muddled in females, which your is, but it's one of this pair (not the tiny ferox or mitis). I gave a new key to both sexes in E&D Newsletter No 22, 7-8 (2017) (all newsletters are now downloadable from this site).  It's extremely unlikely to be in Herefordshire - all the record in the E&D scheme for all Aphrosylus (except one of my own for mitis that I don't believe!) are coastal.  Ray Poulding showed that celtiber feed on barnacles (Poulding, R.H. 1998. The larvae of Aphrosylus celtiber Haliday (Diptera, Dolichopodidae) as predators of the littoral barnacle Chthamalus montagui Southward (Cirripedia, Chthamalidae). Dipterists Digest (Second Series) 5, 70 - 74) and it is most probably that raptor has the same biology.  Aphrosylus raptor is less widespread than celtiber (except for four scattered Scottish records and one in Kent that may be errors); it is found from Dorset to Anglesey, whereas celtiber is all round the British coast (no records for East Anglia).  This probably doesn't help you, but that's what I know about these beasts.

Apologies again for not getting the recording shceme data to the NBN, but just checking for this querie I found yet another grid-ref error (Adrian's - I cannot edit it) putting an Aphrosyus well inland. The database is full of such errors.

Thank you - this is clearly a case where my notebook did not keep pace with my pooter.  We were living in Devon at the time, and no doubt my record stems from work on the south Devon or Cornish coast.