probably a stem-borer.
Larva: The larvae of flies are leg-less maggots without a head capsule (see examples). They never have thoracic or abdominal legs. They do not have chewing mouthparts, although they do have a characteristic cephalo-pharyngeal skeleton (see examples), usually visible internally through the body wall.
Puparium: The puparia of flies are formed within the hardened last larval skin or puparium and as a result sheaths enclosing head appendages, wings and legs are not visible externally (see examples).
Hosts in Great Britain & Ireland: Currently unknown.
elsewhere: Currently unknown.
of year - larvae: Currently unknown.
of year - adults: July.
in Great Britain & Ireland: Britain including Kent (Dartford
and Tunbridge Wells), Hertfordshire (Felden), Oxford (Hill Copse, Hogley,
Yarnton), Dunbarton (Bonhill) (Spencer, 1972b: 44); Glamorganshire (VC41) and Stafford (NBN
elsewhere: Widespread in continental Europe including Austria,
Germany, The Netherlands and Denmark (Spencer,
1976: 155), French mainland, Italian mainland, Spanish mainland
(Martinez in Fauna Europaea).
NBN Atlas links to known host species:
British and Irish Parasitoids in Britain and elsewhere: Currently unknown.