A narrow external stem mine on upper part of stem below flower head.
Pupation external (Spencer, 1976:
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:
of year - mines: August.
of year - adults: Currently unknown.
in Great Britain & Ireland: Middlesex (Scratch Wood - mines
only) (Spencer, 1972b: 55);
Glamorganshire (VC41), North Somerset and South Wiltshire (NBN
elsewhere: Western Europe, uncommon (Spencer,
1990) including Sweden, Finland and N. Germany (Spencer,
1976: 248), Czech Republic, French mainland, Lithuania and Poland
(Martinez in Fauna Europaea).
NBN Atlas links to known host species:
British and Irish Parasitoids in Britain and elsewhere: Currently unknown.