Leaf-mine: Circular, lower-surface blotch, about 5 mm in diameter, often quite a number together on a leaf. Upper surface wart-like, strongly reddish discoloured, opaque. At the lower surface the mine is closed only by the epidermis. The larva is easily visible, as is its food: drops of cell sap that oozes into the mine. Pupation sometimes in the mine, sometimes in the soil. (Bladmineerders van Europa).
The blotches are also illustrated in British Leafminers.
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.
Initially white, later yellowish ( Bladmineerders van Europa).
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: Sonchus arvensis (Corn Sow-thistle), S. oleraceus (Smooth Sow-thistle), S.asper (Rough Sow-thistle)
of year - mines: Larvae from July on (Hering, 1957a); two or more generations per year, pupation of the summer generation(s) in the galls, pupation of the winter generation in the soil (Bayram, Skuhravá & Çobanoğlu (2005a) ( Bladmineerders van Europa).
of year - adults: Currently unknown.
in Great Britain & Ireland: Widespread in England and Wales (NBN
NBN Grid Map:
elsewhere: Widespread in continental Europe including Austria, Belgium, Czech Republic, Denish mainland, Finland, French mainland, Germany, Hungary, Italian mainland, Lithuania, Poland, Romania, Spanish mainland, Sweden, Switerland, The Netherlands, Ukraine, and Yugoslavia (Fauna Europaea).
NBN Interactive Grid Maps of known host species:
British and Irish Parasitoids in Britain and elsewhere: Currently unknown