blotch mine, larvae feeding first towards apex of leaf and then
downwards towards base. Pupation external (Spencer,
shallow corridor, initially running up towards the leaf tip, then
switching direction and descending. Here and there remain small
islands of uneaten leaf parenchyma. Frass in regularly dispersed
granules. Pupation outside the mine (Bladmineerders van Europa).
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.
The larva is described by Griffiths (1955a),
Griffiths (1963b) and
Hering (1956); The larval
mandibles have 5 teeth; the anterior spiracles are greatly enlarged
and unusual in each having 200-250 minute bulbs (adaptation to aquatic
environment) (Spencer, 1972b:
38, fig. 102).
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).
Dimorphic; summer form of normal shape, red and thin shelled; winter
form black, thick shelled and strongly arched (Spencer,
Hosts in Great Britain & Ireland:
of year - mines: Currently unknown.
of year - adults: Currently unknown.
in Great Britain & Ireland: Uncommon. Surrey (Ash Vale)
(Spencer, 1972b: 38); Warwickshire
(Coventry) (Robbins, 1991:
135); South Yorkshire and Monmouthshire (VC35) (NBN
elsewhere: Local in western Europe including Germany, Denmark
and Finland (Spencer, 1976:
95), French mainland and Poland (Martinez in Fauna Europaea).
NBN Atlas links to known host species:
British and Irish Parasitoids in Britain and elsewhere: