1a fleck mine; larva mines from a case: Coleophora violacea

1b corridor or blotch; larva mines from the inside => 2

1c galls, etc => Tables for all parasites per species

2a full depth corridor, overlying the main veins, covered at the inside with silk and therefore opaque; from the corridor broad transparant lobes enter the leaf disc: Cosmopterix zieglerella

2b not this combination of corridor and lobes => 3

3a larva with thoracic feet and a chitinised head; older larvae live free = > 4

3b larv a maggot, mines all its life => 6

4a larva with 4 pairs of abdominal prolegs: Cnephasia incertana

4b 3 pairs of abdominal prolegs => 5

5a small triangular blotch in a vein axil; older larva in a a rolled leaf margin: Caloptilia fidella

5b irregular blotch, not at a definite location; older larva between spun leaves: Hypena proboscidalis

6a corridor long and narrow, following a major vein over a long distance; when the mine gets old this often causes the leaves to tear: Agromyza igniceps

6b corridor shorter and wider, running freely through the leaf => 7

7a corridor widening only little; pupation in the mine in a, usually lower-surface, pupation chamber; rare on this host plant: Chromatomyia horticola

7b corridor strongly widening; larva leaves the mine prior to pupation; very common on this host: Agromyza flaviceps