1a fleck mine => 2

1b corridor and/or blotch => 3

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

2a brownish black sheath case: Coleophora albitarsella

2b composite leaf case: Coleophora pennella

3a corridor at first, later widenend into a full depth primary blotch; the larvae may move, makes then only blotches; larva with thoracic feet and chitinised head: Stephensia brunnichella

3b upper- or lower-surface corridor and/or secondary blotch => 4

4a larva with thoracic feet: Apteropeda orbiculata

4b larva a legless maggot => 5

5aa corridor, never forming a secondary blotch: Chromatomyia horticola

5b a secondary blotch, usually in the leaf tip: Phytomyza origani