1a larva with chitinised head => 2

1b larva a maggot => 4

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

2a larva greyish green, with prolegs; a leaf is completely mined out: Hellula undalis

2b larva bone coloured, without prolegs; mine less extensive => 3

3a larva without feet; mine more or less a gallery: Ceutorhynchus minutus

3b larva with thoracic feet; mine more blotchy: Phyllotreta nemorum

4a a gallery to the end; frass in discrete black grains; pupation in the mine, in a, usually lower-surface, pupal chamber: Chromatomyia horticola

4b mine in the end a blotch; frass powdery or in strings; pupation usually external, never in a pupal chamber => 5

5a frass in black strings: Liriomyza xanthocera

5b frass, powdery, in green clouds, often only visible after the mine has been opened: Scaptomyza flava