1a short gallery, that ends or begins on a thick vein; the larva essentially lives as a borer in the veins, petiole, or stem: Ceutorhynchus pallidactylus

1b the larva does not mine in (though sometimes upon!) the veins => 2

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

2a pinnately branched gallery, main and side branches on top of the midrib and side veins: Liriomyza strigata

2b blotch, or little, not pinnately, branched gallery; mine not determined by the leaf venation => 3

3a larva a maggot; mine partly or entirely upper- or lower-surface => 4

3b larva with chitinised head; mine full depth => 7

4a gallery from start to end => 5

4b blotch, may begin with a gallery => 6

5a pupation within the mine, in a, generally lower-surface, pupal chamber; frass in well-spaced grains: Chromatomyia horticola

5b pupation external; frass in strings: Liriomyza bryoniae

6a frass powdery, in dark green “clouds” in corners of the mine, often visibly only after the mine has been opened: Scaptomyza flava

6b frass in black strings: Liriomyza xanthocera

7a larva with prolegs; older larvae live free at the underside of the leaf: Plutella xylostella

7b no prolegs; larvae mine all their life => 8

8a larva with thoracic legs: Phyllotreta nemorum

8b larva without legs: Ceutorhynchus minutus