1a larva with well recognisable head; mine full depth, transparant => 2

1b larva a maggot; mine upper- or lower-surface, greenish when lighted from behind => 6

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

2a larva with prolegs; older larvae live free; mine mostly quite small => 3

2b no prolegs; larve mines livelong; mine not that small, a corridor => 5

3a body of larva dark: Cnephasia incertana

3b body of larva ± bone coloured => 4

4a older larva live free under a leaf: Plutella xylostella

4b older larvae live in some leaves, held together with silk: Hellula undalis

5a larva without feet: Ceutorhynchus minutus

5b larva with thoracic feet: Phyllotreta nemorum

6a mine a corridor, in the end widening into an irregular blotch => 7

6b a corridor from start to end => 8

7a frass powdery, in green clouds in remote corners of the mine: Scaptomyza flava

7b frass black, in grains or strings: Liriomyza xanthocera

8a corridor pinnately branched, its main and side branches on top of the midrib and lateral veins: Liriomyza strigata

8b several short corridors, starting from the midrib: Ophiomyia beckeri

8c corridor independent of the leaf veins => 9

9a pupation within the mine, in a, generally lower-surface, pupal chamber: Chromatomyia horticola

9b pupation external => 10

10a larva: rear spiraculum with 7-12 papillae: Liriomyza bryoniae

10b rear spiraculum with 3 papillae: Liriomyza brassicae