1a mine full depth, sometimes very small; larva with thoracic feet and a sclerotised head => 2

1b mine upper- or lower-surface, never strikingly small; larva a maggot => 4

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

2a mine tiny; older larvae live free on the leaf: Plutella xylostella

2b mine larger; larvae mine all their life => 3

3a mine largely corridor-like; frass partly in strings; larva without prolegs: Ceutorhynchus minutus

3b mine entirely or largely a blotch; frass in coarse grains; larva with prolegs: Selania capparidana

4a last section of the mine a large, irregular blotch, usually situated over the midrib: Liriomyza xanthocera

4b mine ends as a corridor or secondary blotch, not associated with the midrib => 5

5a larva: rear spiraculum with 3 papillae: Liriomyza brassicae

5b rear spiraculum with 7-12 papillae: Liriomyza bryoniae