1a mine full depth, not associated with the midrib; larva with chitinised head => 2

1b mine upper- or lower-surface (small patches sometimes full depth), associated with the midrib; larva a maggot => 3

1c fleck mine => 5

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

2a larva without feet; mine an untidy corridor: Ceutorhynchus minutus

2b larva with thoracic feet; mine eventually widening into a blotch: Phyllotreta nemorum

3a broad, pinnately branched corridor: Liriomyza strigata

3b irregular blotch => 4

4a frass in thread fragmentsl mine in May-June: Liriomyza xanthocera

4b frass powdery, in blackish-green clouds; mine in May-October: Scaptomyza flava

5a case helicoidal: Apterona helicoidella

5b case tubular: Coleophora onopordiella