1a fleck mine; larva mines from a case: Coleophora vulpecula

1b corridor or blotch => 2

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

2a larva a maggot; mine upper- or lower-surface => 3

2b larva with chitinised head; mine full depth => 4

3a corridor from start to end; frass in a broad green band: Liriomyza congesta

3b corridor, widening into a blotch over the midrib; frass in the the blotch in a few black lumps: Agromyza nana

4a blotch, not unusually small, with much frass, larva mines all its life: Leucoptera onobrychidella

4b small corridor or blotch with little or no frass; older larvae live free among spun leaves => 5

5a larva with whitish markings on the thorax: Aproaerema anthyllidella

5b no whitish markings => 6

6a pinacula colourless (though the bases of the setae are black): Cnephasia incertana

6b pinacula black: Cnephasia asseclana