1a mine upper- or lower-surface, greenish in transparency; frass in 1 or a few large lumps; larva a maggot => 2

1b mine full depth, transparant; frass in small grains; larva with chitinised head => 4

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

2a mine ends in the leaf sheath, there also the puparium; larva: front spiraculum strongly enlarged, bifid, with > 20 papillae: Cerodontha scirpi

2b mine ends in the blade; front spiraculum normal, < 20 papillae => 3

3a larve: near the base of the rear spiraculum a black wart; papillae of the rear spiraculum enlarged, claw-like (also visible in the puparium): Cerodontha angulata

3b rear spiraculum without a black wart, papillae less specialised (occurrence on this host plant uncertain): Cerodontha suturalis

4a larva: anal shield with a thickened rim, ending to diverging teeth: Orthotelia sparganella

4b anal shield withouth a tickend rim, untoothed => 5

5a larvae in Autumn-May => 6

5b larvae in July-August: Monochroa moyses

6a mine begins halfway the blade, runs upwards, then descends to about the level of its begin : Elachista scirpi

6b mine begins in the leaf tip, descending from there: Elachista serricornis