1a larva with chitinised head; in narrow segments of the mine frass in a more or less narrow central line => 2

1b larva a maggot; in narrow sections frass in two rows => 6

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

2a mine narrow and corridor-like till the end => 3

2b mine finally up to half as wide as the leaf => 4

3a larva whitish: Monochroa arundinetella

3b larva grey green: Donacaula forficella

4a pupation and hibernation outside the mine; most of the frass in the upper part of the mine: Elachista maculicerusella

4b pupation and/or hibernation within the mine; most of the frass low in the mine => 5

5a larva body white, retreats at daytime in a silken tube within the mine : Cosmopterix scribaiella

5b larva body brownish red, without a retreat, easily visible: Cosmopterix lienigiella

6a larva: mandible with 1 tooth: Hydrellia griseola

6b mandible with at least 2 teeth => 7

7a mine entirely or partly in the leaf sheath; puparium in the sheath => 8

7b mine in the blade => 9

8a mine entirely in the outside of the leaf sheath: Cerodontha phragmitophila

8b mine begins as a, usually upper-surface, corridor in the blade, then descends into the inside of the sheath: Cerodontha denticornis

9a larva: cephalic skeleton of Phytomyzinae-type; pupation mostly within the mine; rear spiraculum either with > 10 papillae or the papillae strongly disfigured => 10

9b cephalic skeleton of Agromyzinae-type; pupation mostly outside the mine; rear spiraculum with three oval papillae => 12 *

10a puparium strongly narrowing backwards, ending in two large spiracula on long stalks : Cerodontha phragmitidis

10b puparium not narrowing backwards, rear spiracula small => 11

11a larva: the black warts at the outside of the rear spiracula small, without a ‘root’: Cerodontha incisa

11bthese warts large, with a deep ‘root’: Cerodontha pygmaea

12a larva: rear spiracula each on its own stalked basis; mine begins with a transverse row of oviposition marks; the emerging larvae work all in the same direction, at first each in its own corridor, but soon these merge into one elongated blotch => 13

12b rear spiracula on a common base; eggs placed singly, near the leaf margin => 14

13a larva: rear arms of the cephalic skeleton transparent: Agromyza phragmitidis

13b rear arms of the cephalic skeleton black-brown: Agromyza hendeli

14a larva: mandible with 4 teeth; rear spiracula touch each other (occurrence on this host plant doubtful): Agromyza albipennis

14b mandible with 2 teeth; rear spiracula separated by 3 times their diameter: Agromyza graminicola