1a mine full depth; larvae with feet and chitinised head; pupation outside the mine => 2

1b mine upper-surface; larva a maggot; pupation within or outside the mine => 3

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

2a the following Elachistidae have been recorded from Deschampsia. The mines and larvae of many are too incompletely known to place them in a key: Elachistaadscitella, albidella, albifrontella, apicipunctella, argentella, bifasciella, bisulcella, canapennella, cinereopunctella, compsa (occurrence on this plant very doubtful), dimicatella, disemiella, exactella, gleichenella, humilis, luticomella, nobilella, pullicomella, stabilella

3a puparium in the mine => 4

3b pupation outside the mine => 6

4a larva green; puparium red brown; spiracula do not penetrate the epidermis: Cerodontha imbuta

4b larva whitish or hyaline => 5

5a puparium orange brown, front spiracula penetrating the epidermis: Chromatomyia nigra

5b puparium metallic black, spiracula not penetrating: Cerodontha pygmaea

6a larva: cephalic skeleton of Agromyzinae-type * => 7

6b cephalic skeleton of Phytomyzinae-type => 9

7a larva: mandible with 3 teeth: Agromyza lucida

7b mandible with 4 teeth => 8

8a larva: rear spiracula almost touching each other: Agromyza albipennis

8b rear spiracula separated by more than their own diameter: Agromyza nigripes

9a larva: rear spiraculum with 3 papillae => 10

9b rear spiraculum with ≥ 8 papillae: Metopomyza flavonotata

10a frass grains with hazy outlines, arranged irregularly, large and small ones mixed: Liriomyza richteri

10b frass grains with sharp outlines, in two rows, even in size: Liriomyza flaveola