1a fleck mine: Coleophora lixella

1b corridor or blotch => 2

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

2a larva with feet and chitinised head => 3

2b larva a maggot => 5

3a larva with prolegs; rear margin of head convex => 4

3b larva without abdominal feet; rear margin of head deeply excised: Hispa atra

4a a large number of Elachistidae occur on Poa. The larvae of many species are unknown, making the construction of a key impossible: Elachista adscitella, albicapilla, albidella, albifrontella, apicipunctella, argentella, bedellella, bifasciella, canapennella, chrysodesmella, collitella, consortella, dimicatella, elegans, exactella, freyerella, griseella, humilis, luticomella, maculicerusella, obliquella, poae, pollinariella, pomerana, pullicomella, stabilella, subalbidella

5a at the start of the mine (often within a leaf sheath) at the outside an egg shell; larva: mandible with 1 tooth: Hydrellia griseola

5b no egg shell visible; mandible with 2 or more teeth => 6

6a larva: cephalic skeleton of Agromyzinae-type; pupation usually outside the mine => 7 *

6b cephalic skeleton of Phytomyzinae-type; pupation within or outside the mine => 10

7a larva: rear spiracula almost touching each other: Agromyza albipennis

7b rear spiracula at least 2x their diameter apart => 8

8a larva: rear end of cut off obliquely; larvae usually communal; mine greenish => 9

8b rear end of cut off at right angle; larva solitary; mine whitish: Agromyza rondensis

9a larvae in July (1 generations): Agromyza nigrella

9b larvae in June and August (2 generations): Agromyza mobilis

10a pupation outside the mine => 11

10b puparium witihn the mine => 13

11a larva and puparium set with transverse row of long spinelike papillae: Pseudonapomyza atra

11b no such spines => 12

12a larva: rear spiraculum with 3 papillae: Liriomyza flaveola

12b rear spiraculum with 6 papillae: Liriomyza graminivora

12c rear spiraculum with > 10 papillae: Cerodontha flavocingulata

13a puparium: either front or rear spiracula penetrate the epidermis => 14

13b puparium not connected with the outside world (Cerodontha) => 17 **

14a puparium: rear spiracula strongly elongated, fang-shaped, anchoring the puparium into the leaf tissue: Chromatomyia milii

14b rear spiracula normal => 15

15a puparium shining black; rear spiracula penetrate: Cerodontha muscina

15b puparium lighter coloured; front spiracula penetrate => 16

16a puparium monochromous orange brown; front spiracula indistinctly bifid: Chromatomyia nigra

16b puparium yellow to orange brown with a darker ventral length line; front spiracula fist-shaped: Chromatomyia fuscula

17a larva: rear spiraculum with 11-16 papillae; puparium in the leaf sheath: Cerodontha fulvipes, C. denticornis & C. atronitens

17b rear spiraculum with 6 papillae at most; puparium in the blade, fastened in the mine with strands of silk => 18

18a larva: the black warts at the outside of the rear spiracula small, without a “root”: Cerodontha incisa

18b these warts large, with a deep dark “root”: Cerodontha pygmaea