Holcus, yorkshire fog, creeping soft-grass

1b corridor or blotch => 2

1a fleck mine, larva mines from a transportable case => 17

1c galls, etc => 100

2a larva with feet and chitinised head; pupation outside the mine (Elachistidae) => 3

2b larva a maggot; pupation within or outside the mine => 4

3a the mines of the following species are hardly diagnostic and the larve in many cases are insufficiently described; a key cannot be made: Elachista albifrontella, apicipunctella, argentella, bifasciella, canapennella, chrysodesmella, diederichsiella, dimicatella, freyerella, hedemanni, herrichii, humilis, maculicerusella, nobilella, pullicomella, rufocinerea, subnigrella, subocellea, unifasciella

4a larva: mandible with 1 tooth; at the start of the mine (often in a leaf sheath) at the outside an egg shell: Hydrellia griseola

4b mandible with 2 or more teeth; no egg shell visible => 5

5a larva: cephsalic skeleton of Agromyzinae-type; pupation outside the mine => 6 *

5b kcephsalic skeleton of Phytomyzinae-type; pupation within or outside the mine => 7

6a larva: ventrally, behind the mandibles a field with spinulose warts; mandible with 2 teeth: Agromyza mobilis & A. nigrella

6b no such field; mandible with 4 teeth: Agromyza nigripes

7a mine partly or wholly within a leaf sheath: Cerodontha denticornis

7b mine entire in the blade => 8

8a puparium in the mine => 9

8b pupation outside the mine => 14

9a puparium: spiracula penetrate the epidermis => 10

9b puparium not connected with the world outside => 13

10a larva and puparium with strongly enlarged, fang-shaped, rear spiracula that anchor in the leaf tissue: Chromatomyia milii

10b rear spiracula normal => 11

11a puparium shining black; rear spiracula penetrate: Cerodontha muscina

11b puparium orange brown; front spiracula penetrate => 12

12a puparium monochromous; front spiracula indistinctly bifid: Chromatomyia nigra

12b puparium ventrally with a darkened length band; front spiracula fist-shaped: Chromatomyia fuscula

13a larva: the black warts at the outside of the rear spiracula small, without a ‘root’: Cerodontha incisa

13b these warts large, with a deep ‘root’: Cerodontha pygmaea

14a larva and puparium with transverse row of long, spine-like papillae: Pseudonapomyza atra

14b larva and puparium without long spines => 15

15a larva: rear spiraculum with 3 papillae: Liriomyza flaveola

15b rear spiraculum with 6 papillae: Liriomyza phryne

15c rear spiraculum with ≥ 10 papillae => 16

16a larva: above the mandibles a band of fine hairs; both mandibles with 2 teeth: Cerodontha flavocingulata

16b above the mandibles a band of fine warts; one mandible with 1, the other with 3 teeth: Metopomyza flavonotata

17a just behind the mouth the case is somewhat narrowed and clearly bent: Coleophora lixella

17b not so: Coleophora ornatipennella

100a Nematoda => 101

100b Acari => 102

100c Coleoptera => 103

100e Diptera => 104

100f Hemiptera => 105

100d Hymenoptera => 106

100g rust fungi => 107

100h smut fungi => 108

100i powdery and downy mildews => 109

100j other causers => 110

101 – Nematoda

101a Anguinidae: Anguina graminis; Ditylenchus dipsaci; Subanguina radicicola

102 – Acari

102a Eriophyidae: Abacarus hystrix; Aceria tenuis; Aculodes dubius, holcusi

104 – Diptera

104a Cecidomyiidae: Haplodiplosis marginata; Hybolasioptera fasciata; Mayetiola holci

104b Chloropidae: Oscinella frit, nitidissima

105 – Hemiptera

105a Aphididae: Diuraphis holci; Laingia psammae

107 – rust fungi

107a Pucciniaceae: Puccinia coronata, graminis, holcicola, holcina, striiformis

108 – smut fungi

108a Georgefischeriaceae: Jamesdicksonia dactylidis

108b Tilletiaceae: Tilletia controversa, holci

108c Ustilaginaceae: Tranzscheliella hypodytes; Ustilago striiformis

108d Ustilentylomataceae: Ustilentyloma brefeldii

109 – powdery and downy mildews

109a Erysiphaceae: Blumeria graminis

109b Peronosporaceae: Sclerophthora macrospora

110 – other causers

110a Fungi, Ceratobasidiaceae: Ceratorhiza rhizodes

110b Fungi, Clavicipitaceae: Claviceps purpurea; Epichloe clarkii

110c Fungi, Dothideomycetes: Dilophospora alopecuri

* See also the key to grass-inhabiting Agromyza-larvae.