1a blotch, in which eventually an excision is made => 2

1b large blotch, preceded by a corridor that begins on the midrib: Orchestes fagi

1c large blotch without a preceding corridor, containing a discoid cocoon (rare on this host plant): Tischeria decidua

1d tentiform mine => 4

1e small blotch without an excision or preceding corridor => 6

1f corridor => 8

1g elongated, silvery blotch overlying a vein; Phyllonorycter leucographella

1h fleck mine; larva mines from a transportable case: Coleophora currucipennella

1i small, full depth mines of variable, indefinite shape => 10

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

2a the excision is hardly smaller than the mine => 3

2b the excision is much smaller than the mine: Incurvaria oehlmanniella

3a larva with on each thoracic segment a black dorsal plate: Incurvaria koerneriella

3b a black dorsal plate on the pronotum only; meso- and metanotum with only a small dark spot: Incurvaria masculella

4a mine small (< 9 mm), rectangular; lower epidermis brown: Parornix fagivora

4b mine larger, more oval or tubular; lower epidermis green => 5

5a mine oval, ca. 12 mm; cocoon in the mine incrusted with grains of frass; (uncommon): Phyllonorycter messaniella

5b mine more elongate, even tubular; frass in a corner of the mine, the cocoon, without frass, in the other corner; (very common): Phyllonorycter maestingella

6a mine lower-surface, usually not in a vein axil: Parornix fagivora

6b mine full depth, usually in a vein axil => 7

7a larvae in July-August: Caloptilia alchimiella

7b larvae in May, then again in August: Caloptilia robustella

8a corridor ≤ 1 cm; egg shell at start of the mine iridescent: Bucculatrix thoracella

8b corridor > 2 cm; egg shell shining => 9

9a frass coiled; mine usually begins at the leaf margin, winds downwards towards the midrib: Stigmella hemargyrella

9b frass not coiled; mine usually begins near the midrib and zigzags out in the direction of the leaf margin: Stigmella tityrella

10a larva: pinacula colourless (the bases of the setae themselves are black) : Cnephasia incertana

10b pinacula black: Cnephasia asseclana