1a mine full depth; larva with thoracic feet and a well visible head => 2

1b mine upper- or lower-surface; larva a maggot, without feet and apparently headless => 6

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

2a mine small, of indefinite shape, almost without frass; larva grey, with length lines => 3

2b blotch mine, with clear amounts of frass; larva light coloured, with length lines => 4

3a larva: pinacula colourless (the bases of the setae themselves are black): Cnephasia incertana

3b pinacula black: Cnephasia stephensiana

4a larva yellowish green to yellowish brow: Stenoptilia zophodactylus

4b larva pale green => 5

5a on Gentiana clusii, verna: Stenoptilia graphodactyla

5b on G. pneumonanthe: Stenoptilia pneumonanthes

6a pupation within the mine => 7

6b pupation external => 11

7a gallery up to the end => 8

7b finally a blotch => 10

8a gallery stellately branched: Chromatomyia gentianae

8b several galleries all descending from the leaf-tip => 9

9a on G. acaulis, cruciata, and lutea; puparium pale: Chromatomyia gentii

9b on G. punctata; puparium black: Chromatomyiia pseudogentii

10a frass in thick, dark green strands: Chromatomyia skuratowiczi

10b frass in thick grains: Chromatomyia gentianella

10c frass not described (mine on Gentiana acaulis): Chromatomyia hoppiella

11a mine ultimately a large, primary blotch: Chromatomyia vernalis

11b a gallery to the end, but possibly forming a secondary blotc => 12

12a gallery starts in e base of the leaf; on Gentianella species: Liriomyza amarellae

12b gallery begins at a random place: Liriomyza bryoniae