1a full-depth corridor or blotch; the larva spends most of its time as a stem borer: Delia echinata

1b gallery; the larve keeps within the leaf => 2

1c galls, etc => 100

2a pupation within the mine, in a, generally lower-surface, pupl chamber; frass in isolated grains: Chromatomyia horticola

2b pupation outside the mine; frass in strings => 3

3a gallery pinnately branched; main and side branches on top of midrib and side veins: Liriomyza strigata

3b corridor less, and never pinnately, branched: Liriomyza bryoniae

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: Ditylenchus dipsaci

101b Meloidogynidae: Meloidogyne hapla

109 – echte en valse meeldauwen

109a Erysiphaceae: Golovinomyces magnicellulatus; Leveillula taurica; Podosphaera xanthii

109b Peronosporaceae: Peronospora phlogina

110 – other causers

110a Bacteria, Actinomycetales: Rhodococcus fascians

Not included in the key: Liriomyza trifolii.