1a pinnately branched gallery, main and side branches on top of midrib and side veins: Liriomyza strigata

1b gallery not pinnately branched, running independently of the leaf venation => 2

1c galls, etc => 100

2a pupation within the mine, in a, generally lower-surface, pupal chamber; frass in isolated grains: Chromatomyiia cf syngenesiae

2b pupation outside the mine; frass in strings: 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 Aphelenchoidae: Aphelenchoides fragariae

101b Meloidogynidae: Meloidogyne hapla

108 – smut fungi

108a Entylomataceae: Entyloma dahliae

109 – powdery and downy mildews

109a Erysiphaceae: Golovinomyces orontii, spadiceus; Neoërysiphe cumminsiana

110 – other causers

110a Bacteria, Actinomycetales: Rhodococcus fascians

110b Bacteria, Rhizobiales: Agrobacterium tumefaciens

110c Fungi, Pleosporaceae: Alternaria carolinaeana

Not included in the key: Liriomyza trifolii.