Apium, marshwort, celery, fool’s watercress

Incl. Helosciadium

1a corridor < 1 cm long, full depth; larvae with feet and chitinised head, the rear part of their often protrudes from the mine: Epermenia chaerophyllella

1b mine larger, upper-surface; larva a maggot, always fully inserted => 2

1c galls, etc => 100

2a primary blotch mine; primary and secondary feeding lines conspicuous; larva: rear spiracula with 3 papillae => 3

2b corridor or secondary blotch without secondary feeding lines; rear spiracula with > 3 papillae => 4

3a species of continental Europe: Euleia heraclei

3b species of the Canary Islands: Euleia separata

4a puparium in the mine, mostly in an lower-surface pupal chamber; frass in widely separated grains: Chromatomyia horticola

4b puparium formed after the mine has been left; frass in strings => 5

5a mine pinnately branched, main branch overlying the midrib: Liriomyza strigata

5b mine less strongly and never pinnately branched, sometimes a secondary blotch; no association with the midrib: 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

103 – Coleoptera

103a Curculionidae: Calosirus terminatus; Lixus iridis

107 – rust fungi

107a Pucciniaceae: Puccinia apii; Uromyces lineolatus

108 – smut fungi

108a Entylomataceae: Entyloma helosciadii

109 – powdery and downy mildews

109a Erysiphaceae: Erysiphe heraclei

109b Peronosporaceae: Plasmopara apii

110 – other causers

110a Fungi, Mycosphaerellaceae: Septoria apiicola

110b Fungi, Physodermataceae: Physoderma vagans

110c Fungi, Protomycetaceae: Buerenia inundata

110d Fungi, Synchytriaceae: Synchytrium aureum

Not included in the key: Liriomyza trifolii.