Sisymbrium, hedge mustard, rocket

fam. Brassicaceae

1a mine either begins or ends in stem, petiole or midrib => 2

1b mine at most on the midrib, otherwise free in the leaf => 4

1c galls, etc => 100

2a larva withh chitinised head; mine begins on a galled and swollen part of stem or petiole => 3

2b larva a maggot; petiole normal: Scaptomyza flava

3a galled swelling of the stem conspicuous, containing ca. 3 larvae: Ceutorhynchus napi

3b galled swelling weak, usually containing 1 larva: Ceutorhynchus rapae

4a mine full depth; larva with chitinised head: Ceutorhynchus minutus

4b mine upper- or lower-surface (small patches sometimes full depth); larva a maggot => 5

5a corridor from start to end => 6

5b irregular blotch, preceded by a narrow corridor (may be overrun): Scaptomyza flava

6a broad corridor upon the midrib, pinnately branched: Liriomyza strigata

6b corridor little branched, not pinnate, not associated with the midrib => 7

7a puparium in the mine in a, usually lower-surface, pupal chamber; frass in discrete grains: Chromatomyia horticola

7b larva leaves the mine before pupation through a semicicular exit slit; frass in thread fragments => 8

8a larva: rear spiraculum with 3 papillae: Liriomyza brassicae

8b rear spiraculum with 7-12 papillae: 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 Heeroderidae: Heterodera cruciferae

102 – Acari

102a Eriophyidae: Aceria drabae

105 – Hemiptera

105a Aphididae: Lipaphis erysimi, fritzmuelleri

105b Asterolecaniidae: Planchonia arabidis

107 – rust fungi

107a Puccinaceae: Puccinia thlaspeos

109 – echte en valse meeldauwen

109a Erysiphaceae: Erysiphe cruciferarum

109b Peronosporaceae: Hyaloperonospora sisymbrii-loeselii; Peronospora rhaetica, sisymbrii-orientalis

110 – andere veroorzakers

110a Fungi, Albuginaceae: Albugo candida

110c Fungi, Plasmodiophoraceae: Plasmodiophora brassicae

Not included in the key: Apterona helicoidella; Liriomyza xanthocera; Ophiomyia beckeri; Phytomyza rufipes; Plutella xylostella; Scaptomyza griseola.