Hirschfeldia, hoary mustard

fam. Brassicaceae

1a whitish or mottled, irregular blotch overlying the midrib => 2

1b upper- or lower-surface corridor => 3

1c full depth corridor or blotch (not associated with the leaf venation) => 5

1d gallen etc => 100

2a frass powdery, in green “clouds”: Scaptomyza flava

2b frass in back grains or strings: Liriomyza xanthocera

3a pupation within the mine, in a, usually lower-surface, pupal chamber; frass in discrete granules: Chromatomyia horticola

3b pupation outside the mine; frass in strings => 4

4a mine pinnately branched, main branch overlying the midrib: Liriomyza strigata

4b mine not associated with the leaf venation: Liriomyza brassicae

5a miine small (< 1 cm), often irregular; frass in granules; larva, with prolegs, later lives free => 6

5b mijn > 1 cm, frass in strings or lumps; larva, without prolegs, remains in the mine all its life => 7

6a mine contains a little silk; free living larvae among spun leaves: Cnephasia incertana

6b mine contains no silk; free living larvae at the leaf underside: Plutella xylostella

7a frass in thread fragments; mine an untidy corridor; larva without thoracic feet: Ceutorhynchus minutus

7b frass in lumps; mine an irregular blotch; larva with thoracic feet: Phyllotreta nemorum

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: Ceutorhynchus chalibaeus

104 – Diptera

104a Cecidomyiidae: Asphondylia stefanii; Contarinia nasturtii; Gephyraulus raphanistri

109 – powdery and downy mildews

109a Erysiphaceae: >Erysiphe cruciferarum; Leveillula taurica

109b Peronosporaceae: Peronospora erucastri

110 – other causers

110a Fungi, Albuginaceae: Albugo candida

110b Plasmodiophoromycota: Plasmodiophora brassicae

Not included in the key: Ceutorhynchus pallidactylus