1a one or more short galleries radiating from the base of the leaf or the midrib: Psylliodes hyoscyami

1b mine otherwise => 2

1c galls, etc => Tables for all parasites per species

2b gallery => 3

2a large blotch => 5

3a frass in well-separated grains; puparium min the mine, in a, usually lower-surface, pupal chamber: Chromatomyia horticola

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

4a corridor pinnately branched; main branch overlying the midrib Liriomyza strigata

4b corridor not pinnate, freely winding through the leaf: Liriomyza bryoniae

5a at the start of the mine a lower-surface group of elliptic egg shels; larva a maggot: Pegomya hyoscyami

5b no egg shells; larvae with well-visible feet and head => 6

6a the blotch contains appreciable quantities of frass: Phthorimaea operculella

6b blotch (almost) without frass => 7

7a silk is deposited within the mine causing it to contract or pucker: Cnephasia lineata

7b mine flat => 8

8a larval green: Microlechia chretieni

8b larval brown (?): Scrobipalpa ergasima