1a full depth corridor (sometimes quite wide), often beginning at the leaf base or midrib, never seemingly ending upon the midrib; larva with chitinised head: Orthochaetes insignis

1b mine upper- or lower-surface; larva a maggot => 2

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

2a secondary feeding lines conspicuous in the widest parts of the mine => 3

2b no secondary feeding lines apparent => 6

3a mine begins with a long, hair-thin corridor that transverses the leaf, cutting off the distal part that is killed; here the mine continues into a large blotch: Stemonocera cornuta

3b blotch or wide corridor, clearly associated with the midrib; a narrow initial corridor, if at all visible, never cutting off part of the leaf => 4

4a oval lobed blotch with a dark centre (frass concentration): Trypeta artemisiae

4b mine with different shape, no darkened centre => 5

5a mine more or less a corridor: Trypeta zoe

5b mine consists of several connected blotches: Cornutrypeta spinifrons

6a mine a pinnately branched corridor, its main branch positioned over the midrib: Liriomyza strigata

6b mine a corridor, but not pinnately branched, not associated with the midrib => 7

7a puparium in the mine, in a, usually lower-surface, pupal chamber: Chromatomyia cf. syngenesiae

7b larva leaves the mine prior to pupation through a semicircular exit slit => 8

8a long slender upper-surface gallery in Senecio ovatus, often partly following the midrib; frass in discrete grains: Phytomyza senecionis

8b otherwise => 9

9a short, relatively wide upper-surface gallery; frass in pearl chains or strings: Liriomyza erucifolii

9b very long, inconspicuous lower-surface gallery, continued in a much shorter normal upper-surface one: Phytomyza marginella