1a fleck mine => 2

1b corridor or blotch => 4

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

2a hole untidy, not precisely circular; case helicoid: Apterona helicoidella

2b hole exactly circular; case tubular => 3

3a case strongly constricted behind the orifice; usually on the flower heads: Coleophora tanaceti

3b case hardly constricted behind the orifice; a true leaf miner: Coleophora trochilella

4a mine full depth; larva with chitinised head => 5

4b mine upper- or lower-surface; larva a maggot => 6

5a mine begins as a corridor in the leaf base or midrib (after mine change more blotchy and no more associated with leaf base or midrib); larva without feet: Orthochaetes insignis

5b a tentiform mine, not associated with leaf base or midrib; larva with thoracic and abdominal feet: Scrobipalpa proclivella

6a secondary feeding lines conspiduous; a blotch or broad corridor => 7

6b no secondary feeding lines visible; distinctly a corridor => 8

7a oval lobate blotch with a dark central spot (frass accumulation): Trypeta artemisiae

7b corridor or elongate blotch without dark centre: Trypeta zoe

8a pinnately branched corridor positioned over midrib and main lateral veins: Liriomyza strigata

8b mine less strongly and regularly branched, not associated with the leaf venation => 9

9a puparium in the mine, in a, usually lower-surface, pupal chamber: Chromatomyia cf. syngenesiae

9b pupation outside the mine => 10

10a frass in strings; mine completely upper-surface; puparium yellowish; larva: rear spiraculum with 10 paillae at most: Liriomyza tanaceti

10b frass (largely) in discrete grains; initial part of the corridor lower-surface, later, conspicuous, part upper-surface; puparium black; rear spiraculum with 13 papillae at least => 11

11a mine unusually long and slender; larva: rear spiraculum with 18-20 papillae: Phytomyza pullula

11b mine broader, often as wide as a leaf segment; rear spiraculum with 13-17 papillae: Phytomyza tanaceti