1a larva in the midrib, from there excursions into the blade: Napomyza bellidis

1b blotch, possibly with a short initial corridor, usually overrun by the blotch => 2

1c corridor, more or less broadened towards the end => 3

1d fleck mine: Coleophora ramosella

1e mine small, of indefinite shape => 10

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

2a mine contains no frass and is hardly larger than the puparium inside: Hydrellia griseola

2b mine contains frass and is much larger: Calycomyza humeralis

3a corridor full depth; larva with clear, chitinised, head => 4

3b corridor upper-surface; larva a headless maggot => 6

4a corridor starts at the leaf base or the midrib => 5

4b no fixed start position; larva with thoracic feet: Apteropeda orbiculata

5a larva without feet: Orthochaetes insignis

5b larva with thoracic feet: Cnephasia ecullyana

6a main corridor positioned over the midrib, short side branches overlying secondary veins: Liriomyza strigata

6b corridor runs freely through the leaf => 7

7a frass very fine; larva: mandible with 1 tooth Hydrellia griseola

7b frass coarser; mandible with 2 teeth => 8

8a frass in strings: Liriomyza pusilla

8b frass in discrete grains => 9

9a corridor from start to end; larva: rear spiraculum with c. 14 papillae: Phytomyza virgaureae

9b corridor usually widens into a blotch; rear spiraculum with (15-) 18 (-21) papillae: Phytomyza bellidina

10a larva: pinacula colourless (the bases of the setae themselves are black) : Cnephasia incertana

10b pinacula black => 11

11a larva: behind/below the anus a chitinous comb: Cnephasia asseclana

11b anal comb absent: Cnephasia stephensiana