1a fleck mine => 2

1b corridor or blotch => 9

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

2a case helicoidal; holes in the mines not neatly circular, rim not with stubbles of bitten silk: Apterona helicoidella

2b case more or less straight, tubular; rim with stubbles => 3

3a lobe case: Coleophora ptarmicia

3b no lobe case => 4

4a case black => 5

4b case more or less straw coloured => 7

5a case laterally compressed => 6

5b case laterally hardly compressed, tubular: Coleophora ditella

6a mouth angle 0°-10°, case flat on the leaf: Coleophora vibicigerella

6b mouth angle about 45°, case oblique on the leaf: Coleophora partitella

7a case felty or hairy => 8

7b case smooth => 9

8a case slender, felty, up to 12 mm: Coleophora expressella

8bcase squat, long-hairy, much smaller: Coleophora millefolii

9a larva: head and pronotum dark brown to black: C. follicularis

9b head and pronotum very pale brown => 10

10a larva: rear margin of pronotum a fine dark line: Coleophora trochilella

10b rear margin of pronotum with two dark spots: Coleophora gardesanella

11a small, full depth blotch (usually at the leaf margin/tip), where an oval excision is made: Incurvaria praelatella

11b mine different, never with an excision => 12

12a mine full depth, transparent; larva with thoracic feet and a chitinised head => 13

12b mine upper- or lower-surface, not transparent; larva a maggot => 18

13a mine small, of indefinite shape => 14

13b mine larger, corridor or blotch => 15

14a pinacula colourless (only the base of the setae dark): Cnephasia incertana

14b pinacula black: Cnephasia asseclana

15a mine begins as a narrow corridor with a central frass line =>16

15b mine different, blotch or tentiform, without a corridor beginning => 17

16a older larvae make fleck mines, in which the enter the leaf from its very margin: Bucculatrix clavenae

16b older larvae generally live free: Bucculatrix cristatella

17a larva with red dorsal length lines: Scrobipalpa proclivella

17b larva with only dark green dorsal length lines: Sophronia humerella

18a mine with conspicuous primary and secondary feeding lines => 19

18b no feeding lines apparent => 20

19a yellow-brown blotch; most frass concentrated in a blackish centre: Trypeta artemisiae

19b blotch or wide corridor; frass scattered, no dark centre: Trypeta zoe

20a pale green blotch mine: Calycomyza artemisiae

20b corridor mine => 21

21a narrow corridor that ends upon a thick vein: Ophiomyia curvipalpis

21b corridor does not end this way => 22

22a puparium in the mine, usually in a lower-surface pupal chamber: Chromatomyia cf syngenesiae

22b puparium formed after the mine has been vacated => 23

23a frass in strings or pearl chains => 24

23b frass in discrete grains => 25

24a pinnately branched corridor, main branch positioned upon the midrib; larva: rear spiracula with 9-13 papillae: Liriomyza strigata

24b mine not associated with the midrib; rear spiracula with 3 papillae: Liriomyza ptarmicae

25a mine an extremely narrow corridor, even in the thinnest leaf segments; only in Achillea millefolium => 26

25b mine less extreme; in Achillea ptarmica (and garden achillea’s) => 27

26a larvae in May – September; generally the corridor descends from leaf tip to base: Phytomyza pullula

26b larvae in May; generally the corridor ascends from leaf base to tip: Phytomya achilleae

27a mine often follows the midrib over long distances: Phytomyza corvimontana

27bno association with the midrib => 28

28a frass in widely separated grains, therefore not clearly in two rows: Phytomyza ptarmicae

28b frass grains closely set, clearly in two rows: Phytomyza tanaceti