1a mine full depth, finally a blotch; larva with chitinised head => 2

1b upper- or lower-surface corridor; larva a maggot => 3

1c fleck mine => 4

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

2a blotch at leaf margin, with a central dark frass concentration: Pseudorchestes persimilis

2b blotch not necessarily at the leaf margin, no central frass concentration: Digitivalva pulicaria

3a frass in discrete grains; puparium always in the mine: Chromatomyia cf. syngenesiae

3b frass in pearl chains; puparium sometimes in, sometimes outside the mine: Phytomyza conyzae

4a larva in a spatulate leaf case: Coleophora conyzae

4b larva in a tubular silken case => 5

5a case 9-10 mm: Coleophora follicularis

5b case ca. 15 mm: Coleophora inulae