1a mine < 1 cm, full depth, often in numbers together in a leaf axil; larvae, with distinct feet and chitinised head, later live free and cause extensive window feeding: Epermenia chaerophyllella

1b mine > 1 cm, not full depth; larva a maggot => 2

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

2a primary blotch with conspicuous primary and secondary feeding lines; larva: rear spiracula with 3 papillae: Euleia heraclei & Cryptaciura rotundiventris

2b corridor or secondary blotch, at least without secondary feeding lines; rear spiracula with > 3 papillae => 3

3a yellowish green, later red brown, perforate, interparenchymatic blotch: Phytomyza heracleana (occurrence on this host needs confirmation)

3b mine not perforate or inter-parenchymal => 4

4a corridor (very narrow at start, at least locally with parallel margins); may be fairly broad sometimes => 5

4b blotch (broad from the start, nowhere with parallel margins); may be elongated => 7

5a puparium in the mine, usually in an lower-surface pupal chamber: Chromatomyia horticola

5b larva leaves the mine prior to pupation => 6

6a mine with the narrow initial part long, then suddenly widened; widened part along the leaf margin; larva with frontal appendage: Phytomyza adjuncta

6b narrow initial part short, then suddenly widened; widened part not associated with leaf margin; frontal appendage absent: Phytomyza melana

7a blotch irregularly elongate, along the leaf margin; anterior spiraculum bifid: Phytomyza pimpinellae

7b blotch rounded, in the the centre of the leaflet; anterior spiraculum fist shaped: Phytomyza pauliloewii