1a mine < 1 cm long, full depth; larva with feet and chitinised head: Epermenia chaerophyllella

1b mine > 1 cm, upper-surface; larva a maggot => 2

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

2a mine a primary blotch with conspicuous primary and secondary feeding lines: Euleia heraclei

2b mine a corridor or a secondary blotch; feeding lines not apparent => 3

3a puparium formed in the mine, in a, generally lower surface, pupal chamber: Chromatomyia horticola

3b puparium formed after the mine has been left => 4

4a larva leaves the mine through an upper-surface exit slit: Phytomyza conii

4b exit slit lower-surface => 5

5a larva with a frontal appendage; frass grains ill-defined; first part of the gallery lower-surface: Phytomyza chaerophylli

5b no frontal appendage; frass grains sharply delimited; gallery upper-surface throughout: Phytomyza pastinacae