1a mine full depth; larva with thoracic feet and chitinised head: Digitivalva reticulella

1b mine under- or upper-surface; larva a maggot => 2

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

2a pupation within the mine, in an, usually lower-surface, pupal chamber: Chromatomyia cf syngenesiae

2b pupation external => 3

3a frass mostly in separate granules; in fresh mines the primary feeding lines conspicuous: Phytomyza kyffhusana

3b frass mostly in strings; primary feeding lines invisible: Liriomyza strigata