1a larva not only mines the leaf disc but also the petiole and stem, that become partly hollowed out and translucent: Delia echinata

1b mine exclusively in the leaf => 2

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

2a fleck mine; larva in a tubular silken case: Coleophora corsicella

2b no fleck mine => 3

3a mine small (< 1 cm); larva with thoracic feet and a sclerotised head => 4

3b mine larger; larva a maggot => 5

4a pinacula colourless (only the base of the setae black): Cnephasia incertana

4b pinacula black: Cnephasia asseclana

5a mine whitish with few (fine, black) grains of frass; larva: rear spiraculum blunt with 3 clear, hooklike papillae: Amauromyza flavifrons

5b mine greenish; frass powdery in green clouds, mainly along the margin of the mine and in the end of short side branches; rear spiraculum acute, papillae almost invisible: Scaptomyza graminum