1a mine in the pinnulae (‘leaf segments’) that remain flat and are not deformed: Chirosia cinerosa, histricina

1b mine in the petiole, in or below the leaf itself => 2

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

2a mine in the tip of the leaf, that rolls in: Chirosia betuleti

2b mine lower, not causing the leaf tip to roll in; leaf often not well developed, the petiole partly blackened => 3

3a from the mine a drop of froth protrudes, like made by a spittle-bug: Blasticotoma filiceti

3b no froth => 4

4a in places the corridor comes close to the surface of the petiole; larva violet, with distinct head: Heptamelus ochroleucus

4b the corridor remains deep throughout; larva a yellowish maggot: Chirosia griseifrons