Athyrium, lady-fern

fam. Woodsiaceae

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 => 100

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

100a Nematoda => 101

100b Acari => 102

100c Coleoptera => 103

100e Diptera => 104

100f Hemiptera => 105

100d Hymenoptera => 106

100g rust fungi => 107

100h smut fungi => 108

100i powdery and downy mildews => 109

100j other causers => 110

104 – Diptera

104a Anthomyidae: Chirosia betuleti

106 – Hymenoptera

106a Blasticotomidae: Blasticotoma filiceti

106b Tenthredinidae: Aneugmenus coronatus

107 – rust fungi

107a Eocronartiaceae: Herpobasidium filicinum

107b Pucciniastraceae: Hyalopsora polypodii

110 – other causers

110a Fungi, Synchytriaceae: Synchytrium athyrii

110b Fungi, Taphrinaceae: Taphrina athyrii

The ‘petiole’ in ferns comprises both the ‘stalk’ below the green part of the leaf and the ‘midrib’ above.