Dryas, mountain avens

1a fleck mine, larve mines from a portable case => 2

1b no fleck mine; larva mines from the inside => 4

1c galls, etc => 100

2a spatulate leaf case: Coleophora unigenella

2b tubular silken case => 3

3a full grown case before the end with a constriction: Coleophora nubivagella

3b full grown case not constricted: Coleophora derasofasciella

4a corridor along the leaf margin, then widening into a blotch; larve mines all its life: Stigmella dryadella

4b blotch; if an initial corridor is at all visible, it does not run along the leaf margin; the older larve lives free in a leaf that is spun into a pod: Parornix alpicola *

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

105 – Hemiptera

105a Aphididae: Acyrthosiphon svalbardicum

109 – powdery and downy mildews

109a Erysiphaceae: Podosphaera volkartii

110 – other causers

110a Actinobacteria, Frankiaceae: Frankia dryadis

110b Fungi, Phyllachoraceae: Isothea rhytismoides

110c Fungi, Synchytriaceae: Synchytrium cupulatum

* see also Parornix scoticella.

Not included in the key: Stigmella tatrica (biology unknown, host plant not quite certain).