Lysimachia loosestrife
Dichotomous table for leafminers
1a mines small, usually several in a leaf, of indefinite shape; older larvae live free among spun leaves: Cnephasia incertana
1b mine not unusually small, one per leaf => 2
1c galls, etc => Tables for all parasites per species
2a mine full depth, with conspicuous folds; larva later lives free in a leaf cone at the margin of the leaf: Calybites phasianipennella
2b mine lower-surface, without folds; larva remains in the mine till winter: Monochroa conspersella