Y'a que moi qui pense, ici  
 
 
1b blotch, may have a short, quickly widening preceding corridor => 7
7b frass in isolated granules; mines in summer => 9
Mais ensuite, je vous passe les détails, ça ne ressemble pas et ne correspond pas (dates entre autres).
J'en reviens à mes 
Ectodemia. C'est piégeux, quand il y a une galerie mais qu'on ne la voit pas  
 
 
1c blotch, preceded by a long, slender initial corridor => 15
15b mine does not start at an oviposition scar => 16 (ce n'est pas 
Orchestes quercus)
16b mine not epidermal, hardly ever merging; corridor start from a shiny egg shell => 17 (ce n'est pas 
Acrocercops brongniardella)
17b no cut in the blotch => 18
18b corridor part runs parallel to, or away from, the midrib; larva with pale brown head; usually in green leaves : 
Ectoedemia albifasciella
Et hop ! 
 
Oviposition on the upperside of the leaf, next to a vein. The first part of the mine is a narrow corridor, with a broad frass line, running along a vein. Usually the corridor runs away from the midrib, but often it runs along the midrib itself. The corridor widens abruptly into a squarish blotch, containing much frass. Often several mines in a leaf. Pupation external.
Larvae in late-August – September, almost invariably in green, not yellowing, leaves.