Melittis bastard balm
Dichotomous table for leafminers
1a fleck mine: Coleophora albitarsella
1b narrow corridor, followed by a large blotch => 2
1c galls, etc => Tables for all parasites per species
2a frass in the corridor in a broad central green band, with minute grains at either side: Amauromyza labiatarum
2b frass as strings at either side of the corridor: Amauromyza lamii