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