Teesdalia shepherd’s cress
Dichotomous table for leafminers
1a larva a maggot; frass powdery, in green clouds; when held against the light the blotch is irregular in transparency: Scaptomyza flava
1b larva with sclerotised head; frass black, coarser; mine transparent all over => 2
1c galls, etc => Tables for all parasites per species
2a corridor, starting in the leaf base or at a thick vein: Orthochaetes insignis
2b mine begins free in the leaf, corridor-like, but may locally be considerably widened: Ceutorhynchus minutus