1a mine broad, full depth; larva with chitinised head: Scrobipalpa stangei

1b mine narrow, upper- or lower-surface; larva a maggot => 2

1c galls, etc => Tables for all parasites per species

2a frass in thread fragments, about as long as the diameter of the corridor, alternating against one of the sides: Liriomyza angulicornis

2b frass not that regular: Liriomyza latipalpis