1a whitish corridor in leaf or flower stalk: Hydrellia concolor

1b mine much deeper in the tissue of the leaf, or in the pith of the flower stalk – essentially the work of a borer, rather than a miner => 2

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

2a larva with chitinised head: Bagous nodulosus

2b larva a maggot : Phytoliriomyza ornata