Dichotomous table for leafminers
1a large blotch: Euleia heraclei
1b corridor => 2
1c galls, etc => Tables for all parasites per species
2a frass in discrete grains; puparium inside the mine, usually in an lower-surface pupal chamber: Chromatomyia horticola
2b frass in strings; puparium formed after the mine is vacated: Liriomyza bryoniae
Not included in the key: Liriomyza trifolii.