1a fleck mine; case black-brown: Coleophora albitarsella

1b an upper- or lower-surface corridor or secondary blotch => 2

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

2a puation in the mine, in a, usually lower-surface, pupal chamber; frass in widely spaced grains: Chromatomyia horticola

2b pupation outside the mine; frass, at least in part, in string of pearl chains => 3

3a a pinnately branched corridor, main branch overlying the midrib: Liriomyza strigata

3b mine little or not branched, not associated with the midrib; often a secondary blotch: Phytomyza nepetae