1a larva bores in the basis of the stem, making from there short excursions into the lower leaves: Delia platura

1b larva lives in the leaves only; mine a corridor => 2

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

2a frass in isolated grains, lying more than their diameter apart; puparium in the mine, in a, usually lower-surface, pupal chamber: Chromatomyia horticola

2b frass mostly in strings or pearl chains; puparium formed outside the mine => 3

3a corridor pinnately branched, main branch overlying the midrib, side branches overlying the lateral veins; larva: rear spiraculum with 9-13 poapillae: Liriomyza strigata

3b corridor not pinnately branched, winding freely through the leaf; rear spiraculum with 7-9 papillae: Liriomyza bryoniae