1a corridor < 1 cm long, full depth; larva with feet and chitinised head => 2

1b mine longer, upper-surface, larva a maggot: Phytomyza chaerophylli

2a larva solitary; mine somewhat puckered, because silk is deposited inside: Cnephasia incertana

2b larvae comunally; mines flat => 3

2a larvae laterally with a bright yellow length line: Depressaria daucella

2b larvae more or less uniformly coloured: Epermenia chaerophyllella