Tussilago coltsfoot
Dichotomous table for leafminers
1a mine full depth; larva with chitinised head => 2
1b mine upper- or lower-surface; larva a maggot => 8
1c galls, etc => Tables for all parasites per species
2a mine not larger than 1 square cm, often in numbers => 3
2b mine appreciably larger: Scrobipalpula tussilaginis
3a larva without feet => 4
3b larva with legs and prolegs => 5
4a larvae mine all their life: Phytosciara macrotricha
4b older larvae live free, cause window feeding: Phytosciara halterata
5a mines cut through the thicker veins: Platyptilia gonodactyla*
5b mines avoid the heavier vein => 6
6a larva: pinacula colourless (but the base of the setae is black): Cnephasia incertana
6b pinacula black => 7
7a larva: below the anus a black chitinous comb: Cnephasia asseclana
7b anal comb absent: Cnephasia stephensiana
8a mine with conspicuous primary and secondary feeding lines, often blotch-like in the end; frass irregularly scattered; larva: rear spiraculum with 3 papillae => 9
8b mine a corridor without apparent feeding lines; frass in two rows; rear spiraculum with > 3 papillae => 11
9a mine positioned over a thick vein, a corridor or a narrow blotch: Trypeta zoe
9b mine not positioned over a thick vein, a corridor ending in a large blotch => 10
10a mine begins with a long, hair-thin,not widening corridor which cuts off a part of the leaf that becomes necrotic; in this necrotic tissue the corridor widens into a large blotch: Stemonocera cornuta
10b corridor gradually widening, not cutting off a part of the leaf, terminating into a large untidy blotch: Acidia cognata
11a broad, pinnately branched corridor onverlying a thick vein: Liriomyza strigata
11b little branched corridor, not overlying a thick vein => 12
12a gradually widening corridor; larva leaves the mine prior to pupation through a semicircular (upper-surface) exit slit: Phytomyza tussilaginis
12b corridor hardly widening; pupation in the mine => 13
13a corridor upper-surface, grey-green, not exceptionally long; frass in discrete grains: Chromatomyia cf. syngenesiae
13b corridor inter-parenchymal, yellow-green, exceptionally long (up to 20 cm); frass in pearl chains: Phytomyza farfarae
*In more recent literature this species is not recognised as a miner.
Not included in the key: Phytomyza alpina, Phytomyza buhriella; Scrobipalpa acuminatella.