Tussilago, coltsfoot

fam. Asteraceae

1a mine full depth; larva with chitinised head => 2

1b mine upper- or lower-surface; larva a maggot => 8

1c galls, etc => 100

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

100a Nematoda => 101

100b Acari => 102

100c Coleoptera => 103

100e Diptera => 104

100f Hemiptera => 105

100d Hymenoptera => 106

100g rust fungi => 107

100h smut fungi => 108

100i powdery and downy mildews => 109

100j other causers => 110

102 – Acari

102a Eriophyidae: Aceria tussilagofoliae

104 – Diptera

104a Cecidomyiidae: Mycodiplosis coniophaga

107 – rust fungi

107a Coleosporiaceae: Coleosporium tussilaginis

107b Pucciniaceae: Puccinia petasites-pendulae, poarum

109 – powdery and downy mildews

109a Erysiphaceae: Golovinomyces senecionis

110 – other causers

110a Fungi, Synchytriaceae: Synchytrium aureum

*In more recent literature this species is not recognised as a miner.

Not included in the key: Phytomyza alpina, Phytomyza buhriella; Scrobipalpa acuminatella.