Onopordum scotch thistle, cotton thistle
(For a dichotomous table for galls on Onopordum by Hans Roskam click here)
Dichotomous table for leafminers
1a large and long transparant, lobed, blotch, associated with the midrib: Scrobipalpa acuminatella
1b mine not associated with the midrib, smaller, more a corridor => 2
1c galls, etc => Tables for all parasites per species
Dichotomous table for leafminers
1a large and long transparant, lobed, blotch, associated with the midrib: Scrobipalpa acuminatella
1b mine not associated with the midrib, smaller, more a corridor => 2
1c galls, etc => Tables for all parasites per species
2a corridor short; larva later lives free: Agonopterix subpropinquella
2b corridor long or very long; larva remains in the mine until close to pupation => 3
3a corridor very long; larva with chitinised head; frass in a single row; pupation outside the mine: Sphaeroderma testaceum
3b corridor not exceptionally long; frass in a double row; puparium within the mine => 4
4a corridor long, little branched, inter-parenchymal (yellow-green): Phytomyza spinaciae
4b corridor shorter, irregularly branched, not inter-parenchymal (whitish) => 5
5a corridor sides roughly parallel; larva: rear spiraculum with 6-8 papillae: Chromatomyia cf. syngenesiae
5b corridor side irregularly eaten out; rear spiraculum with 12-18 papillae: Phytomyza autumnalis
Not included in the key: Agonopterix arenella; Coleophora onopordiella; Sphaeroderma rubidum.