Leaf-mine: Mine linear, whitish, both upper and lower surface. Pupation internal, at the end of the mine, with the anterior spiracles projecting through the epidermis (Spencer, 1976: 510).

Generally upper-surface corridor. Frass in isolated grains. Pupation in the mine, in a, usually lower-surface, pupal chamber (Bladmineerders van Europa).

Larva: Details unknown. White (Bladmineerders van Europa).

Puparium: White or more rarely darker, brownish (Spencer, 1976: 510). The puparium mostly is white (but parasited puparia are black). The anterior spiracles penetrate the plant epidermis as tiny brown hooks (Bladmineerders van Europa).

Is normally white, but can be brown . The anterior spiracles project through the leaf epidermis (British leafminers).

Comments: Two highly polyphagous species of Chromatomyia, with indistinguishable mines, have been recorded in Britain. These are syngenesiae (Hardy) and horticola (Goureau). Griffiths (1967b) after critical examination of male genitalia, confirmed that the hosts of syngenesiae are almost exclusively genera of Asteraceae, with just two exceptions, one on Daucus [Apiaceae] in Denmark and the other on Pisum [Fabaceae] in California, U.S.A. C. horticola mines numerous plant families including Asteraceae. The two species can only be distinguished by the structure of the male genitalia.

British records of syngenesiae, horticola or 'atricornis' on hosts other than Asteraceae in Britain, are assumed to represent horticola.

British records of horticola and syngenesiae on Asteraceae hosts not based on examination of the genitalia of reared males are treated here as Chromatomyia 'atricornis' and may represent either horticola or syngenesiae.

Recorded in Britain on 27 plant genera in the family Asteraceae and many more elsewhere.

As the mines of horticola and syngenesiae are indistinguishable, the chalcidoid parasitoids recorded from these two species are listed under 'atricornis'.

Leontodon autumnalis is treated as Scorzoneroides autumnalis (Autumn Hawkbit) by Stace (2010).

Hosts in Britain:

Hosts elsewhere:

Time of year - mines: July-August.

Time of year - adults: August.

Distribution in Great Britain and Ireland: Common throughout Britain (Spencer, 1972: 87) including the Inner Hebrides (Isle of Coll) (Bland, 1992), Rum (Bland, in Whiteley, 1994), East Kent, Edinburgh, East Lothian and Linlithgow (NBN Gateway, as Phytomyza syngenesiae, may include records of 'atricornis', horticola and/or syngenesiae).

Also recorded in the Republic of Ireland (Martinez in Fauna Europaea).

NBN Grid map:

Distribution elsewhere: Cosmopolitan. Widespread and common throughout Europe including Denmark, Finland, Sweden (Spencer, 1976: 510), Balearic Is., Canary Is., Czech Republic, ? Faroe Is., French mainland, Germany, Italian mainland, Poland, Portuguese mainland, Sardinia, Sicily, Spanish mainland, Switzerland, The Netherlands and Yugoslavia (Martinez in Fauna Europaea).

Also introduced to U.S.A., Australia and New Zealand (Spencer, 1976: 510).

NBN interactive distribution map(s) of known host species in Great Britain and Ireland and elsewhere:

Parasitoids in Britain and elsewhere: See Chromatomyia 'atricornis'.