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: 433).

Upper-surface, less often lower-surface corridor. Frass in isolated grains. Pupation within the mine, in a, usually lower-surface, pupal chamber (Bladmineerders van Europa).

A long whitish upper surface corridor, which eventually goes lower surface (British leafminers).

Larva: The larvae is described by Dempewolf (2001: 202).

Puparium: Whitish (Spencer, 1976: 433). The anterior spiracles penetrate the plant epidermis as a pair of tiny hooks (Bladmineerders van Europa).

Adult: The adult is illustrated in the Encyclopedia of Life.

Comments: Two highly polyphagous species of Chromatomyia, with indistinguishable mines, have been recorded on Asteraceae in Britain. These are syngenesiae (Hardy), which is almost entirely restricted to Asteraceae and horticola (Goureau), which 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, except when the male genitalia have been examined (i.e. Dahlia), are assumed here 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'.

Hosts cited here include 160 plant genera in 31 families of which 55 plant genera in 19 families are records for Britain.

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

Lavatera arborea is treated as Malva arborea (Tree-mallow) and Lycopersicon esculentum is treated as Solanum lycopersicum (Tomato) by Stace (2010).

Hosts in Britain:

Hosts elsewhere:

Time of year - mines: Bivoltine, late Spring and early Autumn (British leafminers).

Time of year - adults: Unknown.

Distribution in Great Britain and Ireland: Widespread in southern Britain (Spencer, 1972: 87) including Warwickshire (Holbrooks) (Robbins, 1991: 144); Caernarvonshire, Cambridgeshire, East Gloucestershire, East Suffolk, Glamorgan, North Somerset, Pembrokeshire, Surrey and Worcestershire (NBN Gateway, may include records of horticola and/or syngenesiae).

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

NBN Grid map: Note that not all datasets on the NBN Gateway may be available on the map below. If you are an NBN Gateway registered user you can request access for missing datasets via the link 'Open interactive map in new window' below.

Distribution elsewhere: Old World. Common throughout Europe including the Mediterranean area (Spencer, 1976: 432), The Netherlands, Luxembourg (Bladmineerders van Europa), Belgium (de Bruyn and von Tschirnhaus, 1991), Germany (Dempewolf, 2001: 202), ? Albania, Austria, Azores, Canary Is., Corsica, Czech Republic, Denmark, European Turkey, Finland, French mainland, Greek mainland, Hungary, Italian mainland, Lithuania, Madeira, Malta, Norwegian mainland, Poland, Republic of Moldova, Romania, Sardinia, Sicily, Slovakia, Spanish mainland, Sweden, Switzerland and Yugoslavia (Martinez in Fauna Europaea).

Also recorded in Africa, India, China and Japan, but not known from North or South America (Spencer, 1976: 432).

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

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

Adults:

Wing of Chromatomyia horticola