1b > Leaf-miner: 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. A long whitish upper surface corridor, which eventually goes lower surface.

Two highly polyphagous species of Chromatomyia, with indistinguishable mines, have been recorded in Britain. These are syngenesiae (Hardy) and horticola (Goureau) which can only be distinguished by the male genitalia. Both species are widespread in Britain and elsewhere, although syngenesiae is almost entirely restricted to Asteraceae. Records on Asteraceae not based on examination of male genitalia are treated in this account as Chromatomyia 'atricornis'.

Chromatomyia 'atricornis' has been recorded on Erigeron in Britain.

Chromatomyia syngenesiae is recorded on Erigeron elsewhere but not yet on Erigeron in Britain.

Chromatomyia horticola (Goureau, 1851) [Diptera: Agromyzidae]
OR
Chromatomyia syngenesiae Hardy, 1849 [Diptera: Agromyzidae].

1c > Leaf-miner: A short linear mine in first instar, later producing a circular or oval blotch. Frass is excreted in a black mass prior to pupation; puparium firmly glued with frass within the mine (Spencer, 1976: 306).

Large, whitish, upper-surface blotch, preceded by a short corridor that often is overrun later by the developing blotch. The larva hardly produces any frass; the few grains that are present are black and rather coarse. But when the larva is about to pupate, it empties its intestine, which has the effect that the puparium is anchored in the mine by dried frass.

The initial gallery by the first instar larva then leads to a whitish blotch. The puparium is fixed to the inside of the mine by an accumulation of frass.

On Aster, Bellis and Erigeron in Britain and additional genera of Asteraceae elsewhere. Widespread in southern England and continental Europe. Also recorded in Canada, Argentina, South Africa, India, Australia and Papua New Guinea.

Calycomyza humeralis (von Roser, 1840) [Diptera: Agromyzidae].

1d > Leaf-miner: A long, winding leaf-mine on the upper surface of the leaf, with frass widely-spaced in conspicuous black lumps. Pupation internal, at the end of mine (Spencer, 1972b: 28 (fig. 68), 29).

Mines on Sonchus and Taraxacum are illustrated in British leafminers and on Solidago in Bladmineerders van Europa.

On Solidago, but not yet on Erigeron, in Britain. On Aster, Callistephus, Erigeron, Sonchus, Solidago and Taraxacum elsewhere. Only recorded from Kent, Derby, Warwick and East Kent in Britain. Widespread in much of Europe. Also recorded in Japan, Canada and the U.S.A.

Ophiomyia maura (Meigen, 1838) [Diptera: Agromyzidae].

1e > Leaf-miner: A narrow upper surface linear branching mine without apparent feeding lines. Frass in isolated grains and pearl chains. At least in Erigeron older mines turn reddish-brown. Pupation external (Spencer, 1976: 413).

On Erigeron acer and Erigeron canadensis in Britain and additional genera of Asteraceae elsewhere. Known only from Warwick in Britain. Widespread in continental Europe.

Phytomyza erigerophila Hering, 1927 [Diptera: Agromyzidae].

1f > Leaf-miner: Rather narrow corridor, untidy and sometimes branched, starting from the base of the leaf, in particular the midrib. Sides of the corridor irregularly eaten out, not really parallel. Frass mostly present, and then in a central line. The larva is capable of leaving the mine and start a new one elsewhere. These later mines are much broader, and the frass is scattered irregularly..

Host plants unknown in Britain. On numerous genera and species in several plant families, including Carduus, elsewhere. Recorded in southern England. Widespread in continental Europe.

Orthochaetes insignis (Aube, 1863) [Coleoptera: Curculionidae].