Note: Diptera larvae may live in a corridor mine, a corridor-blotch mine, or a blotch mine, but never in a case, a rolled or folded leaf, a tentiform mine or sandwiched between two more or less circular leaf sections in later instars. Pupation never in a cocoon. All mining Diptera larvae are leg-less maggots without a head capsule (see examples). They never have thoracic or abdominal legs. They do not have chewing mouthparts, although they do have a characteristic cephalo-pharyngeal skeleton (see examples), usually visible internally through the body wall. The larvae lie on their sides within the mine and use their pick-like mouthparts to feed on plant tissue. In some corridor miners frass may lie in two rows on alternate sides of the mine. In order to vacate the mine the fully grown larva cuts an exit slit, which is usually semi-circular (see Liriomyza huidobrensis video). The pupa is formed within the hardened last larval skin or puparium and as a result sheaths enclosing head appendages, wings and legs are not visible externally (see examples).

1a > Mine primarily associated with mid-rib.

2

1b > Mine not primarily associated with mid-rib.

3

2a > A whitish blotch-mine along the mid-rib, with lateral offshoots into the leaf blade. Pupation internal. Puparium pale, whitish-yellow

Mine of Ophiomyia pulicaria on Taraxacum officinale Image: Willem Ellis (Bladmineerders van Europa)

On Crepis, Hieracium, Hypochaeris, Leontodon, Picris, Pilosella, Sonchus and Taraxacum in Britain and additional genera of Asteraceae elsewhere. Widespread and common in Britain and continental Europe. Range extending east to Siberia. Also recorded from Canada.

Ophiomyia pulicaria (Meigen, 1830) [Diptera: Agromyzidae].

2b > A white mine along mid-rib, with offshoots into leaf blade. Pupation internal at base of mid-rib. Puparium whitish

On Cicerbita, Leontodon, Sonchus and Taraxacum in Britain and numerous other genera of Asteraceae elsewhere. Widespread in south, but not common, in Britain. Widespread in continental Europe.

Ophiomyia beckeri (Hendel, 1923) [Diptera: Agromyzidae].

3a > A narrow, whitish linear mine. Pupation internal. Puparium white

On Leontodon autumnalis and Taraxacum officinale in Britain and elsewhere. Britain and the Republic of Ireland. Widespread in continental Europe.

Chromatomyia farfarella (Hendel, 1935) [Diptera: Agromyzidae].

3b > 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 (Bladmineerders van Europa). A long whitish upper surface corridor, which eventually goes lower surface (British leafminers).

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 are polyphagous and widespread in Britain and elsewhere, although syngenesiae is almost entirely restricted to Asteraceae (see also 'atricornis').

Chromatomyia horticola is recorded on 55 plant genera in 19 families in Britain but not yet on Leontodon in Britain.

Chromatomya syngenesiae is recorded in Britain on 27 plant genera in the family Asteraceae and many more genera elsewhere, including Leontodon in Britain.

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

3c > A small somewhat irregular, elongate blotch.

On Leontodon and Taraxacum in Britain and Aposeris, Arnoseris, Leontodon and Taraxacum elsewhere, Widespread in Britain and continental Europe.

Liriomyza taraxaci Hering, 1927 [Diptera: Agromyzidae].

3d > Egg is laid beneath the epidermis on the upper leaf surface. Larva mine in basal leaves. Pupation internal. Puparium pale whitish-yellow

On Cichorium and Leontodon in Britain and in addition Lactuca and Taraxacum elsewhere. Uncommon, but widespread in Britain. Widespread in continental Europe, range extending eastwards to Tadzhik S.S.R and Uzbek S.S.R.

Ophiomyia pinguis (Fallén, 1820) [Diptera: Agromyzidae].