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 > Stem miner: An external stem mine. Pupation in the mine.

On Senecio in Britain and elsewhere. Only known from Surrey in Britain and Northern France, Germany and Slovakia in continental Europe.

Ophiomyia senecionina Hering, 1944 [Diptera: Agromyzidae].

1b > Leaf mine.

2

2a > Blotch mine. Pupation external. Puparium yellow

On numerous genera of Asteraceae in Britain and elsewhere. In Britain more common in the north than in the south. Also throughout the Palaearctic Region except the Mediterranean and Middle Eastern areas.

Trypeta artemisiae (Fabricius, 1794) [Diptera: Tephritidae].

2b > An upper surface corridor mine, becoming strongly broadened and blotch-like. The mine can occupy a considerable part of a small leaf. Mines frequently merge, and then accommodate several larvae. Pupation external, in soil. Puparium yellow

On Petasites, Tussilago and possibly Senecio in Britain and elsewhere and in addition Arctium, Homogyne and possibly Senecio elsewhere. Throughout the British Isles. Also recorded in the Republic of Ireland and Widespread in continental Europe.

Acidia cognata (Wiedemann, 1817) [Diptera: Tephritidae].

2c > Corridor mine.

3

3a > Corridor mine primarily following the mid-rib, with lateral offshoots.

4

3b > Corridor mine not primarily following the mid-rib.

5

4a > Leaf-mine. Corridor mine following the mid-rib, with lateral offshoots. Puparium yellow

On numerous genera of Asteraceae. Throughout the British Isles, more common in the south than the north. Also continental Europe.

Trypeta zoe Meigen, 1826 [Diptera: Tephritidae].

4b > Leaf-miner: A distinctive mine primarily above mid-rib, with irregular short lateral offshoots into leaf blade. Pupation external (Spencer, 1972: 51 (fig. 172), 55; Spencer, 1976: 270, 271 (fig. 486)). Branched, whitish, upper-surface corridor; main axis overlying the midrib; side branches overlying the main lateral veins. (In Campanula and Phyteuma the mine is much less branched, sometimes nothing more than a corridor on top of the midrib). Frass in rather long strings. Usually the mines begins as a long and narrow, shallow, tortuous lower-surface corridor that ends upon the midrib but otherwise is not associated with the leaf venation. Often this initial corridor is filled with callus, and then even less conspicuous. Pupation outside the mine (Bladmineerders van Europa). A linear mine on the upper surface, usually following the midrib and showing side branches along the veins. The frass is in strings (British leafminers).

On more than 40 host genera in 15 families in Britain including Senecio. Widespread throughout Britain. Also recorded in the Republic of Ireland. Widespread in continental Europe.

Liriomyza strigata (Meigen, 1830) [Diptera: Agromyzidae]

5a > 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 Senecio in Britain.

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

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

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

5b > Leaf mine. A relatively long irregular linear mine, normally commencing near the apex of the leaf and for a while following the leaf margin.

On Senecio erucifolius and Senecio jacobaea in Britain. Also on Senecio helenitis and Senecio ovatus elsewhere. Uncommon in Britain. Only recorded from Middlesex, Hants, Warwick, Bucks and Surrey. Widespread in continental Europe.

Liriomyza erucifolii Meijere, 1943 [Diptera: Agromyzidae].

5c > Leaf mine. Mine irregularly linear, long, towards end wide. Pupation external. Puparium black

On Senecio jacobaea in Britain. On Senecio alpinus, Senecio jacobaea and Senecio subalpinus elsewhere. A boreal-alpine species, not known south of York in Britain. Also recorded in the Republic of Ireland. Widespread in continental Europe.

Phytomyza alpina Groschke, 1957 [Diptera: Agromyzidae].

5d > Leaf mine. Larva mining both lower and upper surface, unusually long, linear, conspicuously broad, frequently largely on the underside of the leaf. Pupation external. Puparium black

On Crepis, Hieracium, Lapsana, Picris, Pilosella, Senecio, Sonchus and Taraxacum in Britain and additionally other genera of Asteraceae elsewhere. Widespread in southern Britain, also Sutherland, Inner Hebrides and Warwick. Also recorded in the Republic of Ireland and Widespread in much of Europe.

Phytomyza marginella Fallén [Diptera: Agromyzidae].