Key for the identification of the known mines of British
Diptera recorded on Sonchus

1a > Stem-miner: External stem-miner (Spencer, 1972b: 61).

On Sonchus oleraceus in Britain. On Crepis, Lapsana and Sonchus elsewhere. Uncommon, but locally abundant in Britain including London, Essex and Hunts. Widespread in continental Europe. Also recorded in Brazil, Canada, and the Afro-tropical, Australian, East Palaearctic and Oriental regions.

Phytoliriomyza arctica (Lundbeck, 1901) [Diptera: Agromyzidae].

1b > Leaf miner/galler: Circular, lower-surface blotch, about 5 mm in diameter, often quite a number together on a leaf. Upper surface wart-like, strongly reddish discoloured, opaque. At the lower surface the mine is closed only by the epidermis. The larva is easily visible, as is its food: drops of cell sap that oozes into the mine. Pupation sometimes in the mine, sometimes in the soil..

The blotches are also illustrated in British Leafminers.

On Sonchus in Britain and elsewhere. Widespread in England and Wales and in continental Europe.

Cystiphora sonchi (Vallot, 1827) [Diptera: Cecidomyiidae].

1c > Leaf-miner

2

2a > Leaf-miner: Mine primarily associated with the mid-rib.

3

2b > Leaf-miner: Mine not primarily associated with the mid-rib.

4

3a > 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.

A linear mine on the upper surface, usually following the midrib and showing side branches along the veins. The frass is in strings.

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

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

3b > Leaf-miner: A whitish blotch-mine along mid-rib, with offshoots into leaf blade. Pupation takes place at the base of the mid-rib. Puparium yellowish white

On Crepis, Hypochaeris, Lapsana, Mycelis, Picris, Sonchus, Taraxacum and possibly Bellis in Britain and additional genera of Asteraceae elsewhere. Widespread in Britain and throughout much of Europe.

Ophiomyia cunctata (Hendel, 1920) [Diptera: Agromyzidae].

3c > Leaf-miner: A whitish blotch-mine along the mid-rib, with lateral offshoots into the leaf blade. Pupation at base of leaf in petiole (Spencer, 1972b: 25).

Broad corridor overlying the midrib, with short excursion into the blade, mainly in its basal part. Frass concentrated in the basal part of the mine, corridors almost free from frass. Pupation in the mine, also in the basal part.

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].

3d > Leaf-miner: A white mine along mid-rib, with offshoots into leaf blade. Pupation internal at base of mid-rib.

In Asteraceae the larva mostly lives as a borer in the midrib of the leaves. From there short corridors are made into the blade. Also a corridor can be made overlying the midrib. In Euphorbia a small mine is made in the bracts of the inflorescence. The final mine strongly resembles the one of Liriomyza strigata, but the branches are vritually free from frass; this is acccumulated in the resting place of the larva, in the base of the midrib. There also pupation takes place.

Forms a mine along the midrib and has feeding spurs into the leaf. Pupation is in the mine at the base of the midrib.

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].

4a > 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, usually in a lower-surface puparial 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 horticola is recorded on 160 plant genera in 31 families of which 55 plant genera in 19 families, but not yet on Sonchus, in Britain. On Sonchus elsewhere.

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

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

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

4b > Leaf-miner: Larva mining both lower and upper surface, unusually long, linear, conspicuously broad, frequently largely on the underside of the leaf. Pupation external (Spencer, 1972b: 76 (fig. 251); Spencer, 1976: 445 (fig. 780), 446).

Corridor mine. The first part consists of a very long and narrow lower-surface corridor; the mine is quite shollow here, and often inconspicuous. The second part is upper-surface, uusally much shorter, and widens abruptly. Pupation outside the mine.

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, 1923 [Diptera: Agromyzidae].

4c > Leaf-miner: A small primary blotch, often several larvae feeding together (Spencer, 1972b: 56 (fig. 186); Spencer, 1976: 270, 271 (fig. 483)).

Brown, upper-surfsce blotch; often several larvae in a mine. The blotch is preceded by a short initial corridor, often overrun by the later blotch. Frass in a few, small grains. Secondary feeding lines well visible. Pupation outside the mine, exit slit in upper epidermis.

Small upper surface blotch, with occasional galleries leading from the blotch. Often several larvae feeding together.

On Sonchus arvensis, Sonchus asper, Sonchus oleraceus and Sonchus palustris in Britain. On Cichorium, Lactuca, Mycelis, Prenanthes and Sonchus elsewhere. Widespread, at least in south, in Britain. Widespread and common in much of Europe. Also recorded in Canada.

Liriomyza sonchi Hendel, 1931 [Diptera: Agromyzidae].

4d > Leaf-miner: A short, irregular, linear upper surface mine on any part of the leaf. Also recorded from young pods (Bland, 1997a).

Long corridor mine. As a rule the first part of the mine is lower-surface, the later part upper-surface. Often the loops are so dense that a secondary blotch is the result. Because upper- and lower-surface corridor segments often cross, the mine obtains a strange array of transparant patches. There is no association with the midrib. Frass in strings and thread fragments. Pupation outside the mine; exit slit in upper epidermis.

Mine not associated with the veins or midrib of the leaf (It is this character which enables distinction from another Agromyzid pest species - Liriomyza huidobriensis). The larvae may leave one leaf (if not large enough) and enter another leaf, via the petiole). It exits the leaf to pupate through a semi-circular slit in the upper surface of the leaf.

Polyphagous. On 119 plant genera in 31 plant families of which only 4 plant genera in 2 plant families, but not yet on Sonchus, in Britain. Local, probably introduced to Britain. Widespread in continental Europe particularly in Botanical Gardens and glasshouses. Also recorded in Egypt.

Liriomyza bryoniae (Kaltenbach, 1858) [Diptera: Agromyzidae].

On Leontodon and Taraxacum, but not yet on Sonchus, in Britain and Aposeris, Arnoseris, Leontodon and Taraxacum elsewhere, Widespread in Britain and continental Europe.

Liriomyza taraxaci Hering, 1927 [Diptera: Agromyzidae].

4f > 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).

On Solidago, but not yet on Sonchus, 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].

4g > Leaf-miner: The mine begins with a very narrow full depth corridor, that ends upon the midrib. Subsequently a broad corridor, or rather an elongated blotch, is made overlying the midrib; from here broad, lobe-like extensions are made into the blade. Frass in discrete grains. Secondary feeding lines conspicuous. The larva is capable of leaving the mine and restarting in a new leaf, in which case the association with the midrib may be lost. Pupation after vacation of the mine.

On Cichorium, Crepis, Hieracium and Taraxacum, but not yet on Sonchus, in Britain and additionally other genera of Asteraceae elsewhere. North-east Scotland, also throughout Ireland and continental Europe, except the Mediterranean area.

Trypeta immaculata (Macquart, 1835) [Diptera: Tephritidae].