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

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).

See Key to non-Diptera.

1a >Stem-miner: A narrow, inconspicuous stem mine. Pupation at the end of the mine (Spencer, 1976: 64).

Fine, upper- or lower-surface corridor, ending in a thick vein. From there the mine extends finally to the rind of the stem. There also the pupation takes place, usually not far from the root collar. Mines in the stem rind often are conspicuous through a red discoloration.

On Achillea, Achillea millefolium and possibly Anthemis, Matricaria and Medicago sativa, but not yet on Hieracium, in Britain. In Britain widespread in south, not uncommon. On Anthemis, Achillea, Artemisia, Aster, Centaurea, Clinopodium, Crepis, Hieracium, Matricaria, Reichardia, Solidago, Tanacetum, Tripleurospermum, Medicago, Satureja and Stachys elsewhere. Widespread in continental Europe.

Ophiomyia curvipalpis (Zetterstedt, 1848) [Diptera: Agromyzidae].

1b > Stem miner: An external stem mine with frass in two rows of disconnected strips. Pupation in stem at end of mine (Spencer, 1972b: 25; Spencer, 1976: 61 (fig. 63B), 65-6).

Polyphagous. On Campanula, Jasione, Phyteuma [Campanulaceae], Crepis, Hypochaeris and Lapsana [Asteraceae], but not yet on Hieracium, in Britain and additional genera of both families elsewhere. Uncommon in Britain - recorded in London, Warwick and Cambridge. Uncommon but Widespread in continental Europe.

Ophiomyia heringi Stary, 1930 [Diptera: Agromyzidae].

1c> Leaf miner: Mine primarily associated with mid-rib.

2

1d > Leaf miner: Mine not primarily associated with mid-rib.

3

2a > 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, including Hieracium, in Britain. Widespread throughout Britain. Also recorded in the Republic of Ireland. Widespread in continental Europe.

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

2b > 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].

2c > Leaf miner: Mine mainly in basal leaves, running along mid-rib, with short lateral offshoots into leaf blade (Spencer, 1972b: 71). Pupation takes place within the petiole or mid-rib (Spencer, 1976: 489).

Upper-surface corridor in the leaf base, radiating from the base of the midrib. Frass in long strings along the sides of the mine. Primary feeding lines quite conspicuous. Pupation within the mine, in the leaf base or even deeper in the plant.

On Hieracium and Pilosella in Britain and elsewhere. Uncommon in Britain - Argyll, York and Warwick. Widespread in continental Europe.

Phytomyza rufescens von Roser, 1840 [Diptera: Agromyzidae].

3a > 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 marginellaFallén, 1823 [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, 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 'atricornis' has been recorded on Hieracium in Britain.

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

3c > 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 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].

3d > Leaf miner: A small primary upper surface blotch (Spencer, 1976: 251).

Primary upper-surface blotch. Pupation outside the mine.

On Hieracium in Britain and elsewhere. Widespread in Britain and continental Europe

Liriomyza hieracii Kaltenbach, 1862 [Diptera: Agromyzidae].

3e > 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, but not yet on Hieracium, in Britain and additional genera of Asteraceae elsewhere. Known only from Warwick in Britain. Widespread in continental Europe.

Phytomyza erigerophila Hering, 1927 [Diptera: Agromyzidae].