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 > Blotch mine.

2

1b > Corridor mine.

3

2a > Leaf-miner: A whitish-greenish blotch. Pupation external, on the ground (Spencer, 1972: 43, fig. 140; Spencer, 1976: 306-7, fig. 552). A chacteristically pale whitish, usually upper-surface, primary blotch. There is an initial corridor, but traces of it are almost always overrun by the later blotch. The mine is quite opaque; only by opening it can it be ascertained if the mine is still occupied. No feeding lines are apparent. Unlike other blotch mines thay may occur here, Calycomyza mines are totally flat. Pupation outside the mine (Bladmineerders van Europa). A whitish blotch mine occuring on the upper leaf surface. Starts with a short corridor and does not show feeding lines. Superficially similar to the lepidopterous mine made by Leucospilapteryx omissella, but the latter mine turns purple as it ages (British leafminers).

On Artemisia and Eupatorium in Britain and additional Asteraceae elsewhere. Widespread in England and Continental Europe. Also recorded in China, Japan, Colombia and Canada.

Calycomyza artemisiae (Kaltenbach, 1856) [Diptera: Agromyzidae].

2b > Blotch mine. Pupation external. Puparium yellow

On Eupatorium in Britain and additional genera of Asteraceae elsewhere. England, as far north as York, and Wales. Widespread in continental Europe. Also recorded in the East Palaearctic.

Stemonocera cornuta (Scopoli, 1772) [Diptera: Tephritidae].

2c > Blotch mine. Pupation external. Puparium yellow

On numerous genera of Asteraceae, including Eupatorium, 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].

2d > Mine filling apex of leaf segment, with short final section extending further into leaf. Pupation normally in leaf at end of mine.

Mine of Liriomyza eupatoriana on Eupatorium cannabinum Image: Rob Edmunds (British leafminers)

On Eupatorium in Britain and elsewhere. Uncommon in Britain - Wilts and Cambridge. Widespread in continental Europe

Liriomyza eupatoriana Spencer, 1954 [Diptera: Agromyzidae].

3a > Mine primarily associated with the mid-rib.

4

3b > Mine not primarily associated with the mid-rib.

5

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

On numerous genera of Asteraceae, including Eupatorium in Britain. 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 Eupatorium. 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 'atricornis' has been recorded on Eupatorium in Britain.

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

5b > A linear mine commencing with a conspicuous regular spiral and then continuing a considerable distance more or less straight.

On Aster, Eupatorium, Helianthus, Lapsana and Solidago [Asteraceae] and Galeopsis [Lamiaceae] in Britain and continental Europe. Widespread in England. Also recorded in the Republic of Ireland. Widespread in continental Europe and recorded in Canada.

Liriomyza eupatorii (Kaltenbach, 1873) [Diptera: Agromyzidae].

5c > Mine long, linear, upper or lower surface, often adjoining a vein. Puparium black

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

Phytomyza eupatorii Hendel, 1927 [Diptera: Agromyzidae].