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

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 > Leaf-miner: Blotch mine.

2

1b > Leaf-miner: Corridor mine.

3

2a > Leaf-miner: A whitish-greenish blotch. Pupation external, on the ground (Spencer, 1972b: 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.

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.

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 > Leaf-miner: The mine mine begins as a long, hairlike corridor. The last part of it runs perpendicular to a leaf segment. The part of the leaf that thereby is cut off wilts, and here a large blotch is made. Frass scattered in the mine. Mine practically full-depth, yellowish green to reddish brown, with conspicuous secondary feeding lines. Pupation outside the mine. See also Seidel (1926a) for an extensive description of the mine.

On Eupatorium in Britain and additional genera of Asteraceae elsewhere. Widespread in continental Europe. Also recorded in the East Palaearctic.

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

2c > Leaf-miner: The mine begins as an elongated blotch overlying a strong vein; from there broad tunnels radiate that coalesce in the end. All frass is concentrated at a central point in the floor of the mine. As a result the mine has a brownish-black centre and a paler brownish green seam. The larva often (perhaps always at daylight) rests in the centre of the mine. Primary and secondary feeding lines as a rule quite clear. Pupation outside the mine.

An elongated blotch centred over a vein. There are two types: greenish with a blackish centre and entirely reddish-black.

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 > Leaf-miner: Mine filling apex of leaf segment, with short final section extending further into leaf. Pupation normally in leaf at end of mine.

Corridor, almost invariably in the ultimate cm of the tip of a leaf segment. The corridor is contorted so strongly that a compact secondary blotch is formed. When exeptionally the mine is not in the leaf tip, it is closely adjoining the leaf margin; never is a mine formed in the leaf centre. Frass irregular, in black threads and lumps, frequently at wide intervals, on alternate sides of the mine. The mine is upper-surface, except for the very last section that is lower-surface. Here pupation takes place. The puparium projects for about half of its length out of the mine.

A convoluted upper side gallery that may form a secondary blotch filling apex of leaf segment. Frass in closely spaced grains that may form streaks or strings.

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

Liriomyza eupatoriana Spencer, 1954 [Diptera: Agromyzidae].

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

4

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

5

4a > 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 Coreopsis, in Britain. 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, 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 Eupatorium in Britain.

Chromatomyia syngenesiae is recorded on Eupatorium elsewhere but not yet on Eupatorium in Britain.

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

5b > Leaf-miner: Mine long, linear, upper or lower surface, often adjoining a vein (Spencer, 1972b: 74 (fig. 244), 79).

Long corridor, often following the midrib for some distance. The mine is upper- or lower-surface; often the first part lower-surface, then upper-surface. Frass in pearl chains or isolated granules. Pupation outside the mine; exit slit in the lower epidermis.

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 > Leaf-miner: 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].

5d > Leaf-miner: The mine begins as a long, quite narrow corridor, usually not far from the tip of a leaf segment. Usually this corridor follows the leaf margin for some distance, but it may also run freely through the blade and may then be stongly contorted. In the end the corridor is directed towards the midrib, where an elongated blotch is formed, overlying the midrib and some of the larger lateral veins. Frass in a nearly continuous line in the initial corridor, in scattered lumps in the later part of the mine. Primary and secondary feeding lines very conspicuous when seen in transparancy. Pupation outside the mine.

The mine starts as a very narrow corridor, usually close to the tip of a leaf segment and following the leaf margin. The later section of the corridor approaches the main vein, where an elongated blotch is made with long broad finger like extensions that lay over the secondary veins. In the initial corridor the frass forms an almost continuous line, in the blotch it is distributed in large scattered lumps. In fresh mines the secondary feeding lines are clearly visible.

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].