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

2

1b > Leaf miner

3

2a> Stem-miner: A narrow external stem mine on upper part of stem below flower head. Pupation external (Spencer, 1976: 246). Details of puparium unknown.

Only on Achillea millefolium in Britain and elsewhere. In Britain only known from mines collected in Middlesex.

Liriomyza flavopicta Hendel, 1931 [Diptera: Agromyzidae].

2b > Stem-miner: A narrow, inconspicuous stem mine. Pupation at the end of the mine. Puparium yellowish or completely black, anterior spiracles projecting through epidermis (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 (Bladmineerders van Europa).

On Achillea, Achillea millefolium and possibly Anthemis, Matricaria and Medicago sativa 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].

3a > Leaf-miner: Blotch mine. Pupation external. Puparium yellow. 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 (Bladmineerders van Europa). An elongated blotch centred over a vein. There are two types: greenish with a blackish centre and entirely reddish-black (British leafminers).

On numerous genera of Asteraceae, including Achillea, 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].

3b > 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).

3c > Leaf-miner: Linear mine

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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 (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, including Achillea, in Britain and elsewhere. Widespread throughout Britain. Also recorded in the Republic of Ireland. Widespread in continental Europe.

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

4b > Leaf-miner: Mine linear, but not primarily above the midrib.

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5a > Leaf-miner: Mine linear, frequently adjoining mid-rib (Spencer, 1972: 73). Upper-surface corridor; the start may be lower-surface. Pupation outside the mine (Bladmineerders van Europa).

Only on Achillea ptarmica in Britain and elsewhere. Widespread in Britain. Also occurs in west and central Europe.

Phytomyza corvimontana Hering, 1930 [Diptera: Agromyzidae].

5b > 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, but not yet on Achillea, in Britain.

Chromatomyia syngenesiae is recorded in Britain on 27 plant genera in the family Asteraceae and many more genera elsewhere, but not yet on Achillea, in Britain.

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

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

5c > Leaf-miner: A narrow linear mine commencing on lower surface. Puparium yellow (Spencer, 1972: 57; Spencer, 1976: 264). Narrow brownish corridor, either upper- or lower-surface. Frass in strings or pearl chains. Pupation outside the mine. In small leaves the mine can be full-depth and occupy the entire leaf. At least in Achillea millefolium mines are generally found in the top half of the leaf (Bladmineerders van Europa). Posterior spiracles of larva each with 3 bulbs (Spencer, 1972: 57; Spencer, 1976: 264).

On Achillea ptarmica and Achillea millefolium in Britain and elsewhere and other species of Achillea elsewhere. Probably widespread in Britain, at least in south. Widespread in continental Europe and also recorded from Canada.

Liriomyza ptarmicae Meijere, 1925 [Diptera: Agromyzidae].

5d > Leaf-miner: A narrow linear mine, even in the finest subdivisions of the leaves (Spencer, 1972: 77, as matricariae; Spencer, 1976: 478). Very fine corridor, upper- or lower-surface, even in the narrowest leaf segments. The corridor may be up to 14 cm long (Sehgal, 1971a). Generally the corridor descends towards the leaf base. Frass in pearl chains of loose grains, hardly in strings. Pupation outside the mine (Bladmineerders van Europa). Pupal posterior spiracles each with 18-20 bulbs.

On Achillea millefolium, Anacyclus pyrethrum, Anthemis, Tanacetum vulgare, Tripleurospermum, Tripleurospermum maritimum and Tripleurospermum maritimum x inodora in Britain and other Asteraceae elsewhere. Widespread in Britain and continental Europe. Also recorded in Canada.

Phytomyza pullula Zetterstedt, 1848 [Diptera: Agromyzidae].

5e > Leaf-miner: A linear mine, frequently on lower surface at beginning; frass with closely adjoining grains. Upper-surface, often brownish, corridor, in the end often occupying the width of a leaf segment. Older segments of the mine are much less conspicuous, lower-surface and quite shallow. Where upper- and lower-surface stretches overlap transparent patches occur, when the leaf is illuminated from behind. Frass in isolated grains, sometimes locally pearl chains. Pupation outside the mine (Bladmineerders van Europa).

Recorded on Tanacetum but not yet Achillea in Britain; recorded on Achillea, Leucanthemum, Pyrethrum and Tanacetum elsewhere. Probably widespread in England - Surrey (Horsley) (Spencer, 1972: 79) and Warwickshire (Coventry) (Robbins, 1991: 117). Also recorded in the Republic of Ireland: Co. Clare (the Burren) (Spencer, 1972: 79). Widespread in continental Europe

Phytomyza tanaceti Hendel, 1923 [Diptera: Agromyzidae].

Note: The larvae of mining Coleoptera, Hymenoptera and Lepidoptera may live in a corridor mine, a corridor-blotch mine, a blotch mine, a case, a rolled or folded leaf, a tentiform mine or sandwiched between two more or less circular leaf sections in later instars. Larva may pupate in a silk cocoon. The larva may have at least six legs (although they may be reduced or absent), a head capsule and chewing mouthparts with opposable mandibles (see video of a gracillarid larva feeding). Larvae of Hymenoptera and Lepidoptera usually also have abdominal legs (see examples). Frass, if present, never in two rows. Unless feeding externally from within a case the larva usually vacates the mine by chewing an exit hole. Pupa with visible head appendages, wings and legs which lie in sheaths (see examples).