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

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.

1b > Leaf-miner: Initially a linear mine running towards apex of leaf which then turns back and develops into a blotch in the area of the mid-rib (Spencer, 1972b: 37, fig. 114A; Spencer, 1976: 110, fig. 177).

Upper-surface corridor along the leaf margin, running from the leaf base to the tip. Once at the tip the corridor goes down over the midrib, widening considerably. Frass in the corridor part in a broad green central band, with minute black particles at either side. In the final, blotchy part frass in coarse black grains that may sometimes stick together. Pupation outside the mine.

Puparium reddish brown

On Medicago and Melilotus in Britain and elsewhere and in addition Trifolium elsewhere. Widespread in Britain and continental Europe.

Agromyza frontella (Rondani, 1875) [Diptera: Agromyzidae].

1c > Leaf-miner: Larva producing a short narrow linear mine not associated with the margin, which then develops into a conspicuous white blotch centred on the mid-rib. At the end of feeding the larva lies for one or two days along the mid-rib. Pupation external (Spencer, 1972b: 37 (fig. 114b); Spencer, 1976: 126, fig. 213A).

Broad and short hook-like upper-surface corridor, ending in a little blotch in the centre of a leaflet. The blotch is upper-surface as well, but has some deep spots, giving the mine a mottled appearance when hold against the light. Frass in the blotch in a few large lumps. Pupation outside the mine.

A short, broad gallery leading to a conspicuous, roundish white blotch in the centre of the leaf. The blotch is upper surface with full depth spots - comprising of large clumps of frass.

Puparium reddish

On Medicago, Melilotus and Trifolium in Britain and in addition other genera of Fabaceae elsewhere. Common and widely distributed in England. Also recorded in the Republic of Ireland. Widespread and common throughout Europe.

Agromyza nana Meigen, 1830 [Diptera: Agromyzidae].

1d > 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, including Melilotus, in Britain.

Chromatomyia horticola (Goureau, 1851) [Diptera: Agromyzidae].

1e > Leaf-miner: An upper or lower surface shallow winding linear mine, which may develop into a secondary blotch. Pupation external (Spencer, 1976: 240). Puparium orange

Upper- or lower-surface, greenish or whitish corridor, sometimes a blotch. The corridor does not widen much and is not associated with the midrib. Frass in conspicuous thread fragments, alternating along the sides of the corridor. Pupation outside the mine.

The mine is also illustrated in British Leafminers.

On Melilotus and Ononis in Britain and elsewhere and in addition on Cicer, Coronilla, and Hymenocarpos elsewhere.

Liriomyza cicerina (Rondani, 1875) [Diptera: Agromyzidae].

1f > Leaf-miner: An upper surface linear mine with frass in conspicuous greenish strips, largely alternating at each side of the channel. Puparium yellow

Polyphagous. On numerous genera of Fabaceae, including Melilotus, in Britain and elsewhere. Widespread in Britain. Also recorded in the Republic of Ireland and widespread and common throughout most of Europe

Liriomyza congesta (Becker, 1903) [Diptera: Agromyzidae].

1g > 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 Melilotus, 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].