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

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: A long yellowish green leaf-mine. Pupation external, puparium frequently adhering to leaf (Spencer, 1972b: 100; Spencer, 1976: 205).

Long, rather broad corridor, about halfway along the leaf blade. Frass in a few large, black lumps. Puparium formed now in, then outside the mine.

On Carex and Scirpus in Britain and continental Europe. Widespread in the southern Britain. Also recorded in the Republic of Ireland. Widespread in continental Europe. Also recorded in Canada and the U.S.A.

Cerodontha angulata (Loew, 1869) [Diptera: Agromyzidae].

1b > Leaf-miner: A very long mine. Pupation at base of leaf (Spencer, 1972b: 100). Puparium brown

Very long upper-surface corridor, at the end about 1/3 of the width of the leaf. The mine usually begins about halfway along the blade and descends within the leaf sheath. Just before pupation all frass is deposited in one big mass. Puparium within the mine, where it also passes the winter.

On Carex and Scirpus in Britain and Scirpus and Scheonoplectus in continental Europe. Probably widespread in Britain. Widespread in continental Europe. Also recorded in Canada.

Cerodontha scirpi (Karl, 1926) [Diptera: Agromyzidae].

1c > Leaf-miner: Mines and larvae indistinguishable from C. morosa. Mine relatively short and broad, not extending into leaf base. Pupation in the mine (Spencer, 1976: 219).

Upper-surface, interparenchymatous (therefore yellowish) corridor in the middle part of the leaf. The mine starts not far from the leaf tip, descends, and changes direction at least twice. Often in the end the corridor occupies the entire width of the leaf. Larva solitary. Frass in one big lump. Pupation inside the mine. The puparium is glued with frass to both the ceiling and the floor of the mine, parallel to the leaf vein.

On Carex and Scirpus in Britain and elsewhere. Only recorded from Cambridge, Suffolk and Warwick in Britain. Widespread in continental Europe.

Cerodontha suturalis (Hendel, 1931) [Diptera: Agromyzidae].

1d > Leaf-miner: Irregular mine, locally shallow, elsewhere much deeper, giving it a mottled appearance. In broadleaved plants the mine often begins as a blotch with stellate extensions, but sometimes as a very fine, shallow corridor. In grasses the mine often begins in the leaf sheath. The frass is very fine-grained, initially scattered, later in aggregates. The egg is deposited on the plant surface, and the empty egg shell remains visible. But the larvae are able to leave their mine and restart elsewhere, thus mines without an egg shell can be found as well. The larva also leaves the mine before pupation. Pupation takes place in a newly made, small, blotch mine without frass; this mine may be made in another plant (species).

Polyphagpus. On ? Alisma, ? Damasonium, ? Sagittaria, ? Bellis, ? Rorippa, Tropaeolum, ? Lychnis, ? Stellaria, ? Carex, ? Cyperus, ? Scirpus, ? Hydrocharis, ? Stratiotes, ? Lamium, ? Lemna, ? Allium, Arrhenatherum, ? Polygonum, ? Potamogeton, ? Veronica, ? Typha in Britain.

On ? Alisma, ? Damasonium, ? Sagittaria, ? Bellis, ? Rorippa, Tropaeolum, Lychnis, ? Stellaria, Carex, ? Scirpus, Trifolium, ? Hydrocharis, Lamium, ? Lemna, Allium, Papaver, Agrostis, Alopecurus, Apera, Arrhenatherum, Avena, Avenula, Brachypodium, Briza, Bromus, Calamagrostis, Dactylis, Desmazeria, Digitaria, Echinochloa, Eleusine, Elymus, Festuca, Gaudinia, Glyceria, Holcus, Hordeum, Lagurus, Lolium, Panicum, Phalaris, Phleum, Phragmites, Poa, Secale, Setaria, Triticum, ? Polygonum, ? Potamogeton, Veronica, ? Typha and Verbena elsewhere. Widespread in England. Also recorded in the Republic of Ireland. Widespread in the Palaearctic region. Also recorded from Nearctic and Australasian Regions.

Hydrellia griseola (Fallén, 1813) [Diptera: Ephydridae].