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 > Larva forming linear-blotch mine between two veins, not adjoining margin of leaf, frass in distinct black strips or pellets. Puparium reddish brown

On Urtica dioica in Britain. On Parietaria officinalis, Urtica dioica, Urtica pilulifera, Urtica radicans and Urtica urens elsewhere. Widespread in Britain. Also recorded in the Republic of Ireland. Widespread in continental Europe.

Agromyza anthracina Meigen, 1830 [Diptera: Agromyzidae].

1b > Larva forming linear-blotch, adjoining or following the margin of the leaf.

2

2a > Larva forming irregular elongate linear blotch mine, normally adjoining margin of leaf. Puparium reddish brown

On Urtica dioica in Britain. On Urtica dioica and Urtica ilulifera elsewhere. Widespread and common in Britain. Also recorded in the Republic of Ireland. Widespread in continental Europe.

Agromyza pseudoreptans Nowakowski, 1964 [Diptera: Agromyzidae].

2b > Mine generally follows the leaf margin, widening from the initial linear section into an irregular broad blotch; it is dark green when fresh but quickly turns blackish. Puparium reddish brown

On Urtica dioica in Britain. On Urtica dioica, Cannabis, Humulus, Mentzelia and Parietaria elsewhere. Widespread in Britain and continental Europe. Also recorded in Canada.

Agromyza reptans Fallén, 1823 [Diptera: Agromyzidae].