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 > Leaf and stem miner: Eggs are scattered individually over the leaf upper surface; they are only loosely attached to the plant. The egg shell has a honeycomb structure. The larva begins with first mining one of the top leaves completely out. Next the larva moves down to another leaf, by way of a tunnel made in the stem. In this way several leaves are mined out, completely and full depth. In the attacked part of the plant the stem has become translucent; the damage causes the plant tip to wilt. In the first mines almost no frass is to be found, further down it is deposited in coarse grains. Pupation generally outside the mine (Miles, 1953) (Bladmineerders van Europa).

Host records ambiguous. Recorded on ? Agrostemma, ? Arenaria, ? Cerastium, ? Dianthus, ? Gypsophila, ? Lychnis, ? Saponaria, Silene, ? Spergularia, ? Stellaria, Vaccaria, Atriplex, ? Chenopodium, Spinacia and ? Phlox in Britain. Recorded on Amaranthus, Agrostemma, Arenaria, Cerastium, Dianthus, Gypsophila, Lychnis, Saponaria, Silene, Spergularia, Stellaria, Vaccaria, Atriplex, Chenopodium, Spinacia, Phlox and Primula elsewhere. Recorded from Warwick and West Ross in Britain. Widespread in continental Europe.

Delia echinata (Seguy, 1923) [Diptera: Anthomyiidae].

1b > Leaf-miner: A white linear-blotch mine, the linear section sometimes not detectable as it becomes enveloped in later blotch (Spencer, 1976: 162-3, figs 296-7). Upper-surface, less often lower-surface, corridor, followed, and often overrun, by a large blotch. Even when the corridor is overun, it usually remains recognisable in the frass pattern. The mine looks whitish in the field. The blotch does not contain much frass, in the form of small black grains, dispersed and stuck to the floor of the mine. Feeding punctures upper-surface (always?). Pupation outside the mine (Bladmineerders van Europa). A common miner, forming a white linear blotch mine (the blotch may obscure the linear portion of the mine) in both native and garden plants (British leafminers).

On Agrostemma, Dianthus, Lychnis, Saponaria, Silene, Stellaria [Caryophyllaceae] and Atriplex, Beta and Spinacia [Chenopodiaceae] in Britain. Widespread in Britain and continental Europe. Also Canada.

Amauromyza flavifrons (Meigen, 1830) [Diptera: Agromyzidae] .

1c > Leaf-miner: Corridor-blotch mine. The mine starts as a long, narrow, winding corridor running towards the midrib, widening to a blotch. Usually upper-surface, but in small leaves also full-depth parts may occur. The blotch has broad lobes; in their ends most frass is accumulated in the form of green patches or clouds. Sometimes several larvae share mine. Pupation usually in the soil, less often in the leaf (and then generally not in the mine itself but in a small separated mine, that may even be made in the petiole) (Bladmineerders van Europa).

Mine of Scaptomyza graminum on Cerastium glomeratum Image: Jean-Yves Baugnée (Bladmineerders van Europa)

On ? Amaranthus, ? Rorippa, Cerastium, Lychnis, Myosoton, Silene, Stellaria, Atriplex, ? Anthyllis, ? Lupinus, ? Medicago, ? Montia and ? Antirrhinum in Britain and Amaranthus, Lepidium, Moricandia, ? Rorippa, Agrostemma, Arenaria, Cerastium, Coronaria, Corrigiola, Cucubalus, Dianthus, Gypsophila, Lychnis, Moehringia, Myosoton, Polycarpon, Saponaria, Silene, Spergularia, Stellaria, Vaccaria, Viscaria, Atriplex, Beta, Chenopodium, Obione, Salicornia, Spinacia, Anthyllis, Lupinus, Medicago, Allium, Montia, Portulaca and Antirrhinum elsewhere. Widespread in Britain and continental Europe. Scaptomyza graminum (Fallén, 1823) [Diptera: Drosophilidae].