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

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 and stem miner: Apart from mining leaves the stems are excavated. Oviposition takes place on the tips of shoots. The larva at first mines strip-like full depth corridors in the apical leaves, going then into the stem, which it hollows out, so that it becomes translucent. It then searches out leaves further down in which initially it mines depositing frass in strips, but then in blotches. The corridors often lie in one half of the leaf and can be branched. In the blotches the frass is irregularly scattered. Pupation is in the hollow stem or in the ground.

On ? Agrostemma, ? Arenaria, Cerastium, ? Dianthus, ? Gypsophila, ? Lychnis, ? Saponaria, Silene, ? Spergularia, ? Stellaria and Vaccaria [Caryophyllaceae], Atriplex, ? Chenopodium, Spinacia [Chenopodiaceae], Phlox [Polemoniaceae] in Britain. Also recorded on other hosts elsewhere. Known only from Warwick and West Ross in Britain, Europe, Japan, Canada and Alaska.

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

1b > Leaf-miner

2

2b > 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.

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.The mine is also illustrated in the Encyclopedia of Life.

Puparium reddish brown

On numerous genera of Caryophyllaceae and Chenopodiaceae, including Atriplex, in Britain. Widespread but local in Britain. Widespread and not uncommon in much of Europe. Also recorded in Canada.

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

2c > Leaf-miner: Blotch mines, generally occupying an entire leaf, usually containing several larvae. Much, half deliquescent, green frass. Mine indistinguishable from P. exilis or P. hyoscyami.

On Atriplex, Beta and ? Polygonum, but not yet on Solanum, in Britain and additionally Silene and Spinacia [Caryophyllaceae], Chenopodium, Atropa, Hyoscyamus and Solanum [Solanaceae] in continental Europe. Only recorded from Warwick in Britain. Also recorded in the Republic of Ireland, Europe, the East Palaearctic and Nearctic Regions. Widespread in continental Europe including Balearic Is., Canary Is., Czech Republic, Danish mainland, Finland, Greek mainland, Hungary, Italian mainland, Malta, Norwegian mainland, Russia (Central), Sweden, East Palaearctic, Near East, North Africa (Michelsen in Fauna Europaea).

Pegomya betae (Curtis, 1847) [Diptera: Anthomyiidae].

Hosts in Britain unknown. On Atriplex, Beta, Chenopodium and Spinacia elsewhere.

Pegomya cunicularia (Rondani, 1866) [Diptera: Anthomyiidae].

2e > Leaf-miner: Large blotch mine, often with several larvae, beginning with a short deeper corridor at a single egg shell on the surface of the leaf. The broad deep corridor later ends in a blotch but can be recognised (beneath the blotch) by its greater depth. Mine predominantly dorsal or ventral, greenish in transmitted light. Frass grains irregularly scattered except in the initial corridor.

Blotch, mostly occupying almos the entire leaf, containing several larvae. Much, half-deliquescent, greenish-black frass. At the start of the mine at the leaf underside a group of some 5 elliptic egg shells, parallel to each other. However, the larvae can leave their mine and restart elsewhere, so mines without egg shells can occur as well. The larvae do not penetrate into the stem of the plant, neither is the mine full depth (compare Delia species). Mine indistinguishable from P. exilis or P. hyoscyami.

Makes a large upper surface whitish blotch, which can contain several larvae. The frass has a washed out appearance and is greenish. There may be several mines on a leaf and eventually the leaf will be mined and then shrivel up. To identify this miner adults must be reared.

On Silene, Atriplex, Beta, Chenopodium and ? Solanum in Britain and additional genera of Chenopodiaceae and Solanaceae elsewhere. Known only from Inner Hebrides, Ayr and Warwick in Britain. Also recorded in continental Europe and the East Palaearctic.

Pegomya hyoscyami (Panzer, 1809) [Diptera: Anthomyiidae].

2f > Leaf-miner: Blotch.

On Suaeda, but not yet on Atriplex, in Britain and Atriplex, Suaeda and ? Spergularia elsewhere. Widespread in Britain and continental N.W, Europe

Botanophila depressa (Stein, 1907) [Diptera: Anthomyiidae].

2g > Leaf-miner: 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).

On ? Amaranthus, Cerastium, Lychnis, Myosoton, Nasturtium, Silene, Stellaria, Atriplex, ? Anthyllis, ? Lupinus, ? Medicago, ? Montia and ? Antirrhinum in Britain.

On Amaranthus, Lepidium, Moricandia, ? Rorippa, Agrostemma, Arenaria, Cerastium, 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].

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 Atriplex, 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].

2i > Leaf-miner: Broad mine of variable depth. Frass spread irregularly. Pupation usually internal, seldom external.

On ? Atriplex, ? Beta, ? Salicornia, ? Spergularia and ? Sueada in Britain plus Obione elsewhere. Recorded in Britain and the the Republic of Ireland (Zatwarnicki, 2004 in Fauna Europaea). Widespread in continental Europe.

Clanoneurum cimiciforme (Haliday, 1855) [Diptera: Ephydridae].