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

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.

1# > Leaf-miner: Not distinguishable from the mines of P. betae or P. hyoscyami.

On Chenopodium and Solanum in Britain, plus Beta elsewhere. Widespread in continental Europe.

Pegomya interruptella (Zetterstedt, 1855) [Diptera: Anthomyiidae].

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).

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.

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: Oviposition can take place in the leaf, where a short mine is formed. The young larva feeds towards the mid-rib and down into the stem. Alternatively a true mine can be formed in the stem before the larva burrows deeper into the pith. Pupation external (Spencer, 1976: 160).

The larva bores in the pith of the stem, and eats this out while descending as low as the root collar. But before that it makes a linear mine in the green rind of the stem. Occasionally oviposition takes place on a leaf, leading to a fine corridor (without frass) running towards the midrib, and from there to the stem. The place where the larva finally exits the stem for pupation is indicated by a red-ringed hole.

Puparium yellow

On Chenopodium in Britain and Amaranthus and Chenopodium elsewhere. Recorded in Cambridge (Cambridge) and Derby (Worthington). Widespread in continental Europe.

Amauromyza chenopodivora Spencer, 1975 [Diptera: Agromyzidae].

1c > 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.

On Agrostemma, Dianthus, Lychnis, Saponaria, Silene, Stellaria [Caryophyllaceae] and Atriplex, Beta and Spinacia, but not yet on Agrostemma, [Chenopodiaceae] in Britain. Widespread in Britain and continental Europe. Also Canada.

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

1d > 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 [Caryophyllaceae], Atriplex, Beta, Chenopodium [Chenopodiaceae] and possibly Solanum [Solanaceae] 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].

1e > Leaf-miner: Mine indistinguishable from that of P. hyoscyami. A 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.

On ? Beta and ? Chenopodium in Britain and elsewhere. Widespread in Britain incluidng Easterness (VC96), North Devon (VC4), South Lancaster and West Suffolk (VC26) (NBN Gateway). Widespread in continental Europe

Pegomya conformis (Fallén, 1825) [Diptera: Anthomyiidae].

1f > Leaf-mine: Mine indistinguishable from P. betae or P. hyoscyami.

Hosts in Britain unknown. On Chenopodium and Spinacia elsewhere. Pegomya exilis and Pegomya cunicularia were distinguished from Pegomya betae and Pegomya hyoscyami by Michelsen (1980). Material of both [the former species] had previously been assigned to those [two latter] species (Chandler, pers. comm.). It is not known whether any of this previously mis-identified material is British.

Pegomya exilis (Meigen, 1826) [Diptera: Anthomyiidae]

1g > Leaf-miner: The larva makes several full depth blotch mines.

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

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

1i > 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 Chenopodium, in Britain.

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

1j > 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 Chenopodium, 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].

1k > 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).

Polyphagous. On ? Amaranthus, Cerastium, Lychnis, Myosoton, Nasturtium, Silene, Stellaria, Atriplex, ? Anthyllis, ? Lupinus, ? Medicago, ? Montia and ? Antirrhinum, but not yet on Chenopodium, 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].