The leaf and stem mines of British flies and other insects
 

(Coleoptera, Diptera, Hymenoptera and Lepidoptera)

by Brian Pitkin, Willem Ellis, Colin Plant and Rob Edmunds

N.B. Links to the latest version of 'Leafminers and plant galls of Europe' are being edited

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AGROSTIS. Bents. [Poaceae]


About twenty-six species of Agrostis are recorded in Britain. These include the native Velvet Bent (A. canina), Common Bent (A. capillaris), Black Bent (A. gigantea) and Creeping Bent (A. stolonifera).

Twenty British miners are recorded on Agrostis.

A key to the European miners recorded on Agrostis is provided in Bladmineerders van Europa.

Nearly 100 British miners or possible miners are recorded on grasses in Britain.

It is recommended that adults of all miners on grasses be reared to be certain of their identity.



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


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: Larvae feed singly, forming an upper surface linear-blotch mine. Pupation either internal or external, with the puparium loosely glued to the leaf (Spencer, 1976: 91).

Oviposition near the leaf margin, at some distance from the leaf tip. From there develops an upper-surface corridor-blotch. At first the mine ascends as a narrow corridor towards the leaf tip, then the direction turns and the mine, steadily widening, descends in the direction of the leaf base. Frass irregular, in rather coarse grains. Larva solitary. Pupation mostly outside the mine; in that case the puparium often sticks to the leaf (Bladmineerders van Europa).

Mine of Agromyza albipennis on Phalaris arundinacea. Image: © Willem Ellis (Source: Bladmineerders en plantengallen van Europa)
Mine of Agromyza albipennis on Phalaris arundinacea
Image: © Willem Ellis (Bladmineerders van Europa)

On Arrhenatherum, Brachypodium, Bromus, Dactylis, Glyceria, Holcus, Hordeum, Milium, Phalaris and Poa, but not yet on Agrostis, in Britain and additional grasses, including Agrostis, elsewhere. Widespread and common in Britain. Also recorded in the Republic of Ireland. Very common in western Europe and recorded in Canada.

Agromyza albipennis Meigen, 1830 [Diptera: Agromyzidae].

1b > Leaf-miner: Larvae feeding singly, forming a long, widening mine on the upper surface of the leaf, which is generally limited to one side of the leaf. Pupation external, puparium glued to the leaf near the end of the mine (Spencer, 1976: 128).

Broad corridor, generally beginning near the leaf margin or close to the leaf tip. Most of the times the mine remains at one side of the midrib. The mine is upper-surface, but has some full depth, translucent spots here and there. Frass in rather regularly scattered grains. Pupation outside the mine. According to Dempewolf (2004a) only the male genitalia enable a reliable discrimination from A. abipennis and A. graminicola (Bladmineerders van Europa).

On Glyceria and Holcus, but not yet on Agrostis, in Britain and additional genera of grasses, including Agrostis, in continental Europe. Widespread and common in Britain. Widespread in continental Europe. Also recorded in Canada.

Agromyza nigripes Meigen, 1830 [Diptera: Agromyzidae].

1c > Leaf-miner: Upper-surface, unusually short corridor (ca. 4 cm). Sometimes several mines in a leaf. Pupation outside the mine (Bladmineerders van Europa).

On Arrhenatherum and Tragopogon and possibly Agrostis in Britain and Arrhenatherum elsewhere. Widespread but not common in southern England. Also recorded on in the Republic of Ireland and continental Europe.

Liriomyza pusio (Meigen, 1830) [Diptera: Agromyzidae].

1d > Leaf-miner: A narrow whitish linear mine, running down the leaf from the apex, with frass in two rows of separate grains. Pupation external (Spencer, 1976: 246).

Narrow corridor from start to end, whitish, uppper- or lower-surface, genarally running downwards. Mine often along the leaf margin. Frass in distict grains of regular size, alternating along the sides of the corridor. Pupation outside the mine (Bladmineerders van Europa).

Mine of Liriomyza flaveola on Festuca gigantea. Image: © Willis Ellis (Source: Bladmineerders en plantengallen van Europa)
Mine of Liriomyza flaveola on Festuca gigantea
Image: © Willis Ellis (Bladmineerders van Europa)

On Bromus, Dactylis, Holcus and Poa, but not yet on Agrostis, in Britain and additional grasses, including Agrostis, elsewhere. Common and widespread throughout Britain. Also recorded in the Republic of Ireland. Common throughout much of Europe.

Liriomyza flaveola (Fallén, 1823) [Diptera: Agromyzidae].

1e > Leaf-miner: Lower-surface corridor in the top half the leaf blade; the mine changes direction at least two times. One to three larvae in a mine. Frass in rather regular granules (Bladmineerders van Europa).

On Phragmites, but not yet on Agrostis, in Britain and Agrostis, Calamagrostis and Dactylis elsewhere. Probably widespread at least in southern England. Widespread in continental Europe.

Cerodontha atra (Meigen, 1830) [Diptera: Agromyzidae].

1f > Leaf-miner: A lower surface mine. Pupation normally in the ground (Spencer, 1976: 202).

Broad, usually lower-surface corridor in the blade, generally first rising, then descending. Mostly one larva in a mine, but sometimes several mines on a leaf may merge. Frass in grains that gradually become both larger and more widely spaced. Pupation outside the mine (Bladmineerders van Europa).

On Agrostis, Arrhenatherum, Dactylis, Elymus, Festuca, Holcus and Poa in Britain. Widespread in Britain and continental Europe. Also Canada.

Cerodontha flavocingulata (Strobl, 1909) [Diptera: Agromyzidae].

1g > Leaf-miner: Broad elongated mine; the form is dependent of the leaf form of the host plant. Frass green. Usually a number of larvae together in a mine. Pupation in the mine (Bladmineerders van Europa).

On Bromopsis, Dactylis, Elymus and Phalaris, but not yet on Agrostis, in Britain and additional grasses, including Agrostis, elsewhere. Widespread in Britain. Also recorded in the Republic of Ireland. Widespread and common in continental Europe. Also recorded in Japan, U.S.A. and Canada.

Cerodontha incisa (Meigen, 1830) [Diptera: Agromyzidae].

1h > Leaf-miner: Normally several larvae feed together. Pupation in the mine (Spencer, 1976: 198).

Broad elongated blotch. Frass greenish. Larvae generally communal. Pupation within the mine. The black puaria are individially anchored within the mine with a silken thread attached at their rear end. Distinguishable from C. incisa only by means of the larva (Bladmineerders van Europa).

On Arrhenatherum, Brachypodium, Bromus, Bromopsis, Calamagrostis, Dactylis, Deschampsia, Elymus, Festuca, Holcus, Lolium, Molinia and Phalaris, but not yet on Agrostis, in Britain and additional grasses, including Agrostis, elsewhere. Widespread and common in Britain. Also recorded in the Republic of Ireland. Widespread and frequently common in much of Europe. Also recorded in Alaska and Canada

Cerodontha pygmaea (Meigen, 1830) [Diptera: Agromyzidae].

1i > Leaf miner: A substantial linear mine. Pupation internal; posterior spiracles projecting through the epidermis (Spencer, 1976: 449).

Elongated, shallow, upper-surface or lower-surface blotch, not infrequently several in one leaf. Frass in strings or pearl chains. Pupation within the mine (Bladmineerders van Europa)

Mine of Chromatomyia milii on Holcus lanatus. Image: © Willem Ellis (Source: Bladmineerders en plantengallen van Europa)
Mine of Chromatomyia milii on Holcus lanatus
Image: © Willem Ellis (Bladmineerders van Europa)
Chromatomyia milii larva,  lateral
Chromatomyia milii larva, lateral
Image: © Willem Ellis (Bladmineerders van Europa)
Chromatomyia milii larva,  lateral
Chromatomyia milii larva, dorsal
Image: © Willem Ellis (Bladmineerders van Europa)

On Hierochloe, Holcus, Hordeum, Milium and Poa, but not yet on Agrostis, in Britain and additional genera of grasses, including Agrostis, elsewhere. Almost certainly widespread throughout the British Isles. Also recorded in the Republic of Ireland. Widespread from Morocco through central and northern Europe.

Chromatomyia milii (Kaltenbach, 1864) [Diptera: Agromyzidae].

1j > Leaf-miner: Long, narrow, whitish mine. Pupation internal (Spencer, 1976: 453); anterior spiracles projecting through the epidermis.

Whitish, upper-surface, rather narrow corridor with comparatively large frass grains that are laying further apart than their diameter. Pupation within the mine. The anterior spiracles of the orange-brown puparium penetrate the epidermis (Bladmineerders van Europa).

Chromatomyia nigra larva,  lateral
Chromatomyia nigra larva, lateral
Image: © Willem Ellis (Bladmineerders van Europa)
Orchestes fagi larva,  dorsal
Chromatomyia nigra pupa, lateral
Image: © Willem Ellis (Bladmineerders van Europa)

Polyphagous. On numerous genera of grasses, including Arrhenatherum, Avenula and Brachypodium, but not yet on Agrostis, in Britain and additional grasses, including Agrostis, elsewhere. Widespread and common throughout British Isles and much of Europe. Also recorded in Canada, western U.S.A. and Japan.

Chromatomyia nigra (Meigen, 1830) [Diptera: Agromyzidae].

1k > Leaf-miner: A short narrow mine, generally near apex of leaf. Larva with each segment bearing a row of characteristic papilli which are retained in the puparium (Spencer, 1976: 328). Pupation internal.

Transparent, short and narrow mine not far from the leaf tip. Frass in two rows of grains. Pupation outside the mine (Bladmineerders van Europa).

On Avena, Dactylis, Holcus, Hordeum, Lolium, Phalaris, Phragmites, Poa and Secale, but not yet on Agrostis, in Britain and additional other genera of grasses, including Agrostis, elsewhere. Widespread, but local, in south of Britain. Widespread in continental Europe. Also recorded in Canada.

Pseudonapomyza atra (Meigen, 1830) [Diptera: Agromyzidae].

1l > 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) (Bladmineerders van Europa).

Mine of Hydrellia griseola on Glyceria fluitans. Image: © Willem Ellis (Source: Bladmineerders en plantengallen van Europa)
Mine of Hydrellia griseola on Glyceria fluitans
Image: © Willem Ellis (Bladmineerders van Europa)

Polyphagpus. On ? Alisma, ? Damasonium, ? Sagittaria, ? Bellis, ? Rorippa, Tropaeolum, ? Lychnis, ? Stellaria, ? Carex, ? Cyperus, ? Scirpus, ? Hydrocharis, ? Stratiotes, ? Lamium, ? Lemna, ? Allium, Arrhenatherum, ? Polygonum, ? Potamogeton, ? Veronica, ? Typha, but not yet on Agrostis, 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].



Key for the identification of the known mines of British
non-Diptera recorded on Agrostis


Note: The larvae of mining Coleoptera, Hymenoptera and Lepidoptera may live in a corridor mine, a corridor-blotch mine, a blotch mine, a case, a rolled or folded leaf, a tentiform mine or sandwiched between two more or less circular leaf sections in later instars. Larva may pupate in a silk cocoon. The larva may have six legs (although they may be reduced or absent), a head capsule and chewing mouthparts with opposable mandibles (see video of a gracillarid larva feeding). Larvae of Hymenoptera and Lepidoptera usually also have abdominal legs (see examples). Frass, if present, never in two rows. Unless feeding externally from within a case the larva usually vacates the mine by chewing an exit hole. Pupa with visible head appendages, wings and legs which lie in sheaths (see examples).


1a > Leaf-miner: The larva mines from the grass tip downwards and the mine occupies half or the whole of the leaf blade width. A whitish blotch is formed with characteristic narrow streaks of frass (British leafminers). Full depth blotch, slightly inflated, descending from the leaf tip, occupying half or the entire width of the blade. The larva may move and make a new mine elsewhere. In the latter case the mines are fairly short; otherwise an entire blade may be mined out. Frass in a some narrow greyish brown streaks. Pupation outside the mine (Bladmineerders van Europa).

On Dactylis, Deschampsia and Holcus, but not yet on Agrostis, in Britain plus Luzula, Agrostis, Alopecurus, Arrhenatherum, Avena, Avenula, Brachypodium, Bromus, Calamagrostis, Elymus, Festuca Koeleria, Phalaris, Phleum, Poa, Trisetum and Triticum elsewhere. Widespread in Britain, Ireland and continental Europe.

Elachista albifrontella (Hübner, 1817) [Lepidoptera: Elachistidae].

1b > Leaf-miner: Corridor widening while descending from the tip of the leaf. The mine is unusual because the sides are very irregularly scalloped out. Moreover, the mine is not evenly transparent, but rather yellowish green and motly, because the larva leaves patches of parenchyma uneaten, and does not feed full depth. Frass in a few irregular, interrupted length lines. Often 2-3 larvae in a mine. The larvae hibernate in the centre of the mine; after winter they leave their mine and pupate ( Bladmineerders van Europa).

On 'various grasses' in Britain plus Luzula, Agrostis, Arrhenatherum, Brachypodium, Calamagorstis, Dactylis, Deschampsia, Elymus, Festuca, Glyceria, Holcus, Melica, Milium and Poa elsewhere. Widespread in Britain, Ireland and continental Europe.

Elachista apicipunctella Stainton, 1849 [Lepidoptera: Elachistidae].

1c > Leaf-miner: A small narrow mine on a wide variety of grasses. In the spring the larva changes leaves and mines tip downwards. The mine fills the leaf width. The frass is packed in the top of the mine (British leafminers). In autumn the larva makes a narrow corridor a few cm in length, in which it hibernates. In March it moves to a new leaf. Here a transparent, full depth mine is made that descends from the leaf tip, and occupies the entire width of the blade. Most frass is concentrated in the oldest, highest, part of the mine. The larva may leave its mine and restart elsewhere. Pupation outside the mine (Bladmineerders van Europa).

Mine of Elachista argentella on Dactylis glomerata
Mine of Elachista argentella on Dactylis glomerata
Image: © Ben Smart (British leafminers)

On Dactylis glomerata, but not yet on Agrostis, in Britain. On numerous grasses including Agrostis elsewhere. Widespread in Britain and continental Europe. Also recorded in the Republic of Ireland.

Elachista argentella (Clerck, 1759) [Lepidoptera: Elachistidae].

1d > Leaf-miner: Flat, whitish. Pupation outside the mine (Bladmineerders van Europa).

On Holcus mollis in Britain, but not yet on Agrostis, plus Agrostis, Arrhenatherum, Avenula, Deschampsia, Festuca and Poa elsewhere. Widespread in Britain and continental Europe.

Elachista canapennella (Hübner, 1813) [Lepidoptera: Elachistidae].

1e > Leaf-miner: Long, flat, whitish, relatively broad corridor descending from the leaf tip. Frass irregularly scattered. The larva may make several mines during its lifetime. Pupation outside the mine (Bladmineerders van Europa).

On Dactylis, Holcus and Poa, but not yet on Agrostis, in Britain plus Agrostis, Bromus, Festuca, Holcus, Koeleria, Trisetum and Triticum elsewhere. Widespread and reasonably common throughout much of the British Isles except the very far north. Widespread in continental Europe.

Elachista freyerella (Hübner, 1825) [Lepidoptera: Elachistidae].

1f > Leaf-miner: In spring a short corridor is made that is almost stuffed with frass. After hibernation this mine is vacated, and the larva then makes a number of elongated blotches, all descending from the leaf tip. These latter mines are whitish, with irregularly scattered frass (Bladmineerders van Europa).

On Carex, Agrostis, Anthoxanthum, Deschampsia, Festuca, Holcus and Poa in Britain plus Phalaris elsewhere. Widespread in Britain, Ireland and continental Europe.

Elachista humilis Zeller, 1850 [Lepidoptera: Elachistidae].

1g > Leaf-miner: Larva makes a large whitish blotch and mines the leaf downwards. The frass tends to be deposited in the upper part of the mine (British leafminers). Oviposition usually not far from the leaf tip. From there descends an irregular blotch mine. Hering (1957a) describes the mine as flat and quite shallow, giving it a greenish, rather than whitish appearance. Frass initially in the oldest, upper part of the mine, later in strings. The larva can leave its mine and restart elsewhere. Normally only one larva per mine, but sometimes two or even three mines in a leaf. Pupation outside the mine (Bladmineerders van Europa).

On Dactylis, Phalaris, Phragmites and Poa, but not yet on Agrostis, in Britain plus Agrostis, Alopecurus, Arrhenatherum, Brachypodium, Calamagrostis, Elymus, Festuca, Holcus, Trisetum and Triticum elsewhere. Widely distributed in Britain, Ireland and continental Europe.

Elachista maculicerusella (Bruand, 1859) [Lepidoptera: Elachistidae].

1h > Leaf-miner: Mines downwards from leaf tip to stem. Makes a long narrow yellowish mine. May be up to four larvae in one leaf (British leafminers). Long narrow yellowish corridor, descending from the leaf tip to its base; at times 3-4 larvae in a leaf. Often several larvae in a communal mine. Pupation outside the mine (Bladmineerders van Europa).

On Carex, Agrostis, Brachypodium, Deschampsia and Festuca in Britain and Agrostis, Avena, Brachypodium, Calamagrostis, Festuca, Milium and Poa elsewhere. Widespread in Britain and continental Europe.

Elachista stabilella Stainton, 1858 [Lepidoptera: Elachistidae].



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