AGROSTIS. Bents. [Poaceae]

Twenty 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).

Two Diptera miners, the agromyzids Cerodontha flavocingulata and Liriomyza pusio are recorded on Agrostis in Britain, although more species are to be expected (see Arrhenatherum). Miners on grasses should be reared, whenever possible, to confirm their identity.

Elsewhere the grass-feeding agromyzids Agromyza albipennis, Agromyza nigripes, Cerodontha atra, Cerodontha flavocingulata, Cerodontha incisa, Cerodontha pygmaea, Chromatomyia milii, Chromatomyia nigra, Liriomyza flaveola and Pseudonapomyza atra and the polyphagous ephydrid Hydrellia griseola are recorded mining Agrostis.

Two non-Diptera leaf-miners, Elachista humilis and Elachista stabilella, are recorded on Agrostis in Britain (see below).

Elsewhere eight British non-Diptera miners are recorded on Agrostis (see below).

A key to the European miners, based on characteristics of the mines, immature stages and where relevant the larval cases, recorded on Agrostis is provided in Bladmineerders van Europa. This includes Elachista spp., Hydrellia griseola, Agromyza albipennis, Agromyza nigripes, Chromatomyia milii, Chromatomyia nigra, Cerodontha beigerae, Cerodontha incisa, Cerodontha pygmaea, Liriomyza flaveola, Liriomyza pusio, Cerodontha flavocingulata, Pseudonapomyza atra and Cerodontha atra.

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).

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

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

1b > Leaf-miner: A lower surface mine. Normally pupation in the ground. Puparium yellowish brown.

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].

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

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).

Recorded on Dactylis, Deschampsia and Holcus 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).

Recorded on 'various grasses' in Britain plus Luzula, Agrostis, Arrhenatherum, Brahcypodium, 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 Image: Ben Smart (British leafminers)

Recorded on Dactylis glomerata, but not yet on Agrostis, in Britain. Recorded 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).

Recorded on Holcus mollis in Britain 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).

Recorded on Dactylis, Holcus and Poa 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).

Recorded 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).

Recorded on Dactylis, Phalaris, Phragmites and Poa 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).

Recorded 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.