POA. Meadow-grasses. [Poaceae]

Twenty-seven species of Poa are recorded in Britain. These include the native Annual Meadow-grass (P. annua), Flattened Meadow-grass (P. compressa), Wood Meadow-grass (P. nemoralis), Smooth Meadow-grass (P. pratensis) and Rough Meadow-grass (P. trivialis) and the introduced Broad-leaved Meadow-grass (P. chaixii).

Eleven Diptera miners, the agromyzids Agromyza albipennis, Agromyza nigrella, Agromyza rondensis, Cerodontha crassiseta, Cerodontha flavocingulata, Cerodontha fasciata, Cerodontha fulvipes, Chromatomyia milii, Chromatomyia nigra, Liriomyza flaveola and Pseudonapomyza atra, are recorded on Poa in Britain. Miners on grasses should be reared, whenever possible, to confirm their identity.

Spencer (1990) recorded the agromyzid Liriomyza orbona on Bellis perennis, although later he stated the host of L. orbona was unconfirmed, but certainly Gramineae (Spencer, 1976). Later still he gives the hosts as Avena, Deschampsia and Poa (Spencer, 1990), although it is not clear whether any of these are British host records.

Elsewhere the agromyzids Agromyza albipennis, Agromyza nigrella, Agromyza rondensis, Cerodontha atronitens, Cerodontha denticornis, Cerodontha fasciata, Cerodontha flavocingulata, Cerodontha incisa, Cerodontha lateralis, Cerodontha muscina, Cerodontha pymaea, Cerodontha superciliosa, Chromatomyia fuscula, Chromatomyia milii, Chromatomyia nigra, Liriomyza flaveola, Liriomyza graminivora and Pseudonapomyza atra are recorded mining Poa.

Eight non-Diptera miners are recorded on Poa in Britain (see below).

Elsewhere eleven additional British non-Diptera miners are recorded on Poa (see below).

The coloephorid Coleophora lixella is recorded as a seed-feeder on Poa in Britain and elsewhere.

The gelchiid Helcystogramma rufescens spins grass blades and feeds inside the spiral spinning, causing whitening of the grass blade tip.

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

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 at least 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 > Miner and case bearer. The larva lives outside the mine, protected by a case, and feeds on the underlying plant tisses via a hole cut in the epidermis. Mine does not contain frass (Coleophora species)

2

1b > Miner, but not a case-bearer, although it may live sandwiched between two more or less circular sections cut from the leaf in later instars e.g. Incurvaria species. The larva lives mainly inside the mine. Mine usually contains frass

3

2 > Leaf-miner and case-bearer: The young larva eats the receptacle out of a floret of Acinos arvensis, and uses the calyce as its first case. Even before the onset of winter it switches to grasses. The larva then lives in an ochraceous, bivalved, tubular leaf case of c. 9 mm, with a mouth angle of c. 25° (Bladmineerders van Europa).

Recorded on Bromopsis, Dactylis, Holcus, Koeleria, Phleum and Poa in Britain and 'grass species' elsewhere. West Norfolk and West Suffolk in Britain. Unknown elsewhere.

 

Coleophora tricolor Walsingham, 1899 [Lepidoptera: Coleophoridae].

3# >Leaf-miner: Details unknown.

Recorded on Festuca, Koeleria and Poa in Britain. Hosts elsewhere unknown. Britain including South Devon. Widespread in continental Europe.

 

Elachista collitella (Duponchel, 1843) [Lepidoptera: Elachistidae].

3# > Leaf-miner: Details unknown.

Recorded on Poa in Britain and Cynodon and Poa elsewhere. Occurs scattered throughout the UK, except N.Scotland and N. Ireland. Also recorded in the Republic of Ireland. Widespread in continental Europe.

 

Elachista consortella Stainton, 1851 [Lepidoptera: Elachistidae].

3a > Leaf-miner: Tufted hair-grass and blue moor-grass are the main foodplants, the larvae forming gallery mines (UKMoths). Gradually widening corridor, running either upwards or down. All frass is deposited in the earliest part of the mine. Often 2-3 larvae in a mine; in grasses with broad leaves sometimes more than one mine in a leaf (Bladmineerders van Europa).

Recorded on Deschampsia and Sesleria, but not yet on Poa, in Britain and Carex, Brachypodium, Calamagrostis, Deschampsia, Elymus, Festuca, Melica, Milium, Phleum, Poa and Sesleria elsewhere. Occurs in woodland habitats in England, Wales and locally in Ireland. Also recorded in the Channel Is. and the Republic of Ireland. Widespread in continental Europe.

Elachista adscitella Stainton, 1851 [Lepidoptera: Elachistidae].

3b > Leaf-miner: Corridor, 15 cm in the end, descending from the leaf tip. The mine is whtish and shallow at first, then becomes deeper, yellowish white, and more transparant. Pupation external; pupa, not in a cocoon, attached to the leaf (Bladmineerders van Europa).

Recorded on Carex, Eleocharis and Eriophorum, but not yet on Poa, in Britain and Carex, Eleocharis, Eriophorum, Scirpus, Calamagrostis, Deschampsia, Melica and Poa elsewhere. Northern Britain and Ireland. Also recorded in the Republic of Ireland. Widespread in continental Europe.

 

Elachista albidella Nylander, 1848 [Lepidoptera: Elachistidae].

3c > 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, but not yet on Poa, 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].

3d > 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', but not yet on Poa, 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].

3e > Leaf-miner: 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

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

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

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

3f > Leaf-miner: Blotch in the leaf tip; the upper side is practically flat, the lower side can turn somewhat to purple. The larva may mine 2-3 leaves (Bladmineerders van Europa).

Recorded on Avenula pratense, but not yet on Poa, in Britain and Arrhenatherum, Avena, Festuca, Avenula, Phleum and Poa elsewhere. Distibution in Britain uknown. Widespread in continental Europe.

 

Elachista bedellella (Sircom, 1848) [Lepidoptera: Elachistidae].

3g > Leaf-miner: Flat, whitish. Pupation outside the mine (Bladmineerders van Europa).

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

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

3h > Leaf-miner: The larvae mine the blades of various grasses, including meadow-grass and cock's-foot (UKMoths). 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].

3i > 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].

3j > Leaf-miner: Long, narrow, white corridor, descending from close to the leaf tip to the leaf base or even stem. Frass in an inconspicuous grey line. From the stem the larva may enter a new leaf (Steuer, 1987a; Bland, 1996a) (Bladmineerders van Europa).

Recorded on Brachypodium and Dactylis, but not yet on Poa, in Britain and Bromopsis, Dactylis, Deschampsia, Festuca, Lolium, Melica, Milium and Poa elsewhere. Widespread in Britain, Ireland and continental Europe.

Elachista luticomella Zeller, 1839 [Lepidoptera: Coleophoridae].

3k > 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].

3l > Leaf-miner: The mine begins near the leaf tip and descends towards the base. The mine occupies the entire width of the blade. Frass initially scattered, later in an irregular central line. Fully developed mine c. 8 cm long. Probably the larva is capable of leaving its mine and restarting in another leaf. Pupation external (Bladmineerders van Europa).

Recorded on Calamagrostis epigejos, but not yet on Poa, in Britain and Avena, Calamagrostis, Glyceria, Phalaris and Poa elsewhere. Cambridge and East Norfolk in Britain. Widespread in continental Europe.

 

Elachista pomerana Frey, 1870 [Lepidoptera: Elachistidae].

3m > 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, but not yet on Poa, in Britain and Agrostis, Avena, Brachypodium, Calamagrostis, Festuca, Milium and Poa elsewhere. Widespread in Britain and continental Europe.

 

Elachista stabilella Stainton, 1858 [Lepidoptera: Elachistidae].

3n > Leaf-miner: The larva creates a long narrow mine in the blade (UKMoths). Mine fairly translucent. It starts as a narrow corridor, running towards the leaf tip, but this almost invariably is overrun be a later, broad, descending corridor. The centre of the mine contains a vertical tube made of loose silk, in which the larva can quickly move up or down, and in which also most frass gets trapped. The sides of the mine are smooth (contrary to E. gangabella). Mines are difficult to find, because the leaves are wilting when larvae are present (Bladmineerders van Europa).

Recorded on Molinia, but not yet on Poa, in Britain and Carex, Arrhenatherum, Brachypodium, Calamagrostis, Melica, Molinia and Poa elsewhere.

 

Elachista subalbidella Schläger, 1847 [Lepidoptera: Elachistidae].

3o > Leaf-miner: The larvae mine the stems of various coarse grasses (UKMoths; Plant in Pitkin and Plant, 2005).

Recorded on Dactylis and Poa in Britain. Widespread in England and Wales. Also recorded in the Republic of Ireland. Widespread in continental Europe.