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HORDEUM.
Barleys. [Poaceae]
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Twenty-three
species of Hordeum are recorded in Britain. These include
the native Sea Barley (H. marinum), Meadow Barley (H.
secalinum), Six-rowed Barley (H. vulgare) and Wall Barley
(H. murinum).
Six
Diptera miners, the agromyzids Agromyza
albipennis, Agromyza
ambigua, Agromyza
nigrociliata, Chromatomyia
milii and Pseudonapomyza
atra, are recorded on Hordeum in Britain. Miners
on grasses should be reared, whenever possible, to confirm their
identity. Records of Chromatomyia
fuscula and Liriomyza
graminivora, however, are rejected as non-British species.
Elsewhere
the agromyzids Agromyza
ambigua, Agromyza
albipennis, Agromyza
intermittens, Agromyza
luteitarsis, Agromyza
mobilis, Agromyza
nigrella, Agromyza
nigrociliata, Agromyza
rondensis, Cerodontha
denticornis, Cerodontha
incisa, Cerodontha
lateralis, Cerodontha
muscina, Cerodontha
pygmaea, Cerodontha
superciliosa, Chromatomyia
fuscula, Chromatomyia
milii, Chromatomyia
nigra, Liriomyza
flaveola, Liriomyza
graminivora, Liriomyza
strigata, Liriomyza
trifolii and Pseudonapomyza
atra and the ephydrid Hydrellia
griseola are recorded mining Hordeum.
No non-Diptera miners are recorded on Hordeum in Britain.
A key to the European miners, based on characteristics of the mines, immature stages and where relevant the larval cases, recorded on Hordeum is provided
in Bladmineerders van Europa. This includes Agromyza
ambigua, Agromyza
albipennis, Agromyza
intermittens, Agromyza
luteitarsis, Agromyza megalopsis, Agromyza
mobilis, Agromyza
nigrella, Agromyza
nigrociliata, Agromyza
rondensis, Cerodontha
lateralis, Cerodontha
muscina, Cerodontha
pygmaea, Cerodontha
superciliosa, Chromatomyia
fuscula, Chromatomyia
milii, Chromatomyia
nigra, Hydrellia
griseola, Pseudonapomyza
atra, Liriomyza
flaveola, Liriomyza
graminivora but not Cerodontha
incisa, Liriomyza
orbona, Liriomyza
strigata or Liriomyza
trifolii.
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Key for the identification of the mines of British Diptera recorded on
Hordeum
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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).
1a >
Larvae feed singly, forming an upper surface linear-blotch mine.
Pupation either internal or external. Puparium reddish, brown or
black, loosely glued to the leaf.
On
Arrhenatherum, Brachypodium, Bromus, Dactylis,
Glyceria, Holcus, Hordeum, Milium, Phalaris
and Poa in Britain and additional grasses 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-mine normally short and broad. Initially the larva does not
feed towards the apex of the leaf. Pupation external. Puparium yellowish
brown
On
Avena, Hordeum and Secale in Britain and in addition
on Agropyron and Triticum elsewhere. Widespread,
but local, in Britain. Common and Widespread in continental Europe.
Also recorded in Canada and America.
Agromyza
ambigua Fallén, 1823 [Diptera: Agromyzidae].
1c >
A substantial linear mine. Pupation internal.
On
Hierochloe, Holcus, Hordeum, Milium and Poa in Britain
and additional genera of grasses 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].
1d >
The young larva first feeds towards the apex of the leaf, later
turning and feeding downwards. Several larvae can occur together
in a single leaf. Pupation external.
On
Arrhenatherum,
Arrhenatherum, Elymus, Hordeum, Hordeum, Secale and Triticum
in Britain and additional genra of grasses elsewhere. Widespread
in Britain and continental Europe. Also recorded in the East Palaearctic.
Agromyza
nigrociliata Hendel, 1931 [Diptera: Agromyzidae].
1e >
A short narrow mine, generally near apex of leaf.
On
Avena, Dactylis, Holcus, Hordeum, Lolium, Phalaris,
Phragmites, Poa and Secale in Britain and additional
other genera of grasses elsewhere. Widespread, but local, in south
of Britain. Widespread in continental Europe. Also recorded in
Canada.
Pseudonapomyza
atra (Meigen, 1830) [Diptera: Agromyzidae].
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