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(Coleoptera, Diptera, Hymenoptera and Lepidoptera)
by
Brian Pitkin, Willem Ellis, Colin Plant and Rob Edmunds
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FRANGULA.
Alder Buckthorn. [Rhamnaceae]
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Alder
Buckthorn (F. alnus) is the only species of Frangula recorded
in Britain.
Four Britiish miners are recorded on Frangula.
A key to the European miners recorded on Rhamnus
including Frangula is provided in Bladmineerders van Europa.
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Alder Buckthorn
Frangula alnus
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Key for the identification of the known mines of British
insects (Diptera and non-Diptera) recorded on Frangula
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1a > Leaf-miner and case-bearer: The larva lives outside the mine, protected by a case, and feeds on the underlying plant tissues via a hole cut in the epidermis. From that point it eats away as much leaf tissue as it can reach without fully entering the mine. Mine does not contain frass (Coleophora species) |
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1b > Leaf-miner, but not a case-bearer: The larva lives mainly inside the mine. Mine usually contains frass. In later instars the larva may live sandwiched between two more or less circular sections cut from the leaf. |
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2 > Leaf-miner
and case-bearer: Lobe case. The full grown case is about 7 mm long. The mouth angle
is 0°, causing the case to lie flat on the leaf. The case is
gradually enlarged by the addition of rings that are cut out of
the epidermis. The rings become gradually larger, and stick irregularly
out of the contour of the case. The rings are cut out of the lower
epidermis of the mine. This implies that mines may have both normal,
small openings, and large ones. Compare for instance C.
violacea, that cuts rings out of the upper epidermis.
The
larva feeds briefly initially and again after over wintering. It
then aestivates until Autumn. It makes one case which it enlarges
by adding pieces of excised lower epidermis. |
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On Cornus, Frangula, Lonicera, Rhamnus, Symphoricarpos and Viburnum in Britain and Cornus, Frangula, Lonicera,
Rhamnus, Swida, Symphoricarpos and Viburnum elsewhere.
Southern England. Widespread in continental Europe.
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Coleophora
ahenella Heinemann, 1877 [Lepidoptera: Coleophoridae]. |
3a > Leaf-miner: The highly distinctive, violet or purplish spiral mines of this
species are often the key to its discovery. They can be found on
leaves, often several to a leaf. After the initial leaf-mining phase,
the larva feeds externally on the underside of the leaves, creating
small feeding windows, before pupating in a ribbed cocoon typical
of the Bucculatriginae.
A
narrow corridor, densely wound, amost entirely filled with purplish
brown frass. The last 1 to 2 cm of the corridor are free from the
spiral, and almost straight. At this point the mine is left and
the larvae continue to live free on the leaf, causing window feeding.
The empty larval chamber, obviously free from frass, is conspicuousy
slender. The egg, in the very centre of the spiral, is at the leaf
lower side, as is the exit from the mine. |
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Bucculatrix frangutella cocoon
Image: Rob Edmunds (British Leafminers) |
On Frangula and Rhamnus in Britain and elsewhere.
Widespead in England and continental Europe. Also recorded in
the Republic of Ireland.
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Bucculatrix
frangutella (Goeze, 1783) [Lepidoptera: Bucculatricidae]. |
3b > Leaf-miner: The gallery is contorted in a series of S turns. The frass is initailly
cloudy but then darker green being either dispersed or coiled (as
shown). A little area of uneaten leaf is between each traverse.
Finally the frass turns black and is deposited in a central line.
The larva is greenish yellow, head pale brown.
Full
depth corridor, beginning at an under-surface egg shell. The corridor
makes several sharp turns, causing the loops to (mostly) almost
touch each other. In the last section the corridor is appreciably
wider. Frass olive green when fresh, brown later, coiled for most
of the length of the corridor. Pupation outside the mine. |
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On Rhamnus, but not yet on Frangula, in Britain
and Rhamnus and ? Frangula elsewhere. Widespead
in England and continental Europe. Also recorded in the Republic
of Ireland.
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Stigmella
catharticella (Stainton, 1853) [Lepidoptera:
Nepticulidae].
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3c > Leaf-miner: Full depth blotch, invariably beginning at the leaf tip or the tip
of a leaf lobe or tooth. Oviposition site covered by a black, shining
drop of hardened secretion. Frass generally in long threads, but
sometimes in elongated granules. Pupation in the mine, not in a cocoon. |
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On Corylus avellana, but not yet on Frangula,
in Britain. On several genera and species in several
plant families including Frangula elsewhere. Widespread
in Britain and continental Europe.
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Trachys
minutus (Linnaeus, 1758) [Coleoptera:
Buprestidae]. |
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