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

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ACER. Sycamore and Maples. [Aceraceae]


More than twelve species of Acer are recorded in Britain. All are introduced and include Sycamore (A. pseudoplatanus), Field Maple (A. campestre), Norway Maple (A. platanoides) and Silver Maple (A. saccharinum).

Twenty-four British miners are recorded on Alnus.

Sycamore - Acer pseudoplatanus. Image: © Brian Pitkin
Sycamore
Acer pseudoplatanus



Key for the identification of the known mines of British
insects (Diptera and non-Diptera) recorded on Acer


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 or samara-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: The larva initially forms a gallery along the midrib, which then goes out along a vein. The end of this gallery is then excised to construct the first case. It then feeds close to this and makes several small mines (British leafminers). The final case is a small, laterally compressed, squat, spatulate leaf case of 5-6 mm. The dorsal keel has some serrations, remnants of the leaf margin out of which the case was cut. The rear is twovalved, and remarkably broad. The mouth angle is 0-10°. The description and illustration of the final case in Emmet et al. (1996a) is not quite clear. They depict a rather slender case, and state that the mouth angle is 30°. But, as the only illustration in the other literature that would agree with the British badiipennella, they refer to Hering (1957a, fig. 701): this illustration, however, has no resemblance to their own figure, and has a mouth angle of c. 0°. Emmet et al. write that the larva begins its life by making a gallery of 10-15 mm that runs from the midrib along a side vein; out if this mine the first youth case is excised (Bladmineerders van Europa).

On Ulmus, but not yet on Acer, in Britain. On Acer campestre, Acer platanoides, Corylus avellana, Fraxinus, Ulmus glabra, Ulmus minor and Ulmus x hollandica elsewhere. Locally distributed throughout much of England. Widespread in continental Europe.

Coleophora badiipennella (Duponchel, 1843) [Lepidoptera: Coleophoridae].

3a > Samara-miner: Larva mines wing of samara or key

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3b > Leaf-miner: Larva mines leaf

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4a > Samara-miner: The larva feeds on buds in the spring. In the Summer it feeds on seeds forming a gallery in the wing (British leafminers). Oviposition on the wing of a key (samara). The larva makes a short superfical corridor (sometime only the egg is visible) running towards the seed. Finally the seed is eaten out. Attacked fruits remain on the plant. Larva pale amber, head yellowish. Pupation in a brownish cocoon, often on the stem (Bladmineerders van Europa).

On Acer campestre in Britain and Acer campestre and Acer tataricum elsewhere. Widespread in Britain and continental Europe.

Ectoedemia louisella (Sircom, 1849) [Lepidoptera: Nepticulidae].

4b > Samara-miner: In wing of samara, mines into the seed with a short gallery (British leafminers). The egg of the first generation is deposited on the wing of a key. The larva makes a short, superficial corridor (sometimes only the egg is visible), leading towards the seed, that finally is eaten out. Infested samaras are prematurely shed, and should be sought on the ground. The larva of the second generation makes a short mine in the bark of a petiole, and from there penetrates a bud that is consumed from the inside out (Bladmineerders van Europa).

On Acer platanoides in Britain and elsewhere. Widespread in England and continental Europe.

Ectoedemia sericopeza (Zeller, 1839) [Lepidoptera: Nepticulidae].

5a > Leaf-miner: A long usually narrow winding corridor mine with a central line of frass. Larva not living in a rolled or folded leaf, a tentiform mine or sandwiched between two more or less circular leaf sections in later instars

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5b > Leaf-miner: Either a blotch or short corridor which becomes a blotch. Larva may live in a rolled or folded leaf, a tentiform mine or sandwiched between two more or less circular leaf sections in later instars

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6a > Leaf-miner: A long gallery, frass dispersed or linear (British leafminers). Egg invariably at the lower surface. The mine is a full depth corridor, quite variable in length and width. Also the frass pattern is very variable: sometimes a narrow continuous line, sometimes a broad zone. Always there remains a clear zone between the frass and the side of the mine; also the frass is never coiled. The larva is yellow (British leafminers) or pale yellow (Bladmineerders van Europa).

On Acer pseudoplatanus in Britain and on Acer monspessulanum, Acer obtusatum, Acer opalus, Acer pseudoplatanus, Acer saccharinum, Acer sempervirens and tataricum subsp. semenovii elsewhere. Spreading north and west in Britain since its discovery in Hants in 1914. It has now extended its range north to York. Widespread in continental Europe.

Stigmella speciosa (Frey, 1857) [Lepidoptera: Nepticulidae].

6b > Leaf-miner: A gallery filled with green frass. In the older gallery the frass turns brown (British leafminers). A narrow corridor. The coiled frass is greenish (blackish brown in old or dried mines). Generally the entire width of the corridor is filled up, making the mine rather inconspicuous. The sides of the corridor are not straight, rather irregular. The larva is bright green (Bladmineerders van Europa or green (British leafminers) and (Bladmineerders van Europa).

On Acer campestre and Acer platanoides in Britain and Acer campestre, Acer ginnala, Acer platanoides, Acer saccharophorum and Acer tataricum elsewhere. Widespread in England and continental Europe.

Stigmella aceris (Frey, 1857) [Lepidoptera: Nepticulidae].

7a > Leaf-miner: The larva forms a cone and feeds within it (UKMoths). The larva makes a relatively long, lower surface gallery, that widens into a blotch of c. 6 mm long, where all leaf tissue is consumed, leaving only the venation. Later larval stages live free, living in three, successively larger, leaf rolls made of downfolded leaf segments (Bladmineerders van Europa).

On Acer campestre, Acer platanoides and Acer pseudoplatanus in Britain and Acer campestre and Acer platanoides elsewhere. A very rare species in Britain but widespread in continental Europe.

Caloptilia hemidactylella (Denis & Schiffermüller, 1775) [Lepidoptera: Gracillaridae].

7b > Leaf-miner: A broad initial mine from tip to base of leaf, which later contracts. It then folds the leaf edge, later it rolls the whole leaf longitudinally. Compare with C. betulicola, which rolls the leaf transversally (British leafminers). At first the mine is epidermal and rather large, sometimes even occupying the entire length of the leaf. At a later stage the larva begins to consume the tissue below the epidermis, and the mine becomes a tentiform one; the leaf is strongly contracted by then. The epidermis is brown. The mine may be lower-surface or upper-surface. After the mine has been vacated the larva moves twice. At first it lives in a rolled, sometimes just folded, leaf margin, next in a leaf that has been rolled lengthwise. Pupation in a cocoon at the underside of a leaf (Bladmineerders van Europa). Despite the scientific name, the larvae feed on birch leaves (UKMoths). The larva is whitish, head light brown; pronotum without black markings. Pupation under a silk membrane on underside of leaf (UKMoths) or in a transparent, yellow-shining cocoon at the leaf margin (Bladmineerders van Europa).

On Betula, but not yet on Acer, in Britain and Acer, Betula, Betula pendula and Betula pubescens elsewhere. A species of moorland and heath, having a wide distribution over much of mainland Britain. Also recorded in the Republic of Ireland. Widespread in continental Europe.

Caloptilia populetorum (Zeller, 1839) [Lepidoptera: Nepticulidae].

7c > Leaf-miner: At first it inhabits a leaf-mine, then a leaf cone and, finally, a sequence of two leaf rolls. The feeding signs can be confused with those of C. rufipennella on sycamore, so records of C. semifascia should only be made if the adult is reared (UKMoths). The mine begins as an inconspicuous, short, lower-surface epidermal gallery. This widens into a small triangular blotch, usually in a vein axil. The mine in this stage is fairly transparant. Older larvae live free in a leaf cone, made by folding down a leaf segment. In the course of its life the larva makes three cones, of increasing size, on the same leaf or not. Early mine a gallery leading to a squarish blotch. Later forms up to three successive tubes or cones by folding the tips of leaves downwards (British leafminers). Pupation in a flat, parchement-like, shining, yellowish white cocoon on either side of the leaf, generally near the margin (Bladmineerders van Europa).

On Acer campestre and Acer pseudoplatanus in Britain and Acer campestre elsewhere. Widespread in England and South Wales. Widespread in continental Europe.

Caloptilia semifascia (Haworth, 1828) [Lepidoptera: Gracillaridae].

7d > Leaf-miner: Larva initially in a small mine, but later folding the leaf and feeding within (UKMoths).The mine begins as an inconspicuous, lower-surface, epidermal corridor. This widens into a smallish triangular blotch, usually in the axil of a vein; the mine is fairly transparant. Older larvae live free, in in a lobe of the leaf that has been forced downwards and rolled into a cone. In the course of its development the larva makes three (rarely two) of such cones, ascending in size, on the same leaf or not; the first is no more than a downfolded leaf margin. The larva is greenish, head lighter. Pupation in a membranaceous, yellowish cocoon at the underside of a leaf (Bladmineerders van Europa).

On Acer campestre, Acer platanoides and Acer pseudoplatanus in Britain and Acer negundo, Acer platanoides, Acer pseudoplatanus and Acer saccharinum elsewhere. Fairly widespread in Britain. Widespread in continental Europe.

Caloptilia rufipennella (Hübner, 1796) [Lepidoptera: Gracillaridae].

7e > Leaf-miner: The larvae feed on the leaves of lime and birch, mining the leaves when young (UKMoths). Oviposition at the leaf upperside. Mine a short, irregular, full depth corridor, always at the leaf margin, generally in the tip of the leaf. Frassly broadly scattered. The older larva lives free on the leaf (Bladmineerders van Europa).

On Betula and Tilia, but not yet on Acer, in Britain and Acer and Tilia elsewhere. Mainly distributed in the southern half of England. Widespread in continental Europe

Roeslerstammia erxlebella (Fabricius, 1787) [Lepidoptera: Roeslerstammiidae].

7f > Leaf-miner: The larvae mine the leaves at first, then create small feeding windows (UKMoths). Small, full depth, hook-like corridor, usually in a vein axil, with a proportionally large larval chamber. The remainder of the mine almost entirely stuffed with frass. At the start if the mine an iridescent egg shell. The larvae soon leave their mine and start living free on the leaf (Bladmineerders van Europa). The pupa and white ribbed cocoon are illustrated in British leafminers.

Bucculatrix thoracella cocoon
Bucculatrix thoracella cocoon
Image: Rob Edmunds (British leafminers)

On Tilia, but not yet on Acer, in Britain and Acer, Aesculus, Betula, Carpinus, Fagus, Sorbus and Tilia elsewhere. Widely distributed in southern England and Wales. Widespread in continental Europe.

Bucculatrix thoracella (Thunberg, 1794) [Lepidoptera: Bucculatricidae].

7g > Leaf-miner: The larva starts making a corridor of a few mm, followed, and mostly overrun, by a circular blotch of 4-5 mm diameter (Bladmineerders van Europa). Generally several larvae feed in a single leaf, creating a distinctive pattern of feeding windows. The larvae then cut out circular cases and drop to the leaf-litter to continue feeding, leaving behind a leaf containing many circular or oval cut-outs (UKMoths).

On Alnus, Betula, Carpinus, Corylus, Malus and Tilia, but not yet on Acer, in Britain. On several genera and species in several plant families, including Acer monspessulanum, elsewhere. Widelspread in Britain and continental Europe.

Incurvaria pectinea Haworth, 1828 [Lepidoptera: Incurvariidae].

7h > Leaf-miner: The larva mines the leaves causing noticeable brown blotches, often many to one leaf. There is however, a similar-looking fungus which can cause confusion (UKMoths). The mine begins at a flat, oval, somewhat iridescent egg shell at the upperside of the leaf. There starts an epidermal corridor of some mm, that abruptly widens into an upper-surface blotch. The blotch is elongate, often confined between by a pair of lateral veins; its colour is cinnamon, with a darker centre. The frass is not granular, like in Phyllonorycter species, but consists of a tarlike substance covering the floor of the mine. The number of mines can be as much as several tens per leaf. Pupation occurs within the mine (Bladmineerders van Europa). The pupa and whitish silk cocoon are illustrated in British leafminers, UKMoths and the Encyclopedia of Life.

On Acer platanoides, Acer pseudoplatanus, Aesculus flava, Aesculus hippocastanum and Aesculus parviflora in Britain and Acer pseudoplatanus, Aesculus californica, Aesculus glabra, Aesculus hippocastanum, Aesculus pavia and Aesculus sylvatica elsewhere. First recorded in Britain in 2002 in south-west London in 2002. Widely distributed in southern England and Wales where its range is expanding, particularly on Aesculus hippocastanum. Every leaf on a tree can be mined making it very easy to spot. Widespread in continental Europe.

Cameraria ohridella Deschka & Dimic, 1986 [Lepidoptera: Gracillaridae].

7i > Leaf-miner: A large upper-surface (often almost full depth) blotch, without a trace of an initial corridor, beginning in the very tip of a leaf segment. The full grown larva spins itself a disc shaped cocoon within the mine. Like all Heterarthrus species the thoracic feet are reduced to small stumps. Just before, it has made a circle of perforations in the upper epidermis with its mandibles. The cocoon is formed, attached to the upper epidermis, and the larva becomes immobile. The perforated circle of epidermis starts to dry, warps, and finally becomes detached from the surrounding tissue and drops to the ground. The resulting excision has a diameter of about 7 mm, and is best seen when the leaf is held against the light (Bladmineerders van Europa).

The larvae of sawflies have at least six thoracic legs (although they may be reduced or absent), a head capsule and chewing mouthparts with opposable mandibles but no abdominal legs.

On Acer pseudoplatanus in Britain and elsewhere. Widespread in England and continental Europe.

Heterarthrus aceris (Kaltenbach, 1856) [Hymenoptera: Tenthredinidae].

7j > Leaf-miner: A large, practically full depth blotch without an apparent initial corridor, starting in the centre of a leaf. Like all Heterarthrus species the thoracic feet are reduced to small stumps. The full grown larva makes a circular cocoon, attached to upper epidermis. Before that a circular cut has been made in the upper epidermis. The completed cocoon falls out of the mine together with the disk of upper epidermis (Bladmineerders van Europa).

On Acer pseudoplatanus in Britain and elsewhere. Distribution in Britain currently unknown. Distribution in the rest of Europe includes Austria, Germany, Hungary and Switzerland.

Heterarthrus cuneifrons Altenhofer & Zombori, 1987 [Hymenoptera: Tenthredinidae].

7k > Leaf-miner: A large blotch mine is formed from the tip of a leaf. The pupa is formed in the disc - as above (top right). The species has a long feeding period, more than two months (similar to Heterarthrus nemoratus). Completed mines may be found at the end of July in lower regions of Austria. (British leafminers). Like all Heterarthrus species the thoracic feet are reduced to small stumps (Bladmineerders van Europa).

The larvae of sawflies have at least six thoracic legs (although they may be reduced or absent), a head capsule and chewing mouthparts with opposable mandibles but no abdominal legs.

On Acer campestre and Acer pseudoplatanus in Britain and elsewhere. Widespread in continental Europe.

Heterarthrus leucomela (Klug, 1818) [Hymenoptera: Tenthredinidae].

7l > Leaf-miner: A large, upper-surface (often nearly full depth) blotch, without a hint of an initial corridor, beginning in the tip of a leaf segment. Often a well-defined the first section of the mine is much shalllower and green in transparancy. Frass in loose grains. Like all Heterarthrus species the thoracic feet are reduced to small stumps. Like H. aceris the cocoon, that is formed in the mine, drops out of the leaf along with a circular section of the upper epidermis (Bladmineerders van Europa).

The larvae of sawflies have at least six thoracic legs (although they may be reduced or absent), a head capsule and chewing mouthparts with opposable mandibles but no abdominal legs.

On Acer campestre in Britain and elsewhere. Uncommon. Widespread in continental Europe.

Heterarthrus wuestneii (Konow, 1905) [Hymenoptera: Tenthredinidae].

7m > 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 (Bladmineerders van Europa).

On Corylus avellana, but not yet on Acer, in Britain. On several genera and species in several plant families including Acer campestre elsewhere. Widespread in England and continental Europe.

Trachys minutus (Linnaeus, 1758) [Coleoptera: Buprestidae].

7n > Leaf-miner: The initial mine expands to form a full depth blotch. It resembles Phyllonorycter tenerella, but has a mottled lower surface. It then forms two folds (British leafminers). Small, angular, full depth blotch, often in a vein axil. Lower, in the end also upper, epidermis brown. Larval pronotum with four black spots. The larva deposits some silk in the mine, but the quantity is so low that the mine remains practicaly flat. Later the larva leaves the mine and continues feeding within a downfolded leaf margin or leaf tip (Bladmineerders van Europa).

On Carpinus betulus, but not yet on Acer, in Britain. On Acer platanoides, Acer pseudoplatanus, Carpinus betulus, Carpinus orientalis and Ostrya carpinifolia elsewhere. South-east England. Widespread in continental Europe.

Parornix carpinella (Frey, 1863) [Lepidoptera: Gracillariidae].

7o > Leaf-miner: In the first instar the larva mines the leaves, forming short, irregular, blotch-like mines, but in later instars it lives externally, feeding in spun leaves and often twisting those of tender shoots. Larval head light-brown or yellowish brown, edged with black postero-laterally, ocellar area blackish; prothoracic plate black edged with whitish anteriorly; abdomen dull dark green; pinacula distinct, black, sometimes brownish but with black bases to setae; anal plate large, black (Bradley et al., 1973). Small, full depth mine without a definite shape; little frass. Some silk is deposited in the mine. The larva soon leaves the mine and continues feeding among spun leaves (Bladmineerders van Europa).

Polyphagous. On numerous genera and species in several plant families, but not yet on Acer, in Britain. Widespread in Britain and continental Europe.

Cnephasia incertana (Treitschke, 1835) [Lepidoptera: Tortricidae].

7p > Leaf-miner: Oviposition by way of an ovipositor, no egg visible therefore. The larva makes an irregular blotch. The part of the mine nearest to the oviposition site is more thranslucent than the later, in transparancy more greenish, part of the mine. The mine usually lies close to the leaf tip, often several together. After its first moult the larva makes a roundish excision, 3-4 mm in diameter. Sandwiched herein it drops to the ground and continues feeding of dead leaves. The excision occupies about half of the surface of the blotch. Incurvaria larvae, while resting, take a horse-shoe like posture, unlike the larvae of Antispila species (Bladmineerders van Europa).

On Vaccinium myrtillus, Prunus and Rubus chamaemorus, but not yet on Acer, in Britain. On several genera and species of several plant families, including Acer platanoides, elsewhere. Widespread in Britain and continental Europe. Also recorded from the Republic of Ireland.

Incurvaria oehlmanniella (Hübner, 1796) [Lepidoptera: Incurvariidae].

7q > Leaf-miner: The mine is rounded, between veins. The lower epidermis appears smooth or with several small creases (British leafminers). A not too small, lower surface, greyish white tentiform mine, almost always in the centre of the leaf. Lower epidermis with many, very weak, folds. The roof of the mine remains green until a late stage, when it is eaten out completely. Often several mines in a leaf. Pupation in the mine (Bladmineerders van Europa).

On Acer platanoides in Britain and elsewhere. Commonest in south-east England, but is expanding northwards and has recently been found as far north as York. Widespread in continental Europe.

Phyllonorycter platanoidella (Joannis, 1920) [Lepidoptera: Gracillaridae].

7r > Leaf-miner: The mine is small, usually in lobe of leaf, causing the lobe to fold downwards (British leafminers). Relatively small, lower surface tentiform mine. The mine lies often under a leaf segment, and when the mine develops and contracts the segment usually folds down over the mine. The larva also feeds upon the palisade parenchyma of the roof of the mine, causing the upper surface of the leaf to appear damaged. Pupa blackish brown in a tight, thin-walled cocoon that is attached to the floor of the mine; all frass is accumulated in the opposite corner of the mine (Bladmineerders van Europa).

On Acer campestre and Acer tataricum in Britain and Acer campestre elsewhere. Widespread in England and Wales. Widespread in continental Europe.

Phyllonorycter acerifoliella (Zeller, 1839) [Lepidoptera: Gracillaridae].

7s > Leaf-miner: The mine is rounded, between veins. The lower epidermis with several small creases. The leaf may fold downwards if mine is at margin (British leafminers). The mine begins as an inconspicuous lower surface epidermal corridor, beginning at an iridescent egg shell. This corridor is followed, and mostly replaced, by a relatively small, lower-surface, tentiform mine with many weak folds. When the mine happens to lie close to the leaf margin the leaf may fold downwards over the mine. Pupa in the mine, dark brown - black, in a loosely spun cocoon. Frass accumulated in a corner of the mine (Bladmineerders van Europa).

On Acer pseudoplatanus in Britain and elsewhere. Widespread in Britain and continental Europe. Also recorded from Northern Ireland.

Phyllonorycter geniculella (Ragonot, 1874) [Lepidoptera: Gracillaridae].



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