CORNUS. Dogwoods and Dwarf Cornel. [Cornaceae]

Two native species of Cornus are recorded in Britain - Dwarf Cornel (C. suecica) and Dogwood (C. sanguinea). Eight other species have been introduced, including Cornelian-cherry (C. mas), White Dogwood (C. alba), Red-osier Dogwood (C. sericea) and Creeping Dogwood (C. canadensis).

Only one Diptera miner, the agromyzid Phytomyza agromyzina, is recorded on Cornus in Britain and elsewhere.

Two non-Diptera miners are recorded on Cornus in Britain (see below).

Elsewhere seven additional British non-Diptera miners are recorded on Cornus (see below).

A key to the European miners, based on characteristics of the mines, immature stages and where relevant the larval cases, recorded on Cornus is provided in Bladmineerders van Europa. This includes Phytomyza agromyzina, Antispila treitschkiella, Antispila metallella, Coleophora ahenella, Coleophora anatipenella, Coleophora violacea, Incurvaria pectinea and Incurvaria oehlmanniella.

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

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

2a > 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 (Bladmineerders van Europa). 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 (British leafminers).

Recorded 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.

Coleophora ahenella Heinemann, 1877 [Lepidoptera: Coleophoridae].

2b > Leaf-miner and case-bearer: The early case is tiny and the larva makes a series of tiny holes on the leaf. After overwintering it makes a shiny pistol shaped case in spring and window feeds (British leafminers). The young larva, before hibernation, makes tiny mines, sometimes tens in one leaf. After hibernation window feeding is done. In this latter stage the larva lives in a shining black pistol case of about 7 mm, that, with a mouth angle of 70°-80°, stands almost perpendicular on the leaf (Bladmineerders van Europa).

Recorded on Crataegus, Malus, Prunus, Pyrus and Sorbus, but not yet on Cornus, in Britain plus numerous genera and species of several plant families, including Cornus, elsewhere. Occurs in England and Wales, commoner in the south. Widespread in continental Europe.

 

Coleophora anatipennella (Hübner, 1796) [Lepidoptera: Bucculatricidae].

2c > Leaf-miner and case-bearer: The larva feeds on a wide range of trees, shrubs and herbs, favouring Rosaceae, but not exclusively. The fully developed cased larva may be found active in October and again, after winter diapause, in April. Cases, about 6 mm, of diapausing larvae may be found through winter, fixed to a tree or fence post. The dorsal surface of the case is usually covered in leaf fragments, but they can sometimes be worn off almost smooth. The ventral surface is swollen at the middle and has a keel, which usually bends upwards at the posterior. The cases of C. ahenella (on Rhamnus, Frangula, Viburnum and Cornus) and C. potentillae (case less swollen, keel not bent up, resting position less prone) are very similar (UKMoths). Brownish lobe case that lies almost flat on the leaf, either on the upper or on the lower side. Case widest about the middle. Ventrally there is a distinct keel. Mouth angle 0°. Full depth mines rather large. The flaps of cuticular tissue that serve to enlarge the case are cut out of the upper epidermis. (contrary to C. ahenella and C. potentillae, that use tissue from the lower epidermis). The removal of these tissue flaps creates holes that are much larger than those that serve as the entrance to the mine (Bladmineerders van Europa).

Recorded on numerous genera and species in several plant families, not including Cornus, in Britain. Recorded on numerous genera and species in several plant families, including Cornus elsewhere. Widespread in Britain and continental Europe.

 

Coleophora violacea (Ström, 1783) [Lepidoptera: Coleophoridae].

3a > Leaf-miner: A gallery leads to blotch, with oval cut-out 5.5-7 mm long. There are two or three brown specks at start of mine (trial slits made by ovipositor) (British leafminers). The combination of mine and cut-out is very distinctive (UKMoths). Initially a short corridor close to the leaf margin, suddenly widening into a large blotch, that often overruns the corridor. Finally the larva makes an oval excision of 5.5-7 mm long, and drops with it to the ground. In this excision, that now functions as a case, the larva continues living free. Before the onset of winter, pupation takes place within the case. The female makes a number of test punctures, that often can be seen as a curving row of 2-7 brown spots perpendular to the initial corridor (Bladmineerders van Europa).

Recorded on Cornus in Britain and elsewhere. Throughout most of England. Widespread in continental Europe.

Antispila metallella (Denis and Schiffermüller, 1775) [Lepidoptera: Heliozelidae].

3b > Leaf-miner: The initial mine is a short gallery at the leaf edge, which expands to from a blotch. The larva cuts out an oval case 4-5.5 mm long (British leafminers), in which it subsequently lives amongst leaf litter on the ground (UKMoths). Oviposition usually close to the leaf margin. From there starts a corridor of about 1 cm; it contains much frass, is often somehat tortuous in its beginning and as a roll closely follows the leaf margin. After a moult the direction reverses and the larva starts making a full depth blotch that can become several cm long and wide. Here the frass lies in scattered grains. The full grown larva covers an oval section at the margin of the blotch with a light brown pergamon-like layer of silk, cuts this loose and drops within it to the ground. The excision that is made is about 4-4.5 mm long. Unlike A. metallella the female does not makes test punctures before ovipsition (Bladmineerders van Europa).

Recorded on Cornus in Britain and elsewhere. Occurs locally in parts of southern England. Widespread in continental Europe.

 

Antispila treitschkiella (Fischer von Röslerstamm, 1843) [Lepidoptera: Heliozelidae].

3c > 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. Incurvaria larvae, while resting, take a horse-shoe like posture, unlike the larvae of Antispila species. Sandwiched herein it drops to the ground and continues feeding of dead leaves. The excision occupies about half of the surface of the blotch (Bladmineerders van Europa).

Recorded on Vaccinium myrtillus, Prunus and Rubus chamaemorus, but not yet on Cornus, in Britain. Recorded on several genera and species of several plant families, including Cornus, elsewhere. Widespread in much of the British Isles and continental Europe.

 

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

3d > 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).

Recorded on Alnus, Betula, Carpinus, Corylus, Malus and Tilia, but not yet on Cornus, in Britain and Acer, Alnus, Betula, Carpinus, Corylus, Ostrya, Cornus, Robinia, Malus, Prunus, Pyrus and Sorbus elsewhere. Widely distributed in Britain and continental Europe.