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ARNICA. [Asteraceae] |
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Only one alien species of Arnica is recorded in Britain, Arctic Arnica (A. angustifolia). Only Diptera miner, the agromyzid Phytomyza arnicae is recorded on Arnica in Britain. Elsewhere the agromyzids Chromatomyia 'atricornis', Phytomyza arnicae and Phytomyza conyzae and the anthomyiid Pegomyza depressiventris are recorded mining Arnica. No non-Diptera miners are recorded on Arnica in Britain. Elsewhere one British non-Diptera miner, Cnephasia incertana, is recorded on Arnica (see below). A key to the European miners, based on characteristics of the mines, immature stages and where relevant the larval cases, recorded on Arnica is provided in Bladmineerders van Europa. This includes Digitivalva arnicella, Cnephasia stephensiana, Cnephasia incertana, Phytomyza arnicae, Chromatomyia 'atricornis', Phytomyza conyzae and Phytomyza arnicicola but not Pegomyza depressiventris |
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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). 1 > Leaf-miner: Larva forming a short linear mine which develops into a large blotch. Phytomyza arnicae Hering, 1925 [Diptera: Agromyzidae]. |
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Key for the identification of the mines of British
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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).
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1 > 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).
Cnephasia incertana (Treitschke, 1835) [Lepidoptera: Tortricidae] |
| Last updated 31-Jan-2012 Brian Pitkin |  |
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