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PTERIDIUM. Bracken. [Dennstaedtiaceae] |
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Bracken (P. aquilinum), is the only species of Pteridium recorded in Britain. It is a native species. Seven Diptera miners, the agromyzids Phytoliriomyza hilarella and Phytoliriomyza pteridii and the anthomyiids Chirosia grossicauda and Chirosia histricina, are recorded on Pteridium in Britain. The anthomyiids Chirosia albitarsis, Chirosia cinerosa and Chirosia crassiseta are recorded on Pteridium by Ackland in Chandler, (1978) but it is not clear whether these host associations are British or Foreign. Elsewhere the agromyzids Phytoliriomyza hilarella and Phytoliriomyza pteridii and the anthomyiids Chirosia albitarsis, Chirosia cinerosa, Chirosia crassiseta, Chirosia grossicauda and Chirosia histricina are recorded mining Pteridium. No non-Diptera miners are recorded on Pteridium in Britain. Elsewhere one British non-Diptera miner is recorded on Pteridium (see below). |
 Bracken Pteridium aquilinum |
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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 > Mine in the downwards rolled leaf apex. Leaf apex rolls itself downwards as a result of frass of larva on the underside of the leaf midrib and simultaneous growth on its upper side. The leaf is mined dorsally and ventrally on either side of the mid-rib of the frond. Frass irregular, in and next to the mid-rib of the frond.
Chirosia grossicauda (Strobl, 1899) [Diptera: Anthomyiidae]. 1b > Large full depth blotch, covering the entire distal part of a pinnula. The mine begins near the top, where an elliptic egg shell is attached to the underside of the rachis. Larva solitary. The mine contains much frass
Chirosia histricina Rondani, 1866 [Diptera: Anthomyiidae]. 1c > A short linear mine in single section of a frond. Pupation external. Mines practically identical to those of P. pteridii, which may be distinguished from P. hilarella by the male genitalia.
Phytoliriomyza hilarella (Zetterstedt, 1848) [Diptera: Agromyzidae]. 1d > A short linear mine at edge of frond segment. Pupation external. Mines practically identical to those of P. hilerella which may be distinguished from P. pteridii by the male genitalia. Puparium brownish-orange
Phytoliriomyza pteridii Spencer, 1973 [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 > Full-depth corridor or blotch, often positioned along the leaf margin. In the first part much, brown-black, fine-grained frass, later parts of the mine almost free from frass. After hibernation the larva lives free in an untidy case of silk, covered with remants of sori (Bladmineerders van Europa).
Psychoides verhuella Bruand, 1853 [Lepidoptera: Tineidae] |
| Last updated 01-Feb-2012 Brian Pitkin |  |
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