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SILAUM. Pepper-saxifrage. [Apiaceae] |
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Only one species of Silaum is recorded in Britain, the introduced Pepper-saxifrage (S. silaus). Only one Diptera miner, the agromyzid Phytomyza silai, is recorded on Silaum in Britain, although there is an unconfirmed record of Phytomyza sedicola on Silaum. The agromyzid Melanagromyza nibletti bores the stems of Silaum in southern England elsewhere. Elsewhere the agromyzid Phytomyza silai is recorded mining Silaum. No non-Diptera miners are recorded on Silaum in Britain. Elsewhere one British non-Diptera miner is recorded on Silaum (see below). |
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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 > Larva mining initially on lower surface of leaf, later filling the tip of the leaf on the upper surface with a linear blotch mine. Puparium black
Phytomyza silai Hering, 1935 [Diptera: Agromyzidae]. 1b > A linear mine rigidly following the margin of the leaf segment. Puparium black, shining
Phytomyza adjuncta Hering, 1928 [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 > The larvae are often gregarious and feed on the underside of the leaf causing a 'windowing' effect as they eat the mesophyll and lower epidermis. This effect can be seen from the top of the leaf as it discolours (British leafminers). Short, small, irregular, sometimes widened corridor. Mostly a number in a leaf, concentrated in the axils of the midrib and the primary side veins. Each larva makes a number of mines. Often the larva protrudes with its rear end out of the mine, causing most frass to be ejected. While moving, at the leaf underside, silken threads are produced, in wich grains of frass may be trapped. Older larvae live free and cause window feeding, often in a group under a light spinning (Bladmineerders van Europa).
Epermenia chaerophyllella (Goeze, 1783) [Lepidoptera: Epermeniidae] |
| Last updated 02-Feb-2012 Brian Pitkin |  |
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