Polygala [Polygalaceae]

POLYGALA. Common Milkwort. [Polygalaceae]

Five species of Polygala are recorded in Britain. These include the native Dwarf Milkwort (P. amarella), Chalk Milkwort (P. calcarea), Heath Milkwort (P. serpyllifolia) and Common Milkwort (P. vulgaris)

Only one Diptera miner, the agromyzid Liriomyza polygalae, is recorded on Polygala in Britain and elsewhere.

No non-Diptera miners are recorded on Polygala in Britain.

Elsewhere one British non-Diptera miner is recorded on Polygala (see below).

Milkwort
Polygala sp.

Key for the identification of the mines of British Diptera recorded on
Polygala

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: An irregular linear-blotch mine.

On Polygala vulgaris in Britain and in addition Polygala chamaebuxus elsewhere. Known only from Surrey in Britain. Also recorded in the Republic of Ireland. Widespread in continental Europe.

Liriomyza polygalae Hering, 1927 [Diptera: Agromyzidae].

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

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).

1 > Leaf-miner: Rather narrow corridor, untidy and sometimes branched, starting from the base of the leaf, in particular the midrib. Sides of the corridor irregularly eaten out, not really parallel. Frass mostly present, and then in a central line. The legless larva is capable of leaving the mine and start a new one elsewhere. These later mines are much broader, and the frass is scattered irregularly. (Bladmineerders van Europa.

Host plants unknown in Britain. Recorded on numerous genera and species in several plant families, including Polygala, elsewhere. Recorded in southern England. Widespread in continental Europe.

Orthochaetes insignis (Aube, 1863) [Coleoptera: Curculionidae]


	Last updated 07-Feb-2012 Brian Pitkin