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CENTAUREA. Knapweeds, Star-thistles and Cornflowers. [Asteraceae]
Forty species of Centaurea are recorded in Britain. These include the native Common Knapweed (C. nigra), Greater Knapweed (C. scabiosa) and Slender Knapweed (C. debeauxii) and introduced Knapweeds, Star-thistles and Cornflowers. Seven dipterous miners, the agromyzids Chromatomyia 'atricornis', Liriomyza centaureae, Liriomyza strigata, Phytomyza autumnalis, Phytomyza cinerea, Phytomyza continua and Phytomyza spinaciae are recorded on Centaurea in Britain, but the record of Phytomyza continua requires confirmation. The agromyzids Melanagromyza oligophaga and Napomyza hirticornis are recorded boring stems of Centaurea in Britain.	Common Knapweed - Centaurea nigra
The agromyzid Liriomyza trifolii, a polyphagous pest species of ornamental and vegetable crops occasionally intercepted at UK points of entry, is recorded on Centaurea and has been found under glass in England and Wales. All populations have been and continue to be eradicated. The tephritid Philophylla caesio is tentatively recorded on Centaurea in Britain. It is recorded as a petiole miner on Urtica elsewhere. Elsewhere the agromyzids Aulagromyza similis, Chromatomyia horticola, Liriomyza bryoniae, Liriomyza centaureae, Liriomyza strigata, Liriomyza trifolii, Ophiomyia curvipalpis, Phytomyza autumnalis, Phytomyza cinerea and Phytomyza spoliata are recorded mining Centaurea. Elsewhere the agromyzid Napomyza lateralis is recorded in stems of Centaurea. Five non-dipterous leaf- miners are recorded on Centaurea in Britain (see below). Elsewhere three additional British non-dipterous miners are recorded on Centaurea (see below).

Key for the identification of the known Diptera mines in Britain.

1> Mine primarily associated with mid-rib. 2. ->Mine not primarily associated with mid-rib. 3. 2> A distinctive mine, with irregular short lateral offshoots into leaf blade. Pupation external.     Mines of Liriomyza strigata on Sonchus. Image: Crown copyright - courtesy of CSL Liriomyza strigata (Meigen) [Agromyzidae]. -> Larva feeds along the mid-rib, predominantly on the lower surface and there is little evidence of gall-like swelling. Pupation takes place at the base of the midrib. Puparium whitish. Record on Centaurea requires confirmation. Phytomyza continua Hendel [Agromyzidae]. 3> Several larvae feed together. Mine a brownish blotch, at apex of leaf segment,. Pupation in mine. Puparium brown Phytomyza cinerea Hendel [Agromyzidae]. -> Larvae feed singly. 4. 4> Long narrow interparenchymal mine, greenish. Pupation in leaf at end of mine. Puparium white Mines of Phytomyza spinaciae on Cirsium arvense. Image: Willem Ellis (Source: Nederlandse bladmineerders) Phytomyza spinaciae Hendel [Agromyzidae]. ->Mine not interparenchymal. 5. 5> Mine linear, whitish, both upper and lower surface. Pupation internal, at the end of the mine, with the anterior spiracles projecting through the epidermis. Mine of Chromatomyia atricornis on Sonchus olearaceus. Images: Willem Ellis (Source: Nederlandse bladmineerders) Chromatomyia 'atricornis' auctt. [Agromyzidae]. ->A short irregular linear mine with frass in more or less connected threads. Mine of Liriomyza centaurea on Centaurea scabiosa. Image: Willem Ellis (Source: Nederlandse bladmineerders) Liriomyza centaureae Hering [Agromyzidae]. ->Mine long, distinctly greenish. Pupation in mine. Puparium white in early generations and black and shiny in autumn Mine of Phytomyza autumnalis on Centaurea nigra ( Spencer Collection). Image: Brian Pitkin Phytomyza autumnalis Griffiths [Agromyzidae].

Non-dipterous miners recorded on Centaurea in Britain Coleophora conspicuella Zeller, 1849 Lepidoptera: Coleophoridae   Coleophora paripennella Zeller, 1839 Lepidoptera: Coleophoridae Jordanita globulariae (Hübner, 1793) Lepidoptera: Zygaenidae   Orthochaetes setiger (Beck, 1817) Lepidoptera: Curculionidae     Pseudorchestes pratensis (Germar, 1821) Lepidoptera: Curculionidae     Additional British non-dipterous miners recorded on Arctium elsewhere Agonopterix propinquella (Treitschke, 1835) Lepidoptera: Depressariidae   Coleophora peribenanderi Toll, 1943 Lepidoptera: Coleophoridae Scrobipalpa acuminatella (Sircom, 1850) Lepidoptera: Incurvariidae

Last updated 19-Aug-2008  Brian Pitkin