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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 Diptera 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. 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.	Common Knapweed Centaurea nigra
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 agromyzids Napomyza lateralis and Melanagromyza dettmeri are recorded in stems of Centaurea. Five non-Diptera leaf- miners are recorded on Centaurea in Britain (see below). Elsewhere three additional British non-Diptera miners are recorded on Centaurea (see below). A key to the European miners, based on characteristics of the mines, immature stages and where relevant the larval cases, recorded on Centaurea is provided in Bladmineerders van Europa. This includes Aulagromyza similis, Botanophila centaureae, Chromatomyia cf. syngenesiae, Liriomyza centaureae, Liriomyza strigata, Ophiomyia beckeri, Ophiomyia curvipalpis, Phytomyza autumnalis, Phytomyza cinerea, Phytomyza montana, Phytomyza spinaciae, Phytomyza spoliata, Agonopterix arenella, Agonopterix carduella, Agonopterix propinquella, Agonopterix subpropinquella, Apterona helicoidella, Cnephasia asseclana, Cnephasia lineata, Cnephasia sedana, Cnephasia stephensiana, Coleophora brevipalpella, Coleophora caelebipennella, Coleophora conspicuella, Coleophora didymella, Coleophora paripennella, Coleophora peribenanderdi, Coleophora rectilineella, Comasinus setiger, Jordanita chloros, Jordanita globulariae, Jordanita graeca, Jordanita notata, Orthochaetes setiger, Pseudorchestes pratensis, Pseudorchestes cinereus and Pseudorchestes heringi, Pseudorchestes ermischi, Pseudorchestes persimilis, Scrobipalpa acuminatella, Scrobipalpa halonella, Scrobipalpa pauperella , Scrobipalpa perinii, Sphaeroderma testaceum, Sphaeroderma rubidum but not Liriomyza bessarabica or Scrobipalpula psilella.

Key for the identification of the known Diptera mines on Centaurea in Great Britain and Ireland

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 On more than 40 host genera in 15 families in Britain. Widespread throughout Britain. Also recorded in the Republic of Ireland and is widespread and common in Europe. Liriomyza strigata (Meigen) [Diptera: 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. On Carduus and Centaurea in Britain. On Arctium, Carduus, Cichorium and Cirsium elsewhere. Widespread in Britain and Europe. Phytomyza continua Hendel [Diptera: Agromyzidae]. 3> Several larvae feed together. Mine a brownish blotch, at apex of leaf segment,. Pupation in mine. Puparium brown On Centaurea scabiosa in Britain and elsewhere. Uncommon, only recorded from Derby and Warwick in Britain. Germany and Spanish mainland in Europe. Phytomyza cinerea Hendel [Diptera: 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 (Bladmineerders van Europa) On Carduus, Centaurea, Cirsium and Onopordum in Britain and in addition Cnicus and Serratula elsewhere. Only recorded from Warwick and Stafford in Britain. Also recorded in the Repupublic of Ireland. Widespread in Europe, range extending to the Kirghiz Republic of the [former] U.S.S.R. Phytomyza spinaciae Hendel [Diptera: 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. Two highly polyphagous species of Chromatomyia, with indistinguishable mines, have been recorded in Britain. These are syngenesiae (Hardy) and horticola (Goureau). British records of horticola and syngenesiae on Asteraceae hosts not based on examination of the genitalia of reared males are treated here as Chromatomyia 'atricornis'. Chromatomyia 'atricornis' auctt. [Diptera: Agromyzidae]. -> A short irregular linear mine with frass in more or less connected threads. Mine of Liriomyza centaurea on Centaurea scabiosa Image: Willem Ellis (Bladmineerders van Europa) On Centaurea jacea, Centaurea montana, Centaurea nigra and Centaurea nigra. in Britain and additional Centaurea species elsewhere. Widespread in Britain and much of Europe. Liriomyza centaureae Hering [Diptera: 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 On Centaurea montana, Centaurea nigra and possibly Cirsium arvense and Cirsium vulgare in Britain and Centaurea montana, Centaurea nigra, Centaurea scabiosa, Cirsium arvense and Onopordum acanthium elsewhere. Widespread in Britain and Europe. Phytomyza autumnalis Griffiths [Diptera: Agromyzidae].

Non-Diptera miners recorded on Centaurea in Britain Coleophora conspicuella Zeller, 1849 [Lepidoptera: Coleophoridae]   Leaf-miner and case-bearer: A relatively large (12-15 mm), dark brown, lightly curved two-valved sheath case with a narrow ventral keel. Mouth angle 30-45 (Bladmineerders van Europa). More..   Coleophora paripennella Zeller, 1839 [Lepidoptera: Coleophoridae]   Leaf-miner and case-bearer: Larva mines leaves (British leafminers). The larva builds a case from silk, resembling a razor shell in appearance. (UKMoths). The full-grown case is 12 mm long and blackish-brown (British leafminers). The full grown larva lives in a blackish brown trivalved tubular silken case of about 8 mm. The mouth angle is 0°-10°, causing the case to lay almost flat on the leaf (Bladmineerders van Europa). Case of Coleophora paripennella Image: Charles Baker (British leafminers) More..   Orthochaetes setiger (Beck, 1817) [Lepidoptera: Curculionidae]   Leaf-mine: The mine begins in the midrib, especially in a lower leaf, extending into the leaf disc, branching irregularly or pinnately, may also locally be blotch like. The mine is brown and very transparent. Sides very irregularly eaten out. Frass loosely dispersed or in a loose central line, buy may also be pressed against the sides of the corridor. The larva may also leave the mine and restart elsewhere (Bladmineerders van Europa). Mine of Orthochaetes setiger Image: Rob Edmunds (British leafminers) More..   Pseudorchestes pratensis (Germar, 1821) [Lepidoptera: Curculionidae]   Leaf-mine: The larva makes a small full depth blotch, usually in the leaf tip. Frass concentrated in the centre of the mine (Bladmineerders van Europa). More..   Jordanita globulariae (Hübner, 1793) [Lepidoptera: Zygaenidae]   Leaf-mine: The larva makes a large number of untidy full depth mines. The mines contain hardly or no frass. The opening made by the larva in the underside of the leaf is irregular roundish, sometimes more of a slit, large in proportion to the size of the mine, and usually positioned at the side of the mine. The larva mines until just before the pupation, that takes place externally (Bladmineerders van Europa). More.. Additional British non-Diptera miners recorded on Centaurea elsewhere Coleophora peribenanderi Toll, 1943 [Lepidoptera: Coleophoridae]   Leaf-miner and case-bearer: The larva forms a case, approximately 11-12 mm long, beneath a thistle leaf, although burdock may sometimes be used. The shape of the ochreous case varies as, when being enlarged, it is elongated first, and the girth increased subsequently (UKMoths). Yellow-brown to light grey tubular silken case with darker length lines. The case is fairly large (up to 17 mm) and very slender. The rear end is three-valved, the mouth angle about 50°. The larva feeds at the underside of the leaf (Bladmineerders van Europa). Case of Coleophora peribenanderi on Cirsium arvense Image: Willem Ellis (Bladmineerders van Europa) More..   Agonopterix propinquella (Treitschke, 1835) [Lepidoptera: Depressariidae]   Leaf-mine: The eggs of this species are laid on a leaf, with the larvae mining the underside of the leaf, until a late instar when it feeds in a web under the midrib of the leaf, causing visible blotching on the upperside (UKMoths). Short, full depth corridor. The larva relatively long lives as a miner, but finally leaves the mine and continues living in spinning along the midrib at the leaf underside, from where windows are eaten in the leaf (Bladmineerders van Europa). More..   Scrobipalpa acuminatella (Sircom, 1850) [Lepidoptera: Incurvariidae]   Leaf-mine: The mine is brownish and extends along the midrib, sometimes branching (British leafminers). Oviposition on top of the midrib. Immediately after emergence the larva gnaws a cavity in the midrib, and from there an irregular blotch is made adjacent to the midrib. The larva continues living in the midrib that is gradully hollowed out, making from there broad, brownish, full depth excursions in the blade. The mine contains much frass; most of it is concentrated in the area immediately bordering the midrib. Older, no longer occupied parts of the mine often split open. Mines mainly on the lower leaves. The slender larvae move surprisingly fast upon disturbance; when they rest (in daytime) they lie lengthwise in the hollowed midrib. Pupation outside the mine (Bladmineerders van Europa). Mine of Scrobipalpa acuminatella on Cirsium vulgare Image: Willem Ellis (Bladmineerders van Europa) More..

Last updated 11-Aug-2010  Brian Pitkin