The leaf and stem mines of British flies and other insects
 

(Coleoptera, Diptera, Hymenoptera and Lepidoptera)

by Brian Pitkin, Willem Ellis, Colin Plant and Rob Edmunds

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CENTRANTHUS. Valerians. [Valerianaceae]


Three species of Centranthus are recorded in Britain - Annual Valerian (C. calcitrapae), Spanish Valerian (C. macrosiphon) and Red Valerian (C. ruber). All are introduced.

Four British miners are recorded on Centranthus.

A key to the European miners recorded on Centranthus is provided in Bladmineerders van Europa.

Sneezewort - Achillea ptarmica. Image: © Brian Pitkin
Red Valerian
Centranthus ruber



Key for the identification of the known mines of British
insects (Diptera and non-Diptera) recorded on Centranthus


1a > Leaf-miner: A distinctive mine primarily above mid-rib, with irregular short lateral offshoots into leaf blade. Pupation external (Spencer, 1972: 51 (fig. 172), 55; Spencer, 1976: 270, 271 (fig. 486)).

Branched, whitish, upper-surface corridor; main axis overlying the midrib; side branches overlying the main lateral veins. (In Campanula and Phyteuma the mine is much less branched, sometimes nothing more than a corridor on top of the midrib). Frass in rather long strings. Usually the mines begins as a long and narrow, shallow, tortuous lower-surface corridor that ends upon the midrib but otherwise is not associated with the leaf venation. Often this initial corridor is filled with callus, and then even less conspicuous. Pupation outside the mine (Bladmineerders van Europa).

A linear mine on the upper surface, usually following the midrib and showing side branches along the veins. The frass is in strings (British leafminers).

Polyphagous. On more than 40 host genera in 15 families, including Centranthus, in Britain. Widespread throughout Britain. Also recorded in the Republic of Ireland. Widespread in continental Europe.

Liriomyza strigata (Meigen, 1830) [Diptera: Agromyzidae].

1d > Leaf-miner: Mine not primarily associated with mid-rib.

2

2a > Leaf-miner: Mine linear, whitish, both upper and lower surface. Pupation internal, at the end of the mine with the anterior spiracles projecting through the epidermis (Spencer, 1976: 433).

Upper-surface, less often lower-surface corridor. Frass in isolated grains. Pupation within the mine, usually in a lower-surface puparial chamber (Bladmineerders van Europa).

A long whitish upper surface corridor, which eventually goes lower surface (British leafminers).

Two highly polyphagous species of Chromatomyia, with indistinguishable mines, have been recorded in Britain. These are syngenesiae (Hardy) and horticola (Goureau) which can only be distinguished by the male genitalia. Both species are widespread in Britain and elsewhere, although syngenesiae is almost entirely restricted to Asteraceae. Records on Asteraceae not based on examination of male genitalia are treated in this account as Chromatomyia 'atricornis'.

Chromatomyia horticola is recorded on 160 plant genera in 31 families of which 55 plant genera in 19 families, including Centranthus, in Britain.

Chromatomyia horticola (Goureau, 1851) [Diptera: Agromyzidae].

2b > Leaf-miner: An irregular linear mine, which frequently follows the leaf margin, with conspicuous black frass (Spencer, 1972b: 51 (fig.162), 54; Spencer, 1976: 275).

Corridor, often quite contorted, not infrequently a secondary blotch. Frass in strikingly long strings. Pupation outside the mine (Bladmineerders van Europa).

On ? Centranthus, Valeriana and ? Valerianella in Britain and Centranthus, Valeriana and Valerianella elsewhere. Widespread in continental Europe.

Liriomyza valerianae Hendel, 1932 [Diptera: Agromyzidae].

2c > Leaf-miner: A short, irregular, linear upper surface mine on any part of the leaf. Also recorded from young pods (Bland, 1997a).

Long corridor mine. As a rule the first part of the mine is lower-surface, the later part upper-surface. Often the loops are so dense that a secondary blotch is the result. Because upper- and lower-surface corridor segments often cross, the mine obtains a strange array of transparant patches. There is no association with the midrib. Frass in strings and thread fragments. Pupation outside the mine; exit slit in upper epidermis (Bladmineerders van Europa).

Mine not associated with the veins or midrib of the leaf (It is this character which enables distinction from another Agromyzid pest species - Liriomyza huidobriensis). The larvae may leave one leaf (if not large enough) and enter another leaf, via the petiole). It exits the leaf to pupate through a semi-circular slit in the upper surface of the leaf (British leafminers).

On 119 plant genera in 31 plant families of which only 4 plant genera in 2 plant families, but not yet on Centranthus, in Britain. Local, probably introduced to Britain. Widespread in continental Europe particularly in Botanical Gardens and glasshouses. Also recorded in Egypt.

Liriomyza bryoniae (Kaltenbach, 1858) [Diptera: Agromyzidae].



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