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

 

VALERIANA. Valerians. [Valerianaceae]


Four species of Valeriana are recorded in Britain. The include the native Marsh Valerian (V. dioica) and Common Valerian (V. officinalis).

Four British miners are recorded on Valeriana in Britain.

The agromyzid Napomyza elegans is possibly a root feeder on Valeriana officinalis (Spencer, 1972).

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

Marsh Valerian - Valeriana dioica. Image: © Linda Pitkin
Marsh Valerian
Valeriana dioica



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


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.

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

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

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

1b > Leaf-miner: In the first instar the larva mines the leaves, forming short, irregular, blotch-like mines, but in later instars it lives externally, feeding in spun leaves and often twisting those of tender shoots. Larval head light-brown or yellowish brown, edged with black postero-laterally, ocellar area blackish; prothoracic plate black edged with whitish anteriorly; abdomen dull dark green; pinacula distinct, black, sometimes brownish but with black bases to setae; anal plate large, black (Bradley et al., 1973). Small, full depth mine without a definite shape; little frass. Some silk is deposited in the mine. The larva soon leaves the mine and continues feeding among spun leaves.

Polyphagous. On numerous genera and species of several plant families, but not yet on Valeriana, in Britain. On numerous genera and species of several plant families, including Valeriana, elsewhere. Widespread in Britain and continental Europe. Also recorded from the Channel Is.

Cnephasia incertana (Treitschke, 1835) [Lepidoptera: Tortricidae].

1c > 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.

A long whitish upper surface corridor, which eventually goes lower surface .

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 and Valeriana in Britain. On Centranthus, Valeriana and Valerianella elsewhere.

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.

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

Liriomyza valerianae Hendel, 1932 [Diptera: Agromyzidae].



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