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


GENTIANA. Gentians. [Gentianaceae]

Seven species of Gentiana are recorded in Britain. These include the native Alpine Gentian (G. nivalis), Marsh Gentian (G. pneumonanthe) and Spring Gentian (G. verna).

Alpine Gentian (G. nivalis) and Spring Gentian (G. verna) are protected under Schedule 8 of the Wildlife and Countryside Act, 1981.

Three British miners are recorded on Gentiana.

Elsewhere the agromyzids Liriomyza bryoniae and Liriomyza huidobrensis are recorded mining Gentiana. See also Liriomyza species in Glasshouses and/or Quarantine Interceptions.

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

Marsh Gentian - Gentiana pneumonanthe. Image: © Linda Pitkin
Marsh Gentian
Gentiana pneumonanthe

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

1a > Leaf-miner: Mine linear in first instar, later developing into a blotch which is frequently at base of leaf. Pupation internal (Spencer, 1990: 397).

The mine starts as a gallery, but this is engulfed by the upper surface blotch that eventually forms. This mine is in a basal leaf - right on the ground amongst the grasses etc. The mine is usually in basal part of leaf. The larva pupariates in the mine and the spiracles protrude through the upper epidermis.

On Centaurium erythraea and more recently on Gentiana tibetica (from a nursey in southern Scotland) in Britain and elsewhere. Widespread in southern England. Also recorded in the Republic of Ireland and in continental Europe only Germany.

Chromatomyia centaurii Spencer, 1990 [Diptera: Agromyzidae].

1b > Leaf-miner: Initially the larva mines a basal leaf, subsequently feeding in flower buds (which turn yellow), opened flowers and foliage. Full depth irregular blotch that may occupy an entire leaf. Frass in numerous, dispersed, brown grains. Some larvae remain in the mine until shortly before pupation, others leave the mine in an early stage and feed externally on the flower buds and developing fruits.

Mine of Stenoptilia zophodactylus on Gentiana sp. Image: © Willem Ellis (Bladmineerders en plantengallen van Europa)
Mine of Stenoptilia zophodactylus on Gentiana sp
Image: © Willem Ellis (Bladmineerders van Europa)

On Blackstonia, Centaurium and Gentiana in Britain and Blackstonia, Centaurium, Gentiana and Gentianella elsewhere. Widely distributed in southern Britain and continental Europe.

Stenoptilia zophodactylus (Duponchel, 1840) [Lepidoptera: Pterophoridae].

1c > 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.

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.

Polyphagous. On 119 plant genera in 31 plant families of which only 4 plant genera in 2 plant families, but not yet on Gentiana 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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