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

1a > Stem-miner: Reddish stem mine with a mass of black frass at the end of mine. Pupation external (Spencer, 1976: 69).

Hosts in Britain unknown. On Knautia elsewhere. Included as British by Spencer (1972b: 108). Uncommon but widespread in continental Europe with confirmed records from Austria, France, Finland, Greece, Latvia, Norway, Switzerland (Spencer, 1976: 69), Czech Republic, Germany, Hungary, Lithuania and Switzerland (Martinez in Fauna Europaea).

Ophiomyia longilingua (Hendel, 1920) [Diptera: Agromyzidae]

1b > Leaf-miner: Larvae feeding primarily along mid-rib, forming short lateral mines into the leaf blade. Pupation within the mid-rib. the corridors are short in Dipsacus, but longer in Knautia and Succisa. (Spencer, 1976: 480).

The larvae essentially is a borer in the midrib, but makes from there narrow corridors into the blade. In the end also a corridor can be made on top of the midrib. Most frass is deposited within the midrib, to a lesser extent also in the corridors, at the point where they leave the midrib (Hering, 1957, 1967a). Pupation in the mine, generally in the basal part of the tunnel in the midrib, just below the upper epidermis.

The larva feeds along the midrib, making short corridors into the leaf.

On Dipsacus, Knautia and Succisa in Britain. Also Scabiosa elsewhere. Widespread in Britain and continental Europe.

Chromatomyia ramosa (Hendel, 1923) [Diptera: Agromyzidae].

1c > Leaf-miner: Larva feeding mainly in leaf-blade.

2

2a > 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, but not yet on Knautia, in Britain,. Widespread throughout Britain. Also recorded in the Republic of Ireland. Widespread in continental Europe.

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

2b > Leaf-miner: A narrow winding linear mine generally near the apex of the leaf which assumes a striking purplish colour, making the mine itself difficult to detect. Mines have also been found in the sepals. Pupation takes place in a puparial cradle on the lower surface (Spencer, 1976: 510).

Very long, often branched corridor, narrow till very end, for much of its length lower-surface, mostly in the apical part of the leaf. The corridor frequently intersects itself. Frass in discrete grains. Pupation in the mine, Around the mine the leaf almost always turns violet.

On Succisa pratensis, but not yet on Knautia, in Britain. On Dipsacus, Knautia, Scabiosa and Succisa elsewhere. Widespread in Britain and continental Europe.

Chromatomyia succisae (Hering, 1922) [Diptera: Agromyzidae].

2c > Leaf-miner: A long, whitish linear-blotch mine, frequently associated with the mid-rib (Spencer, 1976: 321 (fig. 583), 323).

Unusually long (up to 16 cm), upper-surface, whitish corridor. Often the corridor crosses itself so repeatedly that a secondary blotch develops. Sometimes a few small grains of frass in the initial part of the mine. Otherwise the mine is either completely free from frass, or a few big lumps are deposited at the very end of the corridor. Pupation outside the mine.

The mine is illustrated in the Encyclopedia of Life.

On Knautia and possibly Succisa in Britain. On Centaurea, Knautia and Succisa elsewhere. Widespread in southern Britain and much of Europe. Also recorded in the Republic of Ireland.

Aulagromyza similis (Brischke, 1880) [Diptera: Agromyzidae].

2d > Leaf-miner: Full depth, transparent blotch. Oviposition site, at the leaf upper surface, covered by a brownish black drop of hardened secretion. Frass in granules or thread fragments. Pupation in the mine, not in a cocoon.

Host unknown in Britain. On Knautia, Scabiosa and Succisa elsewhere. East Kent, West Kent and West Suffolk in Britian, widespread in continental Europe.

Note: Since compiling this page, Trachys troglodytes has been recognised as comprising two species - Trachys troglodytes, from E. Kent, W. Kent, W. Suffolk and Trachys subglaber (Rey, 1891) from W. Cornwall, E. Cornwall, S. Devon, S. Wiltshire, Dorset, Isle of Wight, S. Hants, W. Sussex, E. Sussex, E. Kent, S. Essex, Hertfordshire, E. Suffolk, E. Norfolk, Cambridgeshire, E. Gloucestershire, Glamorgan, Merionethshire, S.E. Yorkshire, N.E. Yorkshire. The two species are distinguished by the male aedeagus.

Bílý (2002) says that T. subglaber is probably monophagous and the larvae mine the leaves of devil's-bit scabious Succisa pratensis, and that T. troglodytes larvae mine the leaves of Knautia spp. including field scabious K. arvensis and Scabiosa spp. including small scabious Scabiosa columbaria. Bílý says that T. subglaber prefers wet meadows or marshes in lowland and warm escarpments, whilst T. troglodytes prefers steppes, rocky slopes and uncultivated meadows. This habitat difference presumably partly reflects the preferred habitat of the host plants and would suggest that in Britain T. troglodytes is likely to be found in drier habitats than T. subglaber. However, since the habitats of the putative hosts in Britain are not entirely exclusive, both species might occur together. In Britain most reported host records of T. troglodytes s. lat. are from devil's-bit scabious. Specimens I have examined found in association with this plant are in fact T. subglaber. The larval hosts of T. troglodytes are not known with certainty in Britain but Knautia arvensis which is common in the Breckland of E. Anglia and on the chalk grassland of Kent is the most likely host (Levey, B. 2012. The Coleopterist 21(2): 67-72).

Trachys troglodytes Gyllenhal, 1817 [Coleoptera: Buprestidae]