Comment: 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).
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 (Bladmineerders van Europa).
Larva: The larvae of beetles have a head capsule and chewing mouthparts with opposable mandibles and lack abdominal legs (see examples).
The larva is illustrated in Bladmineerders van Europa.
Pupa: The pupae of beetles have visible head appendages, wings and legs which lie in sheaths (see examples).
Pupation in the mine, not in a cocoon (Bladmineerders van Europa).
Hosts in Great Britain & Ireland: Unknown
of year - larvae: Currently unknown.
of year - adults: Currently unknown.
in Great Britain & Ireland: Recorded in E. Kent, W. Kent, W. Suffolk (Levey, B. 2012. The Coleopterist 21(2): 67-72).
NBN Grid Map:
elsewhere: Widespread in continental Europe including Albania,
Austria, Belgium, Bosnia and Herzegovina, Bulgaria, Crete, Croatia,
Czech Republic, Danish mainland, Estonia, European Turkey, French
mainland, Germany, Greek mainland, Hungary, Italian mainland, Kaliningrad
Region, Latvia, Lithuania, Luxembourg, Poland, Romania, Russia -
Central, Northwest and South, Sicily, Slovakia, Slovenia, Spanish
mainland, Sweden, Switzerland, The Netherlands, Ukraine. Also recorded
in the East Palaearctic (Alonso-Zarazaga in Fauna Europaea).
NBN Interactive Grid Maps of known host species: