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Canthophorus impressus Down Shieldbug
Family: Cydnidae

A dark metallic blue shieldbug with a white margin to the pronotum and corium and a banded connexivum. This species is associated with Bastard Toadflax Thesium humifusum, a rare plant found on chalk downland in parts of southern England. There is one generation per year and the red nymphs may be found until late July, often with adults of the previous year, which are long-lived.

Until recently, British populations were thought to refer to the closely-related Canthophrous dubius (previously Sehirus dubius). These two species can only be separated by dissection.

A rare species found mainly on scattered chalk sites in Oxfordshire, Wiltshire, Dorset and Hampshire. Although the bug has declined and disappeared from many south-eastern counties, it has recently been recorded in East Sussex.

Adult: All year
Length 6-7 mm

see illustrated life stages chart
Canthophorus impressus
Adult: Wilts (March 2012) ©Steve Covey

Canthophorus impressus Canthophorus impressus
Adult on foodplant: Oxon (July 2007) ©Chris Raper

Adult: Hants (May 2009) ©Stuart Read

Canthophorus impressus Canthophorus impressus
Adult and early instar nymph on foodplant: Oxon (July 2007)
©
Chris Raper

Final instar nymph: Oxon (August 2010) ©Tristan Bantock