[2] This species has a wide distribution in the Palaearctic, from 64°N to North Africa and from the British Isles to China.

[3] These bugs prefer deciduous and mixed forests, heathland, gardens, chalk downland and damp flower-rich meadows.

[4] Picromerus bidens is a large (12 to 13.5 mm long) and distinctive predatory shieldbug.

Body colour is quite variable, generally light to dark brown or bluish, with red-brown antennae and legs and two unmistakable thornlike brown projections on the sides of the pronotum (hence the species name bidens, meaning "with two teeth").

[4] Both adults and nymphs of the spiny shieldbugs are predatory, feeding on the larvae of other insects, especially on leaf bugs, beetles, aphids and caterpillars.