Elateridae of the British Isles

Diacanthous undulatus (De Geer, 1774)

Size – 12-18mm.

Description – One of the larger species in Britain. The pronotum is black with a covering of lighter brown hairs. The elytra are strongly patterned with wavy cross lines by a dense covering of hairs. The species is variable, the elytra can be a light grey/brown with darker brown cross lines or a dark ochre/yellow with lighter yellow/cream cross lines. The legs are dark brown. The antennae are very long in the male, extending a way beyond the back of the pronotum and shorter and thinner in the female, extending just beyond the posterior edge of the pronotum.  

National Biodiversity Network map showing the distribution of Diacanthous undulatus across Britain and Ireland.

British and Irish distribution of Diacanthous undulatus (De Geer, 1774) based on records held by the National Biodiversity Network.

Distribution data supplied by:

  • Highland Biological Recording Group

Distribution – Scattered records from north-west Scotland.

Biology – Larvae occupy decaying wood just underneath the bark or layers close to the bark of Birch (Betula spp. ), predominantly in fallen trunks. Pupation occurs in spring after 4-5 years in the larval stage. The imagos are crepuscular.

Habitat – Confined to the Birch woodlands of northern Scotland.