Devil’s Coach Horse Beetle (Ocypus olens)

Ocypus olens belongs to the rove beetle family, of which there are approximately 1000 species found in the UK. A voracious predator of other ground-dwelling invertebrates, including slugs, the devil's coach-horse lives under stones or among plant litter. This beetle is common and widespread - a valuable biological control of garden pests. When disturbed, it puts on a threat display, bending its abdomen upwards and giving off a pungent, defensive chemical from two conspicuous white glands at the end.

Identification:
Adult beetle: 25-28mm in length, long thin body, black in colour. These beetles have short wings and scorpion like pincers. The beetles aren’t poisonous but their bites are quite painful. They also emit a foul smelling odour as a warning sign.

Biology:
Reproduction takes place in the autumn. 14-21 days after mating, the female lays a single egg in a damp, dark place such as in leaf litter and under stones The larva emerges after 30 days and will live mainly underground. It is predacious like the adult, and has a similar diet and defence behaviour. The larva has 3 successive growth stages, called instars. The final larval stage at approximately 150 days reaches 20-26mm in length when pupation begins, taking up to 35 days. The fully grown adult then emerges from the pupae, remaining inactive for up to 2 hours whilst the wings dry out.

Control:
Not considered a public health pest, proofing of doors and removal of harbourages will discourage this casual intruder from entering buildings, wall/floor junctions can be treated with a residual insecticide labelled for crawling insects. Sealing cracks and crevices on the outside of a building and around doors with mortar or mastic will help to prevent these beetles coming in.

Products to control Devil's Coach Horse Beetle: