Limoniscus violaceus belongs to a family of beetles known as click-beetles (Elateridae), so called because they are able to spring into the air with an audible ‘click’ when placed on their backs or threatened.
A characteristic ‘peg and socket’ on the underside of the thorax is part of the mechanism that produces this leap. The hind-angles of the pronotum - the visible thorax - of click-beetles are characteristically pointed.
Worldwide, there are around 9,500 species in the family Elateridae, of which only 67 are found in Britain.
The larvae of Elateridae live in the ground or in rotten wood.
They look similar to mealworm larvae, which are sold as feed in pet shops.
Larvae of most click-beetles are completely harmless, and that includes Limoniscus violaceus. Some related species of click-beetle are serious pests - particularly Agriotes, the notorious ‘wireworms’ that attack cereal and root crops.
Limoniscus violaceus is a distinctive species. It is about 12mm long and the elytra have a blue reflection.