Blue Ground Beetle

Description:

The Blue Ground Beetle (Carabus intricatus) is a large, distinctive native species with metallic blue markings, long legs and sculptured wing-cases; it is the UK’s largest ground beetle.  Despite having wing cases, it cannot fly.

Given its name as a result of the beautifully marked and strikingly blue-coloured wing cases, the Blue Ground Beetle makes its home in damp, deciduous, often ancient, woodlands of Oak and Beech; usually living on south-facing slopes in areas with sparse ground vegetation and abundant veteran trees and dead wood.

Adult Blue Ground Beetles are mainly nocturnal and can be found year-round (where they are present), although they are most active and easiest to see from March until June.

The Blue Ground Beetle was believed extinct in the UK until 1994 when a population of them was discovered in a woodland on Dartmoor.  Since this time, a further 14 populations have been recorded (in Devon, Cornwall and South Wales) with 2 of the populations in Devon being discovered as a part of the Dartmoor Blue Ground Beetle Project during 2022.

The Blue Ground Beetle can be easily confused with some of their smaller, more commonly seen relatives, including the Violet Ground Beetle (Carabus violaceus). The smaller more common beetles, including the Violet Ground Beetle, can be found throughout the UK; they are smaller in size and more purple in their colouring. It would be highly unlikely to find a Blue Ground Beetle outside of its known range.

• Size: Up to 38mm in length
• Life span:  Thought to live 2-3 years
• Diet:  Both the adults and their larvae feed on slugs – most notably the Tree Slug (Limax marginatus) and the Ash-black Slug (Limax cinereoniger).  Both beetle and larvae follow a slugs’ slime trail then, when it makes contact, uses its large pincer jaws to grip their prey, injecting digestive juices into the slug, quickly killing it and turning its insides into ‘slug soup’!
• Reproduction:  Adult beetles mate and lay eggs in the spring, the larvae develop through the summer and new adults emerge in the autumn.
• When to see:  Adults are usually seen at night and can be found year round; they are most active from March to June.
• Population Trend:  Declining particularly across their European range – the Blue Ground Beetle is classed as Nationally Rare within Great Britain and Near Threatened on the IUCN Red List.
• Threats:  Loss of habitat and decline in habitat quality; at least one UK site is known to have been through clear felling and replanting with conifers.  Changes in habitat management, particularly changes in or removal of light grazing in ancient woodlands.
• Fun Fact:  The Blue Ground Beetle has a viscous defence mechanism. When threatened by a predator (or a human come to that), it can squirt a jet of acid from its abdomen.

How you can help: 

Buglife is working to increase awareness of invertebrates and the Blue Ground Beetle through specific projects, such as the Dartmoor Blue Ground Beetle Project and campaigns, but we need your help!

Join a recording scheme and log your finds – join our Blue Ground Beetle Hunt and log any finds, send any records/sightings to the Ground Beetle Recording Scheme or download the iRecord app and get recording!

Do remember that we rely on donations to continue our work.  If you have searched, found and learnt about our incredible invertebrates on our website, please do consider Making a Donation, Becoming a Member or maybe even making a purchase in our shop.  For more ideas on how to support our work find out how to Get Involved.  Thank you 🕷

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