Black-horned Ground Beetle
Chlaenius nigricornis
The Black-horned Ground Beetle is a specialized carabid species that prefers very moist habitats such as marshes, fens, and vegetated shorelines. It reaches a body length of approximately 10 to 12 millimeters and is notable for its metallic green to bronze coloration. The species is an active predator and is considered threatened in many parts of Central Europe due to the loss of natural wetlands.
Details
Identification
Body metallic green or coppery; antennae black (except for the first segment); legs reddish-yellow with dark tibial tips.
Social behavior
Solitary, though often found in high densities at suitable locations.
Diet
Feeds predatorily on small invertebrates such as insect larvae, snails, and worms.
Hunting strategy
Active searching on the ground, often in the sun on mud flats.
Spawning substrate
Moist soil or moss near shorelines.
Overwintering
Overwinters as an adult in leaf litter or under bark.
Ecology
Ecological role
Important predator for regulating small animal populations in semi-aquatic habitats.
Natural predators
Birds, amphibians, and larger predatory insects.
Competitor species
Other hygrophilous ground beetle species such as Agonum species.
Ecosystem service
Pest regulation in wet meadows and riparian areas.
Threats
Habitat loss through drainage, shoreline reinforcement, and agricultural intensification.
Scientific profile
Profile
Distinguishing features
The most important diagnostic feature within the genus Chlaenius is the combination of black antennae (only the first segment may be minimally pale at the base) and pale legs. The upper surface is densely punctured and covered with short hairs (pubescence). The pronotum is heart-shaped and narrower than the elytra.
Habitat
Stenotopic hygrophilous species. It inhabits the riparian zones of standing and slowly flowing waters, marshes, fens, and sedge meadows. It prefers open, sun-exposed mudflats or areas with sparse vegetation near water.
Diet
Zoophagous (predatory); feeds on various small invertebrates such as insect larvae, small worms, snails, and other arthropods of the riparian zone.
Role in food web
Wichtiger Prädator in semiaquatischen Übergangszonen; reguliert Populationen kleiner Invertebraten und dient selbst als Nahrung für Vögel, Amphibien und größere Raubinsekten.
Protection & threats
Status not on standard scale
Main threats
Loss of wetlands due to drainage, riverbank stabilization and channelization, intensive agricultural use of floodplains (nutrient input), and habitat fragmentation.
Population trend
Declining; in the German Red List (BfN), the species is currently listed in category 3 (vulnerable).
Conservation measures
Restoration of floodplains and riparian zones, re-establishment of natural flooding dynamics, protection of fens, and avoidance of pesticide use near water bodies.