Granulated ground beetle
Carabus granulatus
The granulated ground beetle is a medium-sized predatory beetle commonly found in moist habitats such as meadows, riverbanks, and open forests. It reaches a body length of up to 26 mm and is distinguished by its bronze or greenish-black elytra featuring characteristic rows of elongated tubercles. Unlike many other Carabus species, it is occasionally capable of flight, allowing for better dispersal. It serves as a beneficial organism in agriculture by preying on pests like slugs and insect larvae.
Details
Identification
Elytra with three rows of elongated tubercles; color metallic bronze, coppery, or greenish; pronotum is broad and finely punctured.
Social behavior
Solitary; interactions occur primarily during the mating season in spring.
Diet
Predatory diet consisting of mollusks (slugs/snails), earthworms, and various insect larvae.
Hunting strategy
Active hunter that pursues prey on the ground and seizes it with powerful mandibles; uses extraintestinal digestion.
Spawning substrate
Eggs are laid individually in moist soil or under vegetation.
Overwintering
Overwinters as an adult in rotten wood, under loose bark, or in moss cushions.
Ecology
Ecological role
Important predator in the soil ecosystem; regulates populations of small invertebrates and pests.
Natural predators
Birds, hedgehogs, shrews, larger predatory beetles, and amphibians such as common toads.
Competitor species
Other large ground beetle species such as Carabus cancellatus or Carabus nemoralis.
Ecosystem service
Biological pest control in agriculture and forestry by consuming field slugs.
Threats
Habitat loss due to drainage of wetlands and the use of broad-spectrum insecticides.
Scientific profile
Profile
Distinguishing features
Characteristic are the elytra, each with three strong longitudinal ridges, between which rows of oblong tubercles (granules) are located. The elytral suture is often darkly contrasted. Unlike many other Carabus species, C. granulatus is often capable of flight.
Habitat
Prefers moist to wet locations: wet meadows, fens, swamp forests, riparian zones of water bodies, and muddy arable fields. Also found in gardens and parks with high soil moisture. Considered synanthropic in damp agricultural landscapes.
Diet
Carnivorous: Both beetles and larvae predatorily hunt snails, earthworms, and various insect larvae.
Role in food web
Wichtiger Prädator von wirbellosen Tieren (Nützling in der Landwirtschaft, da er Schnecken frisst); dient selbst als Nahrung für Vögel, Igel, Spitzmäuse und Amphibien.
Protection & threats
Main threats
Drainage of wetlands, lowering of the groundwater table, river channelization (loss of floodplains), intensive agriculture (pesticide use), and the loss of deadwood structures for overwintering.
Population trend
Overall still common in Germany, but regionally declining due to progressive habitat fragmentation and desiccation of the landscape.
Conservation measures
Preservation and restoration of wetlands and floodplains, avoidance of drainage, promotion of margin structures, and leaving deadwood in the landscape.