Ground Beetles
Ground beetles are nocturnal predators that patrol the soil for slugs, cutworms, and other pests. These guides cover identifying the common species and keeping them resident in a garden.
Night-shift pest control at soil level. They take slugs, cutworms, and root maggots and ask only for a place to hide by day.
Size
2 to 35 mm
most under 20 mm
Species
Over 40,000
one of the largest beetle families
Diet
Slugs, cutworms, grubs
hunted after dark
Habitat
Under logs and mulch
out on patrol at night
Build
Fast runner, rarely flies
chases prey on foot
Life cycle
Four stages, most of them spent out of sight in the soil.
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Egg Laid singly in damp soil or under debris, well hidden from view.
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Larva A dark, segmented, fast-moving hunter that eats pests down in the soil too.
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Pupa A pale, still stage inside a small earthen chamber below ground.
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Adult Glossy and quick, hiding by day and hunting slugs and caterpillars by night.
Ground beetles run the night shift, and I find them by lifting the same plank I leave in the bed on purpose. Glossy, black, quick, and gone the second the light hits them. They want nothing from me except somewhere undisturbed to sit out the day, which makes them the cheapest pest control I have ever installed.
Sam Fielding · field note · about Sam
Typical season
Adults active spring through fall; many overwinter under logs and leaf litter.
A single ground beetle can eat its own body weight in slugs and cutworms in a night, working the beds long after everything else has gone quiet.