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Ground Beetles: our allies against garden pests

Updated on May 16, 2016
Carabus nemoralis
Carabus nemoralis | Source

Make ground beetles welcome in your garden

Ground beetles are allies in our battle against pests. Around the world there are some 25,000 species of these beetles, and most of them, both larvae and adults, are predators of a wide variety of insects.

Many also attack slugs, snails and earthworms.

Appearance of ground beetles

Ground beetles (Order: Coleoptera; Family: Carabidae) often have grooved wing cases and a metallic green, blue or brown colour, but many also are dull brown or black. They are most active during the night, but can also be seen during the day, running at high speed through vegetation or up and down trees. Although some species can fly, they seldom do. In most species the wings have totally disappeared and the wing cases have grown together to form one strong shield.

This is a big-headed ground beetle, Scarites subterraneus

Scarites subterraneus
Scarites subterraneus | Source
The larva of Callosoma sycophanta eating a caterpillar.
The larva of Callosoma sycophanta eating a caterpillar. | Source

Biology of the ground beetle

Ground beetles deposit single eggs on or in the ground; some dig a small hollow in the ground with the tip of the abdomen into which they lay an egg. A few species use their mandibles to construct mud cells on leaves or low plants.

The females of at least one species (Pterostichus anthracites) guard their eggs until they hatch (see this abstract of the Entomological Review 88 number 8 (2008), 904-909). The larvae are strongly built and have chitinous plates covering their backs. They are fierce predators which hide during day time in self-dug 'corridors' in the ground, from which they emerge at night to hunt. Pupation occurs also in the soil.

Adults eat a wide range of insects, as well as snails, slugs and earthworms, which they grab and chew with their strong mouth parts. Irresistible is also over-ripe fruit. The adults overwinter in cracks and crannies and reappear in early spring. They usually die well before the next autumn.

Some books of interest

Video showing how ground beetles attack and eat their prey

Natural enemies

Just as all insects, ground beetles have their own natural enemies, and are attacked by birds, toads, ants and spiders.

How to lure ground beetles into your garden

  • To protect ground beetles against being attacked, provide them with enough cover: do not remove dead leaves from the soil in late summer and autumn. This not only keeps them out of sight of birds and toads, but also maintains a moist environment which they prefer.
  • Alternatively, provide hiding places in the form of rocks, thick organic mulches or overturned flower pots (with uneven rims or placed on uneven ground) designed, for example, as garden borders. One could put a few pieces of over-ripe fruit near or in these hiding places to lure ground beetles to the garden.

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    • Rosaquid profile image

      Rosaquid 5 years ago

      I am so happy to meet you. I love insects, too. They are some of our most important neighbors. This is most informative. Thank you!

    • SusannaDuffy profile image

      Susanna Duffy 5 years ago from Melbourne Australia

      I think I have beetles like this (or at least their antipodean cousins)

    • Steph Tietjen profile image

      Stephanie Tietjen 5 years ago from Albuquerque, New Mexico

      I have a lot of beetles in my garden which are kept in check by a couple of thrasher birds that live here. I will find holes all round the yard where they've dug up the grubs. And as you suggest I leave the fallen leaves so they have hiding places. The leaves improve the soil anyway. I love this lens and all your bug lenses.

    • Sher Ritchie profile image

      Sher Ritchie 5 years ago

      These ground beetles are amazing - and that they eat snails should be more widely known. The green gardening alternative to snail pellets. Great lens - thanks for sharing.

    • profile image

      JoshK47 5 years ago

      Very cool creatures, these - and useful to boot! Blessed by a SquidAngel!

    • marlies vaz nunes profile image
      Author

      Marlies Vaz Nunes 5 years ago from Amsterdam, the Netherlands

      @LisaMarieGabriel: I so agree!

    • WildFacesGallery profile image

      Mona 5 years ago from Iowa

      Even though they creep me out a little I can appreciate their purpose. Nicely presented.

    • LisaMarieGabriel profile image

      Lisa Marie Gabriel 5 years ago from United Kingdom

      I love your bug lenses! Insects need a good press :)

    • profile image

      anonymous 5 years ago

      Very educational, I really should not dislike these ground beetles.