Species

Predaceous ground beetles belong to the order Coleopters and family Carabidae.

Predaceous ground beetles may be confused with similar-looking, plant-feeding darkling beetles. Ground beetles have enlarged basal segments (trochanters) on their hind legs, unlike the Darkling beetle. Darkling beetles' antennae are attached beneath a distinct ridge on each side of their head; ground beetles do not have this ridge.

Identification

Adults
Adult beetles can be anywhere from 1/8 of an inch to 1 1/4 of an inch long. They are usually heavy-bodied and elongate with a tapered head on one end. They have long legs and thin, threadlike antennae without clubbed ends. Color is usually black or dark brown, sometimes with a colored metallic sheen of green or purple. There may also be spots.

Larvae

Life Cycle

Ground beetles take a year to go through the egg, larva, and pupa stages of development. Females lay eggs on at a time in moist soil. Larvae hatch from the egg and live and feed among the soil and organic matter as they go through their larval development before pupating and becoming adults. Adults can live for another 2-3 years.

Prey

Ground beetles prey on many soil-dwelling pests. Some species will climb trees and attack foliage feeding insects.

Cutworms
Root maggots
Slugs
Snails
Caterpillars

Function

Ground beetles are considered mobile predators. They are fast moving and have excellent eyesight and powerful jaws, all of which they use to their advantage while actively seeking out prey (pests in your garden). Both the larvae and adults are active predators.

Ground beetles live in the soil or in loose leaf matter. They may be found under rocks, logs, flat stones, or soil crevices. They can run fast, and generally do not fly. They are nocturnal, feeding at night and hiding during the day.

Commercial Availability

Ground beetles are not available commercially.

Cultivation Techniques

Low-till gardening techniques will help support the presence of beetles. Maintaining healthy, moist soil will provide attractive areas for adults to lay eggs.

Their presence can be further encouraged by the presence of logs, boards, or flat stones to hide under and hedgerows or other undisturbed vegetation near crops.

Ground beetles are extremely vulnerable to pesticides, so avoiding the use of pesticides, or exercising care when using them can help to encourage preserve ground beetle population.

References

Antonelli, Arthur. "Gardening in Western Washington." 1993. WesternWashingtonUniversity. 18 Sept. 2008
<http://gardening.wsu.edu/library/inse002/inse002.htm>.

Flint, Mary Louise, and Steve H. Dreistadt. Natural Enemies Handbook: The Illustrated Guide to Biological Pest Control. Berkeley: UC Division of Agriculture and Natural Resources and the University of California Press, 1998.

Frahm, Annette, Brendan Jordan and Andrea Imler. A Photo Guide to Beneficial Insects.
King County, 2003.

"Natural Enemies Gallery: Predaceous Ground Beetle—UC IPM." 2004. The University of California. 18 Sept 2008.
< http://www.ipm.ucdavis.edu/PMG/NE/assassin_bugs.html>.