Ground Beetle

Ground Beetles

Ground beetles is a term used to describe the family of beetles Carabidae, in the order Coleoptera. Ground beetles are also known as carabids. This family comprises around 40,000 species worldwide, with 2,339 species residing in the United states (1).

Description

Ground beetles have a large size range within the family group, with a range of size between 0.7-66 mm. This family is known for their long legs and powerful mandibles, which make them distinct from other groupings of beetles. (1) Most species in the adult stage are dark brown or black, shiny, and a bit flattened in shape. Although some can be iridescent blue or green. (2) To identify them from other beetle groups, you can distinguish them by the first abdominal segment not being continuous; instead it is divided by fixed hind coxae (the first leg segment on the beetle.) The front tibia has a prominent notch, on the inside near distal end. Also, the Hind trochanter is elongated, at least a ¼ of the femur. (3)

Life Stages

The ground beetle family has four life stages: egg, larva, pupa, and then adult. The first three life stages are spent underground most of the time. While the adult life stage is spent above ground. (1) Depending on the species of the particular ground beetle, they can lay a few to hundreds of eggs. (2)

Feeding Habits

These beetles are predatory, and therefore important for the biological control of insect pests on farms. The adults hunt from the soil surface, but will also climb down and look for their prey within the soil foliage. Their larvae will be burrowed into the soil, and in this life stage, they seek out and feed on prey directly within the soil. The beetles' prey consists of a wide variety of critters within the soil, consisting of a large amount of other insects and also the seeds of plants. They tend to have a seasonal diet, depending on what's available in the season, they will switch between eating seeds or insects.(1) Some of their food sources include Caterpillars, grubs and adults of other smaller beetles, fly maggots and earthworms. Most of the family class has large, sharp mouthparts to catch and devour prey. (2)

Behavior

Adult carabid beetles have wings, but most rarely fly and some are completely incapable of flight. Some prefer Living mulches like types of clover as a preferred microhabitat for adults. The use of compost on agricultural fields also shows an increased number of ground beetles arriving. This is thought to do so because it adds a cool, moist climate for the beetles. (1) Some species can emit a potent smelling irritant when they are handled and feel threatened. Many species are nocturnal and can be attracted to lights when it's dark. (2)

Ecology and Importance

These beetles play an important role in keeping down pest populations in the soil for agricultural purposes, and also for reducing weed populations from eating the seeds of certain weed species. They are considered one of the most natural and consistent pest management species, since they are long lived and able to stay on agricultural grounds even when crops are not in season. They are also generalist feeders and able to switch their diet depending on what's available that time of year. This makes them an ideal beetle family for management. (1) Ground beetles are not harmful to humans, and will not destroy buildings, eat your food, or clothing. If handled improperly, they do have the potential to pinch skin, (4) but besides this and some having the ability to emit an odor, (2) ground beetles are harmless. They cannot thrive indoors and also cannot reproduce indoors, so populations inside buildings will not accumulate. (4)