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Ground Beetles
Fact Sheet No. 65
February 1989
Alan H. Roe
Insect Diagnostician
Ground beetles belong to the family Carabidae, which is considered to be one of the most
beneficial insect families. Generally, both adults and larvae are predaceous and feed upon a
variety of insect prey, including many important pests.
Description
Most ground beetles adults are dull to shiny black or brown, while a few have iridescent
green, blue, or purple colorations. The head is narrower than the thorax and has prominent
mandibles that are used to crush prey. The beetles are hard-bodied and usually have
longitudinal striations or punctures on the forewings, which cover the back of the insect.
Ground beetle larvae are usually active, slender, and somewhat flattened with three
prominent pairs of legs on the thorax. Their bodies taper slightly toward the tail, which
terminates in two bristly hair-like or spine-like processes.
Habits
Adult ground beetles are usually active at night and hide during the day under stones, loose
bark, boards, or other debris. Adults rarely fly but are fast runners and often flee upon being
disturbed.
Most ground beetle larvae live in burrows just under the soil surface where they feed on
other larvae that enter the ground to pupate. Others are more closely associated with specific
hosts and live in the habitat of the host, for example, rotten logs.
Ground beetles feed on a variety of insects as well as upon snails and slugs. Some of the
more beneficial species feed upon caterpillars and may actively search for their prey on host
plants. Because cutworms and armyworms are also nocturnal, ground beetles are often
effective in reducing their numbers. Other pests which are consumed by ground beetles
include wireworms, May beetle larvae, grasshoppers, and crickets.
Ground beetles are attracted to lights at night and may gather in such large numbers around
light sources that they become a nuisance (in such situations, they often feed upon other
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Ground Beetles Page 2 of 2
insects that are attracted to lights). A few ground beetles, such as the murky ground beetle,
will feed upon berries and can occasionally cause significant damage. The tule beetle,
although not found in Utah, often migrates into homes after rainstorms and is a nuisance
because of its offensive odor. Although there are these examples of ground beetles as minor
pests, the beneficial aspects of the beetles are far more important.
As a note of interest, many ground beetles (for example, the bombardier beetle) can emit an
offensive smelling, hot, volatile liquid which is used for defense. The fluid is produced by
specialized organs in the abdomen and is ejected as the result of a chemical reaction. Such
emissions can often be seen as a puff of "smoke" coming from the beetle.
Control
Because ground beetles are some of the most beneficial insects, control measures are
normally not recommended or required. In some instances control may be warranted if the
beetles cause significant damage to berries or become a major nuisance in the home.
However, the indiscriminate killing of these or other beneficial insects is strongly
discouraged.
Since ground beetles are not usually considered berry pests, no specific chemicals are
registered to control them. Chemicals intended to control other chewing pests on berry crops
should be effective. Before applying any chemical, be sure it is registered for the specific
berry crop and follow all label directions carefully.
It is not uncommon for ground beetles to enter homes, and the presence of a few may
actually be of benefit since they will consume other insects that may be in the home. If the
beetles are so numerous as to be a nuisance, they can often be eliminated by simply
collecting them and placing them outside. More drastic measures include sealing cracks and
crevices in the walls and foundation and checking window screens to see that they fit tightly.
As a last resort, chemicals may be used. Carbaryl (Sevin) sprays or 1% bendiocarb (Ficam)
dust applied around the foundation and beneath and around porches, door sills, and windows
will prevent the beetles from entering.
Precautionary Statement
All pesticides have both benefits and risks. Benefits can be maximized and risks minimized
by reading and following the labeling. Pay close attention to the directions for use and the
precautionary statements. The information on pesticide labels contains both instructions and
limitations. Pesticide labels are legal documents, and it is a violation of both federal and state
laws to use a pesticide inconsistent with its labeling. The pesticide applicator is legally
responsible for proper use. Always read and follow the label.
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