Like all
beetles, Ground Beetles have chewing mouthparts
and hardened front wings (elytra) that meet in a straight line down
the back of the abdomen when closed. Ground beetles are often
black and shiny, but a few species have bright colors. Ground
beetles have long, slender legs and antennae, and a head that is
narrower than their thorax. Ground beetles closely resemble
their relatives the Tiger Beetles
(Cincindelidae), but tiger beetles can be distinguished by the overlapping
sickle-shaped jaws which do not occur on ground beetles. Most
ground beetles do not climb very well, and tend to be found on or
near the ground. Typical
ground beetle larvae are long and slender with dark coloration.
SIZE:
Adult body length up to 35 mm, most species between 5-15 mm. Larvae
up to 35mm.
LIFE
CYCLE
Like
all beetles, ground beetles have "complete" metamorphosis
with egg, larval, pupal, and adult stages. In most ground
beetle species, females lay eggs in soil. Upon hatching, larvae
feed and grow for 1-2 years (in most species) and pupate in small
chambers made of soil. Many species spend the winter in these
chambers, and the adults emerge in spring. Most adult ground
beetles will live for several years. Pictured below are typical
ground beetle larvae.
Ground
beetle larva (B. Newton, 2006)
Ground
beetle larva (B. Newton, 2005)
ECOLOGY
Most ground beetles are
fast-moving predators that feed on small insects, spiders, and other
arthropods. They usually hunt at night by patrolling the ground,
and are found in a variety of habitats, including farmland, wooded
areas, and lawns. During the day, most ground beetles hide under
rocks, logs, and fallen leaves. Ground beetles seldom fly. A
few beetles in this family, such as the seedcorn beetle (Stenolophus
lecontei), are herbivores.
Caterpillar
Hunter, a ground beetle, feeding
on the pupa of another beetle (B. Newton, 2002)
Ground
beetle larvae are also predators, and most species hunt in the same
way as the adults, by patrolling at night and hiding during the day,
although many ground beetle larvae tend to remain undercover even
while hunting: some hunt under fallen leaves, others hunt underground.
PEST
STATUS
Most ground
beetles are predators, and are not considered pests. The seedcorn
beetle, Stenolophus lecontei, is sometimes a minor pest
of stored grain.
COMMON
KENTUCKY GROUND BEETLES
SEARCHERS
GENUS: Calosoma Searchers
are among the largest beetles found in Kentucky, growing to lengths
of 1 1/4". Searchers and their larvae are common
in forested areas, and will eat almost any animal small enough to
catch, including caterpillars, other insects, and earthworms. Larvae
are about the same length as the adults. One of the most common
searchers is the Caterpillar Hunter, also called the Fiery Hunter
or Fiery Searcher. Caterpillar hunters are vibrantly colored
with metallic green elytra (hard front wings) and shiny purple-black
highlights on the legs and thorax.
Caterpillar
Hunter (R. Bessin, 2000)
Calosoma
larva (B. Newton, 2004)
Shown below is a short video of a live Caterpillar Hunter.
WOODLAND
GROUND BEETLES
GENUS: Pterostichus,
Agonum, others
Ground beetles in the Pterostichus,
Agonum, and related genera are often called "Woodland
Ground Beetles." As their name implies, these
beetles are often common in wooded areas, but they are common in other
habitats as well, including lawns and crops. Most species are
shiny, dark-colored, and about 15 mm long.
Woodland
Ground Beetle (B. Newton, 2004)
BIG-HEADED
GROUND BEETLES GENUS:
Scarites Big-headed
Ground Beetles (genus Scarites) are very common
in Kentucky. They are often found in agricultural areas. These
distinctive, shiny-black beetles are usually about 3/4" long,
and are named because of their large mandibles. The larvae are
usually about 3/4" also and resemble the Calosoma larvae
shown above, except that they are more slender.
Big-headed
ground beetle (R. Bessin, 2000)
Big-headed
ground beetle (R. Bessin, 2000)
VIVID
METALLIC GROUND BEETLES GENUS:
Chlaenius Ground
beetles in the Claenius genus are often called "Vivid
Metallic Ground Beetles" because of their vibrant, metallic
colors. These beetles are also covered in tiny hairs. They
are fairly common in Kentucky. The one below was about 15 mm
long.
Vivid
Metallic Ground Beetle (R. Bessin, 2000)
COLLECTING
& PHOTOGRAPHY
Look for ground beetles
and their larvae under rocks, logs, and loose bark. They are
common around homes, barns, gardens, field crops, and woodland areas.
Some species will also crawl or fly to lights at night. A
pitfall trap can also be used to capture ground beetles. It
can be difficult to get a picture of a ground beetle: as soon as
they are exposed to daylight, they often try to escape. Often,
the best plan is to capture one, place it in a regular refrigerator
for about 10 minutes, and then take its picture while it is warming
up. during this period, the beetle will move slowly (it will
recover quickly though, so you have to be fast with your camera!).
GROUND
BEETLE FACTS
Ground beetles are
very closely related to tiger beetles
(family Cicindelidae), and most of the beetles in both of these
groups are predators (both as larvae and adults).
The ground beetle family,
Carabidae, is one of the largest groups of beetles, with over 1700
species in the United States and several hundred species in Kentucky.
Because ground beetles
are so common, there are several web pages devoted to them. Visit
these sites for great information and pictures:
Have you heard any
myths, legends, or folklore about ground beetles? If so, let
us know.
Original document: 25 May 2004
Last updated: 27 Jan 2012
Photos courtesy R. Bessin and B. Newton, University of Kentucky
The Kentucky Critter
Files are maintained by Blake Newton, Department of Entomology, University
of Kentucky.
Contact: blaken@uky.edu
