Ground Beetles - Carabidae

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25,000 species of Carabida in the world

Identification of Ground Beetles


Adult ground beetles are 12mm to 35 mm long, somewhat flattened, sometimes elongate, with thread like antennae (11-segmented), narrow head (projects forward), and hard wing covers meeting in a straight line at the center of the back with numerous fine, parallel ridges running lengthwise.

These active insects, with long legs, large eyes and strong sickle-like mandibles, run rapidly, and are active mostly at night (nocturnal). Ground beetles are usually black though many are brilliantly colored or enhanced by iridescent, metallic blue, green, purple, reddish or other bright markings.

Many species are difficult to distinguish. These insects (predators) feed on other harmful insects and are regarded as very beneficial to agriculture. Larvae are elongate and wormlike in appearance with powerful prominent mandibles. They vary from dirty white to dirty yellow to almost black.

 


Ground Beetles-Carabidae are agile and long-legged. These ground beetles are usually seen scurrying along the ground at remarkable speeds in search of prey. The ground beetles all have lustrous bodies, and some are brightly colored. This makes them so popular with collectors that several species are in serious danger of extinction: examples are Carabus olympiae and C. solieri.

Most of the 25,000 species of Carabidae ground beetles are active at night. Some cannot fly. They are distinguished by their somewhat flattened bodies and by the rows of fore-and-aftridges and furrows that mark their stiff wing covers.

Most ground beetles prefer temperate or even cold climate; only a few species are found in the tropics. The Carabidae are most commonly found living under stones and logs, in gravel along watercourses, and among fallen leaves and other dead vegetation at the bases of trees. Some species, however, live deep in the bowels of the earth, in topsoil, and in caves. Ground beetles of the genus Calosoma are frequently found in trees, and some species live under snow. In the Himalayas, ground beetles have been seen at altitudes of more than 15,000 feet.

Most of the Carabidae are formidable predators, hunting their prey in water, on land, and in trees. Although they feed primarily on arthropods, worms, and mollusks, ground beetles are not squeamish about how they satisfy their voracious appetites, and will prey on a wide variety of animals.

Because of their fierce appetites, ground beetles have been a valuable aid to man in the control of destructive insects. They are sometimes imported into a region to rid it of pests. The ground beetles themselves are rarely destructive. The notable exceptions are members of the genus Zabrus that frequently damage cereal crops.

Carabidae larvae generally live out in the open. A larva can be recognized by its elongated shape, depressed cranium, sharp mandibles, and in most cases, by a pair of bristle like appendages at the end of the abdomen. The diet and habits of the Carabidae larvae usually resemble those of the adults. The pupae form in tiny underground cells, built by adults with secretions from their Malpighian tubes.
 



Corobus. Ground beetles of the genus Cora bus, most often found in cool, damp mountain valleys, are notable in that many of them are unable to fly. Their wings may be rudimentary or entirely atrophied. This distinction has made the Carabus an excellent walker, but has also led to the isolation of Carabus populations and the establishment of a large number of species and local races. Today, more than 1,000 species and geographical races of Carabus are known.

Members of the genus Carabus feed primarily on snails and slugs, but they also hunt various insects and worms. They are nocturnal and, even in the larval stage, are completely at home in aquatic environments, where they hunt mollusks.

 


Cychrus. The genus Cychrus is another group of efficient and highly specialized mollusk hunters; found in damp forest environments, they are equipped with a highly flexible head and thorax, enabling them to dig snails from their shells.

 


Cofosomo. Carabidae of the genus Calosoma, found in forest regions, are marked by their ability to climb trees. One species, C. sycophanta, has proved highly beneficial to man. Preying on such defoliating insects as Tortrix mridana, the cockchafers, and the larvae of Lymantria dispar, the processionary caterpillar, this brilliantly-colored, tree-climbing ground beetle has saved forests of trees, especially the vulnerable deciduous oak, from devastation.

The adult C. sycophanta spends the winter in a tiny underground cell; in the spring, when the sun has warmed the ground sufficiently, it emerges among the mosses and fallen leaves, armed with a tremendous hunger. At this time of the year the larvae of many defoliating insects are in full activity, and C. sycophanta has only to climb the nearest tree to discover a veritable feast. One of the prime victims of this ruthless beetle is the hairy processionary caterpillar (the Lymantria larva). Processionary caterpillars usually move in a regimented fashion; the species found in pines move in single file and those found in oaks form double ranks. C. sycophanta hurls itself upon these defenseless files like a wolf attacking a flock of sheep.

The adult C. sycophanta hunts for about 50 days; then it retires to an underground cell where it rests until the following spring, when the feast begins again. By this time it has eaten the equivalent of 200 to 400 large Lymantria larvae. The females have already gone down and laid their eggs in a niche in the ground. The average female lays about 100 eggs, but some lay as many as 500.

C. sycophanta's war on defoliating insects does not stop when the adults retire for the winter. Just before the adults go underground, the young are hatched and quickly take to the trees. Here they feed on caterpillars, chrysalids and even sluggish Lymantria adults. Day and night they march, surprising their victims and ripping them open with their sharp mandibles. Some seek out the nests of the processionary caterpillars and move in as unwanted guests. The young have been shown to be even more bloodthirsty than their parents, often killing more than they can eat. After about two weeks of slaughter, the C. sycophanta larvae, each having killed about 40 large victims, leave the trees and bury themselves in the ground, where they become pupae. They remain underground during the winter and emerge as adults in the spring.

Commonly found from western Europe to Siberia, C. sycophanta was first introduced in the United States, primarily in New England, in the early years of the 20th century. Many forests in the eastern United States had suffered severe damage due to the accidental importation of Lymantria dispar and Euproctis chrysorrhoea (like L. dispar, the larvae of this species, the browntail moth, feed on foliage). In spite of the massive introduction of C. sycophanta, however, little progress has been made in keeping the populations of these moths under control.

C. sycophanta is commonly called the fiery searcher, perhaps because it sometimes gives off large amounts of a blistering juice. A member of the same genus that is native to North America is Colosoma scrutator. It is almost as large as C. sycophanta,

 


Harpalus. Like C. sycophanta, most species of Carabidae are carnivorous. Some, however, such as the members of the genus Harpalus, are predominantly vegetarians. Members of Harpalus attack flowers, fruit, and the green parts of herbaceous plants, and are therefore a menace to agriculture.

These are small- to medium-sized beetles. Their colors may be green, blue, or black. The black color is usually lusterless and is often characteristic of the females, which are larger than the males. Members of Harpalus are usually found in gardens; during the daylight hours they hide under stones and bricks bordering flower beds.

 


Brachmus. Among the most interesting of all insects are bombardier beetles belonging to the genus Brachinus. Not markedly different in appearance from other Carabidae, they are set apart by a remarkable system of self defense. When attacked, the bombardier beetle ejects a drop of volatile fluid, from the anal glands at the end of its abdomen, into a special stiffened sac.

The sac contains other secretions, and when the fluids are mixed there is an audible explosion like the sound of a tiny balloon bursting. The explosion results in a tiny puff of caustic gas-a smoke screen behind which the bombardier beetle makes its retreat. This gas is so caustic that it can even burn human skin. It is therefore extremely effective in discouraging attackers. And, as the bombardier beetles are quite social little animals, when one member of a group is attacked, a reaction is triggered: the air is often filled with a series of small explosions.

Although they are the most dramatic, bombardier beetles are not the only Carabidae that defend themselves by emitting secretions. Members of the genus Aptinus also eject fluids with an explosive force.

 


Mormolyce phyllodes, a flat, leaf like ground beetle from Java, is one of the few carabids that live in tropical climates. It is said to eject a secretion that can paralyze the human hand for 24 hours.

In addition, this tropical ground beetle displays other remarkable characteristics. The adults, more than two inches in length, have an extraordinary flattened appearance -hence the name phyllodes, meaning "like a leaf. This appearance is caused by blade like extensions from the wrinkled wing covers that enclose the thorax and abdomen.

Members of Mormolyce phyllodes feed on fungi growing on dead trees deep in equatorial forests. The females lay their eggs in the fungi, where the larvae tunnel in. For food, the larvae wait for animals to wander by, and then attack ferociously. If two tunneling larvae should meet, however, they will attack each other without hesitation. According to many specialists, this strange species is on its way to extinction.

 


Trechus. Ground beetles of the genus Trechus are notable for their ability to survive in an enormous variety of environments. They have been found inhabiting Pacific islands as well as the Arctic and Antarctic regions. They also hold the altitude record for Coleoptera. Some have been found high on the slopes of Mount Kenya and at altitudes above 15,000 feet in the Himalayas. Some species of Trechus dwell in caves and are blind; they are found primarily in the Alps, the eastern Carpathians, and the Pyrenees.

 


Omophron. The members of this genus have curiously shaped, compact bodies. They live along sandy shores near the water's edge.

 


Notiophilus. The broad-skulled beetles of this genus are confined to dry, sunny habitats in spite of the fact that the term Notiophilus means "fond of dampness."


The Subfamily Scaritinae. These carabids build complicated burrows along sandy shores. The scarites are unusual in that they alternate between a daytime existence in underground burrows and a nocturnal existence prowling above ground.

 


The Subfamily Bembidiini is represented in most parts of the world. Most of these tiny ground beetles live in damp or even aquatic environments, attacking insects that spend the critical phases of their metamorphoses in water. However, one genus, the blind Anillus, lives underground, mostly under rocks half buried in the soil of wooded hillsides.

 


The Subfamily Pterostichini is an enormous group, consisting of some 5,000 species. One genus, Molops, is found in cool, damp environments, usually in forests or mountains.

 


Laemosthenes. The elongated beetles of this genus tend to inhabit wooded areas, rock piles, and caves. Their ancestors lived in the Mediterranean basin; it is thought that they originated in the southern Aegean area during the Miocene epoch more than 12 million years ago.

Amara. Carabidae of the genus Amara are distributed over much of the Northern Hemisphere, and prefer to live in areas exposed to the sun. They feed on herbaceous plants and often prey on small animals. Many species of Amara are colored green, turquoise, bronze, or black; they can be recognized easily by their boat-shaped, flattened bodies. They are often seen scurrying among rocks and tufts of grass or climbing the stalks of plants.


Chlaenius. The brightly colored Chlaenius, with their brilliant metallic luster, live in marshes or at the edge of mountain streams;

some members of this genus inhabit the banks of brackish lagoons. One notable exception is the small, brilliantly colored Callistus lunatus, which avoids humidity whenever possible, preferring to live in very dry, sheltered environments.

 


Lebia. One member of this genus, a flat beetle known as Lebia scapularis, is extremely beneficial to man. It preys on another coleopteran, the elm leaf beetle (Galerucella luteola), which, as its name suggests, feeds on the foliage of elm trees and can cause serious damage. L. scapularis gorges itself on the eggs and larvae of the elm leaf beetle, thereby keeping a dangerous defoliator in check.

Another species that lives throughout the eastern United States and southern Canada is L. grandis. It can be found under logs and stones.


Rhomborrhina splendida

Rhomborrhina splendida

 


Red Green Beetle


Two-horned Rhinoceros Beetle

 

 

INDEX : Insects   January 11, 2016 02:26:03 PM