BEETLES (Part 2 of 2)   Leave a comment

Water scavenger beetles include more than 1,000 species of primarily tropical aquatic beetles, with approximately 200 species native to North America. Like the true water beetles, water scavenger beetles must find a way of supplying themselves with oxygen while they forage underwater. At the water’s surface, the beetles project their antennae out of the water to capture a bubble of air. Then they place the bubble beneath their bodies to breathe from it as they swim. This bubble makes water scavenger beetles look as though they have a silvery film on their undersides.

Carrion beetles and burying beetles are widely distributed and eat primarily dead animal matter. Many carrion beetles are relatively large and brightly coloured Burying beetles are so named because they dig beneath small dead animals such as rodents, birds, and reptiles until the animal is completely buried beneath the soil. Then the female digs her way down to the carcass and deposits her eggs. Upon hatching, the larvae feed on the body of the dead animal.

Rove beetles have short elytra that do not cover the abdomen. When they are being pursued, rove beetles run with the tip of their abdomens curled over their backs, giving their abdomens the appearance of stingers. One species expels a fluid from the tip of its abdomen that repels attacking ants.

Luminescence, emission of light resulting from causes other than high temperature.

Fireflies are soft-bodied beetles, most of which produce light in special organs located in the undersides of their abdomens. The light is produced by a chemical reaction between oxygen in the air and two chemicals in the firefly’s body. The females of most species have short wings or are wingless. The wingless females and most firefly larvae are often called glow worms Some species in the firefly family do not produce light.

Stag beetles are best known for their enormous, distinctive mandibles. These are most pronounced in the males. Stag beetles are often found in and around rotting logs, on which the larvae feed. Adults are often attracted to outdoor lights.

Scarab beetles include a wide variety of species about 20,000 worldwide. More than 1,300 species occur in North America. Most scarab beetles are stout and robust, but their size varies greatly from one species to another. Some small species are about 0.08 inch (0.2 centimetre) in length, whereas some of the tropical species are the largest beetles in the world up to 6 inches (15 centimetres) in length. Some members of the scarab-beetle family are scavengers: both the larvae and the adults feed on dung and carrion. Others are plant eaters: the larvae eat roots or wood and the adults eat leaves and flowers. Many members of the latter group are agricultural pests. June bugs and May beetles are scarabs.

Click beetles are small to medium-sized beetles with elongated, flattened bodies that have bluntly rounded ends. The largest species reach lengths of about 2 inches (5 centimetres). The larvae of click beetles, called wire worms, cause extensive crop damage in some areas because they feed on underground roots, seeds, and stems.

Metallic wood-boring beetles resemble click beetles in general shape but can be distinguished by their bright metallic colours Some species damage orchards and forests.

Dermestid beetles are mostly small, scavenging beetles. In the household they are particularly harmful to stored foods, leather, furs, and wool products. Although the adults and larvae are scavengers, most of the damage is done by larvae.

Ladybugs, with their roundish, brightly coloured bodies, are the favourite insects of many people. The adults and larvae are often predators of other invertebrates that are agricultural or garden pests, and many fruit growers consider ladybugs to be among the most beneficial of insects.

Darkling beetle, any beetle of the family Tenebrionidae, which includes meal worms, flour beetles, and other species occurring under stones, in dead wood, fungi, and dry vegetable products; most are black or brown.

Darkling beetles include about 15,000 species worldwide. Of the more than 1,400 species in the United States, most are found in the arid South west Most darkling beetles are solid dull black in colour Meal worms are actually the larvae of darkling beetles. Although they are major pests of grain products, meal worms are also commonly raised as food for insect-eating animals such as lizards, frogs, and birds.

Cantharidin, blistering substance obtained from Spanish-fly beetle and other insects of same family.

Blister beetles are elongate, relatively soft-bodied beetles. The adults of most species feed on plants. Blister beetles secrete an irritant called cantharidin. The substance has been used to produce a drug that causes a blistering reaction on the skin most often as a topical skin irritant to remove warts. The substance was first extracted from a bright green blister beetle of southern Europe known as Spanish fly. The drug, also called Spanish fly, was once considered an aphrodisiac, but it can be toxic if taken internally.

Long-horned, wood-boring beetles are often medium-sized to large 0.8 to 2.4 inches (2 to 6.1 centimetres) in length with extremely long antennae. The larvae of these beetles are usually wood-borers that feed on a variety of trees and can cause considerable damage. More than 20,000 species have been described worldwide, and at least 1,200 of these are native to North America. Some are brightly coloured and metallic in appearance.

Leaf beetles are abundant and widely distributed. They are relatively small, and many are brightly coloured and resemble ladybugs. The adults and larvae feed on foliage and also on other plant parts.

Engraver beetle, any of numerous beetles of family Scolytidae; most live under bark of trees and engrave the wood by burrowing.

Bark beetles are considered the most destructive insects of temperate-zone forests. Both the adults and the larvae live beneath the bark of trees. The damage they inflict on the tree depends on the species. Engraver beetles, for example, feed on the inside of the bark and on the surface of the trunk. Other bark beetles bore directly into the trunk and feed on the wood. Ambrosia beetles bore into the tree’s trunk and feed on fungi that live there. Members of the bark-beetle family are dark-coloured. Their antennae are elbowed and have an enlarged, club like end.

Weevils, or snout beetles, constitute an abundant and diverse beetle family with more than 40 subfamilies and 40,000 recognized species. Their most characteristic feature is the beak or snout. It is well-developed, curves downward, and in some species may be twice as long as the body. The snout is used not only for penetration and feeding but also for boring holes in which to lay eggs. The weevils’ antennae are elbowed and club-shaped at the end. Many weevils have no wings; others are excellent fliers. Most are less than 0.25 inch (6 millimetres) in length and are plainly coloured and marked, yet the largest exceed 3 inches (80 millimetres) in length and may be brightly coloured This family includes some extremely destructive pests, such as the grain weevil and the rice weevil.

Taxonomy

Taxonomists divide the Coleoptera into two or more suborders, depending on the classification scheme they prefer. The two suborders common to most schemes are Adephaga and Polyphaga. The suborder Adephaga consists of several families of beetles that are mostly predaceous, including the tiger beetles and ground beetles, the true water beetles, and the whirligig beetles. The suborder Polyphaga contains the majority of beetles.

Tiger beetles and ground beetles belong to the family Carabidae, which contains the largest number of beetle species in North America. (Some taxonomists place tiger beetles in a separate family, Cicindelidae.) Bombardier beetles are also members of the Carabidae family. The true water beetles are in the family Dytiscidae, whirligig beetles are in Gyrinidae, and water scavenger beetles are in Hydrophilidae. Carrion beetles and burying beetles belong to the family Silphidae. Rove beetles are in the family Staphylinidae and have almost as many species in North America as does the family Carabidae. Fireflies and glow worms belong to the family Lampyridae. Stag beetles are in the family Lucanidae. Scarab beetles belong to the family Scarabaeidae, which includes the rhinoceros beetles, Goliath beetles, and dung beetles. Click beetles are in the family Elateridae. Metallic wood-boring beetles are placed in the family Buprestidae. Dermestid beetles belong to the family Dermestidae, and ladybugs are in the family Coccinellidae. Darkling beetles are in the family Tenebrionidae. Blister beetles belong to the family Meloidae. The long-horned wood-boring beetles are classified in the family Cerambycidae, and leaf beetles are placed in the family Chrysomelidae. Bark beetles belong to the family Scolytidae. Weevils belong to the largest family of beetles in the beetle order the family Curculionidae. Bess-bugs belong to the family Passalidae. The death watch beetle is in the family Anobiidae.

Assisted by J. Whitfield Gibbons, Senior Research Ecologist and Professor of Zoology, Savannah River Ecology Laboratory, University of Georgia.

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Posted 2012/01/25 by Stelios in Education

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