Beetle. The Bodies of Beetles

Beetle is one of the most common of all insects. There are about 300,000 species (kinds) of beetles in the world. They live everywhere on earth except in the oceans. Beetles are found in rain forests and in deserts. They live in freezing cold areas and in hot springs. They also inhabit mountain lakes and can even survive in polluted sewers.

Beetles have typical insect body parts, including antennae, three pairs of legs, and a tough exoskeleton (external skeleton). However, unlike other insects, adult beetles have a pair of special front wings called elytra. These wings form leathery covers that protect the beetle's body and delicate hind wings. Because of their shell-like skeleton and hard wing covers, beetles have been called the "armored tanks" of the insect world.

A bombardier beetle, shown here, defends itself by squirting a hot, irritating jet of gas at its attacker. It produces this spray by mixing chemicals from two organs located at the end of its body

A male eastern Hercules beetle, shown here, has a long horn. This beetle is also one of the largest beetles in North America. It grows to 2 ½ inches (6 centimeters) long

Male stag beetles have long jaws that they use to defend themselves. Stag beetles get their name from the jaws, which resemble the antlers of a stag (male deer)

Beetles vary greatly in shape, color, and size. Some, such as click beetles and fireflies, are long and slender. Others, including ladybugs, are round. Most beetles are brown, black, or dark red in color. But some have bright, shiny, rainbow colors. The smallest beetles, feather-winged beetles, measure less than 1/50 inch (0.5 millimeter) long. One of the largest beetles is the Goliath beetle of Africa. It grows about 5 inches (13 centimeters) long and weighs over 1 ½ ounces (42 grams).

Most species of beetles are solitary insects — that is, they live alone and have no family life. The young develop without help from their parents. A few species of beetles are social insects. These beetles spend at least part of their life in family groups.

Beetles have many enemies, including birds, reptiles, and other insects. Most beetles protect themselves from enemies by hiding or by flying away. A few beetles produce bad-smelling chemicals that discourage attackers. Some beetles can bite.

Many beetles are pests because they feed on farm crops, trees, or stored food. But some beetles are helpful to people. For example, ladybugs and certain other beetles save crops by eating insect pests. Other beetles are important because they eat dead plants and animals and thus remove them from the environment.

The bodies of beetles. Like other insects, beetles have a body that is divided into three main parts. These parts are: (1) the head, (2) the thorax, and (3) the abdomen.

The head includes the beetle's mouthparts, eyes, and a pair of antennae. The eyes and antennae are the insect's chief sense organs.

Mouthparts. Beetles have chewing mouthparts. In beetles called weevils, the mouthparts are part of a long snout. A beetle's jaws are called mandibles. A number of beetles have large, pincer like mandibles.

Eyes. Beetles have a compound eye on each side of the head. Each eye consists of a bundle of tiny, light-sensitive lenses. Each lens contributes a small bit of the total image that a beetle sees. Most beetles see motion and colors quite well. A few species are blind.

Antennae vary greatly among beetles. Many beetles have antennae made up of threadlike or beadlike segments. In many of these beetles, the tip segments of the antennae are club-shaped. Some beetles have elbow shaped or featherlike antennae. A beetle's antennae are covered with hairs and special organs that can detect specific odors. Some beetles have special sense organs near the base of the antennae that provide a simple type of hearing. These organs send messages to the brain when certain sounds vibrate the antennae.

The external anatomy of a beetle

The thorax forms the middle of the beetle's body. It consists of three segments, each with a pair of legs. The second and third segments each have a pair of wings.

Legs. Each leg of a beetle has five segments and claws at the end. Most beetles that are fast runners have long, slender legs. Other beetles have short, stout legs, often with flat pads on the bottom. These pads have hundreds of expanded hairs that act like suction cups and enable the beetle to walk upside down on slick surfaces. The legs of digging beetles possess tooth like projections that are used to scrape away soil. Most swimming beetles have flattened hind legs. In some species, these legs are fringed with long hairs to form paddles.

Wings. A beetle's front wings, the elytra, are attached to the second segment of the thorax. The hind wings are attached to the third segment. In most species, the elytra cover the hind wings when the insect is not flying. To fly, a beetle pops open the elytra and holds them upward and outward so it can move its hind wings freely.

The internal anatomy of a beetle. This diagram gives an internal view of a typical female beetle. Included are features of the reproductive, nervous, circulatory, and digestive systems

The abdomen contains the reproductive organs and the chief organs of digestion. It typically consists of 10 segments, though only 5 to 8 segments may be visible. The segments are usually soft on the upper surface where they are covered by the elytra. The undersurface is harder for protection. Each segment of the abdomen has a pair of tiny holes called spiracles. Oxygen enters the beetle's body through the spiracles.