phylum class subclass • order monotypic order suborder family
The hemiptera are divided into four smaller groups based on their physical features. These groups include aphids, mealybugs, and scale insects; cicadas and hoppers; moss bugs; and true bugs. The relationships of whiteflies are uncertain, and they are sometimes included with aphids or hoppers.
Hemipterans are extremely variable in form, ranging from long, slender, and sticklike, to short and round, to very flat. The bodies of female scale insects are completely covered by a waxy shield. They don't even look like insects. Still other species are partially or completely covered in protective secretions of white wax that resemble dust, cotton, or feathers. The wax hides their bodies from predators and helps to seal in moisture. Hemipterans range in size from 0.03 to 4.3 inches (0.8 to 110 millimeters) in length. Their bodies come in a wide variety of bright or dull colors and patterns, and some species are virtually clear or colorless.
They have strawlike mouthparts for piercing plant or animal tissues and sucking out plant sap or body fluids. The mouthparts of most true bugs are long and flexible and are usually brought forward while feeding. The short, bristlelike mouthparts of all other hemipterans are permanently pointed backward toward the front pair of legs. In fact, the mouthparts of aphids, whiteflies, scales, and their relatives are actually attached between the front pair of legs. The antennae (an-TEH-nee), or sense organs, of all true bugs living on land are long and easy to see, but those of aquatic species and other hemipterans are usually short and bristlelike. Compound eyes, or eyes with multiple lenses, are usually present in most hemipterans; some species also have simple eyes, or eyes with only one lens.
Most adult hemipterans have four wings, but some species are wingless. The forewings of true bugs are thick and leathery at the base, but thin and membranelike toward the tip. The wings of true bugs are also folded flat over the back to form an 'X' pattern. The forewings of other hemipterans are entirely clear and membranelike or colored and slightly thickened. In many of these species, such as aphids and cicadas, all four wings have the same texture. Their wings are usually folded like a roof over the body with a single line running down the back. The legs of most hemipterans are especially fitted, or adapted for walking, running, jumping, swimming, or skating on water, grasping prey, or digging. In some species, such as scale insects and whitefly larvae (LAR-vee), the legs are greatly reduced in size or entirely absent.
The larvae of true bugs, or young of animals that must change form before becoming adults, are usually similar in appearance to the adults but are smaller and lack fully developed wings. However, the larvae of some hemipterans are very different from the adults. For example, adult whiteflies are slender with long legs, but their larvae are broad, flat, and lack legs.
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