W. S. Romoser
The order Hemiptera (from the Greek hemi, "half," and ptera, "wings") comprises about 25,000 species of true bugs. They have mouthparts adapted to piercing and sucking, and most have two pairs of wings. The basal half of the forewings, or hemelytra, is leathery, and the remaining half is membranous; the hind wings are also membranous. The antennae are four- or five-segmented and in some species are hidden. Body lengths range from about 2 to 100 mm (0.08 to 4 in). Larvae resemble small, wingless adults. The order was called Heteroptera in some older classifications.
Hemiptera are commonly divided into three groups: aquatic bugs, such as backswimmers, giant water bugs, and water boatmen; semiaquatic, or shore-inhabiting, bugs, such as water striders; and terrestrial bugs, such as assassin bugs, bedbugs, and stinkbugs.
Many bugs emit disagreeable odors from scent glands when disturbed. A large number are able to produce sounds by rubbing certain body parts together. Feeding habits include sucking the juices of plants and of other arthropods, and many bugs are serious pests of domestic plants. A few feed on the blood of various vertebrates, including humans. Several species of triatomid bugs are vectors of Trypanosoma cruzi, a protozoan that causes Chagas' disease in humans in Central and South America.