The word bug is often used to refer to any insect and sometimes even to spiders, which are not insects. Originally a term that meant a hobgoblin or scarecrow, bug had, by the early 1600s, metamorphosed into a term used to describe any of various insects or similar organisms, such as the centipede. But in strict biological usage, a bug (or true bug) is an insect having mouthparts that are adapted for piercing and sucking and are contained in a beak-shaped structure called a rostrum. Thus, an aphid, a leaf bug, and a stink bug are classified as bugs. All insects, including bugs, have six legs and a body divided into three sections—head, thorax, and abdomen. In fact, insect derives from Latin insectum, which is itself a translation of Greek entomon, “segmented, cut up,” the source of our word entomology, “the study of insects.” Spiders, on the other hand, belong to a group called arachnids and are characterized by having eight legs and two body sections—a cephalothorax consisting of a combined head and thorax and an abdomen.
