How many legs does an adult insect have?

An adult insect has six legs, arranged as three pairs on its thorax.

This three-pair arrangement is one of the defining features of insects, which belong to the arthropod class Insecta. Their body is divided into a head, thorax, and abdomen, and each thoracic segment bears one pair of jointed legs. The legs may be radically specialized: grasshoppers jump, bees collect pollen, and water striders skim across water.

The common mix-up is with spiders and other arachnids, which typically have eight legs and lack antennae. Caterpillars can also appear to have more than six legs because they possess soft abdominal prolegs, but only the three thoracic pairs are true insect legs. In the adult stage, those six legs remain the standard pattern, although rare evolutionary exceptions involve legs becoming reduced or vestigial.

The word “hexapod,” meaning six-footed, reflects this basic insect body plan. Along with jointed legs, insects commonly have antennae, a chitinous exoskeleton, and—when winged—up to two pairs of wings attached to the thorax.