Any of very numerous, mostly small arthropods of the class Insecta, having six segmented legs in the adult stage and a body divided into three parts (the head, thorax, and abdomen). The head has a pair of antennae and the thorax usually has one or two pairs of wings. Most insects undergo substantial change in form during development from the young to the adult stage. More than 800,000 species are known, most of them beetles. Other insects include flies, bees, ants, grasshoppers, butterflies, cockroaches, aphids, and silverfish. See Notes at
biomass, bug, entomology.