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Insects are invertebrates in the class Insecta, which contains 28 living orders. The animals that make up this class have a number of distinctive features. Their adult bodies are typically divided into three parts, known as the head, thorax, and abdomen. In addition, they have three pairs of segmented legs attached to the thorax and one pair of antennae. Members of the subclass Pterygota have two pairs of wings as adults. By contrast, some relatively primitive members of the subclass Apterygota are wingless.

Taxonomists (scientists who classify organisms) have recognized more than one million species of insects, more than any other group of organisms. In addition, scientists believe that tens of millions of species of insects remain undiscovered. Currently,...