Insecta In*sec"ta, n. pl. [NL. See Insect.] 1. (Zo["o]l.) One of the classes of Arthropoda, including those that have one pair of antenn[ae], three pairs of mouth organs, and breathe air by means of trache[ae], opening by spiracles along the sides of the body. In this sense it includes the Hexapoda, or six-legged insects and the Myriapoda, with numerous legs. See Insect, n. 2. (Zo["o]l.) In a more restricted sense, the Hexapoda alone. See Hexapoda. 3. (Zo["o]l.) In the most general sense, the Hexapoda, Myriapoda, and Arachnoidea, combined. Note: The typical Insecta, or hexapod insects, are divided into several orders, viz.: Hymenoptera, as the bees and ants; Diptera, as the common flies and gnats; Aphaniptera, or fleas; Lepidoptera, or moths and butterflies; Neuroptera, as the ant-lions and hellgamite; Coleoptera, or beetles; Hemiptera, as bugs, lice, aphids; Orthoptera, as grasshoppers and cockroaches; Pseudoneuroptera, as the dragon flies and termites; Euplexoptera, or earwings; Thysanura, as the springtails, podura, and lepisma. See these words in the Vocabulary.