Any winged insect showing hemimetabolous development, i.e. the eggs hatch into young (called nymphs) that resemble the adults but lack wings; these develop gradually and externally in a series of stages (instars) until the final moult produces the adult insect. There is no pupal stage and metamorphosis is described as incomplete. Exopterygote insects include the mayflies (Ephemeroptera), dragonflies (Odonata), grasshoppers (Orthoptera), and bugs (Hemiptera). Compare endopterygote.