Orthoptera (crickets, grasshoppers, locusts; class Insecta, subclass Pterygota) Order of medium to large, terrestrial insects, whose major diagnostic features include hind legs that are usually modified for jumping (saltatorial), and a pronotum with large, external flanges. Orthopterans are exopterygote, and the external wing buds reverse their orientation in later instars. The fore wings are modified as tegmina. Wings are reduced or absent in some members of all the larger families. Stridulation is commonly exhibited, with the mechanisms involved and the nature of the sounds produced varying widely. Many species live in association with plants, while others are found on the ground among debris, or under rocks. A number of groups burrow in the ground, and some are cave-dwelling. One family even lives in ant nests. Orthopterans may be nocturnal or diurnal, cryptically or brightly coloured, solitary or gregarious. Most species are herbivorous, but some are omnivorous, and a few are predacious. There are more than 20 000 species, some of economic significance.

Orthoptera A large order of exopterygote insects containing the grasshoppers, locusts, crickets, and – in some classification systems – the cockroaches (see Dictyoptera). They are characterized by enlarged hind legs modified for jumping and biting mouthparts and produce sounds by stridulation. The crickets and long-horned grasshoppers (e.g. Gryllus, Tettigonia) have long threadlike antennae and stridulate by rubbing together modified veins on their forewings. The hearing organs are on the front legs. The short-horned grasshoppers and locusts (e.g. Chorthippus, Locusta) have short antennae and stridulate by rubbing pegs on the hind leg against a hardened vein on the forewing. The hearing organs are on the abdomen.