any of approximately 6,000 species of insects (order Orthoptera) that include the katydid, meadow grasshopper, cone-headed grasshopper, and shield-backed katydid. All members of this family, with the exception of the shield-backed grasshopper, are green in colour, have long wings, and inhabit trees, bushes, or shrubs. The shield-backed grasshopper subfamily, which includes the Mormon and coulee crickets, is brown or gray in colour and lives on the ground or in low vegetation. Most species are wingless or have reduced wings.

Tettigoniids are distinguished by having the hearing organs (tympanum) located on the front legs, hairlike antennae that are as long as or longer in length than the body, a sword-shaped ovipositor (in females) for laying eggs, and wing covers that differ in shape. When the male rubs his wing covers together, he produces a song that is used to attract females. Each species has its own characteristic song. Most long-horned grasshoppers spend the winter in the egg stage.