Also known as "long horned grasshoppers" and "bush crickets", the term "katydid" is used mainly in the U.S., Canada, and Australia. The name "katydid" comes from the sound produced by species of the North American genus Pterophylla (literally "winged leaf"). The males of katydids have sound-producing (stridulating) organs located on their front wings which in some species produce sound supposedly like "Katy did, Katy didn't", hence the name. In some species females are also capable of stridulation.

There are about 255 species in North America, but the majority of species live in the tropical regions of the world.

The diet of katydids includes leaves, flowers, bark, and seeds, but many species are exclusively predaceous, feeding on other insects, snails or even small vertebrates.

Subfamilies

Family Prophalangopsidae - Hump-winged grigs
Family Tettigoniidae
- Conocephalinae - Meadow katydids
- Copiphorinae - Coneheaded katydids
- Agraeciinae - Jewel katydids
- Listroscelidinae - Predaceous katydids
- Hetrodinae - Armoured ground katydids
- Bradyporinae - Walking katydids
- Mecopodinae - Sylvan katydids
- Phyllophorinae - Helmet katydids
- Microtettigoniinae - Micro katydids
- Tympanophorinae - Baloon-winged katydids
- Lipotactinae - Big-eyed katydids
- Zaprochilinae - Pollen katydids
- Austrosaginae - Australian katydids
- Phasmodinae - Walking-stick katydids
- Acridoxeninae - Dry leaf katydids
- Ephippigerinae - Saddle-backed katydids
- Meconematinae - Quiet-calling katydids
- Phaneropterinae - False katydids
- Pseudophyllinae - True katydids
- Saginae - Stick katydids
- Tettigoniinae - Shield-backed katydids