Katydid, a long-horned grasshopper that lives chiefly in trees and shrubs. (The term long-horned refers to the antennae.) The katydid is named for its mating call, "Katydid! Katydidn't!'' The call, in most species made by the male only, is produced by rubbing a scraper on one forewing against the toothed edge of the other forewing.

Katydids commonly grow to be 1 1/2 to 2 1/2 inches (38 to 64 mm) long, but some tropical species exceed 6 inches (15 cm). Many katydids are green and have wings resembling leaves, making them difficult for predators to detect among foliage. Others are gray, tan, brown, or pink. The true katydid, common east of the Rockies in North America, is a leaf-winged katydid. Females of this species also make the characteristic call. The oblong-winged katydid has narrower wings, almost uniform in width throughout their length.

Katydids have long, strong hind legs, and four wings that are folded lengthwise when at rest. The wings are filmy and extend far beyond the body. The insects hear through organs, called tympana, located on the forelegs. In most species, the female has a long, sword-shaped ovipositor, an organ on the rear end of the abdomen, used for depositing eggs. In the angular-winged katydid the ovipositor is short and curves upward.

Katydids eat the leaves of trees and shrubs but seldom do much harm. In early fall the females lay eggs on leaves or twigs, or deposit them in crevices in bark, or in slits made in leaf edges with the ovipositor. In spring the eggs produce nymphs that resemble the parents except for size and lack of wings. The nymphs molt, or shed their coverings, several times as they grow. The insects mature in late summer.

Katydids belong to the family Tettigoniidae of the order Orthoptera. The true katydid is Pterophylla camellifolia oblong-winged, Amblycorypha oblongifolia; angular-winged, Microcentrum retinerve.