Katydid

Insects in the cricket family Tettigoniidae are commonly called katydids or bush crickets. There are more than 6,400 species. They are also known as long-horned grasshoppers, to distinguish them from the Caelifera, the true or short-horned grasshoppers. Part of the suborder Ensifera, it is the only family in the superfamily Tettigonioidea.
Primarily nocturnal in habit, with strident mating calls, many katydids exhibit mimicry and camouflage, commonly with shapes and colors similar to leaves. - from Wikipedia