Insects in the family Tettigoniidae are commonly called katydids (especially in North America),[1] or bush crickets.[2] They have previously been known as "long-horned grasshoppers".[3] More than 8,000 species are known.[1] Part of the suborder Ensifera, the Tettigoniidae are the only extant (living) family in the superfamily Tettigonioidea.
They are primarily nocturnal in habit with strident mating calls. Many species exhibit mimicry and camouflage, commonly with shapes and colors similar to leaves.[4]
The family name Tettigoniidae is derived from the genus Tettigonia, first described by Carl Linnaeus in 1758. In Latin tettigonia means a kind of small cicada, leafhopper;[5] it is from the Greek τεττιγόνιον tettigonion, the diminutive of the imitative (onomatopoeic) τέττιξ, tettix, cicada.[6][7] All of these names such as tettix with repeated sounds are onomatopoeic, imitating the stridulation of these insects.[8] The common name katydid is also onomatopoeic and comes from the particularly loud, three-pulsed song, often rendered "ka-ty-did", of the nominate subspecies of the North American Pterophylla camellifolia, belonging to the subfamily Pseudophyllinae, which are known as "true katydids".[9][10]
Tettigoniids range in size from as small as 5 mm (0.20 in) to as large as 130 mm (5.1 in).[11] The smaller species typically live in drier or more stressful habitats which may lead to their small size. The small size is associated with greater agility, faster development, and lower nutritional needs. Tettigoniids are tree-living insects that are most commonly heard at night during summer and early fall.[12] Tettigoniids may be distinguished from the grasshopper by the length of their filamentous antennae, which may exceed their own body length, while grasshoppers' antennae are always relatively short and thickened.
Eggs are typically oval and may be attached in rows to plants. Where the eggs are deposited relates to the way the ovipositor is formed. It consists of up to three pairs of appendages formed to transmit the egg, to make a place for it, and place it properly. Tettigoniids have either sickle-shaped ovipositors which typically lay eggs in dead or living plant matter, or uniform long ovipositors which lay eggs in grass stems. When tettigoniids hatch, the nymphs often look like small, wingless versions of the adults, but in some species, the nymphs look nothing at all like the adult and rather mimic other species such as ants, spiders and assassin bugs, or flowers, to prevent predation. The nymphs remain in a mimic state only until they are large enough to escape predation. Once they complete their last molt (after about 5 successful molts), they are then prepared to mate.[12]
Tettigoniids are found on every continent except Antarctica.[13] The vast majority of katydid species live in the tropical regions of the world.[4] For example, the Amazon basin rain forest is home to over 2,000 species of katydids.[4] However, katydids are found in the cool, dry temperate regions, as well, with about 255 species in North America.