Katydid n. : A large, green, arboreal, orthopterous insect (Cyrtophyllus concavus) of the family Locustidae, common in the United States. The males have stridulating organs at the bases of the front wings. During the summer and autumn, in the evening, the males make a peculiar, loud, shrill sound, resembling the combination Katy-did, whence the name.

Example:
How do I keep a Katydid alive all Winter?

Taxonomy
katydid, cricket, species, family Tettigoniidae, nymph, free encyclopedia, suborder, superfamily, Tettigonioidea, antennae, females, Australia, green bush, leaf, long-horned grasshoppers, insects, search, Fossil range.

Defination from the web:
katydids or bush crickets, and their classification, with a small photograph gallery. ... The family Tettigoniidae, known in American English as katydids and in British English as bush-crickets, contains more than 6,400 species. ...