katydid (n.) Look up katydid at Dictionary.com
insect of the locust family (Microsentrum rhombifolium), 1784, American English (perhaps first used by John Bartram), imitative of the stridulous sound the male makes when it rubs its front wings together. The sound itself is more accurately transcribed from 1751 as catedidist.
[T]heir noise is loud and incessant, one perpetually and regularly answering the other in notes exactly similar to the words Katy did, or Katy Katy did, repeated by one, and another immediately bawls out Katy didn't, or Katy Katy didn't. In this loud clamour they continue without ceasing until the fall of the leaf, when they totally disappear. [J.F.D. Smyth, "A Tour in the United States of America," 1784]