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"...in the family Tettigoniidae, the Long-horned Grasshoppers and Katydids. In order to belong to this club, your antennae have to be as long as or longer than your body... Male Katydids are all about sound (in some species, the females answer, but not loudly). And if their hind set of wings is dedicated to flight, their front pair was made for song. This they accomplish by stridulation (friction), rubbing the rigid edge of one forewing against a comb-like “file” on the other. What they produce may not sound like the classic “katy-did, katy didn’t;” that song is limited to a single genus of True Katydids. Fork-tailed Bush Katydids are the best singers of the “false katydids”, with a repertoire of clicks and buzzes. Because those who produce sound must be able to hear it, katydids have a slit-like ear (tympana) on each front leg. To pick up sound, they raise a leg in a gesture that is reminiscent of humans cupping their hand behind an ear.
Hubbell says that Katydids challenge us to reevaluate our concept of “sound,” because in addition to the clicks and buzzes, some kinds of katydids have an ultra-ultrasonic call, while others produce, by thumping/stamping on twigs in species-specific tempos, vibrations that are detected by other katydids. For many insects there is no line between “heard” and “felt,” and the vocabulary of our sensory experience may be inadequate to express theirs."