Tympanic Organs

in insects, organs of hearing consisting of a tympanic membrane and a set of sensory elements known as chordotonal organs (scolopophores, scolopidia). A more or less widened trachea abuts the tympanic membrane on the inside. The chordotonal organs are attached to the tympanic membrane or to the trachea; they vary in number from two (butterflies) to several dozen (orthopterans) or even hundreds (cicadas). The tympanic organs are situated in the tibiae of the anterior legs in long-horned grasshoppers, crickets, and mole crickets; in the thorax of aquatic true bugs and some butterflies; in the abdomen of some butterflies, locusts, and cicadas; and in the wings of some neuropterons.

Insects use their tympanic organs to receive sound signals from other individuals of their species and the sounds of predators (specifically, the echolocation signals of bats). These receptors react to sounds in a range of 0.2–100 kHz (optimum frequencies 1–40 kHz) in orthopterans, 0.2–20 kHz (optimum frequencies 1–6 kHz) in cicadas, and 1–240 kHz (optimum frequencies 15–60 kHz) in lepidopterans.