How Do Insects Hear?

Insects are the only of all invertebrates which have been proved of being capable of distinguishing sounds. A classic proof is an experiment with crickets, when in one room a chirping male was placed in front of a microphone, and in another room with a speaker — a female. When the microphone was switched on, the female moved to the speaker.

Do not think that the organs of hearing are similar to human ears: they are located not on the insect’s head!

Insect’s eardrum is a thin part of cuticle sensitive to air vibrations. Adjacent to it inside is an extended trachea with nerves coming to it. The sensitive receptors are located either on the trachea or on the eardrum.

In grasshoppers, true crickets, mole crickets these organs are located… on the tibiae of the forelegs, in water bugs and some butterflies — on the chest, in other butterflies, locusts, cicadas — on the abdomen, in some lacewings (Neuroptera or Planipennia) — on the wings.

Sometimes the organs of hearing in insects are represented not by an eardrum, but by other structures sensitive to acoustic vibrations. These are so called chordotonal organs, Johnston's organs, etc. They are present, for example, in mosquitoes on the second segment of antenna.

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It is known that bats have a system of acoustic orientation in flight based on the principle of radar: they emit ultrasonic sounds and perceive their reflections from objects, including flying insects. It was found, however, that some moths hear these sounds and sharply change the direction of flight, once they hear them.