How do insects hear?

CrowdScience listener Lauren from Belgium has complete hearing loss in one ear because all of the sensory hair cells in her inner ear have died. This got her thinking about how complicated the human ear is, with its bones, hairs and fluid all contributing to the sound that allows you to listen to CrowdScience. That, in turn, led to Lauren wondering how other animals hear, especially insects. Do they even have ears?

Presenter Caroline Steel hears Lauren’s call and sets off on a hunt for insect ears. It turns out that you can find them in all sorts of place on the insect body – they just need an air cavity with a membrane across it. The scientist Ronald Hoy jokes that it was his laboratory’s goal to find ‘an ear a year’ - a new insect ear in a different place every year. The bush cricket known as ‘katydid’ has an ear in its forelegs, while the praying mantis keeps an ear right next to its genitals.

There are a vast range of ears in the insect world too, ears that have evolved at least nineteen separate times. Some have a device like a human cochlea that allows the insect to distinguish different frequencies, while others can’t technically ‘hear’ at all, but use vibrations to recognise predators and mates. Which leads Caroline to wonder: when does hearing actually become hearing?