When I was a student of zoology at university, we used to jangle our keys and watch as a moth would suddenly plunge to the ground. No surprise that moths would respond to sound, but what they are really responding to is the greatest threat to a moth. It is the sound we cannot hear - the sound of a bat.
Emitting tiny pulses of ultrasound, bats use radar - echolocation - to 'see' where they are flying and to detect their prey - moths. But in evolution, moths have fought back in the acoustic war. It is a battle as intense and vital as the Battle of Britain in World War 2. Moths can avoid the bat's radar.
|photo courtesy of Emiko Peterson Yoon|
This a war in the sky, a battle of life and death. But all is fair in love and war, and some moths also make love with the sound they make.
Recent studies of moth sound communication reveal that using close-range contact, with low-intensity ultrasound male moths 'whisper' sweet nothings during their courtship with a possible mate. So, a male moth sings a love song - love me tender.
Sexual sound communication in moths may apply to many eared-moths, perhaps even a majority. The low intensities and high frequencies explain why this was overlooked for so long. In nature, our bias leans towards what humans can sense when studying communication in animals. But there is more to a click than meets the...ear. A click can warn, engage, communicate, avoid, confuse, and in the dark, it can be a matter of life or death.
Ray Noble is a Chartered Biologist and Fellow of the Royal Society of Biology.