Country diary: The sound of a dragonfly is a 300m-year-old whisper | Paul Evans

The Marches, Shropshire: It's almost inaudible to us, but it's there, a gentle turbulence with a percussive clicking, ancient and electricBrrrrr, like pegs on bicycle wheels down a street far yet near, a female southern hawker dragonfly sets up a resonance from a whir of wings. Each of the four wings moves independently by the expansion and contraction of the four wing muscles on the thorax, going at 30 to 50 cycles a second and a top speed of 45mph, faster than traffic on the street. Up, down, forwards, backwards, she can turn instantly in six directions. There are 720 permutations, but if the order depends on the dragonfly's intentions, there are 1,958 possible combinations for the six directions of flight.Every movement changes the sound in this space. Each muscle-wing cycle propelling the dragonfly through the air causes turbulence, together with percussive clicking against other wings in a stridulation of ancient insect music. This is composed of individual sounds and their effects that are almost inaudible to us unless digitally modified. Recorded dragonfly flight bears a similar signature to birdsong or speech, clusters of sounds separated by pauses, like breaths between vocalisations where there is a short glide of the wings. Continue reading...