Doesn't look like the Spanish Armada to me, still....

Did ya know Katy Didd was a folkie?

"Night-time in a tropical rainforest, and lonely male Arachnoscelis katydids make their presence known with a burst of intense sound. You won't hear it, though, because they produce the highest-frequency ultrasound of any known insect.

Members of the cricket and grasshopper family are famous for their ability to sing, and most emit chirps at frequencies humans can hear. Some katydids produce ultrasonic chirps by rubbing their forewings together, pushing a scraper on one wing across a series of pegs on the other. This won't do for Arachnoscelis species, though. Fernando Montealegre-Z and Glenn Morris from the University of Toronto in Canada discovered that they chirp at 130 kilohertz, which is too high a frequency to be generated by merely rubbing the wings together.

The researchers collected the katydids from the Colombian rainforest, and as well as measuring their chirps they looked at their wings with an electron microscope. This revealed that as the wings rub against each other, the scraper wedges itself behind one of the pegs and distorts. When released, it springs back into shape, emitting a pulse of ultrasound (Journal of Experimental Biology, vol 209, p 4923).

"By using elastic energy, the animal saves metabolic energy, as the muscles do not contract at an almost impossible speed," says Montealegre-Z."

There ya go!

A