An audible click occurs when froghoppers jump. An audible click occurs when froghoppers jump. (A) During a free jump, a click occurred at the time of take-off. Images were captured at 1000 s-1. A cartoon of a froghopper is shown in the first frame to clarify the images. (B) Aphrophora was fixed ventral surface uppermost in Plasticene™ and with a microphone 5 mm from the right hind leg. Movements of the hind legs were captured at 1000 s-1. The rapid simultaneous movement of both hind legs was accompanied by a click even though the hind legs did not contact anything during their movement. The left image of a ventral view shows the hind legs fully cocked and tucked between the overlying middle legs and the thorax. The right image shows both hind legs fully depressed 1 ms later. (C) Movements of a hind leg were recorded opto-electronically together with the sound, and 10 jump movements by one Aphrophora were superimposed. The first sound occurred only 0.05 ms after the start of the movement. Malcolm Burrows J Exp Biol 2006;209:4622-4637 © The Company of Biologists Limited 2006