A Cracker Butterfly. Rather than a chemical defence, these butterflies rely on camouflage. But it doesn't always work, and Rufous-tailed Jacamars have been recorded taking them (also see below for the butterfly-munching habits of the Jacamar) (c) Richard Brown
Cracker Butterflies are named after their curious ability to crack their wings, a sound audible to humans and used by the butterflies in territorial defence and to startle potential predators. It is thought that the sound is created when veins in the forewing meet at a speed of about 1420mm/sec! A neighbouring vein possibly acts as a resonating chamber to increase the volume of the click.
All Cracker Butterflies rest with their heads pointing downwards. They select trees with bark matching their wing colour and then use these trees as courting territories. Males typically perch on between one and four trees daily, from which they click to attract a mate.