Small Brains, Smart Solutions: Tree Crickets make Optimal Acoustic Aids
Many insects use sound for finding mates. The louder the insect’s advertisement call, the further it travels and the more potential mates it can reach. Only one insect, the tree cricket, modifies and uses an external object called a baffle to make its sound louder. Baffles are made by cutting a hole near the centre of a leaf. They then call from inside this hole, with their wings flat against the leaf surface. Baffles reduce acoustic short-circuiting, and make the cricket sound louder. Not all baffles work equally well though, and Mhatre et al investigated if male tree-crickets with their tiny brains know how to make the best possible baffles. First they figured out what the best possible baffle was. They measured the wing vibrations and sounds of real tree crickets, and used them to simulate a cricket singing from different kinds of baffles. From their simulations, three simple rules emerged that lead to the best baffle: use the largest available leaf, make a hole the size of the wings, and place it at the centre of the leaf. Next, they put the crickets to the test. When offered a choice between two leaves, the tree crickets followed all the rules and produced the best possible baffle: they always picked the larger leaf, made a perfectly sized hole and placed it close to the centre. The discovery that tree-crickets can optimize the acoustics of baffles reveals the underappreciated abilities of insects in manipulating and using external objects as tools.
