This tiny predatory insect, Arachnoscelis, has the highest carrier presently known for any insect sound signal. One probable reason for these ultrasonics is avoidance of bat predators which, as they hunt, use the katydid s song to reveal his location. Ultra-high ultrasonics don t travel far from the singer and so reduce his vulnerability to an eavesdropping bat. But of course this also makes it harder for the katydid female to hear. Currently, Professor Morris is attempting to relate the carrier frequencies of different katydid species to the structure of their ears.
Katydids listen with twice as many eardrums as humans, located out on the front legs.
He is now collecting representative species from Ecuador, chosen for their different carrier frequencies and to examine how the structure of their ears relates to carrier. In the future Glenn and his colleagues will make scale models and test empirically how the internal tube network of each species responds to sounds of different pitch. From this may come new theoretical insights into the conductivity of sound by miniaturized devices.