James H. Fullard
Dept. of Zoology, Erindale College, Univ. of Toronto, 3359 Mississauga Rd., Mississauga, ON L5L 1C6, Canada
Certain tiger moths (Arctiidae) generate trains of high-frequency clicks from specialized structures (tymbals) on their thorax. Although social functions for the sounds have been demonstrated, debate continues on their anti-bat defensive role with aposematism, startle, and/or echolocation disruption being offered as to how the sounds operate. The controversy arises primarily from the near impossibility of observing natural, in-flight behavior of moths and hunting bats. As a result, most of the experiments attempting to explain the sounds have used indirect methods to infer their actions. These studies include examinations of the structure of the sounds, stimulation of stationary moths with artificial bats, and stimulation of trained, laboratory bats with artificial moths. Other laboratories have attempted to exploit the foraging behavior of wild bats in controlled conditions. These studies have not yet satisfactorily explained why arctiids talk but one observation that has become clear is that the defenses of tiger moths, as with most animals, are directed against a variety of predators and that single explanations do not exist for complex behaviors.