Ultrasonic signals in the defense and courtship ofEuchaetes egle Drury andE. bolteri Stretch (Lepidoptera: Arctiidae)

Euchaetes egle Drury andE. bolteri Stretch produce ultrasound using paired thoracic tymbal organs in both defensive and sexual contexts. The defensive ultrasound produced in response to tactile stimulation is fully characterized. The sounds are sexually monomorphic and species specific in the number of sound pulses produced during each flexion and relaxation of the tymbal, peak frequency, peak intensity, and duration of the interval between flexion and relaxation. Ultrasonic signals play a role in the courtship of both species. Males produce ultrasound just prior to contact with females, and it is shown to be important to courtship success inE. egle. Ultrasonic courtship communication is mapped on a recently proposed cladogram for the family Arctiidae. The use of ultrasound in courtship has evolved on at least three occasions within the family.