Saturniid moths can’t hear. Down the evolutionary pike one stop, whistling moths hear well enough. The adaptation arose from a change in lifestyle.
Saturniid moths have the same receptors as whistling moths but they use them to align of body parts, to help adjust the moth’s spatial positioning.
There is a slight thinning of the cuticle over the receptors that changes the appreciation of internal vibrations in saturniid moths to the ability to hear in whistling moths. Male whistling moths rub their knobbed wings together to make a racket of loud ultrasonic pulses. Whistling moths use such signals to stake territory and attract females.