Moths that produce ultrasonic clicks to jam bat echolocation. Some click to startle; others create acoustic 'smoke screens' that make them invisible to sonar.
The acoustic arms race
For millions of years, the night sky has been a battlefield. In this darkness, insect-eating bats are apex predators, using sophisticated biological sonar—echolocation—to find their prey. But their prey is not defenseless. Many nocturnal insects, especially moths, have evolved ears that detect the ultrasonic cries of bats, triggering evasive dives and spirals. Some species do not just listen; they talk back.
Tiger moths (subfamily Arctiinae) have developed an extraordinary countermeasure; they produce their own ultrasonic clicks to combat bat attacks. This interaction is a 65-million-year-old arms race between predator and prey. The coordinates for this point of interest are near Wake Forest University, where researchers like William Conner have conducted significant studies into this acoustic warfare. In a specially designed "bat cave" laboratory, scientists used high-speed infrared cameras and ultrasonic microphones to record the life-or-death struggles between bats and moths, showing the details of this sonic battle.
Jamming the signal
Moths generate their defensive sounds using specialized structures called tymbals. These are corrugated plates of exoskeleton on the thorax that buckle when flexed by muscles, producing a rapid series of clicks, much like a toy clicker. The sounds serve several purposes. For some species that are toxic, the clicks act as an acoustic aposematic signal—a warning that tells the bat, "I taste bad." Bats can learn to associate the sound with an unpleasant meal and avoid those moths in the future.
One species, Grote's bertholdia (Bertholdia trigona), has taken this defense to a new level. It produces clicks at an astonishing rate, up to 4,500 times per second, which is about ten times faster than most other sound-producing moths. This high-density barrage of sound actively jams the bat's sonar. The clicks create an acoustic "smokescreen," interfering with the returning echoes the bat needs to pinpoint its target. The bat knows a moth is nearby but cannot determine its precise location, causing it to miss its attack. Experiments have shown this defense is immediately effective, even on bats that have never encountered a clicking moth before. When the tymbal organs of a Bertholdia trigona are removed, its survival rate against bat attacks plummets. This shows that the clicks are a warning and a direct technological interference.
💡Fun Facts
The tiger moth *Bertholdia trigona* can produce up to 4,500 ultrasonic clicks per second to jam bat sonar.
The sound-producing tymbal organs are located on the moth's thorax and buckle inward and outward like a spring to create clicks.
Not all moth clicks are for jamming; many toxic species use slower clicks as a warning signal, a behavior known as acoustic aposematism.
This acoustic arms race has been ongoing for over 65 million years, leading to multiple independent evolutions of sound production in moths.
The natural habitat for this phenomenon is accessible anytime, but moth and bat activity occurs after dusk. Nearby Pilot Mountain State Park is open daily from 7 AM to 9 PM (spring/summer).
Admission
Free
Accessibility
The park has paved parking lots and some accessible trails. Much of the terrain is natural and can be uneven.