Beetle Sounds: How They’re Made and What They Mean

Often perceived as silent insects, a surprising number of beetle species have developed the ability to produce a wide range of sounds. These acoustic signals are not random noises but are purposeful. They are integral to how these creatures navigate the challenges of survival, from finding a partner to avoiding becoming a meal.

How Beetles Create Sounds

The most common method beetles use for sound production is stridulation, the act of rubbing two body parts together. One specialized body part, known as the “scraper,” is moved across a finely ridged surface called the “file.” The specific body parts involved vary widely across beetle families. For instance, some rub their abdomen against their wing covers, while others scrape a part of their head against their thorax.

Beyond stridulation, beetles employ other acoustic mechanisms. Some species that live in wood or leaf litter use percussion, which involves tapping or drumming a part of their body against the substrate. This action sends vibrations through the material, creating a distinct signal that other beetles can detect.

Another method is the click mechanism, which involves a unique hinge-like structure in the thorax. When a prosternal spine is released from a socket, it generates a powerful click sound and a sudden jump. A less common method is the forcible expulsion of air or fluid, which can create hissing or popping sounds used for defense.

Purposes of Beetle Sounds

One of the primary purposes of beetle sounds is mate attraction. Males often produce specific calls to advertise their presence to potential female partners over a distance. A receptive female may respond with her own sounds, allowing the male to locate her. This acoustic back-and-forth is a form of courtship.

Sound is also a defensive tool. A sudden, unexpected noise can startle a potential predator, creating a brief window for the beetle to escape. Some species produce distinct distress calls when captured, which can be a last-ditch effort to surprise their attacker into releasing them. These defensive sounds are a direct response to a threat.

In some social species, such as bark beetles, sound facilitates group coordination. When a female beetle finds a suitable host tree, she may stridulate while also releasing chemical signals called pheromones. The combination of sound and scent attracts a large number of other beetles to the location. This allows them to launch a mass attack that can overwhelm the tree’s natural defenses.

Notable Sound-Producing Beetles

The Deathwatch Beetle creates a tapping sound by rhythmically banging its head against the wooden surfaces of its habitat. This percussive sound is a mating call, not an omen of death as folklore suggests. A male initiates a series of 4 to 11 taps, and a receptive female taps back, allowing the male to pinpoint her location. The association with death arose because the sounds were most audible in the quiet of old homes where people kept vigil over the sick.

Click beetles are named for their signature sound. When threatened or placed on its back, the beetle uses a specialized spine and groove mechanism in its thorax to snap its body, producing a loud click. This action launches the beetle into the air, helping it to right itself if overturned or to startle a predator. The sound is a byproduct of this rapid release of stored energy.

Longhorn beetles produce audible squeaking or rasping sounds when handled through stridulation. They generate this noise by rubbing the rear margin of their prothorax against a ridged plate on their mesonotum (the middle section of their thorax). This sound is a defensive signal, produced as a distress call when the beetle is grabbed or feels threatened. The sudden, grating noise can cause a predator to hesitate or release the beetle.