Praying mantises are widely recognized insects, known for their predatory stance and camouflage, and are generally regarded as silent creatures. While they do not communicate with song or chatter, mantises can produce audible sounds under specific, high-stress circumstances. These noises are not a form of communication with other mantises but are a powerful defensive measure aimed at larger threats.
The Sounds They Produce
Mantises, particularly larger, winged adults, create noise using two distinct physical mechanisms. One common sound is a noticeable hiss, generated by forcibly expelling air from their respiratory openings, known as spiracles, located along the sides of the abdomen. This forced exhalation requires the mantis to visibly compress its abdomen, resulting in a sound that is quiet but distinct at close range.
The more complex sound is stridulation, a rasping or crinkling noise often described as a hiss. This sound is produced via an abdominoalary mechanism, involving the abdomen and the wings. When threatened, the mantis rapidly moves its metathoracic wings, rubbing specialized structures against the abdomen.
The mechanical components for this noise involve microscopic teeth found on the longitudinal veins of the hindwings. These teeth are scraped over a series of small, peg-like structures located on the abdominal pleura. This action creates a nonresonant, broadband sound that typically features a peak frequency range between 8 and 12 kilohertz. The resulting acoustic output is relatively low in intensity but is sudden and loud enough to be effective at a short range.
The Purpose of Mantis Noise
The sounds a praying mantis produces serve a singular, non-social function: defense. This behavior is a form of secondary defense, deployed only after the insect’s primary strategy of crypsis (camouflage) has failed and a predator is already engaging. The noise is a component of a larger threat display known as deimatic behavior.
The deimatic display is a multimodal event that combines visual and acoustic elements to startle or intimidate a threat. The mantis suddenly raises its body, spreads its raptorial forelegs, and flashes the bright colors or distinct patterns on its hindwings. The sudden, unexpected noise—either a hiss of expelled air or the crinkling stridulation—accompanies this visual transformation.
The purpose of this loud, abrupt noise is to activate a predator’s innate startle response. By combining a sudden visual flash with an unexpected sound, the mantis aims to momentarily confuse or delay the attacker, increasing its chance to escape. Since mantises lack chemical defenses, this bluffing strategy works by making the insect appear larger, more dangerous, or too surprising to be worth the effort.
How Mantises Detect Sound
Despite their ability to produce defensive sound, the mantis’s hearing apparatus is not designed to detect general environmental noise or the sounds of its own species. Most praying mantis species possess a single, specialized auditory organ, or ear, which is unique in the insect world. This single tympanal organ is located on the ventral midline of the body, situated in a deep groove between the metathoracic legs.
The primary function of this solitary ear is not to listen for mates or rivals, but to detect a specific, high-frequency danger. The organ is acutely tuned to ultrasonic frequencies, often exceeding 20 kilohertz, which is above the range of human hearing. This adaptation allows the mantis to intercept the echolocation calls emitted by hunting bats, their main nocturnal predator.
Upon hearing a bat’s ultrasonic pulse, a flying mantis can execute an evasive power dive or a sudden turn to avoid capture. This specialized hearing system is a textbook example of an evolutionary arms race, where a prey species develops a sensory tool to counter a predator’s hunting strategy. Thus, the mantis’s ear is a dedicated survival tool, not a general-purpose listening device.