Dozens of insect species produce clicking sounds, and they do it for reasons ranging from self-defense and mate attraction to simply flipping themselves right-side up. Click beetles, tiger moths, cicadas, deathwatch beetles, cracker butterflies, certain grasshoppers, water boatmen, assassin bugs, and even some caterpillars all generate clicks, each using a different body part and a different physical trick. The variety is striking: a moth clicks ultrasonically to scramble a bat’s sonar, while a tiny aquatic bug clicks underwater loud enough that a person standing on the riverbank can hear it. What unites them is that clicking is cheap, fast, and effective across wildly different ecological contexts.
Click Beetles and Their Built-In Catapult
Click beetles (family Elateridae) are the insects most people associate with clicking sounds. Pick one up and it will snap its body with an audible “click,” launching itself into the air. The mechanism is entirely internal: a spine on the beetle’s thorax catches against a lip on the adjacent body segment, building tension like a cocked spring. When the latch releases, the spine slams forward, producing the click and flinging the beetle upward. Researchers have modeled this latch as a flexible beam bending over a ledge, analogous to a snap-fit fastener in engineering. The spine deflects slightly until it clears the lip, then snaps into a braced position that stores elastic energy before explosive release.1Journal of Experimental Biology. Latching of the click beetle (Coleoptera: Elateridae) thoracic hinge enabled by the morphology and mechanics of conformal structures
Why do click beetles click? The popular assumption is that it’s an escape mechanism, but evidence points more strongly toward self-righting. Click beetles are smooth-bodied and have short legs, making it hard for them to flip over if they land on their backs. The jump launches them nearly vertically each time, and researchers have argued that a dedicated escape jump would more likely send the beetle at a shallow angle to maximize distance from a predator. A near-vertical trajectory, by contrast, is exactly what you’d want to get airborne and land on your feet.2PubMed Central. Jumping without Using Legs: The Jump of the Click-Beetles (Elateridae) Is Morphologically Constrained The click itself may have a secondary startle effect on predators, but the jump’s geometry suggests righting is the primary purpose.
Click beetle fossils extend deep into the Cretaceous. Larvae preserved in Burmese amber, roughly 99 million years old, show body plans closely aligned with modern click beetle anatomy, including the flattened body shape and sclerotized thorax associated with the clicking mechanism’s structural requirements.3Scientific Reports. Click beetle larvae from Cretaceous Burmese amber represent an ancient Gondwanan lineage The clicking snap has been around for a very long time.
Tiger Moths That Jam Bat Sonar
Tiger moths (subfamily Arctiinae) produce rapid ultrasonic clicks using a pair of corrugated structures on their thorax called tymbals. When a muscle contracts, these ribbed membranes buckle inward and outward in quick succession, generating a burst of clicks too high-pitched for human ears but squarely within the frequency range bats use for echolocation. The number of ridges on a moth’s tymbal surface strongly predicts how many clicks it can produce per unit time, with more ridges yielding faster click trains.4PubMed Central. Characteristics of tiger moth (Erebidae: Arctiinae) anti-bat sounds can be predicted from tymbal morphology
These clicks serve at least three distinct anti-bat functions, and which one dominates depends on the moth species and context. Some toxic tiger moths click to warn bats that they taste terrible, functioning as an acoustic version of bright warning coloration. Bats learn to associate the clicks with a bad meal and eventually leave those moths alone. Other moths that are perfectly edible have evolved to mimic those warning clicks, freeloading off the toxic species’ reputation.
The third and most dramatic function is active sonar jamming. The palatable tiger moth Bertholdia trigona produces ultrasonic clicks that interfere directly with the echolocation signals bats use to pinpoint prey during their final attack dive.5PubMed. Tiger moth jams bat sonar Critically, the timing matters: the dogbane tiger moth Cycnia tenera does not respond to a bat’s initial approach calls but waits until the bat enters its terminal attack phase before firing off clicks, suggesting the moth is injecting phantom echoes at the precise moment the bat is trying to lock on.6PubMed. Jamming bat echolocation: the dogbane tiger moth Cycnia tenera times its clicks to the terminal attack calls of the big brown bat Eptesicus fuscus
How effective is this? In controlled experiments, the proportion of successful bat captures dropped steadily as the moth’s click duty cycle increased, with bats catching their prey about three-quarters of the time in silence but losing ground with every percentage-point increase in moth clicking.7PubMed Central. High duty cycle moth sounds jam bat echolocation: bats counter with compensatory changes in buzz duration Bats are not helpless against this defense, though. Some bat species have evolved quieter, “stealth” echolocation. Townsend’s big-eared bat approaches moths so quietly that the moths’ sound-detecting ears never trigger their jamming response, resulting in capture success roughly half again as high against sonar-jamming moths compared to louder-echolocating bat species.8Animal Behaviour. Predator counteradaptations: stealth echolocation overcomes insect sonar-jamming and evasive-manoeuvring defences
Cicadas and Their Tymbal Drums
Cicadas are among the loudest insects alive, and their familiar buzzing song is actually a rapid-fire chain of individual clicks. Like tiger moths, cicadas use tymbals, but theirs are larger and backed by a mostly hollow abdomen that acts as a resonating chamber. When the tymbal muscles contract, the ribbed membrane buckles inward starting at one end and rolling sequentially across each rib. Each rib buckling produces a distinct click. When the muscles relax, the membrane snaps back in the reverse direction, generating another chain of clicks.9PubMed Central. The tymbal of a cicada: nature’s sound-generating metastructure In some species, such as the bladder cicada Cystosoma saundersii, a single tymbal collapse produces two separate sound pulses as different groups of ribs buckle in succession, with the enlarged air-filled abdomen radiating the sound outward.10Journal of Experimental Biology. The Tymbal Mechanism and Song Patterns of the Bladder Cicada, Cystosoma Saundersii
The purpose is straightforward: males click to attract females. The speed at which these individual clicks repeat is so fast that to our ears the sound blurs into a continuous buzz or drone, but slowed down, it resolves into discrete pulses. Researchers have described the cicada tymbal as a natural “metastructure” because of how its geometry amplifies and shapes sound, an engineering feat that has attracted interest from materials scientists looking to design compact, efficient acoustic devices.
Deathwatch Beetles and Head-Banging
Deathwatch beetles (Xestobium rufovillosum) take a blunter approach to clicking: they bang their heads against wood. These beetles live inside timber, and the rhythmic tapping they produce travels through the wood as a vibration that potential mates can detect from some distance away. Males use these taps to locate females, orienting toward the vibrations a female sends back in reply.11Animal Behaviour. Mate location in the deathwatch beetle, Xestobium rufovillosum De Geer (Anobiidae): orientation to substrate vibrations The name “deathwatch” comes from the association between the beetle’s tapping and quiet sickrooms in old houses. In the silence of a nighttime vigil, the rhythmic clicking from infested wooden beams became an eerie background sound people connected with impending death. The beetles themselves are just looking for a date.
Cracker Butterflies
Not all clicking insects are nocturnal or hidden inside wood. The blue cracker butterfly (Hamadryas feronia) produces audible clicks in broad daylight during flight. Males perch on tree trunks and launch into the air when they spot a passing butterfly, producing short bursts of intense, broadband clicks. These clicks are loud, measured at roughly 80 to 100 decibels at close range, with peak energy around 13 to 15 kilohertz. Each burst lasts about half a second and consists of brief double-component clicks lasting just two to three milliseconds apiece.12PubMed. Sound production and hearing in the blue cracker butterfly Hamadryas feronia (Lepidoptera, nymphalidae) from Venezuela
Early researchers assumed the clicks were percussive, caused by the wings clapping together. But experiments showed that males can produce the sound using a single wing, ruling out a simple clap mechanism.12PubMed. Sound production and hearing in the blue cracker butterfly Hamadryas feronia (Lepidoptera, nymphalidae) from Venezuela The exact mechanism remains debated, but it likely involves specialized wing vein structures that snap or buckle during the wing stroke. The clicks appear to be territorial signals, used by males to warn off competing males from their perching sites. Whether females also use the sounds in mate choice is less clear.
Grasshoppers That Clap Their Wings
Some grasshopper species produce clicking or crackling sounds during flight, a behavior entomologists call crepitation. In the Chinese grasshopper Acrida cinerea, researchers confirmed the mechanism by filming tethered males with high-speed cameras. The males generated sounds at the top of each wingbeat by clapping their hindwings together at the end of the upstroke. When researchers physically prevented the hindwings from meeting, the sounds stopped entirely, confirming that the clap itself produced the click. Females were also capable of making sounds using the same mechanism.13Entomological Science. Mechanism of sound production by the Chinese grasshopper Acrida cinerea (Orthoptera: Acrididae) during flight
If you’ve ever walked through a dry grassland and heard crackling bursts as grasshoppers leap out of your path, you may have been hearing crepitation. It likely serves both as a courtship display and as a startling signal to predators, though the relative importance of each function varies by species.
Katydids and the Elastic Scraper
Katydids (family Tettigoniidae) produce their sounds by stridulation, rubbing a scraper on one wing against a file of teeth on the other. In many species, this produces the familiar chirping or buzzing of a summer night. But some katydids generate distinct clicks or tick-like pulses rather than sustained tones. In the neotropical katydid Nastonotus foreli, researchers found that the scraper deforms elastically during the wing stroke, storing energy and releasing it in a snap that effectively doubles the call’s duration without needing faster muscle contractions.14PubMed. Complex wing motion during stridulation in the katydid Nastonotus foreli (Orthoptera: Tettigoniidae: Pseudophyllinae) The katydid’s muscles are actually fast enough to produce the sound directly, but the elastic mechanism appears to have evolved as a way to extend the signal, making it easier for distant females to detect and locate the caller.
Water Boatmen and Underwater Clicks
Perhaps the most improbable clicking insect is a tiny aquatic bug. The lesser water boatman Micronecta scholtzi, barely two millimeters long, produces a mating call by rubbing a ridge on its genitalia against its abdomen while submerged. Despite the insect’s minuscule size, peak sound levels have been estimated at over 99 decibels at one meter, with maxima reaching about 105 decibels.15PLOS ONE. So Small, So Loud: Extremely High Sound Pressure Level from a Pygmy Aquatic Insect (Corixidae, Micronectinae) That makes it, relative to its body size, one of the loudest animals on Earth. Most of the sound energy stays in the water and dissipates before reaching air, but people sitting on the bank of a pond can sometimes hear the chorus.
How does such a small insect generate so much volume? The answer appears to involve the air bubbles the insect carries with it underwater. As a water boatman dives, it traps a thin film of air around its body, and the stridulatory vibrations couple to this air reserve. Modeling suggests that the close-range interaction between the vibrating body and the trapped bubble amplifies sound power exponentially as the distance between them shrinks, essentially turning the bubble into a resonating speaker.16PubMed Central. Extreme call amplitude from near-field acoustic wave coupling in the stridulating water insect Micronecta scholtzi (Micronectinae)
Assassin Bugs and Defensive Stridulation
Assassin bugs in the subfamily Triatominae, the group notorious for transmitting Chagas disease, stridulate when handled by producing an audible squeak or clicking buzz. They do this by rubbing the tip of their folded proboscis (the straw-like mouthpart they use to feed) along a ridged groove on the underside of the thorax. Five species of triatomine bugs were confirmed to stridulate when grabbed, and in at least one species, Dipetalogaster maximus, all five larval stages could produce the sound as well.17Physiological Entomology. Sound production in some triatomine bugs The clicking is a defensive alarm signal, essentially the insect’s version of growling when cornered. It may deter predators or at least startle them long enough for the bug to escape.
Clicking Caterpillars
Even larvae get in on the act. Caterpillars of the polyphemus moth (Antheraea polyphemus) and other silk moth relatives produce clicks by snapping their mandibles together when disturbed. Researchers confirmed the mechanism by filming the larvae’s head movements alongside audio recordings, matching each click to a visible mandibular motion. Scanning electron microscopy of the mandibles revealed textured surfaces that contribute to the sharp, impulsive sound.18Journal of Experimental Biology. Clicking caterpillars: acoustic aposematism in Antheraea polyphemus and other Bombycoidea The clicks function as acoustic warning signals. Many of these caterpillars are chemically defended, and the clicking serves the same role as bright warning colors in other species: it tells predators that attacking will be an unpleasant experience.
Treehoppers and Plant-Borne Vibrations
Some clicking insects never transmit their signals through air at all. Treehoppers (family Membracidae) communicate by sending vibrational pulses through the stems and leaves of the plants they live on. Males and females exchange short click-like signals through the plant tissue, and males use these substrate vibrations to home in on a female’s location. In the thornbug treehopper, males make a series of sampling stops along a stem, pausing to feel the vibrations arriving through their legs, then moving in the direction the wave seems to be coming from. They adjust their behavior based on signal amplitude and the time delay between vibrations reaching their front and back legs, making longer exploratory leaps when they’re far from the source and shorter, more cautious ones as they get closer.19Journal of Experimental Biology. Vibration-guided mate searching in treehoppers: directional accuracy and sampling strategies in a complex sensory environment
For these insects, the plant is the communication medium, and the “click” you’d hear is not airborne sound but a tiny vibration rippling along a twig. The same signal that carries mating information also has to contend with the mechanical complexity of a living plant, where branching stems, leaf nodes, and varying tissue density all distort the vibration in unpredictable ways. Males have apparently evolved search algorithms sophisticated enough to deal with this noisy channel.
Robots Inspired by Clicking Beetles
The click beetle’s latch-and-release mechanism has attracted serious interest from engineers designing small robots. A 2.6-gram untethered microrobot inspired by the click beetle’s jumping mechanism can leap up to 29 times its body height, and its isolated catapult component achieved a jump height of 230 times its own body length, a record for untethered robots of its class.20PubMed. A 2.6-g Untethered Microrobot with Maneuverable Crawling and High Jumping Performance A separate project used light-responsive polymer films that buckle and release energy in a way that mimics the beetle’s thoracic snap, achieving continuous jumping at heights of 35 body lengths with no external power tether, driven entirely by light.21Advanced Functional Materials. Click‐Beetles‐Inspired Light‐Driven Continuous Jumping Robots Based on Janus Azobenzene Polymer Films
What makes the beetle’s mechanism so appealing for engineering is its simplicity and power-to-weight ratio. You store energy slowly, release it almost instantly, and get explosive movement from a tiny, lightweight package with no gears, no wheels, and no legs involved. The challenge for roboticists is replicating the beetle’s ability to reset the latch after each jump, since the beetle’s elastic thorax does this passively while synthetic materials tend to wear out or deform. The light-driven polymer approach sidesteps this by using a material that resets its shape automatically once the light source cycles, mimicking the beetle’s continuous readiness to click again.