The term “clicking sound” describes various insect noises, including sharp mechanical actions, rhythmic tapping, and rapid communication signals. Identifying the source of the click depends on the context, such as whether the noise is heard outdoors or coming from inside a wooden structure. The characteristics of the sound—a single loud snap, a repeating tap, or a continuous rapid pulse—offer important clues to the insect responsible. Determining the origin helps identify if the insect is harmless, a pest, or a source of structural concern.
Insects Known for Mechanical Clicking
The Click Beetle (family Elateridae) produces a distinctive, purely mechanical noise. This sound is a single, loud snap or pop, immediately followed by the beetle vaulting into the air. The action is designed to help the insect escape danger or flip itself upright.
The mechanism is centered on the underside of the beetle’s thorax, between the first and second segments. A rearward-pointing spine, known as the prosternal process, rests on the prosternum. The beetle bends its body backward, creating tension as the spine is leveraged against a corresponding groove on the mesosternum.
Muscles rapidly contract, forcing the spine out of the groove and into a cavity with explosive force, causing the audible click. This sudden release of stored elastic energy acts like a spring, propelling the beetle into the air. The resulting launch can propel the beetle several inches high. This sudden, unpredictable movement is effective both for righting the beetle when it is upside down and for startling a potential predator.
Tapping Sounds Inside Walls and Wood
A clicking sound originating from within a wooden structure, such as a wall, floorboard, or furniture, often signals the presence of the Deathwatch Beetle, Xestobium rufovillosum. This tapping sound is not mechanical but a form of communication used primarily during the mating season. The beetle produces the noise by rhythmically banging its head or mandibles against the wood substrate.
The sound is a series of distinct taps or ticks, typically consisting of four to eleven strikes in a short sequence, which may be mistaken for a ticking clock. Males initiate this tapping to signal their presence to potential mates, and receptive females respond with their own taps to help the male locate them. This behavior is most often heard in quiet, older buildings, which is why the insect earned its ominous name in folklore.
Termite soldiers also use a form of tapping communication inside wood, though it is not a mating call. These termites bang their heads against the gallery walls to create vibrations that serve as a warning signal to the colony. While the sound is a distinct tapping noise, the Deathwatch Beetle is the more common source of the persistent, rhythmic clicking heard from within older wooden structures. The presence of the deathwatch beetle indicates a potential infestation, as its larvae bore tunnels through wood for up to a decade, compromising structural integrity.
Stridulation and Communication Clicks
Many insects that produce sound for communication, such as crickets and katydids, use a method called stridulation, which involves rubbing two body parts together. While these sounds are often described as chirps or trills, certain species produce rapid, short pulses that an observer may perceive as a sharp click or snap. This friction-based sound is distinct from the mechanical snap of the Click Beetle or the head-banging of the Deathwatch Beetle.
In some species of crickets and katydids, the male produces this sound by scraping a file-like structure on one wing against a scraper on the other wing. These acoustic signals are primarily used to attract mates and establish territory. They can vary dramatically in frequency and rhythm; some species produce a loud, sharp snap.
Beyond stridulation, other insects use rapid wing movement or defensive displays to create a click or snap. Large grasshoppers or praying mantises may produce a startling snap or hiss as a defensive maneuver when threatened. This noise, often combined with a sudden visual display like wing-flashing, is meant to startle a predator. These communication clicks and snaps are typically heard outdoors in vegetation, confirming their function as a social or defensive signal.