Cockroaches are often perceived as silent invaders, yet they are fully capable of producing audible noise. The sounds they create fall into two distinct categories: incidental noises, which are the byproduct of their movement and activity, and intentional vocalizations. While most common household species are not known for deliberate sounds, the presence of any noise can offer a strong indication of their activity and population size within a structure.
The Sounds of Movement
The noises most frequently heard by humans are the sounds of a cockroach interacting with its environment. These incidental sounds include a soft, rapid scuttling or a faint pitter-patter as they move across surfaces. Since cockroaches are nocturnal, these sounds are typically most noticeable late at night when ambient noise levels are low.
As they navigate tight voids, their bodies and legs create a rustling or scratching sound against the surrounding material. This activity is often amplified in hollow spaces, which makes the sounds more distinct than a single insect’s movement would suggest. Subtle tapping or clicking noises occur when a cockroach’s body contacts hard surfaces like pipes or wood as they search for food and water. These noises are purely mechanical and do not convey any message.
Intentional Communication
Some cockroach species possess specialized biological mechanisms for producing sounds. These deliberate vocalizations are categorized as either chirping or hissing. Chirping sounds are often generated through a process called stridulation, where the insect rubs two hardened body parts together, such as the edge of the pronotum against the costal veins of the wings.
This acoustic signaling is frequently associated with courtship behavior, used by males to attract a female. Species like the brown-banded cockroach have been observed producing these chirping sounds. Hissing, conversely, is a defensive or aggressive mechanism, produced by forcefully expelling air through modified breathing holes, known as spiracles, located on the abdomen.
The Madagascar Hissing Cockroach (Gromphadorhina portentosa) is the most well-known example, using distinct hisses during aggressive encounters, courtship, and when disturbed. The sounds produced by these mechanisms are highly species-specific and are generally not made by the smaller cockroach species commonly found infesting homes. Common household pests rely more on chemical signals, but these intentional sounds demonstrate a complex auditory communication system.
What Hearing Noise Indicates
Hearing any noise from within walls or dark recesses of a home is a significant indicator of a cockroach presence. Auditory confirmation points toward an established, dense population. The volume and frequency of the sounds correlate directly with the severity of the infestation.
Loud, consistent rustling or scratching, particularly in areas like kitchens or bathrooms, suggests a high number of individuals competing for resources and shelter. Since these insects are primarily active at night, hearing noises after dark confirms their nocturnal foraging habits. The presence of noise indicates the population has grown large enough to be active and numerous enough to produce an audible footprint.