June bugs, or June beetles, are members of the Phyllophaga genus of scarab beetles. They emerge from the soil in late spring and early summer, and the sounds they produce are a common part of the summer atmosphere across North America. These reddish-brown beetles are nocturnal and are frequently drawn to artificial lights. The noises they create vary significantly depending on whether the beetle is in flight or has been disturbed.
The Distinct Sounds of June Bugs
The most familiar sound associated with the June bug is a loud, low-frequency buzzing heard at night near illuminated windows or porch lights. This sound is a byproduct of their unique flight pattern, which is notoriously clumsy. The heavy body and relatively small wings contribute to a poor body-weight-to-wing ratio, leading to the turbulent air displacement that characterizes their flight.
Beyond the flight noise, a quieter, high-pitched sound can be heard if a June bug is caught or handled. This sound is described as a faint squeaking, hissing, or rasping. It is an immediate, defensive reaction, serving as a warning or distress signal when the beetle feels threatened. This secondary sound is a distinct acoustic behavior of the species.
How June Bugs Create Noise
The loud, low-pitched buzz during flight is not a communication signal but an acoustic consequence of rapid, heavy wing movement. As the wings beat to keep the stout body airborne, they create significant air disturbance and vibration. This forceful air movement, combined with the tendency to fly haphazardly, results in the distinctive “thump-thump-thump” sound often heard against windows.
The defensive squeaking or hissing sound is created through a mechanical process called stridulation. Stridulation involves rubbing two specialized body parts together, similar to drawing a scraper across a finely-ridged file. In many scarab beetles, this defensive noise is produced by forcing air out from between the hardened forewings, known as elytra, and the abdomen. The friction and vibration of these body parts generate the rasping sound designed to startle a potential predator.
Identifying Other Noisy Summer Beetles
Many people confuse the noise of the Phyllophaga June bug with other, louder summer insects. The Green June Beetle (Cotinis nitida) is a common source of confusion, as it is a large, metallic-green scarab beetle active during the day. This beetle creates a loud, distinct droning sound, often described as a “vrrrrroooooooom,” while flying low over lawns. Its sound is more sustained and noticeable during daylight hours than the nocturnal buzz of the Phyllophaga species.
Another major source of loud summer noise is the cicada, an insect often mistakenly called a “June bug” in some regions. Cicadas produce an exceptionally loud, sustained, and rhythmic song that can reach volumes of up to 120 decibels. Unlike the June bug’s mechanical flight buzz or defensive rasp, the cicada’s sound is a mating call. It is created by the rapid buckling of specialized drum-like membranes on their abdomen called tymbals. This mechanism results in a far louder, more pervasive sound than any noise a June bug can generate.