Ultrasonic pest repellers — those small plug-in devices that claim to drive away mice, cockroaches, spiders, and mosquitoes with high-frequency sound — are among the best-selling pest control products in America. They're also among the least effective.
The appeal is obvious: plug it in, no chemicals, no traps, no mess. But the scientific evidence is clear, the FTC has taken enforcement action against manufacturers, and pest control professionals universally regard these devices as ineffective.
University studies: Researchers at the University of Arizona, Kansas State University, and multiple other institutions have tested ultrasonic devices against cockroaches, mosquitoes, mice, and rats. The consistent finding: no statistically significant repellent effect compared to control groups.
The FTC's position: The Federal Trade Commission has taken enforcement action against ultrasonic device manufacturers multiple times, most notably in 2001 when it warned 60+ companies that their advertising claims were not supported by scientific evidence. The FTC stated that the devices do not control pests as advertised.
Why they seem to work (briefly): Some users report initial pest reduction after plugging in a device. This is likely due to the novelty effect — the new sound may temporarily startle pests. But animals habituate to sounds rapidly. Within days, the effect disappears entirely. This initial "success" followed by return of pests is consistent across nearly all user reports.
Sound doesn't penetrate: Ultrasonic waves are blocked by furniture, walls, and even curtains. A device in one room has zero effect on pests in the next room — or even behind a couch.
Habituation: All animals habituate to constant stimuli. A sound that initially startles a mouse is background noise within 48 hours.
Species variation: Different pests hear different frequency ranges. No single device can target mice (hearing range 1–100 kHz), cockroaches (very limited acoustic sensitivity), and mosquitoes (attracted to sound, not repelled) simultaneously.
If you want pest control that doesn't involve heavy chemical use, several proven alternatives exist:
For mice: Snap traps and exclusion (sealing entry points). These are more effective than any chemical or electronic device.
For cockroaches: Gel bait exploits their social feeding behavior. A $12 tube of Advion gel bait eliminates more cockroaches than any ultrasonic device ever could.
For spiders: CimeXa desiccant dust in cracks and crevices. No resistance, lasts years, extremely effective.
For mosquitoes: Source reduction (eliminating standing water) and Bti larvicide in permanent water features. Ultrasonic devices are particularly useless against mosquitoes — some research suggests certain frequencies actually attract them.
See our Treatment Method Encyclopedia for 48 proven techniques with effectiveness ratings.