In short, ultrasonic pest repellers emit high-frequency sounds that manufacturers say reduce pest infestation in the home, but laboratory testing has shown that most of these devices do not work as advertised, in violation of FTC guidelines. Ultrasonic pest repellers do not provide a useful degree of protection for most pests, KSU tested ultrasonic devices on a number of arthropods, including cat fleas, cockroaches, spiders, crickets and ants, but the result was only a “fair overall effectiveness rating at best”. What happens to rodents? According to a study published in 1995, ultrasonic rodent repellent devices had a “marginal initial rate of repellency” (30 percent to 50 percent), but no noticeable repellent effect after three to seven days. According to KSU, the ultrasonic pest repeller devices they tested were most effective in reducing the reproductive capacity of the Indian flour moth, which is a common pantry pest.
Their tests observed a 46 percent reduction in the number of Indian meal moth larvae produced when these moths were exposed to ultrasound. Is there hope for the future of ultrasonic pest repellers? The UA notes that “the devices developed by the researchers show positive results, but they have not yet been marketed. Stay tuned. After all, these devices can have a useful future in your home.
I have used two larger ultrasonic pest repeller units (Black & Decker EP1100-A) for the past ten years for larger rodents and similar pests: one in the backyard and one in the garage; and I didn't have a single rodent or similar pest anywhere near the house. For example, a study of rodent repellent devices for the U.S. Department of Agriculture and the National Wildlife Research Center found that rodents stopped responding to ultrasonic sounds after a few days of exposure.
