It seems ingrained in the genes of mankind to invent ways accomplish a useful task while expending very little physical effort. The TV remote control is the epitome of this enterprise in my home but microwave ovens, automatic ice makers and ‘intelligent’ clothes dryers all do their bit to conserve our precious mental and physical energy.
When it comes to pest control, though, methods haven’t changed much since medieval times. Whether roach, mosquito, fly or mouse the two management methods of choice are poison or trapping. You still have to buy the lethal products, figure out how to use them, decide where to place them and manage not to harm yourself in the process.
No wonder that gizmos claiming to “Repel Pests with Ultrasonic Waves” gain instant attention if you are plagued with household invaders.
The theory behind these contrivances is that rodents and insects can hear sounds that are above the range of human senses. By emitting a loud ultrasound, it’s assumed that the creatures will be repelled, driven insane or at least discomfitted. Even the Pied Piper of Hamelin had to blow his flute. If household pests could be sent packing just by plugging in an electronic device, the constant finger motion required for a quick television channel search would be strenuous exercise by comparison!
INTERNET TO THE RESCUE I’m not a college-degreed pest control expert. Neither am I an authority on insect or animal physiology. When I was posed a question about the efficacy of electric ultrasonic repellers on Clark Howard’s radio show recently, I had only fifteen minutes to compose a reply. I turned on my computer and quickly brought up the Ohio State University Extension Factsheet search engine and typed in the term ultrasonic.
Pouring out of my Web browser came dozens of university publications regarding the effectiveness of ultrasonic pest repellers:
“Ultrasonic pest repelling devices have repeatedly been shown to be completely useless.” University of Florida
“Ultrasonic treatment devices (such as ultrasonic flea collars) claimed to rid homes of pests are completely ineffective.” University of North Dakota
“Ultrasonic devices do not meet advertisers claims for their products.” University of Maryland
“With proper use of rodenticide baits, there are few situations where the additional cost of ultrasonic devices is warranted.” University of Saskatchewan
“Ultrasonic devices are frequently advertised as a non-toxic method of cockroach control. However, extensive research has shown that these devices neither kill nor repel cockroaches.” University of Florida
With these testimonials before me, I could give Clark and his listeners a definitive answer. You might wonder, though, why the scientists came to their conclusions.
The reason ultrasonic devices don’t repel animals, even though they can hear sounds we can’t, is that ultrasound does not pack much energy. A sofa, a kitchen cabinet or a wall block almost all of the sound waves. Just as you might quickly roll up your car window when an ambulance howls past, a mouse or rat can duck behind a solid object to hide from loud noise. When food, water and shelter are present, a rodent can easily find different pathways that avoid the ultrasonic sound waves. Insects don’t have ears but they can “feel” sound. Even so, ultrasonic sound dissipates rapidly. A bug crawling more than thirty feet away from a unit can’t even detect ultrasonic noise.
DEER REPELLERS? While on the same Internet search I came across information about another “sound repeller”: the deer whistle. These devices are made to mount on the hood of your car. Air rushing through the whistle will supposedly alert animals that a “Deer Death-Mobile” is coming down the highway. Washington State University reached these conclusions:
“The manufacturers claim that two European studies proved that the whistles work. Not so. They were initially tried in Europe about 25 years ago but research did not prove them to be successful.”
“(A) study from Switzerland concludes that the whistling sound, which is well within the human hearing range, is so weak that it is overlaid by the noise of the moving vehicle. A scientific advisory panel from the World Society for the Protection of Animals states, after extensive review, that there is no known data “that shows that such devices can actually stop an animal crossing the road, which is the main purpose of the device.”
“Even if the devices were effective, they would soon become clogged with insects and dirt (since they are mounted on the front of the vehicle) and would stop working.”
The University of Vermont chimed in regarding stationary ultrasonic devices: “Deer quickly become used to stationery objects and sounds and so, if ultrasonic or similar sound emitters or radios are used, they should be rotated frequently. Mixed results have been reported with the often-expensive ultrasonic units.”
However, Vermont goes on to say “If radios are used, they should be tuned to all-night talk shows, as human voices are more effective than music, and don’t have to be very loud to be effective.”
I conclude from this statement that if you tape my Saturday morning radio show and play it in your garden at night, I could be your most effective sonic deer repellent. And you can accomplish this with about the same amount of energy used to find the remote control under the sofa cushions!