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Did you just find a mouse in the house? Or maybe the snake that crawled out from under the porch has you rattled? Going batty looking for a solution? Maybe you need a high-tech way to solve your pest problem. Then again, maybe you don't. Ultrasonic pest control devices have been on the market for a long time. Their manufacturers and sales personnel lead you to believe that the high-pitched sound produced by the little black boxes (some with red lights to show you they are working) can only be heard by pests, not by other animals or humans. The sounds are so annoying, they say, that pests either leave or die. They also claim that the devices won't harm your pets, like gerbils and hamsters. Not so, say scientists who have worked with these pests and tested some of the equipment. Most insects and animals hear or feel the same range of frequencies that we do. If a sound or frequency doesn't bother us, it is doubtful that it will bother pests. Besides, gerbils, hamsters and rats belong to the same rodent family. Anything that drives away wild mice or rats will drive pet rodents crazy. Scientists would like to find a miracle cure for the severe problem of insect and rodent control. These pests combined would destroy up to 50% of the worlds' food supply if left unchecked. So, ultrasonics and recently subsonics have been tested extensively in the laboratory and field. These devices don't work. Animals placed in cages next to the devices continue to live normal lives. If they are paired with the opposite sex, the researcher soon has more mouths to feed. Testing has also shown that the sounds don't carry far. About half of the energy is gone in 15 feet. None remains at 30 feet. Any object placed in the way blocks the sound and produces a "shadow" (Figure 1). Even if the devices worked in the lab, the energy loss and shadow effects would make them useless in the real world. Insects and mice are good at hiding behind couches or overstuffed chairs. | |
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| Subsonic devices have recently hit the market. Manufacturers claim they are even better than ultrasonic ones. Instead of sending out a high frequency signal, they produce a low frequency sound or vibration. Some are emitted directly from a speaker in a little black box. Of course, the little red light is on to show you it is working because you can't hear the sound. Some producers of subsonic devices say they use the electrical wiring in a house or structure to form a protective shield around the inhabitants and the things they want to protect (Figure 2). The box, plugged into a common outlet, supposedly sets up low frequency vibrations through the electrical wires that neither insects or rodents (or any other pests) can stand. Your pets, of course, are not supposed to be harmed. | |
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| The most ingenious subsonic devices are those used in agriculture. Since there are no electrical wires in a field, metal rods are driven into the ground, connected with wire and attached to the little black box. The producers claim that the vibrations sent out from the rods, through the ground and up the plants, will keep insects and rodents away (Figure 3). | |
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Researchers have proven that these subsonic devices don't work. Texas has even prohibited one firm from selling them in the state. Leave your money in the bank or invest it in some proven management practices. The old saying still holds: "If it looks too good to be true, it probably is." Mousetraps and flyswatters may still be your second-best friends. | |
Leonard R. Askham Former WSU Associate Professor and Associate Research Scientist, Vertebrate Pest Management, Department of Horticulture and Landscape Architecture Issued by Washington State University Cooperative Extension and the U.S. Department of Agriculture in furtherance of the Acts or May 8 and June 30, 1914. Cooperative Extension programs and policies are consistent with federal and state laws and regulations on nondiscrimination regarding race, color, gender, national origin, religion, age, disability, and sexual orientation. Trade names have been used to simplify information; no endorsement is intended. Published January 1992. Subject code 360. A | |
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