A Study on the Effectiveness of Ultrasonic Sound Emitters in Controlling Bat Populations
It has been theorized by various pest control equipment companies that ultrasonic sound emission may be effective in repelling nuisance animal and insect pests. The theory is that a device that produces pulses of sound at very high frequency, above that of human hearing, will act as a deterrent in the event of pest infestations, both because the pests cannot tolerate the sound, and also because the sound might interfere with their ability to communicate with members of the same species.
As with any consumer need, companies will attempt to take advantage and sell products to fit the need. These ultrasonic sound emitters are marketed for the control of almost every major pest species, from rats & mice, to cats & dogs, and even insects like cockroaches. They are also marketed for the control of bats.
It has been soundly and formally concluded by biologists, wildlife experts, and even the government (see the below FTC document), after extensive observation and testing that ultrasonic sound emitters are completely ineffective in repelling, controlling, or affecting in any way the behavior of any wild animal or insect. In short, they are a gimmick.
Learn more: Do bats migrate?
In understanding why they are ineffective, it must be realized that the use of ultrasonic sound emitters was only a theory, and it has never been proven to be even remotely effective. Tests on animals of all kinds have proven that the animals exhibit no change in behavior when exposed to ultrasonic sound emission, even at extremely high levels of volume and frequency. Many of the animals merely investigate the sound source out of curiosity, then ignore it. Furthermore, ultrasonic sound does not reverberate, as lower frequency sound does. This means that once the ultrasonic sound hits a surface, it disappears. Thus, if an animal is living in any kind of crevice, such as a bat living under barrel tile, they won't even be exposed to the sound at all.
As a nuisance wildlife control expert, I have had many years of field observation with these devices. I routinely work on wildlife problems in which ultrasonic sound machines have been used in an initial attempt to correct the problem. I have worked in attics filled with rats, where the building owners have installed up to six ultrasonic sound emitters. To prove that they are ineffective (as if the continuing presence of rats was not enough), I have placed rat traps directly next to the machines, and caught rats in those areas. Furthermore, in regard to bat control, I have worked on several bat projects in which property owners have installed ultrasonic sound emitters pointed at the areas of bat infestation with no effects on the presence or behavior of bats.
I keep in close contact with dozens of nuisance wildlife and bat control experts across the country, and it is well understood by all that products such as ultrasonic sound emitters and naphthalene (moth ball) based deterrent products are completely ineffective. In fact, there are no effective or registered bat repellent products sold.
Find out more about bats: Do bats avoid light?
The only way to control bat populations is with a professional bat eviction - the bats must be removed from the structure, and all of the entry points that the bats use to gain entry must be permanently sealed. It is illegal to kill a colony of bats, and it is ineffective to trap and relocate them (they will find their way back to their home, even over a distance of several hundred miles). The proper way to control bat populations, as understood by bat professionals and advocated by Bat Conservation International, the leading authority on bat behavior and control methods, is through eviction and exclusion.
Please read the attached articles as further proof that ultrasonic sound emitters have no value in controlling or affecting any animal or insect species.
This is a document issued by the Federal Trade Commission (www.ftc.gov):
FTC Warns Manufacturers and Retailers of Ultrasonic Pest-control Devices
Staff of the Federal Trade Commission's Division of Enforcement today announced that they have sent warning letters to more than 60 manufacturers and retailers of ultrasonic pest-control devices, stating that efficacy claims about those products must be supported by scientific evidence. FTC staff reviewed print and catalog advertisements and conducted a "surf" of Internet sites marketing such devices. They found that many of the advertisements make explicit claims about the products' ability to eliminate rodents or repel insects. According to staff, these types of claims may not be in compliance with the FTC Act, which prohibits false and deceptive advertising.
Between 1985 and 1997, the FTC brought law enforcement actions against six companies that allegedly made false and unsubstantiated claims about the effectiveness of ultrasonic devices in controlling rodent and insect infestations. Each of those cases was resolved by consent order. In those prior actions, the FTC challenged the following types of claims:
Prior FTC complaints alleged that any reaction by rodents to ultrasound would be temporary at best because rodents become accustomed to ultrasound and will return to their nesting or feeding areas even in the presence of an ultrasonic device. Furthermore, previous FTC complaints alleged that ultrasound devices do not control insects.
The warning letters urged manufacturers and retailers of ultrasonic pest-control devices to examine their advertising and ensure they have competent and reliable scientific evidence to support claims that a product eliminates or repels certain pests. Staff advised the manufacturers and sellers that if they have misrepresented the benefits of their products, or if their claims are not properly substantiated, they may be subject to legal action. FTC staff will continue to monitor the advertising of ultrasonic pest-control devices to ensure that claims made to consumers are not false or deceptive.
- Eliminates rodent infestations;
- Repels insects;
- Serves as an effective alternative to conventional pest-control products;
- Increases or assists the effectiveness of other pest-control methods;
- Eliminates fleas on dogs or cats; and
- Scientific tests prove product effectiveness.
This is a document issued by the Washington State University Cooperative Extension and the U.S. Department of Agriculture, Vertebrate Pest Management Department:
Ultrasonic and Subsonic Pest Control Devices
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.
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.
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).
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.
For more bat control information, go back to the Florida bat control page.
If you don't live in Florida, click here for the National Directory of Wildlife Trappers.