Electronic pest control

Electronic pest control is the name given to the use of any of the several types of electrically powered devices designed to repel or eliminate pests, usually rodents or insects.

Numerous electronic pest control devices are readily available throughout the world. Hardware stores and garden centers usually stock some sort of electronic device advertised to repel a variety of pests and one can also find them on the internet. Although these devices have been around for at least 20 years, they have only recently become popular and widely advertised, probably due to their environmentally friendly claims.

There is a wide range of opinion about these devices. Some people claim that they work for them, while others claim they are not effective at all.

Since these devices are not regulated under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) in the United States, the US EPA does not require the same kind of efficacy testing that it does for chemical pesticides.

Types of Devices

There are basically two types of electronic pest control devices widely available, these are Ultrasonic and Electromagnetic.

Ultrasonic devices operate by emitting short wavelength, high frequency sound waves too high in pitch to be heard by the human ear (all frequencies greater than 20,000 Hz). This is due to limitations in human hearing. Humans can not hear ultrasound because the eardrum does not vibrate fast enough, but some animals such as dogs, bats and rodents can hear well into the ultrasonic range. Some insects, such as grasshoppers and locusts can detect frequencies from 50,000 Hz to 100,000 Hz, and moths and lacewings can detect ultrasound as high as 240,000 Hz produced by insect-hunting bats.

Insects detect sound by special hairs or sensilla located on the antennae (mosquitoes) or genitalia (cockroaches), or by more complicated tympanal organs (grasshoppers, locusts, moths and butterflies).

Electromagnetic pest repelling devices claim to alter the electromagnetic (EM) field of household wiring, and vibrate the electromagnetic field that always exists around the wiring in the walls of your house.

Effects on Pests

"Ultrasound and Arthropod Pest Control" an extensive Kansas State University study confirmed that ultrasonic sound devices do have both a repellent effect as well as a reduction in mating and reproduction of various insects. However, the results were mixed and ultrasonic sound had little or no effect on some pests. Ultrasonic devices were highly effective on crickets while the same devices had little repellent effect on cockroaches. Additionally the results were mixed with some devices being effective while others having no effect depending on the test subject. The study also concluded there was no effect on ants or spiders in any of the tests. They concluded, based on the mixed results, that more research is needed to improve these devices.

A 2002 study by Genesis Laboratories Inc. does lend some credence to the ability of electronic repellent devices to repel certain pests in controlled environments. “Preliminary study of white-footed mice behavior in the test apparatus demonstrated a significant preference for the non-activated chamber among both sexes.” This study was sponsored by Global Instruments, the maker of the "Pest-a-cator" series of electronic repellent devices.

In 2003, the Federal Trade Commission required Global Instruments, the maker of the Pest-A-Cator/Riddex series of electromagnetic pest control devices, to discontinue any claims for their efficacy until they are backed by credible scientific evidence. This ban continues to be in effect.

Victor Pest managed to obtain positive results from independent researchers which resulted in two ultrasonic devices being granted registration by the Canadian EPA(PMRA). The results from the tests were the device “successfully repelled the rodents from the protected area in 13 of the 17 sites. This represents a 81.3% success rate...the average number of days before rodent activity was stopped was six days.”^{[citation needed]}

Cockroaches initially respond to electronic pest control devices by moving about a bit more than usual, but don't appear overly eager to escape from the sound waves. This includes devices that emit uniform frequency as well as changing frequencies of ultrasound. Rodents adjust to the ultrasound (or any new sound) and eventually ignore it. However, researchers were able to use the increased cockroach activity to good effect by increasing the rate they caught the roaches in sticky traps. At best, ultrasonic waves have only a partial or temporary effect on rodents. Numerous studies have rejected ultrasonic sound as a practical means of rodent control.

Tests of commercial ultrasonic devices have indicated that rodents may be repelled from the immediate area of the ultrasound device for a few minutes to a few days, but they will nearly always return and resume normal activities. Other tests have shown that the degree of repellence depends on the frequency, intensity, and the pre-existing condition of the rodent infestation. The intensity of such sounds must be so great that damage to humans or domestic animals would also be likely. Commercial ultrasonic pest control devices do not produce sounds of such intensity.^{[citation needed]}

Safety

Professor Tim Leighton from the Institute of Sound and Vibration Research, Universtity of Southampton, United Kingdom produced a 83 page paper entitled "What is Ultrasound" which was published in 2007. In the paper Leighton expressed concern about the growth in commercial products which exploit the discomforting effects of in-air ultrasound (to pests for whom it is within their audible frequency range, or to humans for whom it is not, but who can experience unpleasant subjective effects and, potentially, shifts in the hearing threshold). Leighton claims that commercial products are often advertised with cited levels which cannot be critically accepted due to lack of accepted measurement standards for ultrasound in air, and little understanding of the mechanism by which they may represent a hazard.

The UK's independent Advisory Group on Non-ionising Radiation (AGNIR) produced a 180 page report on the health effects of human exposure to ultrasound and infrasound in 2010. The UK Health Protection Agency (HPA) published their report, which recommended an exposure limit for the general public to airborne ultrasound sound pressure levels (SPL) of 70 dB (at 20 kHz), and 100 dB (at 25 kHz and above).

In Popular Culture

A Black-throated Magpie-Jay is featured in a season 5 episode of The Big Bang Theory, sending Sheldon into an ornithophobic episode and causing him to build an ultrasonic noise generator in an attempt to drive the bird from his windowsill. He only succeeds in shattering his window.

References

• Federal Trade Commission. News Release, 2001 [1]
• Federal Trade Commission. Consent Agreement [2]

See also

• Bug zapper
• Radio wave pest control
• Pest control