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 that are too high in pitch to be heard by the human ear (all frequencies greater than 20,000 Hz). Humans are unable to hear sounds higher than 20 kHz due to physiological limitations of the cochlea. 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.
Read more about this topic: Electronic Pest Control
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