Ultrasonic Plug in Pest Repeller, safe humane pest control - repels rats, mice, squirrels, bedbugs, ants, mosquitoes and other biting insects. These units eradicate pests by emitting twin ultrasonic waves which attacks the pests nervous system and repels them. These special repellers also provide pest control protection to house building wall cavities, voids and any loft space. The units also has a night light sensor built in.