Electronic & Ultrasonic Cockroach Repellers

These are dual-action units. The ultrasonic setting emits sound above the range of human hearing into the room; the electromagnetic setting sends pulses through the house wiring instead, with an LED showing which is running. Pest-Stop lists cockroaches among the pests its indoor repellers target, and describes the waves as causing auditory distress to crawling insects, discouraging their presence in the home. There is no poison and nothing to clear up.

Use both. Cockroaches shelter in warm cavities - behind and under fridges, ovens and pipework - and those harbourages have to be baited and treated directly. Start with cockroach bait traps and the rest of the cockroach control range, then run a repeller alongside them.

Ultrasonic output goes into the room the unit is plugged into. The electromagnetic setting sends pulses through the building's electrical wiring instead, so a single unit can cover multiple rooms on the same circuit. Units are sold by the area they cover - one room, small house or large house - so check the coverage stated on the product page and choose to suit the space.

No. Ultrasonic sound does not pass through walls, closed doors or furniture, and carpets, curtains and upholstery absorb it. Plug the unit into an open part of the room with nothing in front of it, or switch to the electromagnetic setting where you need to reach beyond one room.

There is no active substance and no poison - the unit plugs in and runs on mains power, so there is nothing to touch or swallow, and Pest-Stop states its indoor repellers are harmless to pets, children and pregnant women. The exception is pet rodents and rabbits: hamsters, gerbils, guinea pigs, rabbits and chinchillas hear well into the ultrasonic range and may be distressed, so do not run one in a room where they are kept. Use as directed.

It depends when you are seeing them. Sightings at night, near the kitchen, usually mean the harbourage has never been treated - bait and treat behind and underneath appliances, in pipe voids and around the motor housing where it is warm. Cockroaches out in daylight point to a larger population being pushed into the open, which is the stage to stop relying on a deterrent and treat properly. Read our guide on getting rid of cockroaches yourself, and call a professional if activity spreads beyond one room.

In the room with the problem, at socket height, with nothing solid in front of it - not behind a sofa, inside a cupboard or under a shelf. Leave it running continuously rather than switching it on and off, and keep it clear of soft furnishings that would absorb the sound.