Rat and mouse article

Do Rodent Repellents Work?

Updated November 4, 2026

UF/IFAS says there's no evidence ultrasonic devices push rodents out of their home range. Scents and sprays don't fix an established problem either. Sanitation, traps and sealing do.

Not well enough to count on. UF/IFAS says there's no evidence ultrasonic devices will or can push rodents out of their home range, and notes evidence that they can cause hearing loss in pets, especially dogs. Scent repellents like peppermint oil, and sprays sold for engines and attics, may bother a rodent for a while, but they don't remove food, close gaps or catch the rats already living in your attic.

Here's a closer look at each type, and what to do instead.

Ultrasonic plug-ins

These devices plug into an outlet and give off high-pitched sound people can't hear. The UF/IFAS roof rat publication is direct about them: there's no evidence these devices will or can push rodents out of their home range. Sound also doesn't pass through walls, insulation or furniture, so a plug-in in the hallway does nothing for rats in the attic. The same publication says there's evidence ultrasonic devices can cause hearing loss in pets, especially dogs.

Peppermint oil and other scents

Peppermint oil, cotton balls soaked in plant oils and pouches of dried herbs are popular because they're cheap and smell nice. The trouble is that a rodent with a nest, a food supply and a route in has strong reasons to stay. A smell that fades in a few days in Miami heat doesn't change that. The UF/IFAS publications cited here rely on sanitation, trapping and sealing, not scents.

Repellent sprays

Sprays sold for car engines, attics and garden beds often use strong odors or bitter tastes. They may discourage gnawing on one spot for a while, but they need reapplying, rain washes them off, and they don't address why the rodents are there. If a product is a registered pesticide, follow its label exactly.

Mothballs

Mothballs are a pesticide with their own label. Using a pesticide in a way its label doesn't allow is against federal law, so read the label before putting them anywhere. In an attic or a garage they're more likely to bother the people in the house than an established rat colony.

Cats and dogs

A cat may catch the odd mouse that wanders into the kitchen, and a dog may bark at the ceiling. Neither reaches rats in the attic or mice inside a wall, and neither closes the gaps. Pets also complicate trapping and baiting, so tell the provider about them.

What works instead

The steps that actually work take more effort than a plug-in, but they hold:

1. Take away food: pick up fallen fruit, store pet food and seed in hard containers, bring bowls in at night
2. Take away cover: trim palms, clear wood piles, keep storage off the floor
3. Trap the rodents already inside with snap traps along their runways
4. Seal every gap with metal once trapping is done
5. Cut the bridges: prune trees off the roof and fit trunk guards

Why the yard matters in Miami

Roof rats here live in palms and fruit trees and travel 150 yards from the den for food or water, per UF/IFAS. A repellent inside the house does nothing about a mango tree feeding rats outside your bedroom window. UF/IFAS recommends pruning trees so limbs stay off the roof and wires, and fitting sheet metal bands 18 to 24 inches wide around trunks. See rats in palms and fruit trees.

Where a repellent might fit

Some people use a repellent as a short stopgap, say in a car that has to sit for a week, while they set up traps and sealing. That's fine as long as it isn't the whole plan. If you hear rodents overhead or find fresh droppings, the next step is trapping and then sealing.

While you wait for a technician, sealed food and a clean kitchen do more than any scent.

Signs a repellent isn't working

If you plugged in a device or spread a scent and still hear running overhead, find fresh droppings or see new gnawing after a week, it isn't working. Don't wait longer. Rodents breed fast; UF/IFAS says roof rats can have four or five litters a year. Switch to trapping and sealing.

Bleach, ammonia and dryer sheets

Household products like bleach, ammonia and dryer sheets get passed around as rodent repellents. Bleach is useful for cleaning up after rodents, which is how the CDC uses it, but pouring it around the house doesn't keep rats out. Mixing bleach and ammonia is dangerous. Stick to cleaning with them, and handle the rodents with traps and sealing.

Related services: Rodent Exclusion, Rats in Palms, Fruit Trees and Yards, Rat Control