What Smell Do Rats Hate the Most: Is there Any POINT in Trying!

Yup, it’s rat season (well…it’s baby rat season) and it’s when momma rats have a decision to make as to where they build their nest. They want it quiet, dry, safe….and within walking distance to food. They DON’T want it near loud noises, flood prone areas, dogs and in proximity to smells that they hate. So, will it be your garage or the neighbor’s?

The good news is…yes, there a particular odors that persuade a rat to turn around and go the other way. The bad news is these odors are difficult to obtain, fade quickly and quite frankly, aren’t going to be pleasing to your nasal passages either.

But, try if we must, let’s get into what smells rats don’t like and from there, you can pick the lesser of the evils to deal with.

What do Rats Hate?

Rats hate going hungry,they also hate certain chemicals, a few essential oils, a common vegetable, natural predators and some easy to grow plants.

Chemicals Rats Hate

As a survival mechanism, some odors hated by rats are chemical compounds that occur naturally in the urine of animals that prey on rats, such as foxes, coyotes, ferrets and bobcats. The chemicals are 2-phenylethylamine and trimethylthiazoline (TMT).

This little discovery has driven people to buy any or all of the following: fox urine, ferret urine, bobcat urine, wolf urine, coyote urine, mountain lion urine…the list goes on and the products above can come in liquid, pellets (granules) or flakes.

Now to be fair, rats don’t really “hate” the smell, but rather, they understand they should pay attention, and perhaps not continue moving towards the source.

Great! I’ll Stock Up on Wildlife Urine

Not so fast. There have more in depth studies that test a rats stress response when presented with urine and feces of a ferret vs. the stress response when presented with the scent of a ferret’s actual body and fur odor.

In all cases, the rats were mildly stressed when they detected the ferret urine, but they still went about their rat business, relatively undeterred.

Conversely, when the rats were exposed to a freshly used ferret towel that had absorbed the natural body odors of the ferret, the rats stopped what they were doing and demonstrated signs of “looking for a way out.”

What does this mean? Well, perhaps rats have a way of detecting the age or freshness of urine and feces and that skill helps them determine the level of threat? I mean after all, we can identify old dog feces vs. fresh with our own eyes. Certainly a rat’s keen sense of smell can help it identify whether or not a predator IS or WAS nearby.

Essential Oils that Repel Rats – Easy to Obtain

Only a few small scientific studies have found that rats do not like the smell of some specific essential oils. Essential oils are chemical compounds extracted from plants.

Certain plants have unique aromatic compounds such as peppermint, eucalyptus, or citronella. One study looked at wintergreen oil, chili, peppermint, bergamot, and geranium oil with the oils used alone or in combination. 

While all of the above seemed initially effective at stopping a rat, most of these studies conclude that more research is needed to determine the use of essential oil extracts as rat repellants on a large scale.

All in all, they are definitely worth trying if you happen to have these fragrances on hand, and especially during nesting season. If we can get a rat to stop and take up shelter elsewhere, well…that’s certainly worth trying.

In the end though, it seems that a rat’s sense of smell includes the ability to assess impending threat level. Which is why people become disenchanted when they buy products with high price tags.

Use caution with essential oils and plants if you have house pets. Many oils and plants are toxic or upsetting to dogs, cats, rabbits, horses, etc.,

Do Onions Keep Rats Away?

It’s true to say most people are repelled by the smell of onions, and it’s no different for rats. Onions are a good non-toxic way of ridding your home of our furry little enemies.

Place a few slices in areas you think are attracting the rats, and remember to replace them when it goes rotten. They will soon scurry off in search of a new family to annoy. 

Do Cats or Dogs Keep Rats Away? 

Rats really hate the smell of their enemies. If you have pets such as dogs or cats, the smell is a strong deterrent for the furry little animals.

When rats are exposed to odors from animals they consider the predator’s stress hormones to be released. 

The smell of urine from cats and dogs alerts rats to potential dangers and is highly likely to send them away, tail between their legs (literally). 

A caveat to this method of keeping rats at bay is the effect of fear. Try to avoid setting your cat on a rat if you spot one.

Cornered rats will be aggressive and can release parasites that carry disease and may be harmful to your beloved pet, so exercise caution in this area. 

Moth Balls for Rat Prevention

You may have heard that moth balls are a deterrent for rats and whilst this is true you should be cautious if using this method.

The chemical naphthalene is toxic and causes red blood cells to malfunction by reducing the cells’ ability to carry oxygen around the body. It’s likely you would need a hefty amount of mothballs to effectively get rid of rats.

When used to stop moths from chewing clothes, the method is relatively safe as they are placed in a sealed container.

If you use mothballs for rats you are using them in the open so you’re exposing yourself as well as the rats to the dangers of a toxic chemical.

So despite some popular opinion, moth balls are not the best solution for pest control. 

A Rat’s Sense of Smell Depends on its Nose and Brain

Exactly how a rat’s nose and brain work together to detect and identify odors is still a little bit of a mystery to scientists. What is known is that a rat’s nose is nearly as keen as that of a dog.

Olfactory receptor cells are found within a rat’s nose in an area called the olfactory epithelium. The olfactory epithelium is a fancy term for a thin sheet of mucus-coated sensory tissue.  Tiny threadlike substances called cilia are present in the olfactory epithelium.

When the cilia detect an odorant, an electrical signal is sent to the brain where a structure called the olfactory bulb somehow decodes and recognizes the smell. This part of the process is complicated but suffice it to say, the rat knows the scent and then eagerly scampers towards it, such as delicious food, or hightails away from it, as in the case of a natural oils from a living ferret.

But what’s more likely to happen is that the rat detects the smell, and then uses their brain to help them make a decision. Much like a human might detect the smell of a fire, look outside to see neighbor Bob in his backyard burning tree-limbs, and then go on with the day, unworried.

A Rat’s Sense of Smell is Critical to Its Survival

Rats depend on their sense of smell for their survival.  Their ability to distinguish a wide variety of scents helps them find food, seek shelter, avoid predators, and reproduce.

When first born, rats are deaf and blind, and they can only detect their mother and her milk by their sense of smell.  When they are old enough to leave the nest, they rely heavily on their sense of smell to find food, which they will be able to access even through the tiniest of holes.

Rats have a second way of processing odors that involves a body part near their nose called a vomeronasal organ. Its primary function is believed to be receive and process smells related to reproduction. But, we’ll save this topic for another time.


There are some smells that rats dislike, and the presence of these odors may help to keep rats from invading your home or garage.  Unfortunately, these scents can also be offensive to humans, difficult to find and most importantly extremely unreasonable to maintain.

Urine and feces doesn’t illecit the same response as the scent of the actual, live predator. Certainly rats, like most mammals, can use many senses to determine the age of urine and feces and therefore, are not going to become stressed or afraid when detecting the fragrance of month old feces or urine.

If you want to go the natural route, strong herbs like mint and fragrant grasses and citronella may be somewhat helpful when it comes to where the rat decides to nest. It’s worth a shot because these plants or yard fixtures can serve a decorative purpose as well.

A more effective approach to rat control is to reduce the attractiveness of nesting. Seal off holes and cracks, remove junkpiles, fill gaps in fences so rats don’t have the sense of easy escape. And of course, don’t invite rats with easy food sources.

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