We come across this a lot and its clearly something that has been passed from generation to generation and so is now entrenched in folklore and legend.
Much like witchcraft, superstitions, tales of dragons and other suchlike, the concept stems from the dark ages before science came to be and peppermint oil unfortunately falls into this category.
So if you are of the kind that believes the Earth is flat then continue to fear the edge and put your faith fully in peppermint oil to solve your rat problem! It won’t work.
The more modern mind focuses on science and realises root cause must be tackled rather than showing Evil the crucifix and relying on repellents but we still meet plenty of people out there putting their trust (and money) in this.
So what was the medieval idea behind it?
Rats & mice are nocturnal creatures and don’t rely much on vision – they are what’s known as an olfactory animal with their primary senses being touch & smell
So in essence they sniff and feel their way round the world and the sensitivity of their touch & smell is hugely greater than ours (we are very much a visionary animal)
Substances such as peppermint oil have volatile menthols in them which is why they have a strong smell
We have a very blunt sense of smell so what smells strong to us will smell overpowering to a rat – try holding a bottle of smelling salts under the nose of a cat or dog and watch its reaction! (they won’t thank you for it btw and will treat you with suspicion for the rest of their days)
People in the dark ages literally lived life alongside rats and mice and their constant observation of them allowed them to work out that strong smells repelled them
Given they didn’t really have baits/poisons in those days they therefore used what they had access to so substances such as cat hair, certain herbs, tar, perfumes etc. were used to try and keep these animals away from their food and beds
But they realised this only had a limited effect – ultimately they were happy with that as they were so used to living with them anyway
Modern standards of living have moved away from this luckily so relying on a mild repellent effect is akin to urinating on an infected wound rather than opting for antibiotics
Sure urine may have some sterilising qualities (although this maybe further folklore) and might calm an infection for a day or so but ultimately it won’t stop it and 2 weeks later you’ll be biting down on a leather strap whilst a ‘doctor’ saws the infected limb off (if we are to keep with the medieval analogy)
Likewise a rat or mouse is going to initially turn away from something like peppermint oil but much like a scarecrow in a field or a bubble stream to shark, they will ultimately just ignore it if a food source is present!
Far better these days to embrace the understand & technology that we have now and allow Pestology to stop them entering the building fabric in the first place – we know where the devil lives, why and how he gets into buildings so we simply focus on not giving him the opportunity in the first place to come in and sniff your peppermint oil
In our opinion, peppermint oil can stay in the cabinet with the silver bullets, horseshoes, saints toenails etc. for when the real reaper comes knocking!