Most recommended method! Tried and tested! Soak cottonwool balls in peppermint oil and place strategically around your house (ie roof, compost heap, in cupboards, etc) to deter rats and mice. They, quite simply, do not like the smell and will move off, taking their offspring with them.
This isn’t an overnight method, and will take a few weeks to work. Replace balls as necessary.
The best way to keep rats off your property is to remove any access to food or shelter. Rats are attracted to pet food and bird seed as well as garbage. Garbage and food should be stored in metal or heavy duty plastic containers. You need to seal any access to your house, even very small holes as young rats and mice can squeeze through any opening they can fit their head through.
If you need to remove rats from your home or business by killing them, please use snap traps, and do not use poison or glue traps which are inhumane. Snap traps kill instantly and so are more humane.
If you want to remove wild rats from your home without harming them, you can use a live trap. Live traps are usually available from humane societies and feed stores. The best thing is to put the trap out and fix it so the door won’t close at first so the rats will get used to eating out of it. The best bait is peanut butter put directly on the treadle. Once you know rats are eating the bait, you can set the trap. Doing it this way insures that the rat doesn’t accidently set the trap off before he goes in. If that happens, he would never go in the trap again.
Now, the tricky part is where to release him. You can’t just let rats go in forest or field. They must have source of water, and around water they will be able to find things to eat such as insects, worms, snails, fish, frogs, etc. So the best place to release them is at a permanent source of water such as a creek, river, lake or pond.
In most parts of the country, the common wild rats are Norway rats (Rattus Norvegicus), also called brown, sewer or barn rats. In warmer climates the roof rat (Rattus rattus), also called the black rat or tree rat, can be found and is often the most common wild rat in these areas. Roof rats must be released in an area where there is water and trees.
“If you don’t mind having some wild rats on your property, but want to prevent the birth of too many, you can try this old-time remedy for birth control that was reported to work for wild rats by one person. Mix the herbs pennyroyal and asafeotida with split peas. Unfortunately she did not tell me amounts so try equal amounts of each. Then mix it all with peanut butter to make a thick “cookie dough.” The woman who told me this many years ago reported that the numbers of wild rats dwindled slowly as the rats died off and did not reproduce.”
– source unknown