Rat and Mouse Catching

A little while back I had to deal with a bit of a rat and mouse problem and, like most people, I called in the experts. The guy who turned up was really friendly and we got chatting about what he did for a living. I have to admit it was one of the most fascinating conversations I’ve every had, I’d never even begun to imagine how much there is to know about catching rodents.

Anyway, to cut a long story short for the most part he reckoned that if you have the stomach for it you should give it a go yourself first time around and only then if it doesn’t work call in the experts.  Keep in mind I’m not a expert this is just what I was told by someone who is.

Important Point 1

The first thing you should keep in mind is these animals aren’t your friends and they aren’t cute and fluffy. Ok, they are cute and fluffy but they are most certainly not your friends. They will damage the fabric of your property and they can spread disease, although the truth about that is surprising. In particular they will chew through electrical cables and gnaw on plastic pipes.

Important Point 2

These animals are vermin and should be killed not trapped and released. The best possible outcome for the animal if you trap and release it is that it will find it’s way back into your property. More likely it will be killed by the rat or mouse who’s territory you just inadvertently released it into.


Rats are surprisingly clean animals and almost never cause disease in humans. The only real concern is Leptospirosis, also known as Weils disease, but transmission to humans is rare. Essentially it requires the direct contact of rat urine with an open wound or some other intimate contact. Leptospirosis will quickly become inactive after the urine dries.

Mice in contrast are dirty animals and should be dealt with quickly – they have no bladder control which means they spread urine over everything and carry a wide variety of diseases that humans can catch.


Poison is far and away the most efficient way to deal with rats and mice. It appears to be relatively painless and fairly quick. The only downside is that it can cause the animal to die somewhere that is inaccessible. The smell of a rotting rat is not pleasant but it should only last a week or so and there are chemicals you can put down that will mask the smell although it’s questionable if they improve the situation. Another sure sign you’ve killed one is a sudden outbreak of blue bottles.

For rats use Bromadiolone 0.005% and for mice use Difenacoum. Rodex wax blocks seem to work well and are laced with an attractant as well as the poison the rats also like them because they are perfect for gnawing on. Getting rats to take poison can be hard if they have a better food source somewhere else so remove all possible other food sources, in particular make sure they can’t get to dry dog food as they love it.

Technically once the infestation is dealt with the poison should be removed but if using blocks and they are secure from other animals then they can stay in place forever to stop any new infestations in the future.

Don’t worry overly about pets eating the poison as it’s full of Bitrex and there’s so little poison you would struggle to kill a medium sized dog as the fatal dose would be about a litre of blocks.

Rats are very neophobic (scared of new things) so they will avoid the poison on day one, eat a little on day two and if they are feeling fine they will eat more on subsequent days. Anything poisons enough to kill them on day one you wouldn’t want in the environment so the poison is designed to build up in the rat over a number of days until it kills them.

Where to Put Poison

It’s important to trace where the rats are going and put poison on their path so that they come across it regularly. They are creatures of habit so  cramming the poison up a corner away from where they go won’t work.

To find their paths look for things that you would expect to be dusty that aren’t such at the tops of pipes. This may mean lifting floorboards and crawling around underneath things. Rats won’t generally walk around an exposed area and they certainly won’t walk across the middle of a room! Imagine you are only 10cm tall and think where you’d walk / climb if the world wanted to eat you. You can often find clean paths in a layer of dust which is a sure sign of a problem.

If there’s a hole in a wall or piece of wood look for black grease / oil marks. Rats coats are very oily and it rubs off as they run past things. This takes time to build up though so if you see it you’ve probably had an infestation for a while.

Use your nose to find them by smell, rats will use a specific area as a toilet. Don’t put the poison in this area but use it as a starting point to work back to an area where you can put down poison.

A Rats Life and Habits


A female rat will often break away from the group to have young with a litter typically being 3 or 4 pups. A rats range can be anything up to 3/4 mile so they could be eating from a wide variety of places.

Removing rats from a modern houses is generally harder than in an old house. Although it’s much harder for the rat to get in to a modern house once they are in they are hard to get out because of all the voids left for insulation.

Rats won’t generally swim through a water trap (e.g. a toilet), it’s not unknown but it’s rare and you should look for other points of access. Check your property all over for holes larger than 2.5cm as that is likely the route of access. If you assume that rats can fly you stand a chance of thinking in a way that will help you find how they are getting in.

Don’t leave water out for pets at night, rats needs to drink regularly and will set up home near a reliable water supply. Essentially all pets will be scared of rats and with good reason, rats can jump, scratch and bite and do a lot of damage.

If you happen to corner a rat do not attempt to pick it up with your hands even if you suspect it’s dead as you really don’t want to get bitten. Prod it with a stick to find out if it’s alive and if it is dead then use something like a spade to pick it up and dispose of it correctly. If it’s not dead, well the spade can be used then as well… In all seriousness if it’s not dead you have to make a judgement call. I’m assuming it’s poisoned as no healthy rat would let you corner it, if you think it will run off to die then perhaps consider trying to throw a bucket over it while nature takes it course. If you have the stomach for it you could finish it yourself but it’s messy, moving it while it’s alive is possible but it’s difficult.

Image: Tomas Čekanavičius