Where are mice getting in ?

[EmilyGilmoreenergy]

My MIL lives in a terrace with concrete floors on ground floor, she has mice ( lived there over 30 years it's a new issue) but we can't understand where they are getting in to proof it.

Council pest control have done three visits and left bait that seems to reduce the issue for a bit but they had no firm answers.

I will get them back out but in the meantime does anyone have any advice to try and work out where they are getting in ?

I thought about leaving powder paint by the bait so they leave tracks to follow.

She isn't sleeping and it is having a huge effect on her well-being so we need to try and get it sorted as quickly as possible.

Oh btw next door say they don't have them and the other way is empty but environmental health went out and inspected their yard and said there's no indication of mice there or that it would attract mice.
Thanks

They could be getting in under the door or if there is any gap between the door and the frame. Or through an air vent. Or coming in from next door via joined attics (just because next door don’t know they have mice doesn’t mean they don’t also have them!)

If she leaves doors or windows open to air the house, they could also have got in that way. They breed so fast you only need to have been vulnerable once when a pregnant mouse got in and you will quickly have an infestation unfortunately

I read somewhere they can get in teeny tiny gaps - like the size of a pencil or something daft.

putting flour or sand to track them is actually a clever idea!

we get them in our garage coming under the door, and the gap is miniscule.

Thanks , the thought of them above your head in the loft is awful isn't it, I'm going to try talc and get quotes from different pest control people.

Mice can literally get in anywhere, 5mm is all they need. Don't bother with pest control, get one of the little plastic traps, they work great and better than having bait down

Does she have air bricks? You can buy mesh grills for those.
Anywhere she has a pipe going in mice can get in. They also climb a it doesn't have to be ground level.
The pest control guy I had was very thorough - pulled out the washing machine, pulled off the kick boards in the kitchen, looked around the boiler pipes, got in to the loft. He checked around the outside and told me what do do (those grills for example). He came back twice after to check. You need someone who knows what they're doing.

Thanks I have just spoken to the council guy that has already been he thinks they are coming up from a sub basement houses like here's have that's not accessible by humans so sounds like it must be as pp have said a tiny gap somewhere.

If you can stick a pencil through, a mouse can get in. I advise the humane raps the releasing outside somewhere. That way you get to see their cute cute faces and get a chance to observe how clever they are. This will magic away ant feelings of revulsion you may have towards them. They really are quite lovely creatures 😍

Sorry for typos. Traps, then, any

they could be in the roof and then coming down through walls of plaster board and moving through floor boards etc. They could be moving into your house from neighbours etc (through floors etc) Don't bother with sand or talc this won't help you. They can come through crevices in brick work /foundations.
Where are you actually seeing the mice?
Has anyone been up in tthe roof? - get up their and bait it.

Online you can buy sticky paper for catching mice and whilst a lot of people will say this is cruel it may help reduce your infestation and relieve your sisters stress levels. This paper can be positioned in places which will help let you know where they come from (it will be better than talc!!)

You need to bait and trap relentlessly. When you think numbers have dropped up your defences and maintain them long term.

You can buy rodent tracking gel and powder, might help to identify where they are getting in

Radiator pipes maybe. Look to see if there are any gaps.

I had them coming in through the tumble drier air vent, they learned to push up the flaps whenever they wanted. Sorted it by getting a mouse proof mesh panel, bending it to shape so the flaps so they still had room to open, and wedging it in place.

My best tip is be scrupulous with food scraps and crumbs. Mice like to live within about 30' of a food source, a pest controller told me, so as long as there's nothing around for them to eat, they will move on.

Has she seen evidence of them nibbling anything?

They will also chew up and pinch things like paper and cardboard, or material, to make nests. If you can eliminate that, it might help.

Gaps between the floorboards, around the edge of radiator pipes or wires. They only need to be absolutely tiny for this, cable holes or pipe holes in the bases of units, if you notice a black oily residue on the wires or pipes when you wipe them with your hand this is a sign rodents have been there. Any tiny holes in brickwork literally not even big enough for your finger to poke through mean that a mouse can get through. Tiny tiny holes in wooden window or door frames, in the backs of cupboards. All are big enough for mice to get through, they may travel
From the outside along the back of cupboards. Or underfloors, pop-up and then come into the room by your cupboards. Or underfloor under and then under carpets. Into your room, the possibilities are endless. They may travel under entire joined houses before popping up in your house. The trick is to look for any hole in your house and stuff. It with steel wire wall. They should help to keep them at bay. It's a real detective exercise. Investigate for every hole and block it. So the mice getting in to stop the problem.

As others have said mice get get through tiny tiny gaps... so filling in all the gaps is going to be a challenge.

You can get a special dust that they walk through and then you can trace where they've gone seeing the fluorescent dust they take with them.

Unfortunately if you catch them with a humane trap and release - they are likely to keep coming back in.

Obviously make sure you dont leave food around. be super vigilant clearing down any surfaces where food is prepared. Put any food in cupboards into plastic or glass containers. Also if you use soap powder keep an eye on that too as they have been know to eat that too.

Mice aren't too bad, but rats are hell to get rid of.
Containers for ALL food. They will even nibble the plastic lids on glass bottles.
Wipe all crumbs away.
Humane traps.
Block all holes you can.

I don't find the plug in things work, or peppermint oil.

Wipe down food surfaces thoroughly every morning.

We have had them - they came in 2 ways. One way was through a gap we hadn’t noticed in the outlet water pipe from the kitchen sink to the outside, the second was down the unused chimney. So I would advice checking those areas.

Humane traps don’t work. Either you release them close to your house in which case they just come straight back in, or you take them some distance from your house and release them and they die quickly of starvation/exposure or from predators. It’s actually more humane just to kill them quickly with a snap trap or an electric shock trap. The sticky ones are the most inhumane because they will try and gnaw their leg off to get free and struggle for hours until you find them and then you have to dispatch them with a hammer or something 😱

@Katrinawaves 🥺

Thanks for everyone's advice it's very useful and I will get right on it.

We only once ever had one mouse... little dude made his way in and out through the hole the gas pipe ran through to the meter.

To be honest he stayed in the gas cupboard and did minimal damage, think he was just looking for a warm spot for winter. Did help himself to a cookie and a chocolate coin though lol.