Advice about mice - well mice in cavity wall

[Hanno Verian]

Hi,

We have a mouse or two that have set up residence in one of our internal cavity walls, this has given them access to the space between the ceiling and floorboards and it sounds like they are Line Dancing in there.

We cant access this to put traps in because we have underfloor heating that mean that even if we lift the upstairs floorboards we cant access the joist space. There is no way of accessing the wall cavity short of cutting a hole in the plasterboard and masking it with a vent/useless power socket, I'm wary about using ultrasonic devices because of our dogs, has anyone else had this problem and how did you get around it

 

[Pearlsasinger]

The ultrasonic devices might not help but they won't bother your dogs. They are set up to deter rodents, so unless you have pet hamsters/ gerbils you should be fine to use them.

 

[PurBee]

Figure out how they got in there, and theyre probably still using it as entrance/exit for food runs - so you can lure them out by their ‘door’ with a trap/food.

They can get through very small holes….we had a rat chew a 1.5 inch hole through wooden joists to get inside during winter. So mice can squeeze through much smaller gaps.

edit: i saw the rat - it was as thick as my calf! Couldnt believe its doorway was so small!

 

[Hanno Verian]

The ultrasonic devices might not help but they won't bother your dogs. They are set up to deter rodents, so unless you have pet hamsters/ gerbils you should be fine to use them.

Thanks I will look into it...

 

[Melody Grey]

Figure out how they got in there, and theyre probably still using it as entrance/exit for food runs - so you can lure them out by their ‘door’ with a trap/food.

They can get through very small holes….we had a rat chew a 1.5 inch hole through wooden joists to get inside during winter. So mice can squeeze through much smaller gaps.

edit: i saw the rat - it was as thick as my calf! Couldnt believe its doorway was so small!

Second this with finding their access point. Run traps along the wall where the mice will run (not randomly in the open). Chocolate is the best lure in my experience.

 

[scruffyponies]

If you can't get the blighter to come out, can you get bait into the space? I don't normally like using poison, but at least under the floor / in the walls there's no chance of any non-target beasties eating it.
Be warned, if they die in the walls there'll be a really funky smell for a few days, and usually some blue-bottles. Not good, but better than a proper mouse infestation.

 

[spotty_pony]

The ultrasonic devices won’t bother your dogs - I have one and the dogs have never even appeared to notice it. I am not sure it is very effective however as I have seen mice since and the only way I have got rid of them is with traps. If you can’t get to them, they must be coming in through somewhere outside maybe? You need to search for the tiniest of cracks and then place a trap near them.

 

[lynz88]

If you can't get the blighter to come out, can you get bait into the space? I don't normally like using poison, but at least under the floor / in the walls there's no chance of any non-target beasties eating it.
Be warned, if they die in the walls there'll be a really funky smell for a few days, and usually some blue-bottles. Not good, but better than a proper mouse infestation.

This is a GOD AWFUL smell so I personally would prefer to use traps. At least tthis way they can't eat the poison, run off somewhere else and die where you can't get at them. I remember as a kid we had a mouse die in the basement somewhere as we were trying to sell the house. Worst 2 weeks of my life. Years and years later I came home from holidays and as soon as I stepped into the flat I knew what smell I had come across....I messaged the flatties who said they didn't smell a thing (they must have been extremely plugged up!). Went searching the traps we had set about a month prior and sure enough.....when we got rid of it, one of my flatmates said "I didn't realize that was the smell of a dead mouse..." (ohh do they COULD smell it!!!). My only comment was: that was a freshly dead mouse. If you had of left it another 8-12 hours you wouldn't know what hut you it is so, so awful...!!!!

 

[Sossigpoker]

We recently had this. I bought a humane trap and used peanut butter as bait. I knew where they got in (an air vent put in for wood burner, not properly sealed around it). Once I got one , I released the mouse elsewhere and put a temporary seal around the vent. Once I heard more rustling , I opened it up and put the humane trap out again.
Kept repeating until I didn't hear any more rustling and then put a permanent seal around the vent.

They love peanut butter and on one occasion the trap was activated within 10 minutes of me putting it out!

 

[Gloi]

If you aren't sure where they are getting in and out of the skirtings putting talc down lets you track their routes.

 

[Hanno Verian]

Thanks for the advice, can anyone recommend a ultrasonic device, I've been looking on Amazon but there isn't one that leaps out at me. I have a suspicion that they are coming in under some decking, where we have bifold doors and getting into the external wall, we have really thick walls, and getting from there into the internal cavity wall.

I was considering cutting a hole into one of the internal walls to let me put a trap in covering the hole with a vent to make it look tidier.

 

[Hanno Verian]

If you aren't sure where they are getting in and out of the skirtings putting talc down lets you track their routes.

I see no evidence of them in the house.... I've got baited traps under a kitchen unit and in an attic, but they are sticking to one area... they may be eating the debris from a bird feeder that's outside