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Mouse Problem

Summary: The first step in resolving a mouse problem is to figure out where they are getting in and properly closing those holes. Don't do anything else until you have properly excluded the mice.

Diane; Clarksville, MD asks:

We recently moved into a house that was infested with mice in the attic. We did not know that there were mice in the attic, later we found that they had been using the basement ceiling as a "runway". We hired an exterminator to clean up the attic and the basement. We thought we were done when we started hearing noises again in the attic. We were told that there "stragglers" and just keep trapping them. So far we have trapped two.

We hired another roof inspector since the house inspector completely missed the infestation and we were losing confidence in our exterminator. He believes that the mice are digging into the mulch and going behind the brick facade and entering the attic. They can also enter the basement ceiling from this location. He suggests that we remove the mulch away from the exterior of the house and dig an area ten inches by ten inches, the length of the brick wall, and fill with concrete mixed with glass.


After many contractors and many differing opinions we are still not sure how to proceed. Some told us that they don't believe that the concrete idea is possible, but they will certainly take our money and pour the concrete. Others think that the mice are coming in underneath the cement steps since it appears that our walkway has buckled in places. There may be a hollow space underneath.

We are very confused and not sure hoe to proceed. Thanks.

Ask the Exterminator says:

Whoa! Too many suggestions from too many sources. Everyone slow down and let’s think clearly about what is happening here.
The very first rule in rodent control is figure out how the mice are getting inside and close those entryways. Remember that a mouse only needs a hole the size of a dime to squeeze through. As long as it can get its head through, the body will stretch out and follow. So, grab a good flashlight and mirror with an extension handle and start looking for openings. Look high and low. That’s what the mirror is for.

Do not use foam to seal holes. The mice will quickly chew through that stuff. Instead, use quick setting cement and hardware cloth. Any hardware store carries it and it is always stored next to the chicken wire. It comes in rolls and requires a tin snip to cut to size. Be sure to check spaces under the brick siding. Folding over a piece of the hardware cloth and stuffing it into those openings will keep rodents out.
Cut tall grass and weeds away from the foundation walls. Fill ground tunnels with pea gravel. The mice cannot dig through the stuff. Make sure mulch is not touching the brick siding. You should be able to see the foundation walls.
If the mice are finding a way inside under the steps you need only to go inside and look for an opening and signs of rodent activity along the inside wall, adjacent to the steps. Once you are sure you have closed up ALL holes you can begin to finish off the mice already inside the house.

You did not mention what they are eating inside the house. Pet food? Your food? Mice won’t venture far from their nests (15 to 25 feet max), so if you are seeing mice in different parts of the house you can assume there is more than one nest.

If the attic has insulation you may be looking at removing and replacing it. Mouse urine cannot be effectively removed once they have soiled the insulation. Plus, the insulation gives them lots of places to hide and hinders your trapping efforts.
Now, go and read how to properly pre-bait and trap for mice. You can do this by purchasing a dozen inexpensive snap traps. Read plus lots more articles at

Diane responds:

Hardware cloth

The exterminator put mesh over all the external pipes and vents. I did a detailed inspection of the basement from the top of the foundation to the ceiling and there were no holes in the wood behind the insulation, though the insulation had clearly been tunneled through. There was one huge gap (3"x6") between an air duct and the floor board, which did have many mouse droppings near it. Basically, the hole in the floor was cut too big for the duct. I sealed that with a screwed-down piece of sheet metal leaving a 1/4" gap.

We've only ever heard or seen mice in the attic. The attic has had multiple traps in it for several weeks now. Some are without bait, while others are baited with small pieces of potato chips or some of the poison bait our exterminator left. There is also an electronic trap in the attic and one in the garage. They are all mounted, as shown in your videos, perpendicular to the walls. Other than the first night I set them, when we caught the last mouse so far, none have been triggered and there have been no additional noises.

We think the last part of the puzzle is checking and closing off the bottom of the brick-front and filling in the holes the chipmunks dug along the foundation, based on the roof inspector's assessment. Thanks for the tip on the hardware cloth and pea gravel. I'm going to try that before the cement, since it sounds like it will do the job and cost 100 times less. Also thanks for the advice on leaving open foundation below the brick. Our old house in NJ didn't have that, so I assumed it was normal.

Again, thanks for your help.


02 Sep 2010, 07:19
We've noticed strange things in our kitchen over the past few weeks. In our pantry closet a bag of those Lipton Sidedishes had a hole ripped in it and so did a brownie mix that was in a bag. So we cleaned out the pantry real good and put new contact paper down and put the stuff that was in plastic bags into those thick plastic ice cream containers that have a lid and haven't noticed anything there since. Soon after we noticed that the plastic garbage bag in the garbage can under our sink was chewed up around the edges. I noticed this when I was changing the bag for the weekly garbage. I put a new plastic bag in and this morning I looked and it was chewed up around the edges again (it's one of this garbage can with a lid that pops up) so whatever it is doesn't get inside, but chews the part of the bag that sticks over the edge. The other odd thing is that the paper towels that were under the sink still with the plastic wrapper on were also chewed on. We have noticed a few tiny black droppings on the kitchen table and on the sink counter. We keep the kitchen clean and recently painted the pantry area and had to move everything out and saw nothing. We mop the floor every week and never see anything. We cleaned the counter real good and have not seen anything on the counter since, but now whatever it is, is chewing up the plastic bag around our garage can and chewing on the paper towels, this happened 2 days in a row. Anything that could be edible in the kitchen we have either moved into closed cupboards or sealed and placed in zip lock bags so that it is not accessible. We did see a black dropping by the bread box, but since it's sealed, nothing got into it. It's getting frustrating. We have cleaned the entire kitchen and made the food inaccessible and have not seen whatever it is, it appears to act at night because we notice things in the morning when we come downstairs. It appears to come in at night and leave since we have not seen it. The stove is next to the sink and we use it quite a bit and it gets hot so we know it's not behind there. It's really annoying since we try to cut off any source of food it can have and now it's chewing up the edges of our garbage bag and attacking the extra paper towels (which we have since moved to the pantry on the top shelf) It's just odd because we have done everything to keep the kitchen clean and cut off any source of food and it still appears to come in at night and leave. Nothing has been noticed in any other part of the house. Please help. Thank you.
Ask the Exterminator
02 Sep 2010, 08:31
It sounds like a mouse is in your house. The article above and the two suggested links mentioned in the article will provide all the steps you must take to capture your visitor.
15 Apr 2011, 09:41
I live in an apartment and the mice are coming though the front door. How can I stop that?
Ask the Exterminator
15 Apr 2011, 09:47
Mice can get through holes as small as a dime. Sounds like you need to replace the threshold of the door.
18 Dec 2011, 18:27
can a mouse chew through a 2x4
21 Dec 2011, 14:36
I have had problems with mice in TWO of the houses I've lived in, and both of them had vinyl siding. The vinyl corners that are used provide a direct path to the soffet area where they can get in. I found this website:

An exterminator I hired a while back looked at my vinyl corners and knew instantly that it was the means of egress. He had some sort of stainless steel wool and black foam mixture that he used to block up the vinyl corners. Then he spent several months trapping and poisoning until there was no more sign. If you have an elaborate problem, trapping might be like peeing in the ocean. My infestation was to the point that he wanted to hit them with everything. After 5 or 6 months of regularly changing traps and bait boxes, there were no more signs of mice.

OF course, the downside to poisoning, is that there will be mouse carcasses rotting in your attic. It shouldn't really be a problem if you don't poke your head up there too often. The smell will go away once the carcass dehydrates and becomes part of the insulation. The only time I smelled anything foul inside the house, was when one mouse decided to die right on top of one of my recessed canned my walk-in closet! P.U.
13 Apr 2012, 16:08
I live in an apt and have mice---I have seemed them 6x times in the last 7months. I have not found droppings, nor gnawed/ chewed boxes, bags, groceries -- but they are here. I have had at least 3x exterminator visits; moved the fridge and stove and no droppings nor holes. Not sure of their entry point, nor the location of their food source. I purchased glue traps (38 over 7 months), poison, peppermint oil, steel wool, ultrasonic repellents --- and nothing. Lately the mouse/mice have been more noisy and visible--in 1 evening 3 sighthings. Any recommendations?
13 Apr 2012, 17:13

I have always had the best luck with the standard old mouse trap. Just the old wooden "Victor" brand trap and peanut butter. Make sure to use the chunky peanut butter and wedge a peanut or two into the holes in the trap so the mouse has to work at it. Otherwise, they often lick the trap clean without setting it off. Good Luck!
Ask the Exterminator
14 Apr 2012, 07:48
Mice stay fairly close to their nests their entire lives. Focus your trapping efforts near the spot(s) where you have actually seen live mice. The snap traps will only work if placed properly. They must be toching the wall and must be positioned perpendicular to the wall. You don't need to bait the trap with food. You can use a tiny piece of cotton. Mice are always looking for fresh nesting materials.
18 Dec 2012, 18:34
We have a loft conversion which is our bedroom. We still have some loft spaces for storage around the side of the bedroom. Recently, in the loft spaces, I have been hiding presents for the children for Christmas. Tonight when I went up there to get some presents out, I noticed that a huge chocolate coin I had bought had been nibbled out quite a bit(there was quite a chunk missing) and in the plastic bag there was lots of finely chewed foil, which had surrounded the coin.

Can you tell me what pest it would be doing this in the loft space, and what we should do? Obviously, I have moved all edible things from there now.

28 Jul 2013, 00:29
I'm tired of throwing out brand new bags of chips because of a small mouse in the bag. Is it Ok to eat 3/4 of the bag?
Ask the Exterminator
29 Jul 2013, 21:20
I wouldn't eat it. Use a black light and you will see mouse urine all over the bag.
22 Aug 2013, 23:19
"He suggests that we remove the mulch away from the exterior of the house and dig an area ten inches by ten inches, the length of the brick wall, and fill with concrete mixed with glass."

This sounds like a potential disaster. Any attempt to block the weep holes must also allow water to drain out, otherwise it might build up and destroy the framing of the house. The Exterminator's suggestion of hardware cloth and cement will probably allow enough drainage if it's not packed too tightly. They also make wicks especially for this purpose, as well as vented metal caps for certain sized holes. Mouse invasions (as much as I like them individually) are bad, but moisture damage, rot and mold are even worse.
30 Oct 2013, 10:11
I hear a scratching sound in the ceiling between 1st floor and second. late at night and even if I have the TV on it still there. I also noticed some stains on the ceiling approx. 2"x6". now I have traps in the basement and seems that there are no sign of mice in the basement anymore. I hear it at the same corner of the room and hear it run across the room. but not every night only once in while months can go by and nothing. its driving me crazy I can figure it out its been like 4-5 years.
please help me with this mystery..TY
22 Nov 2014, 12:12
If we have evidence of mice in one particular area in the basement, does that mean that is where their entry point is likely to be? Or might it be far away, but they travel to this particular area because they like it there? We are not sure where to look for openings.
02 Jan 2015, 16:25
We recently moved in to a house in London and after a short while we notice scratching from under the floor and smell of mice, it was then a matter of time till they started coming up to different parts of the house and we had to use glue trap as they would not come near any poison or snap traps, problem is worst in winter.

I'm thinking of bying a snake and let it loose thrugh the4 air vent, I just dont want them under the house any more.
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