Mouse in the House
October 22, 2006 2:50 AM   Subscribe

We definitely have mice in our garage. I'm worried they may be in our attic or our house interior and I need some advice.

So I'll break it down into a few pieces

* How do you estimate the size of an infestation? I've put sticky traps and poison all over our garage and in key parts inside the house. We've caught a few in the garage, none inside the house. I am interesting in figuring out how many mice we started with, and whether that number is decreasing.

* With the traps it's straightforward, fine one with a mouse, throw it away. With the poison, I'll find one that's been well nibbled (they're blocks of poison) but I've yet to find a dead mouse (not in a trap). Assuming that the poison is lethal in the doses that they're eating, where are they? Did they go outside to die, or, more likely, are they deep under some stuff, in a hole, in the attic, etc? Are traps alone effective enough, especially since I now need to worry about mice rotting away in various places?

* At what point do you consider calling in a professional? There is no evidence that they are getting into our food, the dogs food, etc. There has been a definite increase in activity in the garage, I found, for example, that a bag of ant poison had been eaten through, of all things, and a nest made inside. I suspect they are coming in because it's starting to get colder and wetter outside.

* Also, we live in a new house built in what was an empty field 6 months ago. So these mice are probably "field mice" right, and so this is the first wave that is moving indoors. Does that change anything? When we first moved in we had spiders EVERYWHERE but the numbers have died down since we remove them whenever we find them.
posted by RustyBrooks to Home & Garden (14 answers total) 2 users marked this as a favorite
Are there any points which could be obvious ingress points for the mice? A pest controller once told me that a hole you can fit a biro into is big enough for mice to get in. He advised (as well as the usual traps / poison) stuffing any holes with coarse wire wool, as the mice apparently hate the texture of the stuff.

Unfortunately this isn't a permanent solution - as I found when I turned on the kitchen light once as saw one of the little bastards on a worktop. It shot to the back of the sink, danced comically around on the wire wool at the back for a few seconds, before disappearing down a hole in it.

After that, I renewed all the wire wool, and didn't see another mouse (or evidence of one) in the rest of the time we lived in that place.

Of course, now I've re-read your post and realised that your place is a new-build, so I guess it's unlikely that there are obvious holes. Hmm...
posted by coach_mcguirk at 3:13 AM on October 22, 2006

I found traps and poison to be a complete waste of time. What worked for me was the wire wool treatment described by coach_mcguirk. I stuffed every hole with as much of the stuff as I could get in and never saw another mouse - this was after weeks of waiting for other methods to make any difference.
posted by teleskiving at 3:32 AM on October 22, 2006

We get mice. The only time I've seen them inside is where there's been an easily available food source for them to get at. Once we removed whatever it was they were eating they stopped showing up. We keep our food in high cupboards, and as much of it as possible in jars and boxes. We have a closed bin which stands well away from any easy means of access. I daresay if we were a bit more scrupulous about cleaning we'd discourage them further, but so long as they're not near the food or rubbish, I don't mind them that much.

I still see signs of them from time to time, but I accept it as part of living in the countryside. My father has failed to get rid of his mice with fifteen years of trying. You're never going to seal the house up well enough to keep them out completely. New-build houses are probably actually even worse, with all the cavities you get with drylined walls and suchlike. And even if you stop seeing them about, that doesn't mean they're not there.

If you actually did manage to nail the entire population this year, by poison or traps, there'd be a new batch back next year. So my recommendation is to manage the problem by keeping them out of your food and bins and so on.

We have cats, too, and they seem to help keep the numbers down. You definitely see results with cats...
posted by tomsk at 3:52 AM on October 22, 2006

Did you just turn your heat on? Around this time of year (less so in Texas and other warmer states), mice come inside because it's warmer.

As said before, if you can plug all ingresses, you'll remove the problem, except that mice don't need much to get in. I had mice in a storage unit that I thought was pretty well-sealed. Traps work. Poisons typically work, but more likely the mice are going to wherever they're nesting to die. One of the major features of rodent poison is that it doesn't kill right away. Rodents have enough memory/brain so that if they see a dead compatriot near something it ate it will avoid the poison.

By the way, one of the more common rodent poisons is warfarin sodium which is used to treat hypercoagulation in humans. Mice that eat too much die of internal bleeding. Don't combine this with snap traps unless you want a bloody mess.
posted by plinth at 5:19 AM on October 22, 2006

There are country mice, and there are city mice. Field mice that just came in out of the cold are easy to trap. Domesticated mice will not fall for poison unless they are babies, so put that near where you think the nest may be. For the street-smart mice, replace traps with fresh ones frequently, change up the bait, move the traps around and arrange with obstacles placed in their presumed path. Also place traps at bottlenecks where they might run in a panic when you turn on the lights at night.

Inaccessable dead mice might be accompanied by a mini infestation of flies. The maggots will eat the mouse, once there are no corpses around the flies will die off.
posted by StickyCarpet at 5:29 AM on October 22, 2006

There's an old saw about if you see one mouse you've got ten, so there's a good chance they're in the house now.

We've got four cats and it's not enough. Reusable snap traps are not nice but work - brand 'The Better Mousetrap' works for us. The cats told us we had some about a month ago, took out a dozen in a week, two generations. It works to keep putting the trap in the same place as you've caught one, since mice from the same nest seem to take the same path.

I haven't liked poison since living in a trailer where a mouse died in the wall and stunk for months.
posted by dragonsi55 at 6:14 AM on October 22, 2006

Reusable traps? Yuck. I like to toss both the trap and mouse together, and most of the traps are cheap enough to do this. Peanut butter makes great bait. I feed our mice only the organic stuff.
posted by caddis at 6:36 AM on October 22, 2006

1) You can't guess the size of the infestation. It all depends on the ones you haven't caught. If it's contains a pregnant mother or mice of breeding age, you're got trouble. If it's the same number of mice but they're young/old, you've got much less trouble.

2) Mouse poison generally makes them thirsty so they'll typically leave the house to find water and die. The few that burrow somewhere very deep and you're more ilkley to smell them than find them.

3) Call a professional now. Not sure how long you've had the poison/traps out, but if you've caught more than one in a brief time, you've got mouse problems. And if you haven't figured out where they're getting in, you're going to keep having them. A professional can help advise you about where they're getting in and what they're after.

I'll vouch for the steel wool treatment. And yes, a mouse can get in any hole the size of your little finger. Or if they can make a hole that big.

They might not only be seeking food, they might be seeking nesting material. Elevate or recycle your piles newspaper, cardboard boxes, spare blankets/towels/rags and anything else that could be chewed up for nests.

But, if they got into your brand new house, you may just have to live with them. Your house isn't getting any fewer holes...
posted by Ookseer at 6:56 AM on October 22, 2006

Response by poster: OK, lots of good info. For some clarification, these *are* country mice. The area we live in was pasture until development spread out here. If you go 2 blocks from our house it's horse breeders and grazing cattle. So I think these are almost certainly mice that usually live outside.

There are no obvious holes. They can probably get into and out of our garage easy enough because they don't really attempt to make garages impenetrable here. I don't know if mice can climb brick or not, but if they can, then they could probably get in around the eaves.

I suspect that if they're in the house, we brought them in ourselves. I had some boxes in the garage that I brought in recently, before i realized there were mice in the garage.

I've caught 2 mice in the garage. One of them was obviously on his way back from eating some poison because he had a chunk of the green stuff on him.

If they stay in the garage I don't have too much of a problem with that. I'm not sqeamish about them and I'd prefer to not kill them but I can't have them in my house. We don't have cats, but we do have dogs, which would kill a mouse if they could - indoors though I don't think they have much chance. They've caught some outdoors though, in the open.
posted by RustyBrooks at 8:39 AM on October 22, 2006

Our property had a really bad rat and mouse infestation when we moved in (next door to a large field, yard covered in ivy; during the walk-through, a rat scampered through an open patio door in plain view). We went through with the sale, we thought surely our two cats and two terriers would quickly take care of the pest problem.

The pets couldn't be bothered. In their view, rodents do not come out of Royal Canin bags.

We called in an exterminator who set up some traps but I wasn't all that impressed with the results; rats were regularly capering in the carport and I kept finding mice in the kitchen. We didn't want to use poisons as I was afraid our dog or cats would eat a poisoned mouse. We fired the exterminator and started setting up our own traps: glue traps baited with dog kibble seemed to be the best combo (while mice were easy to catch with snap traps, we never caught a single rat with one).

We reached a uneasy d├ętente where the rodents were no longer actively entering the rooms of house but we could hear them in the walls (!) so we started locating and blocking all possible entry points with metal flashing or wire mesh. We discovered a common route in was adjacent to pipes entering/exiting the house, spaces you wouldn't expect a wine cork could fit were easily accommodating 8" rats. We hit all the ivy with Roundup and created a 2' dead zone between the house and the yard. All of these helped a little but we still had rodents.

The final solution turned out to be the Damned Opie, a semi-feral obsessive compulsive orange tabby who left a minimum of five dead rodents on our doorstep every day for six months after we adopted him. We eventually found his trophy stash in our shed: nearly 700 tails (which represented the rodents he didnt leave on our doorstep as those tributes all had their tails). I'm still agog over just how many rodents were out there, given that while we did see one or two fairly frequently, the cat managed to kill well over a thousand in less than a year.
posted by jamaro at 9:06 AM on October 22, 2006 [3 favorites]

The foam insulation in a can is great for filling holes and blocking the mice. Take some wire mesh, shove it in any hole you can stick a pencil in, then take the can of foam and spray some foam in there too. When it hardens (about an hour later) you'll have wire mesh encased in a plastic material that will give mice pause to get through. It should keep them at bay for awhile. Meanwhile, be sure to keep checking your traps / poison on a regular basis.

That all said, when we first got to this house the mice problem was really bad. My uncle who lives on the farm gave us some have-to-have-a-license-to-get-it grade mouse poison that did the trick.
posted by maxpower at 2:36 PM on October 22, 2006 [1 favorite]

Response by poster: Holy crap, a mouse walked off with one of the sticky traps. I found it about 8 feet away. It looks like he got one paw stuck in it and dragged it behind him, and then escaped when he got to the washing machine, which the trap got caught on.
posted by RustyBrooks at 4:06 PM on October 22, 2006

I'll second the peanut butter mention. We tried that before resorting to poison, and it worked just fine in the snap-traps.
posted by candyland at 8:39 PM on October 22, 2006

Another good thing with cats (cats that are mousers, not all of them are, but the owner will know) is that their behaviour in the garage can tip you off as to the level of problem - it's a rude measurement, to be sure, but if there are mice the cat will be very happy to be there.

I also second high, contained food. It makes sense anyway, and, while we're not rural, it greatly decreased the number of wanderers we found in the pantry - as did training my step-father not to chase stray cats off the lawn.
posted by Sparx at 11:52 PM on October 22, 2006

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