How are these sucker getting in?

[TractorGuy]

I have a package unit with supply and return ducts connected to it and running up into the attic through a boxed in structure at that end of the house. Some years back a big ol rat got in there and chewed through the duct insulation and chewed a hole in the supply duct. He died from ingesting the fiberglass insulation and my whole house wreaked of dead rat. I finally removed the metal shroud between the unit and the duct structure and found him laying on top of the duct. He had dug under the metal shroud to get in so I buried some hardware cloth on both sides to prevent future invasions.

 

[dmccarty]

Mice are incredibly resourceful, and can flatten themselves to a point that seems biologically impossible in order to get in through the smallest cracks and holes.

I was thinking maybe you had return air plenums boxed in by your walls that extended up to the attic and were not appropriately sealed. Mice don't seem to have a problem going up a brick wall into the attic.

Years ago, mice were getting into our attic which was driving me nuts because I had built the house so critters could not get into the attic! :shocked: I could not figure out how they were climbing up a brick wall and then getting into the attic.....

Until I saw a black snake climbing the brick wall. :shocked: It was obvious the snake was following the scent of the mice even though it was straight up a brick wall! What the snake showed me was that the mice were following the Coax cable up the wall which then went into the attic. There was a small hole the coax went through in the soffet to get into the attic. The mice were able to squeeze through that very small opening to get into the attic. :shocked: I would hear them when it was cold at night digging into the ceiling drywall! Course I found mouse poo all over the attic as well. I put some steel wool in the little, itty bitty hole and that stopped them. PITA.

My dad said he saw a mouse climbing into the attic from our front porch. I am hoping he just saw a lizard because I have never seen the mice, much less during the day.

Later,
Dan

 

[stephenh]

Mice can flatten themselves to just about the thickness of the skull, so any small crevice is a go for them.

 

[Cougsfan]

Moth balls and mint, as Kentucky suggested are a good solution, along with a unspoiled, unpampered outdoor cat.

 

[ponytug]

Yup, they are resourceful little animals, but yuck! Anything around a quarter of an inch and up is fair game as an entry point for mice. So, yes, tiny cracks and holes need to be filled in. Around here, they carry hantavirus, (map), with a one in three to one in twenty fatality rate, so my tolerance level is zero. I use P100 respirators anytime I have to go in an area that has rodent droppings.

If you are getting them in your return air duct, I would bet on a make up air vent with screening that is too large or not sealing, or a gap in the duct near where the intake is in the house with the mice crawling between the duct itself and the house side vent.

FWIW: I use "Fireblock" foam on all of the plumbing feed throughs after I found mice getting to the attic via the bathtub drain cutout and thence up an interior wall to the attic. I also found some coming into the crawl space along a furnace drain line. The hole didn't look like it had a quarter inch gap, but once it was sealed, the mice quit getting in. If the hole is any size, I use 1/8" galvanized screening first to keep them from gnawing through, and then fire block.

All the best,

Peter

 

[Richard]

A couple of hungry cats will look after the mouse, rat, tree rat and chipmunk problems.

...and sometimes a rabbit problem even if you didn't know you had a rabbit problem. Ask me how I know once I walked into the basement bathroom (fully finished with walk in shower). On TWO occasions....

1. Walk into door, cat is sitting with his back to me. I interrupted him. He turns around like "what's up dude???" He was eating the shoulder meat of a young rabbit that was missing its head. No traffic out here so I'm presuming the cat offed the head but, don't know that.

2. Other time, same cat had rabbit cornered in the shower. The shower has full glass door, rabbit was inside trying to escape the cat who was playing "cat & rabbit". Rabbit would dash, panic, turn and dash again, only to keep hitting the tile walls. It was a bloody mess in there (as in it was a mess that was bloody)

Two years or so ago, cat had what appeared to be a piece of rice stuck to his mouth. Curious, I ent to move it and it didn't move....he flinched. Turns out it was a canine tooth that was coming out and pointed forward. Got him to the vet and the vet pulled all of his canine teeth (all four).

Ever since the tooth extraction, he's converted to an indoor only cat (has a door to go outside but rarely does) and his days of dragging back mice & rabbits seem to be over.

 

[oosik]

My house sits on solid bedrock. I have an unfinished basement which is used for storage. I kept the basement heated( to around 65F) until I noticed mouse droppings. Now it's unheated and no mice.

Cougsfan & Looking4new have the solution I prefer. Barn cats - several of them. I live in a very rural location and have an unlimited supply of mice and chipmunks. Hard to determine which of the two I despise most. Open hoods on my vehicles will keep most out of those areas. Plus a generous supply of Peppermint oil soaked cotton in my truck. Moth balls may help also but I MUCH prefer the smell of Peppermint in my truck.

Unfortunately, my last barn cat became a meal for either an owl or coyote. So..... I'm, again, looking for replacements.

If you live "rural" then you must realize that rodent problems are an on-going concern. You will not be able to eliminate. You can, however, control to an acceptable level.

 

[PuffyC]

We used to get mice in the house all the time and I never could figure out why. Then one day I notice the cat would go outside, catch a mouse, then secretly bring it in the house alive so she could play with it (through the doggie door). Moral of the story: cats don't always improve a mouse problem. The best mouse/rat killing machine I've ever seen? A miniature dachshund. We have one and she puts most cats to shame. She's only 8 pounds (weighs less than the cat) and is utterly relentless in not only telling us if there's a rodent around, but she won't stop until it's dead. She even caught and killed a squirrel once who got a little too brave. On a side note, here's a story about a group of people who go rat hunting in NYC using a pack of small dogs like that, and some of those city-fed, post-lockdown rats are big enough to fight back:

Meet the rat hunters: Dogs join the fight against NYC’s rodent problem

 

[ruffdog]

Our Bichon Frise dog is like that too^^^^^

 

[Frankenkubota]

Mice are incredibly resourceful, and can flatten themselves to a point that seems biologically impossible in order to get in through the smallest cracks and holes.

I've heard if they can get their heads in, they can get the rest in.